package config

import (
	"fmt"
	"os"
	"strings"

	"github.com/joho/godotenv"
	"github.com/spf13/viper"
)

// Config 应用配置。
type Config struct {
	App     AppConfig     `mapstructure:"app"`
	Server  ServerConfig  `mapstructure:"server"`
	Redis   RedisConfig   `mapstructure:"redis"`
	AI      AIConfig      `mapstructure:"ai"`
	Storage StorageConfig `mapstructure:"storage"`
	Log     LogConfig     `mapstructure:"log"`
}

type AppConfig struct {
	Env     string `mapstructure:"env"`
	Version string `mapstructure:"version"`
}

type ServerConfig struct {
	Host         string `mapstructure:"host"`
	Port         int    `mapstructure:"port"`
	ReadTimeout  int    `mapstructure:"read_timeout"`
	WriteTimeout int    `mapstructure:"write_timeout"`
}

// Addr 返回 host:port 地址。
func (s ServerConfig) Addr() string {
	return fmt.Sprintf("%s:%d", s.Host, s.Port)
}

type RedisConfig struct {
	Addr     string `mapstructure:"addr"`
	Password string `mapstructure:"password"`
	DB       int    `mapstructure:"db"`
}

type AIConfig struct {
	STT STTConfig `mapstructure:"stt"`
	LLM LLMConfig `mapstructure:"llm"`
	TTS TTSConfig `mapstructure:"tts"`
}

type STTConfig struct {
	Provider string `mapstructure:"provider"`
	APIKey   string `mapstructure:"api_key"`
	Model    string `mapstructure:"model"`
	Endpoint string `mapstructure:"endpoint"`
}

type LLMConfig struct {
	Provider string `mapstructure:"provider"`
	APIKey   string `mapstructure:"api_key"`
	Model    string `mapstructure:"model"`
	Endpoint string `mapstructure:"endpoint"`
	Timeout  int    `mapstructure:"timeout"`
}

type TTSConfig struct {
	Provider string  `mapstructure:"provider"`
	APIKey   string  `mapstructure:"api_key"`
	Model    string  `mapstructure:"model"`
	Voice    string  `mapstructure:"voice"`
	Speed    float64 `mapstructure:"speed"`
	Endpoint string  `mapstructure:"endpoint"`
	Timeout  int     `mapstructure:"timeout"`
}

type StorageConfig struct {
	Driver string `mapstructure:"driver"`
	DSN    string `mapstructure:"dsn"`
}

type LogConfig struct {
	Level  string `mapstructure:"level"`
	Format string `mapstructure:"format"`
}

// Load 加载配置。优先级：环境变量 > config.{env}.yaml > config.yaml。
func Load() (*Config, error) {
	v := viper.New()
	v.SetConfigName("config")
	v.SetConfigType("yaml")
	v.AddConfigPath(".")
	v.AddConfigPath("./config")
	v.AddConfigPath("./backend")

	// 默认值
	v.SetDefault("app.env", "dev")
	v.SetDefault("server.host", "0.0.0.0")
	v.SetDefault("server.port", 8080)
	v.SetDefault("server.read_timeout", 30)
	v.SetDefault("server.write_timeout", 30)
	v.SetDefault("redis.addr", "localhost:6379")
	v.SetDefault("redis.db", 0)
	v.SetDefault("ai.stt.provider", "deepgram")
	v.SetDefault("ai.stt.model", "nova-2")
	v.SetDefault("ai.stt.endpoint", "wss://api.deepgram.com/v1/listen")
	v.SetDefault("ai.llm.provider", "openai")
	v.SetDefault("ai.llm.model", "gpt-4o")
	v.SetDefault("ai.llm.endpoint", "https://api.openai.com/v1")
	v.SetDefault("ai.llm.timeout", 10)
	v.SetDefault("ai.tts.provider", "openai")
	v.SetDefault("ai.tts.model", "tts-1")
	v.SetDefault("ai.tts.voice", "mimo_default")
	v.SetDefault("ai.tts.speed", 1.0)
	v.SetDefault("ai.tts.endpoint", "https://api.openai.com/v1")
	v.SetDefault("ai.tts.timeout", 5)
	v.SetDefault("storage.driver", "memory")
	v.SetDefault("log.level", "info")
	v.SetDefault("log.format", "console")

	// 读取基础配置文件
	_ = v.ReadInConfig() // 文件不存在不报错

	// 根据 APP_ENV 覆盖
	env := os.Getenv("APP_ENV")
	if env == "" {
		env = v.GetString("app.env")
	}
	if env != "" {
		v.SetConfigName("config." + env)
		_ = v.MergeInConfig()
	}

	// 加载 .env 文件（不覆盖已有环境变量）
	// 按优先级尝试：当前目录、上级目录（兼容从 backend/ 或项目根目录启动）
	_ = godotenv.Load()
	_ = godotenv.Load("../.env")

	// 环境变量覆盖
	v.SetEnvPrefix("CAMTALK")
	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
	v.AutomaticEnv()

	var cfg Config
	if err := v.Unmarshal(&cfg); err != nil {
		return nil, fmt.Errorf("config unmarshal: %w", err)
	}

	// 填充默认值
	if cfg.Server.Host == "" {
		cfg.Server.Host = "0.0.0.0"
	}
	if cfg.Server.Port == 0 {
		cfg.Server.Port = 8080
	}
	if cfg.App.Env == "" {
		cfg.App.Env = "dev"
	}

	return &cfg, nil
}