package main

import (
	"crypto/rand"
	"encoding/hex"
	"sync"
	"time"
)

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
}