package config

import (
	"log/slog"
	"strings"

	"github.com/fsnotify/fsnotify"
	"github.com/spf13/viper"
)

// DoubaoConfig holds 火山引擎豆包 ASR credentials.
type DoubaoConfig struct {
	AppID       string   `mapstructure:"app_id"`
	AccessToken string   `mapstructure:"access_token"`
	ResourceID  string   `mapstructure:"resource_id"`
	Hotwords    []string `mapstructure:"hotwords"` // 本地热词列表
}

// SecurityConfig holds authentication settings.
type SecurityConfig struct {
	Token string `mapstructure:"token"`
}

// ServerConfig holds server settings.
type ServerConfig struct {
	Port    int  `mapstructure:"port"`
	TLSAuto bool `mapstructure:"tls_auto"`
}

// Config is the top-level configuration.
type Config struct {
	Doubao   DoubaoConfig   `mapstructure:"doubao"`
	Server   ServerConfig   `mapstructure:"server"`
	Security SecurityConfig `mapstructure:"security"`
}

// defaults returns a Config with default values.
func defaults() Config {
	return Config{
		Doubao: DoubaoConfig{
			ResourceID: "volc.seedasr.sauc.duration",
		},
		Server: ServerConfig{
			Port:    8443,
			TLSAuto: true,
		},
	}
}

// Load reads config from file (or uses defaults if file doesn't exist).
// Empty path defaults to "config.yaml".
func Load(path string) (Config, error) {
	if path == "" {
		path = "config.yaml"
	}

	v := viper.New()
	v.SetConfigFile(path)
	v.SetConfigType("yaml")

	// Set defaults
	def := defaults()
	v.SetDefault("doubao.resource_id", def.Doubao.ResourceID)
	v.SetDefault("server.port", def.Server.Port)
	v.SetDefault("server.tls_auto", def.Server.TLSAuto)

	// Allow env var overrides (e.g., VOICEPASTE_DOUBAO_APP_ID)
	v.SetEnvPrefix("voicepaste")
	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
	v.AutomaticEnv()

	// Read config file (ignore error if file doesn't exist)
	if err := v.ReadInConfig(); err != nil {
		if _, ok := err.(viper.ConfigFileNotFoundError); !ok {
			return Config{}, err
		}
		slog.Warn("config file not found, using defaults", "path", path)
	}

	var cfg Config
	if err := v.Unmarshal(&cfg); err != nil {
		return Config{}, err
	}

	return cfg, nil
}

// WatchAndReload starts watching config file for changes and reloads automatically.
// Empty path defaults to "config.yaml".
func WatchAndReload(path string) {
	if path == "" {
		path = "config.yaml"
	}

	v := viper.New()
	v.SetConfigFile(path)
	v.SetConfigType("yaml")

	// Set defaults (same as Load)
	def := defaults()
	v.SetDefault("doubao.resource_id", def.Doubao.ResourceID)
	v.SetDefault("server.port", def.Server.Port)
	v.SetDefault("server.tls_auto", def.Server.TLSAuto)

	v.SetEnvPrefix("voicepaste")
	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
	v.AutomaticEnv()

	// Initial read (ignore error if file doesn't exist)
	if err := v.ReadInConfig(); err != nil {
		if _, ok := err.(viper.ConfigFileNotFoundError); !ok {
			slog.Warn("config watch: initial read failed", "err", err)
		}
	}

	// Watch for changes
	v.WatchConfig()
	v.OnConfigChange(func(e fsnotify.Event) {
		slog.Info("config file changed, reloading", "file", e.Name)
		var cfg Config
		if err := v.Unmarshal(&cfg); err != nil {
			slog.Error("config reload failed", "err", err)
			return
		}
		slog.Info("config reloaded successfully")
	})
}

// Get returns the current config snapshot.
// Note: After switching to Viper, this is deprecated.
// Use viper.Get* methods or Load() directly instead.
func Get() Config {
	return defaults()
}