package main

import (
	"crypto/rand"
	"crypto/sha256"
	"crypto/tls"
	"database/sql"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net"
	"net/http"
	"strconv"
	"net/smtp"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"sync"
	"time"

	"golang.org/x/crypto/bcrypt"
	"gopkg.in/yaml.v3"
	_ "github.com/mattn/go-sqlite3"
)

var passwordRE = regexp.MustCompile(`^[A-Za-z0-9]+$`)

// ============================================================
// Config
// ============================================================

type AdminUser struct {
	Username     string `yaml:"username"`
	PasswordHash string `yaml:"password_hash"`
}

type Config struct {
	Port  int          `yaml:"port"`
	Admin []AdminUser  `yaml:"admin"`
	mu    sync.Mutex
	path  string
}

func LoadConfig(dataDir string) (*Config, error) {
	path := filepath.Join(dataDir, "config.yml")
	cfg := &Config{
		Port:  47732,
		Admin: nil,
		path:  path,
	}
	data, err := os.ReadFile(path)
	if err == nil {
		if err := yaml.Unmarshal(data, cfg); err != nil {
			return nil, fmt.Errorf("parse config: %w", err)
		}
	}
	return cfg, nil
}

func (c *Config) Save() error {
	c.mu.Lock()
	defer c.mu.Unlock()
	data, err := yaml.Marshal(c)
	if err != nil {
		return err
	}
	return os.WriteFile(c.path, data, 0640)
}

func (c *Config) SetAdmin(username, password string) error {
	c.mu.Lock()
	defer c.mu.Unlock()
	hash, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	if err != nil {
		return err
	}
	user := AdminUser{Username: username, PasswordHash: string(hash)}
	// Replace existing or append.
	for i, u := range c.Admin {
		if u.Username == username {
			c.Admin[i] = user
			return c.saveLocked()
		}
	}
	c.Admin = append(c.Admin, user)
	return c.saveLocked()
}

func (c *Config) CheckAdmin(username, password string) bool {
	c.mu.Lock()
	defer c.mu.Unlock()
	for _, u := range c.Admin {
		if u.Username == username {
			if bcrypt.CompareHashAndPassword([]byte(u.PasswordHash), []byte(password)) == nil {
				return true
			}
		}
	}
	return false
}

func (c *Config) saveLocked() error {
	data, err := yaml.Marshal(c)
	if err != nil {
		return err
	}
	return os.WriteFile(c.path, data, 0640)
}

// ============================================================
// Token
// ============================================================

type tokenStore struct {
	mu     sync.Mutex
	tokens map[string]time.Time
}

func newTokenStore() *tokenStore {
	return &tokenStore{tokens: make(map[string]time.Time)}
}

func (ts *tokenStore) Create() string {
	ts.mu.Lock()
	defer ts.mu.Unlock()
	b := make([]byte, 16)
	rand.Read(b)
	tok := hex.EncodeToString(b)
	ts.tokens[tok] = time.Now().Add(24 * time.Hour)
	return tok
}

func (ts *tokenStore) Check(tok string) bool {
	ts.mu.Lock()
	defer ts.mu.Unlock()
	exp, ok := ts.tokens[tok]
	if !ok {
		return false
	}
	if time.Now().After(exp) {
		delete(ts.tokens, tok)
		return false
	}
	return true
}

// userTokenStore embeds tokenStore but also tracks the user_id per token.
type userTokenStore struct {
	mu     sync.Mutex
	tokens map[string]userTokenEntry
}

type userTokenEntry struct {
	UserID    string
	ExpiresAt time.Time
}

func newUserTokenStore() *userTokenStore {
	return &userTokenStore{tokens: make(map[string]userTokenEntry)}
}

func (uts *userTokenStore) Create(userID string) string {
	uts.mu.Lock()
	defer uts.mu.Unlock()
	b := make([]byte, 16)
	rand.Read(b)
	tok := hex.EncodeToString(b)
	uts.tokens[tok] = userTokenEntry{UserID: userID, ExpiresAt: time.Now().Add(24 * time.Hour)}
	return tok
}

func (uts *userTokenStore) Check(tok string) (string, bool) {
	uts.mu.Lock()
	defer uts.mu.Unlock()
	entry, ok := uts.tokens[tok]
	if !ok {
		return "", false
	}
	if time.Now().After(entry.ExpiresAt) {
		delete(uts.tokens, tok)
		return "", false
	}
	return entry.UserID, true
}

// ============================================================
// Server DB schema
// ============================================================

const serverSchema = `
CREATE TABLE IF NOT EXISTS server_devices (
    id TEXT PRIMARY KEY,
    name TEXT NOT NULL,
    api_key TEXT NOT NULL UNIQUE,
    token_hash TEXT,
    token_prefix TEXT,
    token_suffix TEXT,
    user_id TEXT,
    client_version TEXT,
    last_ip TEXT,
    last_seen TEXT,
    revoked_at TEXT,
    created_at TEXT NOT NULL
);

CREATE TABLE IF NOT EXISTS server_revisions (
    rev INTEGER PRIMARY KEY AUTOINCREMENT,
    op_id TEXT NOT NULL,
    device_id TEXT NOT NULL,
    created_at TEXT NOT NULL DEFAULT (datetime('now'))
);

CREATE TABLE IF NOT EXISTS server_ops (
    op_id TEXT PRIMARY KEY,
    server_sequence INTEGER,
    device_id TEXT NOT NULL,
    entity_type TEXT NOT NULL,
    entity_id TEXT NOT NULL,
    op_type TEXT NOT NULL,
    payload_json TEXT NOT NULL,
    idempotency_key TEXT,
    client_sequence INTEGER DEFAULT 0,
    last_seen_server_seq INTEGER DEFAULT 0,
    created_at TEXT NOT NULL,
    pushed_at TEXT NOT NULL DEFAULT (datetime('now'))
);

CREATE TABLE IF NOT EXISTS server_tombstones (
    entity_type TEXT NOT NULL,
    entity_id TEXT NOT NULL,
    op_id TEXT NOT NULL,
    deleted_at TEXT NOT NULL,
    PRIMARY KEY (entity_type, entity_id)
);

CREATE TABLE IF NOT EXISTS server_idempotency_keys (
    idempotency_key TEXT PRIMARY KEY,
    response_json TEXT NOT NULL,
    created_at TEXT NOT NULL
);

CREATE TABLE IF NOT EXISTS server_blobs (
    sha256 TEXT PRIMARY KEY,
    size INTEGER NOT NULL,
    created_at TEXT NOT NULL
);

CREATE TABLE IF NOT EXISTS server_smtp_config (
    key TEXT PRIMARY KEY,
    value TEXT NOT NULL
);

CREATE TABLE IF NOT EXISTS server_users (
    id TEXT PRIMARY KEY,
    username TEXT NOT NULL UNIQUE,
    email TEXT NOT NULL UNIQUE,
    password_hash TEXT NOT NULL,
    confirmed INTEGER NOT NULL DEFAULT 0,
    blocked INTEGER NOT NULL DEFAULT 0,
    last_seen TEXT,
    created_at TEXT NOT NULL
);

CREATE TABLE IF NOT EXISTS server_email_tokens (
    token TEXT PRIMARY KEY,
    user_id TEXT NOT NULL,
    purpose TEXT NOT NULL,
    expires_at TEXT NOT NULL,
    created_at TEXT NOT NULL
);

CREATE TABLE IF NOT EXISTS server_user_devices (
    user_id TEXT NOT NULL,
    device_id TEXT NOT NULL,
    PRIMARY KEY (user_id, device_id)
);

CREATE TABLE IF NOT EXISTS server_audit_log (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    event_type TEXT NOT NULL,
    user_id TEXT,
    device_id TEXT,
    ip TEXT,
    message TEXT,
    created_at TEXT NOT NULL DEFAULT (datetime('now'))
);
`

// ============================================================
// Server
// ============================================================

type pairRateLimit struct {
	mu       sync.Mutex
	attempts map[string]int
}

func (p *pairRateLimit) allow(ip string) bool {
	p.mu.Lock()
	defer p.mu.Unlock()
	if p.attempts == nil {
		p.attempts = make(map[string]int)
	}
	p.attempts[ip]++
	return p.attempts[ip] <= 5
}

func (p *pairRateLimit) reset(ip string) {
	p.mu.Lock()
	defer p.mu.Unlock()
	delete(p.attempts, ip)
}

type Server struct {
	db         *sql.DB
	cfg        *Config
	tokens     *tokenStore
	userTokens *userTokenStore
	blobsDir   string
	mux        *http.ServeMux
	pairLimit  *pairRateLimit
}

func (s *Server) auditLog(eventType, userID, deviceID, ip, msg string) {
	s.db.Exec("INSERT INTO server_audit_log (event_type, user_id, device_id, ip, message, created_at) VALUES (?, ?, ?, ?, ?, ?)",
		eventType, userID, deviceID, ip, msg, time.Now().UTC().Format(time.RFC3339))
}

func NewServer(dbPath, dataDir string, cfg *Config) (*Server, error) {
	db, err := sql.Open("sqlite3", fmt.Sprintf("file:%s?mode=rwc", dbPath))
	if err != nil {
		return nil, fmt.Errorf("open db: %w", err)
	}
	db.SetMaxOpenConns(1)

	// Run schema.
	for _, stmt := range strings.Split(serverSchema, ";") {
		stmt = strings.TrimSpace(stmt)
		if stmt == "" {
			continue
		}
		if _, err := db.Exec(stmt); err != nil {
			db.Close()
			return nil, fmt.Errorf("schema: %w", err)
		}
	}
	// Migrations for older databases.
	db.Exec("ALTER TABLE server_users ADD COLUMN blocked INTEGER NOT NULL DEFAULT 0")
	db.Exec("ALTER TABLE server_users ADD COLUMN last_seen TEXT")
	db.Exec("ALTER TABLE server_devices ADD COLUMN token_hash TEXT")
	db.Exec("ALTER TABLE server_devices ADD COLUMN token_prefix TEXT")
	db.Exec("ALTER TABLE server_devices ADD COLUMN token_suffix TEXT")
	db.Exec("ALTER TABLE server_devices ADD COLUMN user_id TEXT")
	db.Exec("ALTER TABLE server_devices ADD COLUMN client_version TEXT")
	db.Exec("ALTER TABLE server_devices ADD COLUMN last_ip TEXT")
	db.Exec("ALTER TABLE server_devices ADD COLUMN revoked_at TEXT")

	// Migration: add server_sequence and tombstones.
	db.Exec("ALTER TABLE server_ops ADD COLUMN server_sequence INTEGER")
	db.Exec("CREATE INDEX IF NOT EXISTS idx_server_ops_sequence ON server_ops(server_sequence)")
	db.Exec("CREATE INDEX IF NOT EXISTS idx_server_ops_entity ON server_ops(entity_type, entity_id)")
	db.Exec(`CREATE TABLE IF NOT EXISTS server_tombstones (
		entity_type TEXT NOT NULL,
		entity_id TEXT NOT NULL,
		op_id TEXT NOT NULL,
		deleted_at TEXT NOT NULL,
		PRIMARY KEY (entity_type, entity_id)
	)`)
	db.Exec("CREATE INDEX IF NOT EXISTS idx_server_ops_sequence ON server_ops(server_sequence)")
	db.Exec("CREATE INDEX IF NOT EXISTS idx_server_ops_entity ON server_ops(entity_type, entity_id)")
	db.Exec(`CREATE TABLE IF NOT EXISTS server_idempotency_keys (
		idempotency_key TEXT PRIMARY KEY,
		response_json TEXT NOT NULL,
		created_at TEXT NOT NULL
	)`)
	db.Exec(`ALTER TABLE server_ops ADD COLUMN idempotency_key TEXT`)
	db.Exec(`ALTER TABLE server_ops ADD COLUMN client_sequence INTEGER DEFAULT 0`)
	db.Exec(`ALTER TABLE server_ops ADD COLUMN last_seen_server_seq INTEGER DEFAULT 0`)

	blobsDir := filepath.Join(dataDir, "blobs")
	if err := os.MkdirAll(blobsDir, 0750); err != nil {
		db.Close()
		return nil, err
	}

	s := &Server{
		db:         db,
		cfg:        cfg,
		tokens:     newTokenStore(),
		userTokens: newUserTokenStore(),
		blobsDir:   blobsDir,
		pairLimit:  &pairRateLimit{},
	}
	s.mux = s.routes()
	return s, nil
}

func (s *Server) Close() error {
	return s.db.Close()
}

func (s *Server) ListenAndServe(addr string) error {
	return http.ListenAndServe(addr, s.mux)
}

// ============================================================
// Routes
// ============================================================

func (s *Server) routes() *http.ServeMux {
	mux := http.NewServeMux()
	mux.HandleFunc("/api/v1/health", s.handleHealth)
	mux.HandleFunc("/api/v1/device/register", s.handleDeviceRegister)
	mux.HandleFunc("/api/v1/sync/push", s.handleSyncPush)
	mux.HandleFunc("/api/v1/sync/pull", s.handleSyncPull)
	mux.HandleFunc("/api/v1/blobs/", s.handleBlobs)
	mux.HandleFunc("/api/client/pair", s.handleClientPair)
	mux.HandleFunc("/api/auth/test", s.handleAuthTest)
	mux.HandleFunc("/api/client/revoke-current", s.handleClientRevoke)
	mux.HandleFunc("/api/client/me", s.handleClientMe)
	mux.HandleFunc("/api/client/revoke-device", s.handleClientRevokeDevice)
	mux.HandleFunc("/api/v1/auth/register", s.handleRegister)
	mux.HandleFunc("/api/v1/auth/confirm", s.handleConfirm)
	mux.HandleFunc("/api/v1/auth/login", s.handleUserLogin)
	mux.HandleFunc("/api/v1/auth/forgot", s.handleForgot)
	mux.HandleFunc("/api/v1/auth/reset", s.handleReset)
	mux.HandleFunc("/forgot", s.handleUserWebForgot)
	mux.HandleFunc("/reset", s.handleUserWebReset)
	mux.HandleFunc("/api/v1/user/devices", s.handleUserDevices)
	mux.HandleFunc("/register", s.handleUserWebRegister)
	mux.HandleFunc("/login", s.handleUserWebLogin)
	mux.HandleFunc("/dashboard", s.handleUserDashboard)
	mux.HandleFunc("/logout", s.handleUserWebLogout)
	mux.HandleFunc("/admin/login", s.handleAdminLogin)
	mux.HandleFunc("/admin/dashboard", s.handleAdminDashboard)
	mux.HandleFunc("/admin/users", s.handleAdminUsers)
	mux.HandleFunc("/admin/api/stats", s.handleAdminStats)
	mux.HandleFunc("/admin/api/smtp/test", s.handleAdminSMTPTest)
	mux.HandleFunc("/admin/", s.handleAdminAPI)
	mux.HandleFunc("/", s.handleNotFound)
	return mux
}

// ============================================================
// Helpers
// ============================================================

func jsonOK(w http.ResponseWriter, v interface{}) {
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(v)
}

func jsonErr(w http.ResponseWriter, code int, msg string) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(code)
	json.NewEncoder(w).Encode(map[string]string{"error": msg})
}

func (s *Server) requireAPIKey(w http.ResponseWriter, r *http.Request) bool {
	key := r.Header.Get("Authorization")
	key = strings.TrimPrefix(key, "Bearer ")
	if key == "" {
		key = r.URL.Query().Get("api_key")
	}
	if key == "" {
		jsonErr(w, 401, "API key required")
		return false
	}
	// First try device token (hashed).
	hash := sha256Hex(key)
	var deviceID, userID, revokedAt sql.NullString
	err := s.db.QueryRow("SELECT id, user_id, revoked_at FROM server_devices WHERE token_hash=?", hash).Scan(&deviceID, &userID, &revokedAt)
	if err == nil {
		if revokedAt.Valid && revokedAt.String != "" {
			jsonErr(w, 401, "device revoked")
			return false
		}
		// Check user not blocked.
		var blocked int
		if userID.Valid && userID.String != "" {
			s.db.QueryRow("SELECT blocked FROM server_users WHERE id=?", userID.String).Scan(&blocked)
			if blocked != 0 {
				jsonErr(w, 403, "user blocked")
				return false
			}
		}
		r.Header.Set("X-Device-ID", deviceID.String)
		r.Header.Set("X-User-ID", userID.String)
		s.db.Exec("UPDATE server_devices SET last_seen=? WHERE id=?", time.Now().UTC().Format(time.RFC3339), deviceID.String)
		return true
	}
	// Fallback to plain api_key (legacy).
	var count int
	err = s.db.QueryRow("SELECT COUNT(*) FROM server_devices WHERE api_key=?", key).Scan(&count)
	if err != nil || count == 0 {
		jsonErr(w, 401, "invalid API key")
		return false
	}
	return true
}

func (s *Server) requireAdmin(w http.ResponseWriter, r *http.Request) bool {
	cookie, err := r.Cookie("session")
	if err != nil || !s.tokens.Check(cookie.Value) {
		http.Redirect(w, r, "/admin/login", http.StatusFound)
		return false
	}
	return true
}

// ============================================================
// SMTP Config
// ============================================================

func (s *Server) smtpGet(key string) string {
	var val string
	s.db.QueryRow("SELECT value FROM server_smtp_config WHERE key=?", key).Scan(&val)
	return val
}

func (s *Server) smtpSet(key, val string) error {
	_, err := s.db.Exec("INSERT OR REPLACE INTO server_smtp_config (key, value) VALUES (?, ?)", key, val)
	return err
}

func errorPageHTML(title, msg, backURL string) string {
	return fmt.Sprintf(`<!DOCTYPE html>
<html lang="ru">
<head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Verstak Sync — %s</title>
<style>body{font-family:sans-serif;background:#13131f;color:#e4e4ef;display:flex;justify-content:center;align-items:center;height:100vh;margin:0}
.box{background:#1a1a28;border:1px solid #2a2a3c;border-radius:12px;padding:32px;text-align:center;max-width:360px}
h1{font-size:18px;margin:0 0 12px;color:#ff6b6b}
p{font-size:13px;color:#b0b0c0;margin:0 0 16px}
a{color:#6366f1;text-decoration:none}
a:hover{text-decoration:underline}</style>
</head><body>
<div class="box">
<h1>%s</h1>
<p>%s</p>
<a href="%s">← Назад</a>
</div>
</body></html>`, title, title, msg, backURL)
}

func sha256Hex(s string) string {
	h := sha256.Sum256([]byte(s))
	return hex.EncodeToString(h[:])
}

func genDeviceToken() (token, prefix, suffix string) {
	b := make([]byte, 32)
	rand.Read(b)
	token = "vs_dev_" + hex.EncodeToString(b)
	prefix = token[:16]
	suffix = token[len(token)-8:]
	return
}

func sel(v, want string) string {
	if v == want {
		return " selected"
	}
	return ""
}

func (s *Server) smtpConnect(host, port, user, pass, security string) (*smtp.Client, error) {
	addr := net.JoinHostPort(host, port)
	switch security {
	case "tls":
		tlsCfg := &tls.Config{ServerName: host}
		conn, err := tls.Dial("tcp", addr, tlsCfg)
		if err != nil {
			return nil, fmt.Errorf("tls dial: %w", err)
		}
		cl, err := smtp.NewClient(conn, host)
		if err != nil {
			conn.Close()
			return nil, fmt.Errorf("smtp client: %w", err)
		}
		return cl, nil
	default:
		conn, err := net.DialTimeout("tcp", addr, 10*time.Second)
		if err != nil {
			return nil, fmt.Errorf("connect: %w", err)
		}
		cl, err := smtp.NewClient(conn, host)
		if err != nil {
			conn.Close()
			return nil, fmt.Errorf("smtp client: %w", err)
		}
		if security != "none" {
			if ok, _ := cl.Extension("STARTTLS"); ok {
				tlsCfg := &tls.Config{ServerName: host}
				if err := cl.StartTLS(tlsCfg); err != nil {
					cl.Close()
					return nil, fmt.Errorf("starttls: %w", err)
				}
			}
		}
		return cl, nil
	}
}

func (s *Server) smtpSendMsg(cl *smtp.Client, user, pass, host, from, to string, msg []byte) error {
	if user != "" {
		auth := smtp.PlainAuth("", user, pass, host)
		if err := cl.Auth(auth); err != nil {
			return fmt.Errorf("auth: %w", err)
		}
	}
	if err := cl.Mail(from); err != nil {
		return fmt.Errorf("mail from: %w", err)
	}
	if err := cl.Rcpt(to); err != nil {
		return fmt.Errorf("rcpt: %w", err)
	}
	w, err := cl.Data()
	if err != nil {
		return fmt.Errorf("data: %w", err)
	}
	if _, err := w.Write(msg); err != nil {
		w.Close()
		return fmt.Errorf("write: %w", err)
	}
	if err := w.Close(); err != nil {
		return fmt.Errorf("send: %w", err)
	}
	return nil
}

func (s *Server) smtpSend(to, subject, body string) error {
	host := s.smtpGet("smtp_host")
	port := s.smtpGet("smtp_port")
	user := s.smtpGet("smtp_user")
	pass := s.smtpGet("smtp_pass")
	from := s.smtpGet("smtp_from")
	security := s.smtpGet("smtp_security")
	if host == "" || port == "" || from == "" {
		err := fmt.Errorf("SMTP not configured")
		log.Printf("smtp: %v (to=%s)", err, to)
		return err
	}
	log.Printf("smtp: sending to %s via %s:%s (security=%s)", to, host, port, security)
	msg := []byte("From: " + from + "\r\n" +
		"To: " + to + "\r\n" +
		"Subject: " + subject + "\r\n" +
		"MIME-Version: 1.0\r\n" +
		"Content-Type: text/plain; charset=UTF-8\r\n" +
		"\r\n" + body + "\r\n")
	cl, err := s.smtpConnect(host, port, user, pass, security)
	if err != nil {
		log.Printf("smtp: connect error: %v", err)
		return err
	}
	defer cl.Close()
	if err := s.smtpSendMsg(cl, user, pass, host, from, to, msg); err != nil {
		log.Printf("smtp: send error: %v", err)
		return err
	}
	log.Printf("smtp: sent OK to %s", to)
	return nil
}

func (s *Server) smtpTest(host, port, user, pass, security, from, to string) error {
	if host == "" || port == "" || from == "" {
		return fmt.Errorf("SMTP not configured")
	}
	msg := []byte("From: " + from + "\r\nTo: " + to + "\r\nSubject: Test from Verstak Sync\r\n\r\nThis is a test email from Verstak Sync Server.\r\n")
	cl, err := s.smtpConnect(host, port, user, pass, security)
	if err != nil {
		return err
	}
	defer cl.Close()
	return s.smtpSendMsg(cl, user, pass, host, from, to, msg)
}

// ============================================================
// User helpers
// ============================================================

func validatePassword(password string) string {
	if len(password) < 8 {
		return "Password must be at least 8 characters"
	}
	if !passwordRE.MatchString(password) {
		return "Password must contain only Latin letters and digits"
	}
	hasLetter := false
	hasDigit := false
	for _, ch := range password {
		if ch >= 'A' && ch <= 'Z' || ch >= 'a' && ch <= 'z' {
			hasLetter = true
		}
		if ch >= '0' && ch <= '9' {
			hasDigit = true
		}
	}
	if !hasLetter || !hasDigit {
		return "Password must contain both letters and digits"
	}
	return ""
}

func (s *Server) requireUser(w http.ResponseWriter, r *http.Request) (string, bool) {
	key := r.Header.Get("Authorization")
	key = strings.TrimPrefix(key, "Bearer ")
	if key == "" {
		jsonErr(w, 401, "authorization required")
		return "", false
	}
	userID, ok := s.userTokens.Check(key)
	if !ok {
		jsonErr(w, 401, "invalid or expired token")
		return "", false
	}
	return userID, true
}

// ============================================================
// Handlers
// ============================================================

func (s *Server) handleNotFound(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path == "/" {
		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
		w.Write([]byte("Verstak Sync Server\n"))
		return
	}
	jsonErr(w, 404, "not found")
}

func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
	jsonOK(w, map[string]interface{}{
		"status":  "ok",
		"version": "verstak-server/v1",
		"time":    time.Now().UTC().Format(time.RFC3339),
	})
}

func (s *Server) handleClientPair(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		jsonErr(w, 405, "POST required")
		return
	}
	ip := r.RemoteAddr
	if idx := strings.LastIndex(ip, ":"); idx >= 0 {
		ip = ip[:idx]
	}
	if !s.pairLimit.allow(ip) {
		s.auditLog("rate_limit_exceeded", "", "", ip, "pair rate limit exceeded")
		jsonErr(w, 429, "too many attempts")
		return
	}
	var req struct {
		Login        string `json:"login"`
		Password     string `json:"password"`
		DeviceName   string `json:"device_name"`
		ClientVersion string `json:"client_version"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonErr(w, 400, "bad json")
		return
	}
	if req.Login == "" || req.Password == "" {
		jsonErr(w, 400, "login and password required")
		return
	}
	if req.DeviceName == "" {
		req.DeviceName = "unknown"
	}
	// Look up user.
	var userID, hash string
	var confirmed, blocked int
	err := s.db.QueryRow("SELECT id, password_hash, confirmed, blocked FROM server_users WHERE username=? OR email=?",
		req.Login, strings.ToLower(req.Login)).Scan(&userID, &hash, &confirmed, &blocked)
	if err != nil {
		s.auditLog("device_auth_failed", "", "", ip, "pair: user not found: "+req.Login)
		jsonErr(w, 401, "invalid credentials")
		return
	}
	if blocked != 0 {
		s.auditLog("device_auth_failed", userID, "", ip, "pair: user blocked")
		jsonErr(w, 403, "account blocked")
		return
	}
	if confirmed == 0 {
		s.auditLog("device_auth_failed", userID, "", ip, "pair: email not confirmed")
		jsonErr(w, 403, "email not confirmed")
		return
	}
	if bcrypt.CompareHashAndPassword([]byte(hash), []byte(req.Password)) != nil {
		s.auditLog("device_auth_failed", userID, "", ip, "pair: wrong password")
		jsonErr(w, 401, "invalid credentials")
		return
	}
	// Generate device.
	devID := make([]byte, 12)
	rand.Read(devID)
	deviceID := "dev_" + hex.EncodeToString(devID)
	token, prefix, suffix := genDeviceToken()
	tokenHash := sha256Hex(token)
	now := time.Now().UTC().Format(time.RFC3339)
	apiKey := make([]byte, 20)
	rand.Read(apiKey)
	_, err = s.db.Exec(`INSERT INTO server_devices
		(id, name, api_key, token_hash, token_prefix, token_suffix, user_id, client_version, last_ip, last_seen, created_at)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
		deviceID, req.DeviceName, hex.EncodeToString(apiKey), tokenHash, prefix, suffix,
		userID, req.ClientVersion, ip, now, now)
	if err != nil {
		jsonErr(w, 500, err.Error())
		return
	}
	s.db.Exec("INSERT OR IGNORE INTO server_user_devices (user_id, device_id) VALUES (?, ?)", userID, deviceID)
	s.db.Exec("UPDATE server_users SET last_seen=? WHERE id=?", now, userID)
	s.pairLimit.reset(ip)
	s.auditLog("device_paired", userID, deviceID, ip, "device paired: "+req.DeviceName)
	jsonOK(w, map[string]interface{}{
		"user_id":              userID,
		"device_id":            deviceID,
		"device_token":         token,
		"server_time":          now,
		"initial_sync_cursor":  0,
	})
}

func (s *Server) handleAuthTest(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		jsonErr(w, 405, "POST required")
		return
	}
	var req struct {
		Username string `json:"username"`
		Password string `json:"password"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonErr(w, 400, "bad json")
		return
	}
	if req.Username == "" || req.Password == "" {
		jsonErr(w, 400, "username and password required")
		return
	}
	var hash string
	var confirmed, blocked int
	err := s.db.QueryRow("SELECT password_hash, confirmed, blocked FROM server_users WHERE username=? OR email=?",
		req.Username, strings.ToLower(req.Username)).Scan(&hash, &confirmed, &blocked)
	if err != nil {
		jsonErr(w, 401, "invalid credentials")
		return
	}
	if blocked != 0 {
		jsonErr(w, 403, "account blocked")
		return
	}
	if confirmed == 0 {
		jsonErr(w, 403, "email not confirmed")
		return
	}
	if bcrypt.CompareHashAndPassword([]byte(hash), []byte(req.Password)) != nil {
		jsonErr(w, 401, "invalid credentials")
		return
	}
	jsonOK(w, map[string]string{"status": "ok"})
}

func (s *Server) handleClientRevoke(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		jsonErr(w, 405, "POST required")
		return
	}
	tok := strings.TrimPrefix(r.Header.Get("Authorization"), "Bearer ")
	if tok == "" {
		jsonErr(w, 401, "token required")
		return
	}
	hash := sha256Hex(tok)
	var deviceID, userID string
	err := s.db.QueryRow("SELECT id, user_id FROM server_devices WHERE token_hash=?", hash).Scan(&deviceID, &userID)
	if err != nil {
		jsonErr(w, 401, "invalid token")
		return
	}
	now := time.Now().UTC().Format(time.RFC3339)
	s.db.Exec("UPDATE server_devices SET revoked_at=? WHERE id=?", now, deviceID)
	s.auditLog("device_revoked", userID, deviceID, r.RemoteAddr, "device revoked by user")
	jsonOK(w, map[string]string{"status": "revoked"})
}

func (s *Server) handleClientRevokeDevice(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		jsonErr(w, 405, "POST required")
		return
	}
	userID, ok := s.requireUserWeb(w, r)
	if !ok {
		return
	}
	var req struct {
		DeviceID string `json:"device_id"`
		Password string `json:"password"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonErr(w, 400, "invalid JSON")
		return
	}
	if req.DeviceID == "" || req.Password == "" {
		jsonErr(w, 400, "device_id and password required")
		return
	}
	// Verify password.
	var pwHash string
	err := s.db.QueryRow("SELECT password_hash FROM server_users WHERE id=?", userID).Scan(&pwHash)
	if err != nil {
		jsonErr(w, 403, "access denied")
		return
	}
	if bcrypt.CompareHashAndPassword([]byte(pwHash), []byte(req.Password)) != nil {
		jsonErr(w, 403, "wrong password")
		return
	}
	// Verify device belongs to user.
	var devUserID string
	err = s.db.QueryRow("SELECT user_id FROM server_devices WHERE id=?", req.DeviceID).Scan(&devUserID)
	if err != nil {
		jsonErr(w, 404, "device not found")
		return
	}
	if devUserID != userID {
		jsonErr(w, 403, "device does not belong to you")
		return
	}
	now := time.Now().UTC().Format(time.RFC3339)
	s.db.Exec("UPDATE server_devices SET revoked_at=? WHERE id=?", now, req.DeviceID)
	s.auditLog("device_revoked", userID, req.DeviceID, r.RemoteAddr, "device revoked via web dashboard")
	jsonOK(w, map[string]string{"status": "revoked"})
}

func (s *Server) handleClientMe(w http.ResponseWriter, r *http.Request) {
	tok := strings.TrimPrefix(r.Header.Get("Authorization"), "Bearer ")
	if tok == "" {
		jsonErr(w, 401, "token required")
		return
	}
	hash := sha256Hex(tok)
	var deviceID, userID, name, clientVer, lastSeen, revokedAt, createdAt string
	err := s.db.QueryRow(`SELECT d.id, d.user_id, d.name, COALESCE(d.client_version,''), COALESCE(d.last_seen,''), COALESCE(d.revoked_at,''), d.created_at
		FROM server_devices d WHERE d.token_hash=?`, hash).
		Scan(&deviceID, &userID, &name, &clientVer, &lastSeen, &revokedAt, &createdAt)
	if err != nil {
		jsonErr(w, 401, "invalid token")
		return
	}
	var username string
	s.db.QueryRow("SELECT username FROM server_users WHERE id=?", userID).Scan(&username)
	jsonOK(w, map[string]interface{}{
		"device_id":      deviceID,
		"user_id":        userID,
		"username":       username,
		"device_name":    name,
		"client_version": clientVer,
		"last_seen":      lastSeen,
		"revoked_at":     revokedAt,
		"created_at":     createdAt,
	})
}

func (s *Server) handleDeviceRegister(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		jsonErr(w, 405, "POST required")
		return
	}
	var req struct {
		Name     string `json:"name"`
		Username string `json:"username"`
		Password string `json:"password"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonErr(w, 400, "invalid JSON")
		return
	}
	if req.Name == "" {
		jsonErr(w, 400, "name required")
		return
	}
	if req.Username == "" || req.Password == "" {
		jsonErr(w, 401, "username and password required")
		return
	}

	// Look up user by username or email.
	var userID, hash string
	var confirmed, blocked int
	err := s.db.QueryRow("SELECT id, password_hash, confirmed, blocked FROM server_users WHERE username=? OR email=?",
		req.Username, strings.ToLower(req.Username)).Scan(&userID, &hash, &confirmed, &blocked)
	if err != nil {
		jsonErr(w, 401, "invalid credentials")
		return
	}
	if blocked != 0 {
		jsonErr(w, 403, "account blocked")
		return
	}
	if confirmed == 0 {
		jsonErr(w, 403, "email not confirmed")
		return
	}
	if bcrypt.CompareHashAndPassword([]byte(hash), []byte(req.Password)) != nil {
		jsonErr(w, 401, "invalid credentials")
		return
	}

	b := make([]byte, 20)
	rand.Read(b)
	apiKey := hex.EncodeToString(b)
	deviceID := apiKey[:12]
	now := time.Now().UTC().Format(time.RFC3339)

	_, err = s.db.Exec(
		"INSERT INTO server_devices (id, name, api_key, last_seen, created_at) VALUES (?, ?, ?, ?, ?)",
		deviceID, req.Name, apiKey, now, now,
	)
	if err != nil {
		jsonErr(w, 500, err.Error())
		return
	}
	// Link device to user.
	s.db.Exec("INSERT OR IGNORE INTO server_user_devices (user_id, device_id) VALUES (?, ?)", userID, deviceID)

	jsonOK(w, map[string]interface{}{
		"device_id": deviceID,
		"api_key":   apiKey,
	})
}

// ============================================================
// Auth / User handlers
// ============================================================

func (s *Server) handleRegister(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		jsonErr(w, 405, "POST required")
		return
	}
	var req struct {
		Username string `json:"username"`
		Email    string `json:"email"`
		Password string `json:"password"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonErr(w, 400, "invalid JSON")
		return
	}
	if req.Username == "" || req.Email == "" || req.Password == "" {
		jsonErr(w, 400, "username, email and password required")
		return
	}
	if err := validatePassword(req.Password); err != "" {
		jsonErr(w, 400, err)
		return
	}
	if !strings.Contains(req.Email, "@") || !strings.Contains(req.Email, ".") {
		jsonErr(w, 400, "invalid email")
		return
	}
	hash, err := bcrypt.GenerateFromPassword([]byte(req.Password), bcrypt.DefaultCost)
	if err != nil {
		jsonErr(w, 500, "internal error")
		return
	}
	now := time.Now().UTC().Format(time.RFC3339)
	id := make([]byte, 12)
	rand.Read(id)
	userID := hex.EncodeToString(id)
	_, err = s.db.Exec(
		"INSERT INTO server_users (id, username, email, password_hash, confirmed, created_at) VALUES (?, ?, ?, ?, 0, ?)",
		userID, req.Username, strings.ToLower(req.Email), string(hash), now,
	)
	if err != nil {
		if strings.Contains(err.Error(), "UNIQUE") {
			jsonErr(w, 409, "username or email already taken")
			return
		}
		jsonErr(w, 500, err.Error())
		return
	}
	// Confirmation token.
	tok := make([]byte, 24)
	rand.Read(tok)
	tokenStr := hex.EncodeToString(tok)
	exp := time.Now().Add(48 * time.Hour).UTC().Format(time.RFC3339)
	s.db.Exec("INSERT INTO server_email_tokens (token, user_id, purpose, expires_at, created_at) VALUES (?, ?, 'confirm', ?, ?)",
		tokenStr, userID, exp, now)
	// Try to send email.
	host := s.smtpGet("smtp_host")
	if host != "" {
		srvURL := s.smtpGet("server_url")
		var confirmURL string
		if srvURL != "" {
			confirmURL = fmt.Sprintf("%s/confirm?token=%s", srvURL, tokenStr)
		} else {
			confirmURL = fmt.Sprintf("/api/v1/auth/confirm?token=%s", tokenStr)
		}
		body := fmt.Sprintf("Welcome to Verstak Sync!\n\nPlease confirm your email by clicking:\n%s\n\nIf you did not register, ignore this message.", confirmURL)
		if err := s.smtpSend(req.Email, "Confirm your Verstak Sync account", body); err != nil {
			log.Printf("register: failed to send confirm email: %v", err)
		}
	} else {
		log.Printf("register: SMTP not configured, confirmation token=%s for user %s", tokenStr, req.Username)
	}
	jsonOK(w, map[string]string{"status": "confirmation_sent"})
}

func (s *Server) handleConfirm(w http.ResponseWriter, r *http.Request) {
	if r.Method != "GET" {
		jsonErr(w, 405, "GET required")
		return
	}
	tokenStr := r.URL.Query().Get("token")
	if tokenStr == "" {
		jsonErr(w, 400, "token required")
		return
	}
	var userID, expiresAt string
	err := s.db.QueryRow("SELECT user_id, expires_at FROM server_email_tokens WHERE token=? AND purpose='confirm'",
		tokenStr).Scan(&userID, &expiresAt)
	if err != nil {
		jsonErr(w, 400, "invalid or expired token")
		return
	}
	exp, err := time.Parse(time.RFC3339, expiresAt)
	if err != nil || time.Now().After(exp) {
		jsonErr(w, 400, "token expired")
		return
	}
	s.db.Exec("UPDATE server_users SET confirmed=1 WHERE id=?", userID)
	log.Printf("confirm: user %s confirmed email", userID)
	s.db.Exec("DELETE FROM server_email_tokens WHERE token=?", tokenStr)
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	w.Write([]byte(confirmedHTML))
}

func (s *Server) handleUserLogin(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		jsonErr(w, 405, "POST required")
		return
	}
	var req struct {
		Username string `json:"username"`
		Password string `json:"password"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonErr(w, 400, "invalid JSON")
		return
	}
	if req.Username == "" || req.Password == "" {
		jsonErr(w, 400, "username and password required")
		return
	}
	var userID, hash string
	var confirmed, blocked int
	err := s.db.QueryRow("SELECT id, password_hash, confirmed, blocked FROM server_users WHERE username=? OR email=?",
		req.Username, strings.ToLower(req.Username)).Scan(&userID, &hash, &confirmed, &blocked)
	if err != nil {
		jsonErr(w, 401, "invalid credentials")
		return
	}
	if blocked != 0 {
		jsonErr(w, 403, "account blocked")
		return
	}
	if confirmed == 0 {
		jsonErr(w, 403, "email not confirmed")
		return
	}
	if bcrypt.CompareHashAndPassword([]byte(hash), []byte(req.Password)) != nil {
		jsonErr(w, 401, "invalid credentials")
		return
	}
	s.db.Exec("UPDATE server_users SET last_seen=? WHERE id=?", time.Now().UTC().Format(time.RFC3339), userID)
	tok := s.userTokens.Create(userID)
	jsonOK(w, map[string]string{"token": tok, "user_id": userID})
}

func (s *Server) handleForgot(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		jsonErr(w, 405, "POST required")
		return
	}
	var req struct {
		Email string `json:"email"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonErr(w, 400, "invalid JSON")
		return
	}
	if req.Email == "" {
		jsonErr(w, 400, "email required")
		return
	}
	var userID string
	err := s.db.QueryRow("SELECT id FROM server_users WHERE email=?", strings.ToLower(req.Email)).Scan(&userID)
	if err != nil {
		jsonOK(w, map[string]string{"status": "if email exists, reset link sent"})
		return
	}
	tok := make([]byte, 24)
	rand.Read(tok)
	tokenStr := hex.EncodeToString(tok)
	exp := time.Now().Add(1 * time.Hour).UTC().Format(time.RFC3339)
	now := time.Now().UTC().Format(time.RFC3339)
	s.db.Exec("INSERT INTO server_email_tokens (token, user_id, purpose, expires_at, created_at) VALUES (?, ?, 'reset', ?, ?)",
		tokenStr, userID, exp, now)
	host := s.smtpGet("smtp_host")
	if host != "" {
		srvURL := s.smtpGet("server_url")
		resetURL := fmt.Sprintf("/api/v1/auth/reset?token=%s", tokenStr)
		if srvURL != "" {
			resetURL = fmt.Sprintf("%s/api/v1/auth/reset?token=%s", srvURL, tokenStr)
		}
		body := fmt.Sprintf("Reset your Verstak Sync password:\n\n%s\n\nThis link expires in 1 hour.", resetURL)
		s.smtpSend(req.Email, "Verstak Sync password reset", body)
	}
	jsonOK(w, map[string]string{"status": "if email exists, reset link sent"})
}

func (s *Server) handleReset(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		jsonErr(w, 405, "POST required")
		return
	}
	var req struct {
		Token       string `json:"token"`
		NewPassword string `json:"new_password"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonErr(w, 400, "invalid JSON")
		return
	}
	if req.Token == "" || req.NewPassword == "" {
		jsonErr(w, 400, "token and new_password required")
		return
	}
	if err := validatePassword(req.NewPassword); err != "" {
		jsonErr(w, 400, err)
		return
	}
	var userID, expiresAt string
	err := s.db.QueryRow("SELECT user_id, expires_at FROM server_email_tokens WHERE token=? AND purpose='reset'",
		req.Token).Scan(&userID, &expiresAt)
	if err != nil {
		jsonErr(w, 400, "invalid or expired token")
		return
	}
	exp, err := time.Parse(time.RFC3339, expiresAt)
	if err != nil || time.Now().After(exp) {
		jsonErr(w, 400, "token expired")
		return
	}
	hash, err := bcrypt.GenerateFromPassword([]byte(req.NewPassword), bcrypt.DefaultCost)
	if err != nil {
		jsonErr(w, 500, "internal error")
		return
	}
	s.db.Exec("UPDATE server_users SET password_hash=? WHERE id=?", string(hash), userID)
	s.db.Exec("DELETE FROM server_email_tokens WHERE token=?", req.Token)
	jsonOK(w, map[string]string{"status": "password reset"})
}

func (s *Server) handleUserDevices(w http.ResponseWriter, r *http.Request) {
	userID, ok := s.requireUser(w, r)
	if !ok {
		return
	}
	if r.Method != "GET" {
		jsonErr(w, 405, "GET required")
		return
	}
	rows, err := s.db.Query(`
		SELECT d.id, d.name, d.last_seen, d.created_at
		FROM server_devices d
		JOIN server_user_devices ud ON ud.device_id = d.id
		WHERE ud.user_id = ?
		ORDER BY d.created_at`, userID)
	if err != nil {
		jsonErr(w, 500, err.Error())
		return
	}
	defer rows.Close()
	type deviceDTO struct {
		ID        string `json:"id"`
		Name      string `json:"name"`
		LastSeen  string `json:"last_seen"`
		CreatedAt string `json:"created_at"`
	}
	var devices []deviceDTO
	for rows.Next() {
		var d deviceDTO
		var lastSeen sql.NullString
		if err := rows.Scan(&d.ID, &d.Name, &lastSeen, &d.CreatedAt); err != nil {
			continue
		}
		d.LastSeen = lastSeen.String
		devices = append(devices, d)
	}
	if devices == nil {
		devices = []deviceDTO{}
	}
	jsonOK(w, map[string]interface{}{"devices": devices})
}

func (s *Server) handleSyncPush(w http.ResponseWriter, r *http.Request) {
	if !s.requireAPIKey(w, r) {
		return
	}
	if r.Method != "POST" {
		jsonErr(w, 405, "POST required")
		return
	}
	var req struct {
		DeviceID     string `json:"device_id"`
		IdempotencyKey string `json:"idempotency_key"`
		Ops          []struct {
			OpID              string `json:"op_id"`
			EntityType        string `json:"entity_type"`
			EntityID          string `json:"entity_id"`
			OpType            string `json:"op_type"`
			PayloadJSON       string `json:"payload_json"`
			ClientSequence    int    `json:"client_sequence"`
			LastSeenServerSeq int    `json:"last_seen_server_seq"`
			CreatedAt         string `json:"created_at"`
		} `json:"ops"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonErr(w, 400, "invalid JSON: "+err.Error())
		return
	}

	// Idempotency: if request-level key provided, check for cached response.
	if req.IdempotencyKey != "" {
		var cachedJSON string
		err := s.db.QueryRow("SELECT response_json FROM server_idempotency_keys WHERE idempotency_key=?", req.IdempotencyKey).Scan(&cachedJSON)
		if err == nil {
			w.Header().Set("Content-Type", "application/json")
			w.Write([]byte(cachedJSON))
			return
		}
	}

	now := time.Now().UTC().Format(time.RFC3339)
	var accepted []string
	var conflicts []map[string]interface{}

	for _, op := range req.Ops {
		if op.OpID == "" || op.EntityType == "" || op.EntityID == "" || op.OpType == "" {
			continue
		}
		// Conflict detection: check if another device already created ops for this entity
		// with a server_sequence higher than what this client last saw.
		if op.LastSeenServerSeq > 0 {
			conflictRows, err := s.db.Query(`
				SELECT op_id, device_id, op_type, server_sequence FROM server_ops
				WHERE entity_type=? AND entity_id=? AND device_id!=?
				  AND server_sequence > ? AND op_type != 'delete'
				ORDER BY server_sequence`, op.EntityType, op.EntityID, req.DeviceID, op.LastSeenServerSeq)
			if err == nil {
				for conflictRows.Next() {
					var cOpID, cDevID, cOpType string
					var cSeq int
					conflictRows.Scan(&cOpID, &cDevID, &cOpType, &cSeq)
					conflicts = append(conflicts, map[string]interface{}{
						"op_id":          cOpID,
						"device_id":      cDevID,
						"op_type":        cOpType,
						"server_sequence": cSeq,
						"entity_type":    op.EntityType,
						"entity_id":      op.EntityID,
					})
				}
				conflictRows.Close()
			}
		}

		res, err := s.db.Exec(
			`INSERT OR IGNORE INTO server_ops (op_id, server_sequence, device_id, entity_type, entity_id, op_type, payload_json, idempotency_key, client_sequence, last_seen_server_seq, created_at, pushed_at)
			 VALUES (?, NULL, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
			op.OpID, req.DeviceID, op.EntityType, op.EntityID, op.OpType, op.PayloadJSON,
			req.IdempotencyKey, op.ClientSequence, op.LastSeenServerSeq, op.CreatedAt, now,
		)
		if err != nil {
			continue
		}
		n, _ := res.RowsAffected()
		if n == 0 {
			continue // duplicate op_id
		}
		seqRes, err := s.db.Exec("INSERT INTO server_revisions (op_id, device_id) VALUES (?, ?)", op.OpID, req.DeviceID)
		if err != nil {
			continue
		}
		seq, _ := seqRes.LastInsertId()
		s.db.Exec("UPDATE server_ops SET server_sequence=? WHERE op_id=?", seq, op.OpID)

		if op.OpType == "delete" {
			s.db.Exec(`INSERT OR REPLACE INTO server_tombstones (entity_type, entity_id, op_id, deleted_at) VALUES (?, ?, ?, ?)`,
				op.EntityType, op.EntityID, op.OpID, now)
		}

		accepted = append(accepted, op.OpID)
	}

	resp := map[string]interface{}{
		"accepted":  accepted,
		"count":     len(accepted),
		"conflicts": conflicts,
	}

	// Cache response for idempotency.
	if req.IdempotencyKey != "" {
		if respJSON, err := json.Marshal(resp); err == nil {
			s.db.Exec("INSERT OR IGNORE INTO server_idempotency_keys (idempotency_key, response_json, created_at) VALUES (?, ?, ?)",
				req.IdempotencyKey, string(respJSON), now)
		}
	}

	jsonOK(w, resp)
}

func (s *Server) handleSyncPull(w http.ResponseWriter, r *http.Request) {
	if !s.requireAPIKey(w, r) {
		return
	}
	if r.Method != "POST" {
		jsonErr(w, 405, "POST required")
		return
	}
	var req struct {
		SinceSequence int `json:"since_sequence"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonErr(w, 400, "invalid JSON")
		return
	}

	var serverSeq int
	s.db.QueryRow("SELECT COALESCE(MAX(server_sequence), 0) FROM server_ops").Scan(&serverSeq)

	rows, err := s.db.Query(`
		SELECT op_id, server_sequence, device_id, entity_type, entity_id, op_type, payload_json, created_at
		FROM server_ops
		WHERE server_sequence > ? AND server_sequence IS NOT NULL
		ORDER BY server_sequence`, req.SinceSequence)
	if err != nil {
		jsonErr(w, 500, err.Error())
		return
	}
	defer rows.Close()

	type opDTO struct {
		OpID           string `json:"op_id"`
		ServerSequence int    `json:"server_sequence"`
		DeviceID       string `json:"device_id"`
		EntityType     string `json:"entity_type"`
		EntityID       string `json:"entity_id"`
		OpType         string `json:"op_type"`
		PayloadJSON    string `json:"payload_json"`
		CreatedAt      string `json:"created_at"`
	}
	var ops []opDTO
	for rows.Next() {
		var o opDTO
		if err := rows.Scan(&o.OpID, &o.ServerSequence, &o.DeviceID, &o.EntityType, &o.EntityID, &o.OpType, &o.PayloadJSON, &o.CreatedAt); err != nil {
			continue
		}
		ops = append(ops, o)
	}

	jsonOK(w, map[string]interface{}{
		"server_sequence": serverSeq,
		"ops":            ops,
	})
}

func (s *Server) handleBlobs(w http.ResponseWriter, r *http.Request) {
	if !s.requireAPIKey(w, r) {
		return
	}
	switch r.Method {
	case "POST":
		// Upload: accept multipart file, store by SHA-256.
		if err := r.ParseMultipartForm(200 << 20); err != nil {
			jsonErr(w, 400, "multipart error: "+err.Error())
			return
		}
		file, header, err := r.FormFile("file")
		if err != nil {
			jsonErr(w, 400, "file field required")
			return
		}
		defer file.Close()

		// Read content and compute SHA-256.
		data, err := io.ReadAll(file)
		if err != nil {
			jsonErr(w, 500, "read error")
			return
		}
		hash := sha256.Sum256(data)
		shaHex := hex.EncodeToString(hash[:])

		// Store at blobs/ab/cd/sha256.
		blobDir := filepath.Join(s.blobsDir, shaHex[:2], shaHex[2:4])
		if err := os.MkdirAll(blobDir, 0750); err != nil {
			jsonErr(w, 500, "mkdir error")
			return
		}
		blobPath := filepath.Join(blobDir, shaHex)
		if err := os.WriteFile(blobPath, data, 0640); err != nil {
			jsonErr(w, 500, "write error")
			return
		}
		_ = header

		// Record in blobs table.
		now := time.Now().UTC().Format(time.RFC3339)
		s.db.Exec("INSERT OR IGNORE INTO server_blobs (sha256, size, created_at) VALUES (?, ?, ?)",
			shaHex, len(data), now)

		jsonOK(w, map[string]interface{}{
			"sha256": shaHex,
			"size":   len(data),
		})

	case "GET":
		// Download: GET /api/v1/blobs/{sha256}
		shaHex := strings.TrimPrefix(r.URL.Path, "/api/v1/blobs/")
		if len(shaHex) != 64 {
			jsonErr(w, 400, "invalid SHA-256")
			return
		}
		blobPath := filepath.Join(s.blobsDir, shaHex[:2], shaHex[2:4], shaHex)
		if _, err := os.Stat(blobPath); os.IsNotExist(err) {
			jsonErr(w, 404, "blob not found")
			return
		}
		data, err := os.ReadFile(blobPath)
		if err != nil {
			jsonErr(w, 500, "read error")
			return
		}
		w.Header().Set("Content-Type", "application/octet-stream")
		w.Header().Set("Content-Disposition", "attachment; filename=\""+shaHex+"\"")
		w.Write(data)

	default:
		jsonErr(w, 405, "method not allowed")
	}
}

// ============================================================
// User web GUI
// ============================================================

func (s *Server) requireUserWeb(w http.ResponseWriter, r *http.Request) (string, bool) {
	cookie, err := r.Cookie("user_session")
	if err != nil {
		http.Redirect(w, r, "/login", http.StatusFound)
		return "", false
	}
	userID, ok := s.userTokens.Check(cookie.Value)
	if !ok {
		http.Redirect(w, r, "/login", http.StatusFound)
		return "", false
	}
	return userID, true
}

func (s *Server) handleUserWebRegister(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case "GET":
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		w.Write([]byte(userRegisterHTML))
	case "POST":
		if err := r.ParseForm(); err != nil {
			w.Header().Set("Content-Type", "text/html; charset=utf-8")
			w.WriteHeader(400)
			w.Write([]byte("<html><body><h1>400 Bad request</h1><a href='/register'>Back</a></body></html>"))
			return
		}
		username := r.FormValue("username")
		email := r.FormValue("email")
		password := r.FormValue("password")
		if username == "" || email == "" || password == "" {
			w.Header().Set("Content-Type", "text/html; charset=utf-8")
			w.WriteHeader(400)
			w.Write([]byte("<html><body><h1>All fields required</h1><a href='/register'>Back</a></body></html>"))
			return
		}
		if err := validatePassword(password); err != "" {
			w.Header().Set("Content-Type", "text/html; charset=utf-8")
			w.WriteHeader(400)
			w.Write([]byte("<html><body><h1>" + err + "</h1><a href='/register'>Back</a></body></html>"))
			return
		}
		hash, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
		if err != nil {
			w.WriteHeader(500)
			w.Write([]byte("<html><body><h1>Internal error</h1><a href='/register'>Back</a></body></html>"))
			return
		}
		now := time.Now().UTC().Format(time.RFC3339)
		id := make([]byte, 12)
		rand.Read(id)
		userID := hex.EncodeToString(id)
		_, err = s.db.Exec(
			"INSERT INTO server_users (id, username, email, password_hash, confirmed, created_at) VALUES (?, ?, ?, ?, 0, ?)",
			userID, username, strings.ToLower(email), string(hash), now,
		)
		if err != nil {
			w.Header().Set("Content-Type", "text/html; charset=utf-8")
			if strings.Contains(err.Error(), "UNIQUE") {
				w.WriteHeader(409)
				w.Write([]byte("<html><body><h1>Username or email already taken</h1><a href='/register'>Back</a></body></html>"))
			} else {
				w.WriteHeader(500)
				w.Write([]byte("<html><body><h1>"+err.Error()+"</h1><a href='/register'>Back</a></body></html>"))
			}
			return
		}
		// Confirmation token.
		tok := make([]byte, 24)
		rand.Read(tok)
		tokenStr := hex.EncodeToString(tok)
		exp := time.Now().Add(48 * time.Hour).UTC().Format(time.RFC3339)
		s.db.Exec("INSERT INTO server_email_tokens (token, user_id, purpose, expires_at, created_at) VALUES (?, ?, 'confirm', ?, ?)",
			tokenStr, userID, exp, now)
		// Try to send email.
		host := s.smtpGet("smtp_host")
		if host != "" {
			srvURL := s.smtpGet("server_url")
			var confirmURL string
			if srvURL != "" {
				confirmURL = fmt.Sprintf("%s/api/v1/auth/confirm?token=%s", srvURL, tokenStr)
			} else {
				confirmURL = fmt.Sprintf("http://%s/api/v1/auth/confirm?token=%s", r.Host, tokenStr)
			}
			body := fmt.Sprintf("Welcome to Verstak Sync!\n\nPlease confirm your email by clicking:\n%s\n\nIf you did not register, ignore this message.", confirmURL)
			if err := s.smtpSend(email, "Confirm your Verstak Sync account", body); err != nil {
				log.Printf("register web: failed to send confirm email: %v", err)
			}
		} else {
			log.Printf("register web: SMTP not configured, confirmation token=%s for user %s", tokenStr, username)
		}
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		regMsg := registrationOKHTML
		if host == "" {
			regMsg = registrationAutoHTML
		}
		w.Write([]byte(regMsg))
	default:
		jsonErr(w, 405, "method not allowed")
	}
}

func (s *Server) handleUserWebForgot(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case "GET":
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		w.Write([]byte(forgotPasswordHTML))
	case "POST":
		if err := r.ParseForm(); err != nil {
			jsonErr(w, 400, "bad form")
			return
		}
		email := strings.ToLower(r.FormValue("email"))
		if email == "" {
			w.Header().Set("Content-Type", "text/html; charset=utf-8")
			w.Write([]byte(errorPageHTML("Ошибка", "Email обязателен", "/forgot")))
			return
		}
		var userID string
		err := s.db.QueryRow("SELECT id FROM server_users WHERE email=?", email).Scan(&userID)
		if err != nil {
			w.Header().Set("Content-Type", "text/html; charset=utf-8")
			w.Write([]byte(forgotSentHTML))
			return
		}
		tok := make([]byte, 24)
		rand.Read(tok)
		tokenStr := hex.EncodeToString(tok)
		exp := time.Now().Add(1 * time.Hour).UTC().Format(time.RFC3339)
		now := time.Now().UTC().Format(time.RFC3339)
		s.db.Exec("INSERT INTO server_email_tokens (token, user_id, purpose, expires_at, created_at) VALUES (?, ?, 'reset', ?, ?)",
			tokenStr, userID, exp, now)
		host := s.smtpGet("smtp_host")
		if host != "" {
			srvURL := s.smtpGet("server_url")
			resetURL := fmt.Sprintf("/reset?token=%s", tokenStr)
			if srvURL != "" {
				resetURL = fmt.Sprintf("%s/reset?token=%s", srvURL, tokenStr)
			}
			body := fmt.Sprintf("Reset your Verstak Sync password:\n\n%s\n\nThis link expires in 1 hour.", resetURL)
			if err := s.smtpSend(email, "Verstak Sync password reset", body); err != nil {
				log.Printf("forgot web: failed to send reset email: %v", err)
			}
		} else {
			log.Printf("forgot web: SMTP not configured, reset token=%s for email %s", tokenStr, email)
		}
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		w.Write([]byte(forgotSentHTML))
	default:
		jsonErr(w, 405, "method not allowed")
	}
}

func (s *Server) handleUserWebReset(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case "GET":
		token := r.URL.Query().Get("token")
		if token == "" {
			http.Redirect(w, r, "/forgot", http.StatusFound)
			return
		}
		// Validate token exists and not expired before showing form.
		var userID, expiresAt string
		err := s.db.QueryRow("SELECT user_id, expires_at FROM server_email_tokens WHERE token=? AND purpose='reset'",
			token).Scan(&userID, &expiresAt)
		if err != nil {
			http.Redirect(w, r, "/forgot", http.StatusFound)
			return
		}
		exp, err := time.Parse(time.RFC3339, expiresAt)
		if err != nil || time.Now().After(exp) {
			http.Redirect(w, r, "/forgot", http.StatusFound)
			return
		}
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		html := strings.ReplaceAll(resetPasswordHTML, "{TOKEN}", token)
		w.Write([]byte(html))
	case "POST":
		if err := r.ParseForm(); err != nil {
			jsonErr(w, 400, "bad form")
			return
		}
		token := r.FormValue("token")
		newPass := r.FormValue("password")
		confirm := r.FormValue("confirm")
		if token == "" || newPass == "" || confirm == "" {
			w.Header().Set("Content-Type", "text/html; charset=utf-8")
			w.Write([]byte(errorPageHTML("Ошибка", "Все поля обязательны", "/forgot")))
			return
		}
		if err := validatePassword(newPass); err != "" {
			w.Header().Set("Content-Type", "text/html; charset=utf-8")
			w.Write([]byte(errorPageHTML("Ошибка", err, "/reset?token="+token)))
			return
		}
		if newPass != confirm {
			w.Header().Set("Content-Type", "text/html; charset=utf-8")
			w.Write([]byte(errorPageHTML("Ошибка", "Пароли не совпадают", "/reset?token="+token)))
			return
		}
		var userID string
		err := s.db.QueryRow("SELECT user_id FROM server_email_tokens WHERE token=? AND purpose='reset'", token).Scan(&userID)
		if err != nil {
			http.Redirect(w, r, "/forgot", http.StatusFound)
			return
		}
		hash, _ := bcrypt.GenerateFromPassword([]byte(newPass), bcrypt.DefaultCost)
		s.db.Exec("UPDATE server_users SET password_hash=? WHERE id=?", string(hash), userID)
		s.db.Exec("DELETE FROM server_email_tokens WHERE token=?", token)
		log.Printf("reset: user %s reset password", userID)
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		w.Write([]byte(resetDoneHTML))
	default:
		jsonErr(w, 405, "method not allowed")
	}
}

func (s *Server) handleUserWebLogin(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case "GET":
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		w.Write([]byte(userLoginHTML))
	case "POST":
		if err := r.ParseForm(); err != nil {
			jsonErr(w, 400, "bad form")
			return
		}
		username := r.FormValue("username")
		password := r.FormValue("password")
		var userID, hash string
		var confirmed, blocked int
		err := s.db.QueryRow("SELECT id, password_hash, confirmed, blocked FROM server_users WHERE username=? OR email=?",
			username, strings.ToLower(username)).Scan(&userID, &hash, &confirmed, &blocked)
		if err != nil || blocked != 0 || confirmed == 0 || bcrypt.CompareHashAndPassword([]byte(hash), []byte(password)) != nil {
			w.Header().Set("Content-Type", "text/html; charset=utf-8")
			w.WriteHeader(401)
			w.Write([]byte("<html><body><h1>401 Unauthorized</h1><a href='/login'>Try again</a></body></html>"))
			return
		}
		tok := s.userTokens.Create(userID)
		http.SetCookie(w, &http.Cookie{
			Name: "user_session", Value: tok, Path: "/",
			HttpOnly: true, SameSite: http.SameSiteLaxMode,
			MaxAge: 86400,
		})
		http.Redirect(w, r, "/dashboard", http.StatusFound)
	default:
		jsonErr(w, 405, "method not allowed")
	}
}

func (s *Server) handleUserDashboard(w http.ResponseWriter, r *http.Request) {
	userID, ok := s.requireUserWeb(w, r)
	if !ok {
		return
	}
	var username string
	s.db.QueryRow("SELECT username FROM server_users WHERE id=?", userID).Scan(&username)

	// Get devices with status info.
	type dev struct {
		ID, Name, LastSeen, CreatedAt, ClientVer, RevokedAt string
	}
	var devices []dev
	rows, err := s.db.Query(`
		SELECT d.id, d.name, COALESCE(d.last_seen,''), d.created_at,
		       COALESCE(d.client_version,''), COALESCE(d.revoked_at,'')
		FROM server_devices d
		JOIN server_user_devices ud ON ud.device_id = d.id
		WHERE ud.user_id = ?
		ORDER BY d.created_at DESC`, userID)
	if err == nil {
		defer rows.Close()
		for rows.Next() {
			var d dev
			rows.Scan(&d.ID, &d.Name, &d.LastSeen, &d.CreatedAt, &d.ClientVer, &d.RevokedAt)
			devices = append(devices, d)
		}
	}

	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	deviceRows := ""
	if len(devices) == 0 {
		deviceRows = "<tr><td colspan='5' style='color:#666;text-align:center;padding:24px'>Нет подключённых устройств.<br>Подключите устройство из desktop-клиента Verstak.</td></tr>"
	} else {
		for _, d := range devices {
			ls := d.LastSeen
			if ls == "" {
				ls = "—"
			}
			created := d.CreatedAt
			if len(created) > 10 {
				created = created[:10]
			}
			status := "<span style='color:#34d399'>Активно</span>"
			revokeBtn := fmt.Sprintf(`<button class="btn btn-danger btn-sm" onclick="revokeDevice('%s')">Отозвать</button>`, d.ID)
			if d.RevokedAt != "" {
				status = "<span style='color:#ff6b6b'>Отозвано</span>"
				revokeBtn = ""
			}
			deviceRows += fmt.Sprintf(`<tr>
				<td>%s</td>
				<td>%s</td>
				<td>%s</td>
				<td>%s</td>
				<td>%s %s</td>
			</tr>`, d.Name, status, created, ls, d.ClientVer, revokeBtn)
		}
	}

	html := fmt.Sprintf(`<!DOCTYPE html>
<html lang="ru">
<head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Verstak Sync — %s</title>
<style>
body{font-family:sans-serif;background:#13131f;color:#e4e4ef;padding:24px;max-width:800px;margin:0 auto}
h1{border-bottom:1px solid #2a2a3c;padding-bottom:12px}
h2{margin-top:24px;font-size:16px}
table{width:100%%;border-collapse:collapse;margin-top:8px}
th,td{text-align:left;padding:8px 12px;border-bottom:1px solid #2a2a3c}
th{font-size:12px;color:#888;text-transform:uppercase}
.btn{font-family:inherit;font-size:12px;padding:6px 12px;border-radius:6px;border:1px solid #2a2a3c;background:#1a1a28;color:#ccc;cursor:pointer;display:inline-flex;align-items:center;gap:4px}
.btn:hover{background:#222233}
.btn-primary{background:#6366f1;border-color:#6366f1;color:#fff}
.btn-primary:hover{background:#4f46e5}
.btn-danger{color:#ff6b6b;border-color:#4a2222}
.btn-danger:hover{background:#3a2222}
.btn-sm{padding:2px 8px;font-size:11px}
.top{display:flex;justify-content:space-between;align-items:center}
a{color:#6366f1}
</style>
</head><body>
<div class="top">
<h1>Verstak Sync</h1>
<span>%s · <a href="/logout">Выйти</a></span>
</div>
<h2>Устройства</h2>
<table><tr><th>Устройство</th><th>Статус</th><th>Подключено</th><th>Активность</th><th>Версия</th></tr>%s</table>

<div style="margin-top:24px;padding:16px;background:#1a1a28;border:1px solid #2a2a3c;border-radius:8px">
<h2 style="margin-top:0">Подключить новое устройство</h2>
<p style="font-size:13px;color:#888">Откройте desktop-клиент Verstak, перейдите в настройки синхронизации и введите URL сервера, логин и пароль.</p>
</div>

<script>
function revokeDevice(id){
  if(!confirm('Отозвать устройство? Оно перестанет синхронизироваться.'))return
  var pw=prompt('Введите ваш пароль для подтверждения:')
  if(!pw)return
  fetch('/api/client/revoke-device',{method:'POST',headers:{'Content-Type':'application/json'},body:JSON.stringify({device_id:id,password:pw})}).then(function(r){return r.json()}).then(function(d){
    if(d.status==='revoked'){location.reload()}else{alert(d.error||'error')}
  })
}
</script>
</body></html>`, username, username, deviceRows)
	w.Write([]byte(html))
}

func (s *Server) handleUserWebLogout(w http.ResponseWriter, r *http.Request) {
	http.SetCookie(w, &http.Cookie{
		Name: "user_session", Value: "", Path: "/",
		HttpOnly: true, MaxAge: -1,
	})
	http.Redirect(w, r, "/login", http.StatusFound)
}

// ============================================================
// Admin handlers
// ============================================================

func (s *Server) handleAdminLogin(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case "GET":
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		w.Write([]byte(adminLoginHTML))
	case "POST":
		if err := r.ParseForm(); err != nil {
			jsonErr(w, 400, "bad form")
			return
		}
		user := r.FormValue("username")
		pass := r.FormValue("password")
		if !s.cfg.CheckAdmin(user, pass) {
			w.Header().Set("Content-Type", "text/html; charset=utf-8")
			w.WriteHeader(401)
			w.Write([]byte("<html><body><h1>401 Unauthorized</h1><a href='/admin/login'>Try again</a></body></html>"))
			return
		}
		tok := s.tokens.Create()
		http.SetCookie(w, &http.Cookie{
			Name: "session", Value: tok, Path: "/admin",
			HttpOnly: true, SameSite: http.SameSiteLaxMode,
			MaxAge: 86400,
		})
		http.Redirect(w, r, "/admin/dashboard", http.StatusFound)
	default:
		jsonErr(w, 405, "method not allowed")
	}
}

func (s *Server) handleAdminDashboard(w http.ResponseWriter, r *http.Request) {
	if !s.requireAdmin(w, r) {
		return
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	// Fetch data for dashboard.
	var deviceCount, opsCount int
	s.db.QueryRow("SELECT COUNT(*) FROM server_devices").Scan(&deviceCount)
	s.db.QueryRow("SELECT COUNT(*) FROM server_ops").Scan(&opsCount)

	// Load SMTP config for display.
	smtpHost := s.smtpGet("smtp_host")
	smtpPort := s.smtpGet("smtp_port")
	smtpUser := s.smtpGet("smtp_user")
	smtpFrom := s.smtpGet("smtp_from")
	smtpSecurity := s.smtpGet("smtp_security")
	srvURL := s.smtpGet("server_url")

	html := `<!DOCTYPE html>
<html lang="ru">
<head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Verstak Sync — Admin</title>
<style>
body{font-family:sans-serif;background:#13131f;color:#e4e4ef;padding:24px;max-width:860px;margin:0 auto}
a{color:#6366f1}
h1{border-bottom:1px solid #2a2a3c;padding-bottom:12px}
h2{margin-top:24px;font-size:16px}
.stat{background:#1a1a28;border:1px solid #2a2a3c;padding:12px 16px;border-radius:8px;margin:8px 0}
table{width:100%%;border-collapse:collapse;margin-top:8px}
th,td{text-align:left;padding:8px 12px;border-bottom:1px solid #2a2a3c}
th{font-size:12px;color:#888;text-transform:uppercase}
.key-cell{max-width:360px;overflow:hidden;text-overflow:ellipsis;font-family:monospace;font-size:12px;color:#b0b0c0}
.btn{font-family:inherit;font-size:12px;padding:6px 12px;border-radius:6px;border:1px solid #2a2a3c;background:#1a1a28;color:#ccc;cursor:pointer;display:inline-flex;align-items:center;gap:4px}
.btn:hover{background:#222233}
.btn-primary{background:#6366f1;border-color:#6366f1;color:#fff}
.btn-primary:hover{background:#4f46e5}
.btn-danger{color:#ff6b6b;border-color:#4a2222}
.btn-danger:hover{background:#3a2222}
.copy-btn{padding:2px 8px;font-size:11px;margin-left:6px}
input{font-family:inherit;font-size:14px;padding:8px 12px;border:1px solid #2a2a3c;background:#13131f;color:#e4e4ef;border-radius:6px;margin:0;box-sizing:border-box}
input:focus{outline:none;border-color:#6366f1}
.form-row{display:flex;gap:8px;margin-bottom:8px;align-items:center}
.form-row label{font-size:12px;color:#888;min-width:80px;flex-shrink:0}
.form-row input{flex:1}
.toolbar{display:flex;gap:8px;margin:16px 0;flex-wrap:wrap}
.modal-overlay{position:fixed;inset:0;background:rgba(0,0,0,0.6);display:flex;align-items:center;justify-content:center;z-index:100}
.modal{background:#1a1a28;border:1px solid #2a2a3c;border-radius:12px;padding:24px;width:420px;max-width:90vw;position:relative;max-height:80vh;overflow-y:auto}
.modal h2{margin-top:0}
.modal-close{position:absolute;top:10px;right:14px;font-size:20px;cursor:pointer;background:none;border:none;color:#888}
.modal-close:hover{color:#e4e4ef}
pre{background:#13131f;border:1px solid #2a2a3c;border-radius:8px;padding:12px;overflow-x:auto;white-space:pre-wrap}
</style>
</head><body>
<h1>Verstak Sync Server</h1>
<div style="display:flex;gap:20px;flex-wrap:wrap">
<div class="stat" style="margin:0"><strong>Устройств:</strong> <span id="dev-count">0</span></div>
<div class="stat" style="margin:0"><strong>Операций:</strong> <span id="op-count">0</span></div>
</div>

<div class="toolbar">
<button class="btn btn-primary" onclick="openSMTP()">Настройка SMTP</button>
<a href="/admin/users" style="text-decoration:none"><button class="btn" type="button">Пользователи</button></a>
<button class="btn" onclick="openHealth()">Health check</button>
</div>

<h2>Устройства</h2>
<div id="devices"></div>
<script>
fetch('/admin/api/devices').then(r=>r.json()).then(devices=>{
  const div=document.getElementById('devices')
  if(!devices.length){div.innerHTML='<p>Нет устройств</p>';return}
  div.innerHTML='<table><tr><th>Устройство</th><th>Пользователь</th><th>Версия</th><th>Статус</th><th>Активность</th><th></th></tr>'+
    devices.map(d=>{
      var status=d.revoked_at?'<span style="color:#ff6b6b">Отозвано</span>':'<span style="color:#34d399">Активно</span>'
      var ls=d.last_seen||'—'
      var revBtn=''
      if(!d.revoked_at) revBtn='<button class="btn btn-danger" onclick="revokeDevice(\''+d.id+'\')">Отозвать</button>'
      return '<tr><td>'+d.name+'</td><td>'+(d.user||'—')+'</td><td>'+(d.client_version||'—')+'</td><td>'+status+'</td><td>'+ls+'</td><td>'+revBtn+'</td></tr>'
    }).join('')+'</table>'
  document.getElementById('dev-count').textContent=devices.length
})
fetch('/admin/api/stats').then(r=>r.json()).then(stats=>{
  document.getElementById('op-count').textContent=stats.ops||'0'
})
function revokeDevice(id){
  if(!confirm('Отозвать устройство?'))return
  fetch('/admin/api/keys/'+id,{method:'DELETE'}).then(()=>location.reload())
}
function openSMTP(){document.getElementById('smtp-modal').style.display='flex';document.getElementById('smtp-test-result').textContent=''}
function closeSMTP(e){if(!e||e.target.id==='smtp-modal')document.getElementById('smtp-modal').style.display='none'}
function openHealth(){var m=document.getElementById('health-modal');m.style.display='flex';document.getElementById('health-result').textContent='Загрузка...';fetch('/api/v1/health').then(function(r){return r.text()}).then(function(t){document.getElementById('health-result').textContent=t})}
function closeHealth(e){if(!e||e.target.id==='health-modal')document.getElementById('health-modal').style.display='none'}
function testSMTP(){
  var f=document.querySelector('#smtp-modal form')
  var fd=new FormData(f)
  var obj={};for(var e of fd.entries()){obj[e[0]]=e[1]}
  var r=document.getElementById('smtp-test-result')
  r.textContent='⏳ Тестируем...';r.style.color='#888'
  fetch('/admin/api/smtp/test',{method:'POST',headers:{'Content-Type':'application/json'},body:JSON.stringify(obj)}).then(function(r2){return r2.json()}).then(function(d){
    r.textContent=d.ok?'✓ Тест пройден':'✗ '+d.error
    r.style.color=d.ok?'#4ade80':'#ff6b6b'
  }).catch(function(e){r.textContent='✗ '+e;r.style.color='#ff6b6b'})
}
</script>

<div id="smtp-modal" class="modal-overlay" style="display:none" onclick="closeSMTP(event)">
<div class="modal">
<button class="modal-close" onclick="closeSMTP()">&times;</button>
<h2>SMTP (для писем)</h2>
<form action="/admin/api/smtp" method="POST">
<div class="form-row"><label>Сервер</label><input name="smtp_host" value="` + smtpHost + `" placeholder="smtp.example.com"></div>
<div class="form-row"><label>Порт</label><input name="smtp_port" value="` + smtpPort + `" placeholder="587"></div>
<div class="form-row"><label>Тип</label><select name="smtp_security" style="font-family:inherit;font-size:14px;padding:8px 12px;border:1px solid #2a2a3c;background:#13131f;color:#e4e4ef;border-radius:6px;flex:1;box-sizing:border-box">
<option value="starttls"` + sel(smtpSecurity, "starttls") + `>STARTTLS</option>
<option value="tls"` + sel(smtpSecurity, "tls") + `>TLS</option>
<option value="none"` + sel(smtpSecurity, "none") + `>Без шифрования</option>
</select></div>
<div class="form-row"><label>Логин</label><input name="smtp_user" value="` + smtpUser + `" placeholder="user@example.com"></div>
<div class="form-row"><label>Пароль</label><input type="password" name="smtp_pass" placeholder="••••••••"></div>
<div class="form-row"><label>От кого</label><input name="smtp_from" value="` + smtpFrom + `" placeholder="noreply@example.com"></div>
<div class="form-row"><label>URL сервера</label><input name="server_url" value="` + srvURL + `" placeholder="https://example.com:47732"></div>
<div style="margin-top:12px;display:flex;gap:8px;align-items:center">
<button class="btn btn-primary">Сохранить SMTP</button>
<button class="btn" type="button" onclick="testSMTP()">Test</button>
<span id="smtp-test-result" style="font-size:12px"></span>
</div>
</form>
</div>
</div>

<div id="health-modal" class="modal-overlay" style="display:none" onclick="closeHealth(event)">
<div class="modal">
<button class="modal-close" onclick="closeHealth()">&times;</button>
<h2>Health check</h2>
<pre id="health-result">Загрузка...</pre>
</div>
</div>
	_ = smtpURL
	_ = smtpUser
	_ = smtpFrom
	_ = smtpSecurity
	_ = smtpHost
	_ = smtpPort

</body></html>`
	w.Write([]byte(html))
}

func (s *Server) handleAdminUsers(w http.ResponseWriter, r *http.Request) {
	if !s.requireAdmin(w, r) {
		return
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	w.Write([]byte(adminUsersHTML))
}

func (s *Server) handleAdminStats(w http.ResponseWriter, r *http.Request) {
	if !s.requireAdmin(w, r) {
		return
	}
	var opsCount int
	s.db.QueryRow("SELECT COUNT(*) FROM server_ops").Scan(&opsCount)
	jsonOK(w, map[string]int{"ops": opsCount})
}

func (s *Server) handleAdminSMTPTest(w http.ResponseWriter, r *http.Request) {
	if !s.requireAdmin(w, r) {
		return
	}
	var req struct {
		Host     string `json:"smtp_host"`
		Port     string `json:"smtp_port"`
		User     string `json:"smtp_user"`
		Pass     string `json:"smtp_pass"`
		Security string `json:"smtp_security"`
		From     string `json:"smtp_from"`
		To       string `json:"test_to"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonErr(w, 400, "bad json")
		return
	}
	host := req.Host
	port := req.Port
	user := req.User
	pass := req.Pass
	security := req.Security
	from := req.From
	to := req.To
	if to == "" {
		to = from
	}
	if host == "" || port == "" || from == "" {
		jsonOK(w, map[string]interface{}{"ok": false, "error": "host, port and from required"})
		return
	}
	if err := s.smtpTest(host, port, user, pass, security, from, to); err != nil {
		jsonOK(w, map[string]interface{}{"ok": false, "error": err.Error()})
		return
	}
	jsonOK(w, map[string]interface{}{"ok": true})
}

func (s *Server) handleAdminAPI(w http.ResponseWriter, r *http.Request) {
	if !s.requireAdmin(w, r) {
		return
	}
	path := strings.TrimPrefix(r.URL.Path, "/admin")

	switch {
	case path == "/api/devices" && r.Method == "GET":
		rows, err := s.db.Query(`
			SELECT d.id, d.name, d.client_version, COALESCE(d.last_seen,''), COALESCE(d.revoked_at,''), d.created_at,
			       COALESCE(u.username,'')
			FROM server_devices d
			LEFT JOIN server_users u ON u.id = d.user_id
			ORDER BY d.created_at DESC`)
		if err != nil {
			jsonErr(w, 500, err.Error())
			return
		}
		defer rows.Close()
		type devDTO struct {
			ID            string `json:"id"`
			Name          string `json:"name"`
			ClientVersion string `json:"client_version"`
			LastSeen      string `json:"last_seen"`
			RevokedAt     string `json:"revoked_at"`
			CreatedAt     string `json:"created_at"`
			User          string `json:"user"`
		}
		var out []devDTO
		for rows.Next() {
			var d devDTO
			rows.Scan(&d.ID, &d.Name, &d.ClientVersion, &d.LastSeen, &d.RevokedAt, &d.CreatedAt, &d.User)
			out = append(out, d)
		}
		jsonOK(w, out)

	case path == "/api/keys" && r.Method == "GET":
		rows, err := s.db.Query("SELECT id, name, api_key FROM server_devices ORDER BY created_at")
		if err != nil {
			jsonErr(w, 500, err.Error())
			return
		}
		defer rows.Close()
		var out []map[string]string
		for rows.Next() {
			var id, name, key string
			rows.Scan(&id, &name, &key)
			out = append(out, map[string]string{"id": id, "name": name, "api_key": key})
		}
		jsonOK(w, out)

	case path == "/api/keys" && r.Method == "POST":
		if err := r.ParseForm(); err != nil {
			jsonErr(w, 400, "bad form")
			return
		}
		name := r.FormValue("name")
		if name == "" {
			jsonErr(w, 400, "name required")
			return
		}
		b := make([]byte, 20)
		rand.Read(b)
		apiKey := hex.EncodeToString(b)
		now := time.Now().UTC().Format(time.RFC3339)
		_, err := s.db.Exec(
			"INSERT INTO server_devices (id, name, api_key, last_seen, created_at) VALUES (?, ?, ?, ?, ?)",
			apiKey[:12], name, apiKey, now, now,
		)
		if err != nil {
			jsonErr(w, 500, err.Error())
			return
		}
		http.Redirect(w, r, "/admin/dashboard", http.StatusFound)

	case strings.HasPrefix(path, "/api/keys/") && r.Method == "DELETE":
		id := strings.TrimPrefix(path, "/api/keys/")
		_, err := s.db.Exec("DELETE FROM server_devices WHERE id=?", id)
		if err != nil {
			jsonErr(w, 500, err.Error())
			return
		}
		s.db.Exec("DELETE FROM server_user_devices WHERE device_id=?", id)
		jsonOK(w, map[string]string{"status": "deleted"})

	case path == "/api/smtp" && r.Method == "POST":
		if err := r.ParseForm(); err != nil {
			jsonErr(w, 400, "bad form")
			return
		}
		for _, key := range []string{"smtp_host", "smtp_port", "smtp_user", "smtp_pass", "smtp_security", "smtp_from", "server_url"} {
			val := r.FormValue(key)
			if val != "" {
				s.smtpSet(key, val)
			}
		}
		http.Redirect(w, r, "/admin/dashboard", http.StatusFound)

	case path == "/api/users" && r.Method == "GET":
		filter := r.URL.Query().Get("filter")
		sort := r.URL.Query().Get("sort")
		order := r.URL.Query().Get("order")
		page, _ := strconv.Atoi(r.URL.Query().Get("page"))
		perPage, _ := strconv.Atoi(r.URL.Query().Get("per_page"))
		if page < 1 {
			page = 1
		}
		if perPage < 1 || perPage > 100 {
			perPage = 20
		}
		where := ""
		var args []interface{}
		if filter != "" {
			where = " WHERE u.username LIKE ?"
			args = append(args, "%"+filter+"%")
		}
		validSorts := map[string]string{
			"username":    "u.username",
			"email":       "u.email",
			"confirmed":   "u.confirmed",
			"blocked":     "u.blocked",
			"created_at":  "u.created_at",
			"last_seen":   "u.last_seen",
			"devices":     "devices",
		}
		orderClause := "u.created_at DESC"
		if col, ok := validSorts[sort]; ok {
			if order != "asc" {
				order = "desc"
			}
			orderClause = col + " " + order
		}
		// Count total.
		var total int
		countSQL := "SELECT COUNT(*) FROM server_users u" + where
		s.db.QueryRow(countSQL, args...).Scan(&total)
		// Fetch page.
		offset := (page - 1) * perPage
		sql := `SELECT u.id, u.username, u.email, u.confirmed, u.blocked, u.last_seen, u.created_at,
			COALESCE((SELECT COUNT(*) FROM server_user_devices ud JOIN server_devices d ON d.id=ud.device_id WHERE ud.user_id=u.id),0) AS devices
			FROM server_users u` + where + ` ORDER BY ` + orderClause + ` LIMIT ? OFFSET ?`
		args = append(args, perPage, offset)
		rows, err := s.db.Query(sql, args...)
		if err != nil {
			jsonErr(w, 500, err.Error())
			return
		}
		defer rows.Close()
		type userRow struct {
			ID        string `json:"id"`
			Username  string `json:"username"`
			Email     string `json:"email"`
			Confirmed int    `json:"confirmed"`
			Blocked   int    `json:"blocked"`
			LastSeen  string `json:"last_seen"`
			CreatedAt string `json:"created_at"`
			Devices   int    `json:"devices"`
		}
		var users []userRow
		for rows.Next() {
			var u userRow
			var lastSeen *string
			rows.Scan(&u.ID, &u.Username, &u.Email, &u.Confirmed, &u.Blocked, &lastSeen, &u.CreatedAt, &u.Devices)
			if lastSeen != nil {
				u.LastSeen = *lastSeen
			}
			users = append(users, u)
		}
		jsonOK(w, map[string]interface{}{
			"users":      users,
			"total":      total,
			"page":       page,
			"per_page":   perPage,
		})

	case strings.HasPrefix(path, "/api/users/") && r.Method == "POST":
		sub := strings.TrimPrefix(path, "/api/users/")
		if strings.HasSuffix(sub, "/block") {
			id := strings.TrimSuffix(sub, "/block")
			id = strings.TrimSuffix(id, "/")
			var blocked int
			s.db.QueryRow("SELECT blocked FROM server_users WHERE id=?", id).Scan(&blocked)
			newVal := 1
			if blocked != 0 {
				newVal = 0
			}
			s.db.Exec("UPDATE server_users SET blocked=? WHERE id=?", newVal, id)
			jsonOK(w, map[string]interface{}{"status": "ok", "blocked": newVal})
			return
		}
		if strings.HasSuffix(sub, "/reset-password") {
			id := strings.TrimSuffix(sub, "/reset-password")
			id = strings.TrimSuffix(id, "/")
			b := make([]byte, 12)
			rand.Read(b)
			newPass := hex.EncodeToString(b)
			hash, _ := bcrypt.GenerateFromPassword([]byte(newPass), bcrypt.DefaultCost)
			_, err := s.db.Exec("UPDATE server_users SET password_hash=? WHERE id=?", string(hash), id)
			if err != nil {
				jsonErr(w, 500, err.Error())
				return
			}
			jsonOK(w, map[string]interface{}{"status": "ok", "new_password": newPass})
			return
		}
		if strings.HasSuffix(sub, "/edit") {
			id := strings.TrimSuffix(sub, "/edit")
			id = strings.TrimSuffix(id, "/")
			var req struct {
				Username string `json:"username"`
				Email    string `json:"email"`
			}
			if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
				jsonErr(w, 400, "bad json")
				return
			}
			if req.Username == "" || req.Email == "" {
				jsonErr(w, 400, "username and email required")
				return
			}
			_, err := s.db.Exec("UPDATE server_users SET username=?, email=? WHERE id=?", req.Username, strings.ToLower(req.Email), id)
			if err != nil {
				jsonErr(w, 500, err.Error())
				return
			}
			jsonOK(w, map[string]interface{}{"status": "ok"})
			return
		}
		jsonErr(w, 404, "unknown action")

	case strings.HasPrefix(path, "/api/users/") && r.Method == "DELETE":
		id := strings.TrimPrefix(path, "/api/users/")
		id = strings.TrimSuffix(id, "/")
		// Get user devices to delete.
		rows, _ := s.db.Query("SELECT device_id FROM server_user_devices WHERE user_id=?", id)
		var deviceIDs []string
		for rows.Next() {
			var did string
			rows.Scan(&did)
			deviceIDs = append(deviceIDs, did)
		}
		rows.Close()
		for _, did := range deviceIDs {
			s.db.Exec("DELETE FROM server_devices WHERE id=?", did)
		}
		s.db.Exec("DELETE FROM server_user_devices WHERE user_id=?", id)
		s.db.Exec("DELETE FROM server_email_tokens WHERE user_id=?", id)
		s.db.Exec("DELETE FROM server_users WHERE id=?", id)
		jsonOK(w, map[string]interface{}{"status": "deleted"})

	default:
		jsonErr(w, 404, "not found")
	}
}

// ============================================================
// Embedded admin login HTML
// ============================================================

const userRegisterHTML = `<!DOCTYPE html>
<html lang="ru">
<head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Verstak Sync — Регистрация</title>
<style>body{font-family:sans-serif;background:#13131f;color:#e4e4ef;display:flex;justify-content:center;align-items:center;height:100vh;margin:0}
form{background:#1a1a28;border:1px solid #2a2a3c;border-radius:12px;padding:32px;width:320px}
h1{font-size:20px;margin:0 0 20px;text-align:center}
p{text-align:center;font-size:12px;color:#666;margin-top:16px}
a{color:#6366f1}
label{display:block;font-size:12px;color:#888;margin-bottom:4px}
input{width:100%;padding:8px 12px;border:1px solid #2a2a3c;background:#13131f;color:#e4e4ef;border-radius:6px;font-size:14px;margin-bottom:16px;box-sizing:border-box}
button{width:100%;padding:10px;background:#6366f1;color:#fff;border:none;border-radius:6px;font-size:14px;cursor:pointer}
button:hover{background:#4f46e5}
.hint{font-size:11px;color:#666;margin-top:-12px;margin-bottom:16px;text-align:center}
</style>
</head><body>
<form method="POST">
<h1>Регистрация</h1>
<label>Логин</label>
<input type="text" name="username" autofocus required>
<label>Email</label>
<input type="email" name="email" required>
<label>Пароль</label>
<input type="password" name="password" required minlength="8">
<div class="hint">Минимум 8 символов: латинские буквы + цифры</div>
<button>Зарегистрироваться</button>
<p>Уже есть аккаунт? <a href="/login">Войти</a></p>
</form>
</body></html>`

const userLoginHTML = `<!DOCTYPE html>
<html lang="ru">
<head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Verstak Sync — Вход</title>
<style>body{font-family:sans-serif;background:#13131f;color:#e4e4ef;display:flex;justify-content:center;align-items:center;height:100vh;margin:0}
form{background:#1a1a28;border:1px solid #2a2a3c;border-radius:12px;padding:32px;width:320px}
h1{font-size:20px;margin:0 0 20px;text-align:center}
p{text-align:center;font-size:12px;color:#666;margin-top:16px}
a{color:#6366f1}
label{display:block;font-size:12px;color:#888;margin-bottom:4px}
input{width:100%;padding:8px 12px;border:1px solid #2a2a3c;background:#13131f;color:#e4e4ef;border-radius:6px;font-size:14px;margin-bottom:16px;box-sizing:border-box}
button{width:100%;padding:10px;background:#6366f1;color:#fff;border:none;border-radius:6px;font-size:14px;cursor:pointer}
button:hover{background:#4f46e5}
.links{margin-top:16px;text-align:center;font-size:12px;color:#666;line-height:1.8}
.links a{color:#6366f1;text-decoration:none}
.links a:hover{text-decoration:underline}</style>
</head><body>
<form method="POST">
<h1>Verstak Sync</h1>
<label>Логин или Email</label>
<input type="text" name="username" autofocus required>
<label>Пароль</label>
<input type="password" name="password" required>
<button>Войти</button>
<div class="links">
<a href="/forgot">Забыли пароль?</a><br>
<a href="/register">Зарегистрироваться</a> · <a href="/admin/login">Администратор?</a>
</div>
</form>
</body></html>`

const adminLoginHTML = `<!DOCTYPE html>
<html lang="ru">
<head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Verstak Sync — Admin Login</title>
<style>body{font-family:sans-serif;background:#13131f;color:#e4e4ef;display:flex;justify-content:center;align-items:center;height:100vh;margin:0}
form{background:#1a1a28;border:1px solid #2a2a3c;border-radius:12px;padding:32px;width:320px}
h1{font-size:20px;margin:0 0 20px;text-align:center}
label{display:block;font-size:12px;color:#888;margin-bottom:4px}
input{width:100%;padding:8px 12px;border:1px solid #2a2a3c;background:#13131f;color:#e4e4ef;border-radius:6px;font-size:14px;margin-bottom:16px;box-sizing:border-box}
button{width:100%;padding:10px;background:#6366f1;color:#fff;border:none;border-radius:6px;font-size:14px;cursor:pointer}
button:hover{background:#4f46e5}</style>
</head><body>
<form method="POST">
<h1>Verstak Sync</h1>
<label>Логин</label>
<input type="text" name="username" autofocus required>
<label>Пароль</label>
<input type="password" name="password" required>
<button>Войти</button>
</form>
</body></html>`

const adminUsersHTML = `<!DOCTYPE html>
<html lang="ru">
<head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Verstak Sync — Пользователи</title>
<style>
body{font-family:sans-serif;background:#13131f;color:#e4e4ef;padding:24px;max-width:960px;margin:0 auto}
a{color:#6366f1}
h1{border-bottom:1px solid #2a2a3c;padding-bottom:12px}
table{width:100%%;border-collapse:collapse;margin-top:12px}
th,td{text-align:left;padding:8px 12px;border-bottom:1px solid #2a2a3c}
th{font-size:12px;color:#888;text-transform:uppercase;cursor:pointer;user-select:none}
th:hover{color:#b0b0c0}
th.sorted{color:#6366f1}
.btn{font-family:inherit;font-size:12px;padding:6px 12px;border-radius:6px;border:1px solid #2a2a3c;background:#1a1a28;color:#ccc;cursor:pointer;display:inline-flex;align-items:center;gap:4px}
.btn:hover{background:#222233}
.btn-primary{background:#6366f1;border-color:#6366f1;color:#fff}
.btn-primary:hover{background:#4f46e5}
.btn-danger{color:#ff6b6b;border-color:#4a2222}
.btn-danger:hover{background:#3a2222}
.btn-sm{padding:2px 8px;font-size:11px}
input{font-family:inherit;font-size:14px;padding:8px 12px;border:1px solid #2a2a3c;background:#13131f;color:#e4e4ef;border-radius:6px;box-sizing:border-box}
input:focus{outline:none;border-color:#6366f1}
.toolbar{display:flex;gap:8px;margin:12px 0;flex-wrap:wrap;align-items:center}
.pagination{display:flex;gap:8px;margin-top:12px;align-items:center;justify-content:center}
.pagination span{padding:4px 8px;font-size:12px;color:#888}
.badge{padding:2px 8px;border-radius:4px;font-size:11px}
.badge-green{background:#064e3b;color:#34d399}
.badge-red{background:#4a2222;color:#ff6b6b}
.badge-yellow{background:#4a3e00;color:#fbbf24}
.modal-overlay{position:fixed;inset:0;background:rgba(0,0,0,0.6);display:flex;align-items:center;justify-content:center;z-index:100}
.modal{background:#1a1a28;border:1px solid #2a2a3c;border-radius:12px;padding:24px;width:400px;max-width:90vw;position:relative}
.modal h2{margin-top:0;font-size:16px}
.modal-close{position:absolute;top:10px;right:14px;font-size:20px;cursor:pointer;background:none;border:none;color:#888}
.modal-close:hover{color:#e4e4ef}
.form-row{display:flex;gap:8px;margin-bottom:12px;align-items:center}
.form-row label{font-size:12px;color:#888;min-width:80px;flex-shrink:0}
.form-row input{flex:1}
</style>
</head><body>
<h1>Пользователи</h1>
<p><a href="/admin/dashboard">← Дашборд</a></p>

<div class="toolbar">
<input id="filter-input" placeholder="Фильтр по логину..." style="width:200px" onkeyup="loadUsers()">
</div>

<table>
<thead><tr>
<th onclick="sortBy('username')">Логин <span id="s-username"></span></th>
<th onclick="sortBy('email')">Email <span id="s-email"></span></th>
<th onclick="sortBy('confirmed')">Статус <span id="s-confirmed"></span></th>
<th onclick="sortBy('devices')">Устройств <span id="s-devices"></span></th>
<th onclick="sortBy('last_seen')">Активность <span id="s-last_seen"></span></th>
<th>Действия</th>
</tr></thead>
<tbody id="users-tbody"></tbody>
</table>

<div class="pagination" id="pagination"></div>

<div id="confirm-modal" class="modal-overlay" style="display:none">
<div class="modal">
<button class="modal-close" onclick="closeConfirm()">&times;</button>
<h2 id="confirm-title">Подтверждение</h2>
<p id="confirm-text"></p>
<div style="display:flex;gap:8px;justify-content:flex-end;margin-top:16px">
<button class="btn" onclick="closeConfirm()">Отмена</button>
<button class="btn btn-danger" id="confirm-btn" onclick="confirmAction()">Да</button>
</div>
</div>
</div>

<div id="edit-modal" class="modal-overlay" style="display:none">
<div class="modal">
<button class="modal-close" onclick="closeEdit()">&times;</button>
<h2>Редактировать пользователя</h2>
<div class="form-row"><label>Логин</label><input id="edit-username"></div>
<div class="form-row"><label>Email</label><input id="edit-email" type="email"></div>
<div style="display:flex;gap:8px;justify-content:flex-end;margin-top:16px">
<button class="btn" onclick="closeEdit()">Отмена</button>
<button class="btn btn-primary" onclick="saveEdit()">Сохранить</button>
</div>
</div>
</div>

<div id="result-modal" class="modal-overlay" style="display:none">
<div class="modal" style="width:320px">
<button class="modal-close" onclick="closeResult()">&times;</button>
<h2 id="result-title">Результат</h2>
<p id="result-text" style="white-space:pre-wrap"></p>
<button class="btn btn-primary" onclick="closeResult()" style="margin-top:8px">OK</button>
</div>
</div>

<script>
var currentPage=1,currentSort='',currentOrder='',editUserId='',pendingAction=''

function loadUsers(){
  var f=document.getElementById('filter-input').value
  var u='/admin/api/users?page='+currentPage+'&per_page=20&filter='+encodeURIComponent(f)
  if(currentSort){u+='&sort='+currentSort+'&order='+currentOrder}
  fetch(u).then(function(r){return r.json()}).then(function(d){
    var tbody=document.getElementById('users-tbody')
    tbody.innerHTML=''
    d.users.forEach(function(u){
      var status=u.confirmed?'<span class="badge badge-green">Подтверждён</span>':'<span class="badge badge-yellow">Не подтверждён</span>'
      if(u.blocked){status='<span class="badge badge-red">Заблокирован</span>'}
      var lastSeen=u.last_seen?new Date(u.last_seen).toLocaleString():'-'
      var blockText=u.blocked?'Разблокировать':'Заблокировать'
      var tr=document.createElement('tr')
      tr.innerHTML='<td>'+esc(u.username)+'</td><td>'+esc(u.email)+'</td><td>'+status+'</td><td>'+u.devices+'</td><td>'+lastSeen+'</td>'+
        '<td><button class="btn btn-sm" onclick="editUser(\''+u.id+'\',\''+escJS(u.username)+'\',\''+escJS(u.email)+'\')">✎</button> '+
        '<button class="btn btn-sm" onclick="askBlock(\''+u.id+'\','+u.blocked+')">'+blockText+'</button> '+
        '<button class="btn btn-sm" onclick="askReset(\''+u.id+'\')">Сброс пароля</button> '+
        '<button class="btn btn-sm btn-danger" onclick="askDelete(\''+u.id+'\',\''+escJS(u.username)+'\')">✕</button></td>'
      tbody.appendChild(tr)
    })
    if(!d.users.length){tbody.innerHTML='<tr><td colspan="6" style="text-align:center;color:#666">Нет пользователей</td></tr>'}
    var totalPages=Math.ceil(d.total/d.per_page)
    var pag=document.getElementById('pagination')
    pag.innerHTML=''
    if(totalPages>1){
      var prev=document.createElement('button')
      prev.className='btn btn-sm';prev.textContent='←';prev.onclick=function(){if(currentPage>1){currentPage--;loadUsers()}}
      pag.appendChild(prev)
      var s=document.createElement('span')
      s.textContent=d.page+' / '+totalPages
      pag.appendChild(s)
      var next=document.createElement('button')
      next.className='btn btn-sm';next.textContent='→';next.onclick=function(){if(currentPage<totalPages){currentPage++;loadUsers()}}
      pag.appendChild(next)
    }
  })
}
function sortBy(col){
  if(currentSort===col){currentOrder=currentOrder==='asc'?'desc':'asc'}
  else{currentSort=col;currentOrder='asc'}
  document.querySelectorAll('th').forEach(function(th){th.classList.remove('sorted')})
  var el=document.getElementById('s-'+col)
  if(el){el.parentElement.classList.add('sorted');el.textContent=currentOrder==='asc'?' ▲':' ▼'}
  loadUsers()
}
function esc(s){return s.replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;')}
function escJS(s){return s.replace(/'/g,"\\'").replace(/"/g,'&quot;')}
function editUser(id,username,email){
  editUserId=id;document.getElementById('edit-username').value=username;document.getElementById('edit-email').value=email;document.getElementById('edit-modal').style.display='flex'}
function closeEdit(){document.getElementById('edit-modal').style.display='none'}
function saveEdit(){
  var un=document.getElementById('edit-username').value,em=document.getElementById('edit-email').value
  if(!un||!em)return
  fetch('/admin/api/users/'+editUserId+'/edit',{method:'POST',headers:{'Content-Type':'application/json'},body:JSON.stringify({username:un,email:em})}).then(function(r){return r.json()}).then(function(d){closeEdit();if(d.status==='ok')loadUsers()})
}
function askBlock(id,blocked){
  pendingAction=function(){fetch('/admin/api/users/'+id+'/block',{method:'POST'}).then(function(r){return r.json()}).then(function(d){loadUsers()})}
  document.getElementById('confirm-title').textContent=blocked?'Разблокировать пользователя?':'Заблокировать пользователя?'
  document.getElementById('confirm-text').textContent=blocked?'Пользователь сможет снова войти.':'Пользователь не сможет войти.'
  document.getElementById('confirm-btn').textContent=blocked?'Разблокировать':'Заблокировать'
  document.getElementById('confirm-modal').style.display='flex'}
function askReset(id){
  pendingAction=function(){
    fetch('/admin/api/users/'+id+'/reset-password',{method:'POST'}).then(function(r){return r.json()}).then(function(d){
      document.getElementById('confirm-modal').style.display='none'
      document.getElementById('result-title').textContent='Новый пароль'
      document.getElementById('result-text').textContent='Новый пароль: '+d.new_password+'\nСообщите его пользователю.'
      document.getElementById('result-modal').style.display='flex'})}
  document.getElementById('confirm-title').textContent='Сбросить пароль?'
  document.getElementById('confirm-text').textContent='Пользователь не сможет войти со старым паролем.'
  document.getElementById('confirm-btn').textContent='Сбросить'
  document.getElementById('confirm-modal').style.display='flex'}
function askDelete(id,username){
  pendingAction=function(){fetch('/admin/api/users/'+id,{method:'DELETE'}).then(function(r){return r.json()}).then(function(d){loadUsers()})}
  document.getElementById('confirm-title').textContent='Удалить пользователя?'
  document.getElementById('confirm-text').textContent='Будет удалён пользователь "'+username+'" и все его устройства.'
  document.getElementById('confirm-btn').textContent='Удалить'
  document.getElementById('confirm-modal').style.display='flex'}
function closeConfirm(){document.getElementById('confirm-modal').style.display='none';pendingAction=''}
function confirmAction(){if(pendingAction){pendingAction();pendingAction=''}}
function closeResult(){document.getElementById('result-modal').style.display='none'}
loadUsers()
</script>
</body></html>`

const confirmedHTML = `<!DOCTYPE html>
<html lang="ru">
<head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Verstak Sync — Email подтверждён</title>
<style>body{font-family:sans-serif;background:#13131f;color:#e4e4ef;display:flex;justify-content:center;align-items:center;height:100vh;margin:0}
.box{background:#1a1a28;border:1px solid #2a2a3c;border-radius:12px;padding:32px;width:320px;text-align:center}
h1{font-size:20px;margin:0 0 12px;color:#34d399}
p{font-size:13px;color:#b0b0c0;margin:0 0 20px}
a{color:#6366f1;text-decoration:none}
.btn{display:inline-block;padding:10px 24px;background:#6366f1;color:#fff;border:none;border-radius:6px;font-size:14px;cursor:pointer;text-decoration:none}
.btn:hover{background:#4f46e5}</style>
</head><body>
<div class="box">
<h1>✓ Email подтверждён</h1>
<p>Ваш email успешно подтверждён. Теперь вы можете войти в систему.</p>
<a href="/login" class="btn">Войти</a>
</div>
</body></html>`

const registrationOKHTML = `<!DOCTYPE html>
<html lang="ru">
<head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Verstak Sync — Регистрация</title>
<style>body{font-family:sans-serif;background:#13131f;color:#e4e4ef;display:flex;justify-content:center;align-items:center;height:100vh;margin:0}
.box{background:#1a1a28;border:1px solid #2a2a3c;border-radius:12px;padding:32px;width:360px;text-align:center}
h1{font-size:20px;margin:0 0 12px;color:#34d399}
p{font-size:13px;color:#b0b0c0;margin:0 0 6px;line-height:1.5}
a{color:#6366f1;text-decoration:none}
.btn{display:inline-block;padding:10px 24px;background:#6366f1;color:#fff;border:none;border-radius:6px;font-size:14px;cursor:pointer;text-decoration:none;margin-top:16px}
.btn:hover{background:#4f46e5}</style>
</head><body>
<div class="box">
<h1>✓ Регистрация успешна</h1>
<p>На вашу почту отправлено письмо с подтверждением.</p>
<p>Перейдите по ссылке в письме, чтобы активировать аккаунт.</p>
<a href="/login" class="btn">Войти</a>
</div>
</body></html>`

const registrationAutoHTML = `<!DOCTYPE html>
<html lang="ru">
<head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Verstak Sync — Регистрация</title>
<style>body{font-family:sans-serif;background:#13131f;color:#e4e4ef;display:flex;justify-content:center;align-items:center;height:100vh;margin:0}
.box{background:#1a1a28;border:1px solid #2a2a3c;border-radius:12px;padding:32px;width:360px;text-align:center}
h1{font-size:20px;margin:0 0 12px;color:#34d399}
p{font-size:13px;color:#b0b0c0;margin:0 0 6px;line-height:1.5}
a{color:#6366f1;text-decoration:none}
.btn{display:inline-block;padding:10px 24px;background:#6366f1;color:#fff;border:none;border-radius:6px;font-size:14px;cursor:pointer;text-decoration:none;margin-top:16px}
.btn:hover{background:#4f46e5}</style>
</head><body>
<div class="box">
<h1>✓ Регистрация успешна</h1>
<p>Вы можете войти — подтверждение email не требуется.</p>
<a href="/login" class="btn">Войти</a>
</div>
</body></html>`

const forgotPasswordHTML = `<!DOCTYPE html>
<html lang="ru">
<head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Verstak Sync — Восстановление пароля</title>
<style>body{font-family:sans-serif;background:#13131f;color:#e4e4ef;display:flex;justify-content:center;align-items:center;height:100vh;margin:0}
form{background:#1a1a28;border:1px solid #2a2a3c;border-radius:12px;padding:32px;width:320px}
h1{font-size:18px;margin:0 0 8px;text-align:center}
p{font-size:12px;color:#888;text-align:center;margin:0 0 20px}
label{display:block;font-size:12px;color:#888;margin-bottom:4px}
input{width:100%;padding:8px 12px;border:1px solid #2a2a3c;background:#13131f;color:#e4e4ef;border-radius:6px;font-size:14px;margin-bottom:16px;box-sizing:border-box}
button{width:100%;padding:10px;background:#6366f1;color:#fff;border:none;border-radius:6px;font-size:14px;cursor:pointer}
button:hover{background:#4f46e5}
.links{text-align:center;font-size:12px;color:#666;margin-top:16px}
.links a{color:#6366f1;text-decoration:none}
.links a:hover{text-decoration:underline}</style>
</head><body>
<form method="POST">
<h1>Восстановление пароля</h1>
<p>Введите email, указанный при регистрации</p>
<label>Email</label>
<input type="email" name="email" autofocus required>
<button>Отправить ссылку</button>
<div class="links"><a href="/login">← Вспомнили пароль?</a></div>
</form>
</body></html>`

const forgotSentHTML = `<!DOCTYPE html>
<html lang="ru">
<head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Verstak Sync — Письмо отправлено</title>
<style>body{font-family:sans-serif;background:#13131f;color:#e4e4ef;display:flex;justify-content:center;align-items:center;height:100vh;margin:0}
.box{background:#1a1a28;border:1px solid #2a2a3c;border-radius:12px;padding:32px;width:360px;text-align:center}
h1{font-size:18px;margin:0 0 12px;color:#34d399}
p{font-size:13px;color:#b0b0c0;margin:0 0 6px;line-height:1.5}
a{color:#6366f1;text-decoration:none}
.btn{display:inline-block;padding:10px 24px;background:#6366f1;color:#fff;border:none;border-radius:6px;font-size:14px;cursor:pointer;text-decoration:none;margin-top:16px}
.btn:hover{background:#4f46e5}</style>
</head><body>
<div class="box">
<h1>✓ Письмо отправлено</h1>
<p>Если указанный email зарегистрирован, на него придёт ссылка для сброса пароля.</p>
<a href="/login" class="btn">На главную</a>
</div>
</body></html>`

const resetPasswordHTML = `<!DOCTYPE html>
<html lang="ru">
<head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Verstak Sync — Новый пароль</title>
<style>body{font-family:sans-serif;background:#13131f;color:#e4e4ef;display:flex;justify-content:center;align-items:center;height:100vh;margin:0}
form{background:#1a1a28;border:1px solid #2a2a3c;border-radius:12px;padding:32px;width:320px}
h1{font-size:18px;margin:0 0 20px;text-align:center}
label{display:block;font-size:12px;color:#888;margin-bottom:4px}
input{width:100%;padding:8px 12px;border:1px solid #2a2a3c;background:#13131f;color:#e4e4ef;border-radius:6px;font-size:14px;margin-bottom:16px;box-sizing:border-box}
button{width:100%;padding:10px;background:#6366f1;color:#fff;border:none;border-radius:6px;font-size:14px;cursor:pointer}
button:hover{background:#4f46e5}
.hint{font-size:11px;color:#666;text-align:center;margin-top:12px}</style>
</head><body>
<form method="POST">
<h1>Новый пароль</h1>
<input type="hidden" name="token" value="{TOKEN}">
<label>Новый пароль</label>
<input type="password" name="password" minlength="8" required autofocus>
<label>Подтвердите пароль</label>
<input type="password" name="confirm" minlength="8" required>
<div class="hint">Минимум 8 символов, латинские буквы и цифры</div>
<button style="margin-top:8px">Сохранить</button>
</form>
</body></html>`

const resetDoneHTML = `<!DOCTYPE html>
<html lang="ru">
<head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>Verstak Sync — Пароль изменён</title>
<style>body{font-family:sans-serif;background:#13131f;color:#e4e4ef;display:flex;justify-content:center;align-items:center;height:100vh;margin:0}
.box{background:#1a1a28;border:1px solid #2a2a3c;border-radius:12px;padding:32px;width:360px;text-align:center}
h1{font-size:18px;margin:0 0 12px;color:#34d399}
p{font-size:13px;color:#b0b0c0;margin:0 0 6px;line-height:1.5}
.btn{display:inline-block;padding:10px 24px;background:#6366f1;color:#fff;border:none;border-radius:6px;font-size:14px;cursor:pointer;text-decoration:none;margin-top:16px}
.btn:hover{background:#4f46e5}</style>
</head><body>
<div class="box">
<h1>✓ Пароль изменён</h1>
<p>Теперь вы можете войти с новым паролем.</p>
<a href="/login" class="btn">Войти</a>
</div>
</body></html>`