package config

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
)

const (
	AppConfigVersion  = 1
	ConfigDirName     = "verstak"
	AppConfigFileName = "config.json"
)

// AppConfig is the global application config stored at ~/.config/verstak/config.json.
type AppConfig struct {
	Version           int            `json:"version"`
	VaultPath         string         `json:"vault_path"`
	Theme             string         `json:"theme"`
	Language          string         `json:"language"`
	EnabledTemplates  []string       `json:"enabled_templates"`
	EnabledPlugins    []string       `json:"enabled_plugins"`
	FirstRunCompleted bool           `json:"first_run_completed"`
	Window            WindowConfig   `json:"window,omitempty"`
	Vault             VaultAppConfig `json:"vault,omitempty"`
}

type WindowConfig struct {
	Width  int `json:"width,omitempty"`
	Height int `json:"height,omitempty"`
}

// VaultAppConfig holds per-vault settings in the global config.
type VaultAppConfig struct {
	VaultID   string       `json:"vault_id,omitempty"`
	CreatedAt string       `json:"created_at,omitempty"`
	Sync      SyncSettings `json:"sync,omitempty"`
}

// SyncSettings holds sync configuration for the current vault.
type SyncSettings struct {
	Enabled      bool   `json:"enabled"`
	ServerURL    string `json:"server_url"`
	DeviceID     string `json:"device_id"`
	DeviceName   string `json:"device_name"`
	SyncInterval int    `json:"sync_interval"`
	LastStatus   string `json:"last_status"`
	LastSyncAt   string `json:"last_sync_at"`
	LastError    string `json:"last_error,omitempty"`
}

func DefaultAppConfig() *AppConfig {
	return &AppConfig{
		Version:          AppConfigVersion,
		Theme:            "system",
		Language:         "ru",
		EnabledTemplates: []string{"folder", "project", "client", "document", "recipe"},
		EnabledPlugins:   []string{},
	}
}

// ConfigDir returns ~/.config/verstak (or platform equivalent).
func ConfigDir() (string, error) {
	cfgDir, err := os.UserConfigDir()
	if err != nil {
		return "", err
	}
	return filepath.Join(cfgDir, ConfigDirName), nil
}

// AppConfigPath returns the path to config.json.
func AppConfigPath() (string, error) {
	dir, err := ConfigDir()
	if err != nil {
		return "", err
	}
	return filepath.Join(dir, AppConfigFileName), nil
}

// EnsureConfigDir creates the config directory if it doesn't exist.
func EnsureConfigDir() (string, error) {
	dir, err := ConfigDir()
	if err != nil {
		return "", err
	}
	if err := os.MkdirAll(dir, 0o750); err != nil {
		return "", err
	}
	return dir, nil
}

// LoadAppConfig reads the global config from disk. Returns nil if the file doesn't exist.
func LoadAppConfig() (*AppConfig, error) {
	path, err := AppConfigPath()
	if err != nil {
		return nil, err
	}
	data, err := os.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			return nil, nil
		}
		return nil, fmt.Errorf("read config: %w", err)
	}
	if len(data) == 0 {
		return nil, nil
	}
	var cfg AppConfig
	if err := json.Unmarshal(data, &cfg); err != nil {
		return nil, fmt.Errorf("parse config: %w", err)
	}
	return &cfg, nil
}

// SaveAppConfig writes the global config to disk.
func SaveAppConfig(cfg *AppConfig) error {
	path, err := AppConfigPath()
	if err != nil {
		return err
	}
	if _, err := EnsureConfigDir(); err != nil {
		return err
	}
	data, err := json.MarshalIndent(cfg, "", "  ")
	if err != nil {
		return err
	}
	return os.WriteFile(path, data, 0o640)
}

// DefaultVaultPath returns the default vault location.
func DefaultVaultPath() (string, error) {
	dir, err := ConfigDir()
	if err != nil {
		return "", err
	}
	return filepath.Join(dir, "vault"), nil
}