package config

import (
	"fmt"
	"strings"

	"github.com/spf13/viper"
)

type ServerConfig struct {
	Server struct {
		Listen string `mapstructure:"listen"`
		Port   string `mapstructure:"port"`
	} `mapstructure:"server"`

	Database struct {
		Type string `mapstructure:"type"`
		Host string `mapstructure:"host"`
		// Port int `mapstructure:"port"`
		// User string `mapstructure:"user"`
	} `mapstructure:"database"`

	Auth struct {
		JWTSecret string `mapstructure:"jwt_secret"`
	} `mapstructure:"auth"`

	Storage struct {
		Type  string `mapstructure:"type"`
		Local struct {
			RootDir string `mapstructure:"root_dir"`
		} `mapstructure:"local"`
		S3 struct {
			Endpoint string `mapstructure:"endpoint"`
			Bucket   string `mapstructure:"bucket"`
		} `mapstructure:"s3"`
	} `mapstructure:"storage"`
}

func setDefaultConfig(v *viper.Viper) {

}

// Bind Environment Variables to config
func bindEnvVariables(v *viper.Viper) {
	// 设置环境变量前缀
	v.SetEnvPrefix("MYGO")

	// 使viper能够从环境变量读取配置
	v.AutomaticEnv()

	// 将环境变量中的下划线转换为点，如MYGO_SERVER_PORT对应server.port
	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))

	// 明确绑定特定环境变量
	// v.BindEnv("server.host", "MYGO_SERVER_HOST")
	// v.BindEnv("server.port", "MYGO_SERVER_PORT")
	// v.BindEnv("database.host", "MYGO_DB_HOST")
	// v.BindEnv("database.port", "MYGO_DB_PORT")
	// v.BindEnv("database.user", "MYGO_DB_USER")
	// v.BindEnv("database.password", "MYGO_DB_PASSWORD")
}

// parseConfig unmarshals viper config into ServerConfig
func parseConfig(v *viper.Viper) (*ServerConfig, error) {
	config := &ServerConfig{}
	if err := v.Unmarshal(config); err != nil {
		return nil, fmt.Errorf("failed to parse config: %w", err)
	}
	return config, nil
}

// Load config file
func loadConfigFile(v *viper.Viper, configPath string) (*ServerConfig, error) {
	v.SetConfigType("yaml")

	if configPath != "" {
		v.SetConfigFile(configPath)
		if err := v.ReadInConfig(); err != nil {
			return nil, fmt.Errorf("failed to load config file %s: %w", configPath, err)
		}
		return parseConfig(v)
	}

	v.SetConfigName("config")
	configPaths := []string{".", "./config"}
	for _, path := range configPaths {
		v.AddConfigPath(path)
	}

	if err := v.ReadInConfig(); err != nil {
		if _, ok := err.(viper.ConfigFileNotFoundError); ok {
			return nil, nil // No config file found is not an error
		}
		return nil, fmt.Errorf("config file read error: %w", err)
	}
	return parseConfig(v)
}

// LoadConfig is the main entry point for configuration loading
func LoadConfig(configPath string) (*ServerConfig, error) {
	v := viper.New()
	setDefaultConfig(v)

	fileConfig, err := loadConfigFile(v, configPath)
	if err != nil {
		return nil, err
	}

	if fileConfig != nil {
		fmt.Printf("Loaded config from %s\n", v.ConfigFileUsed())
	} else {
		fmt.Println("Using default configuration (no config file found)")
	}

	bindEnvVariables(v)
	return parseConfig(v)
}