// Package config 负责加载和管理应用配置
// 使用 viper 从 YAML 配置文件中读取配置项
package config

import (
	"fmt"
	"log"

	"github.com/spf13/viper"
)

// AppConfig 全局配置实例
var AppConfig *Config

// Config 应用配置结构体
type Config struct {
	Server   ServerConfig   `mapstructure:"server"`
	Database DatabaseConfig `mapstructure:"database"`
	JWT      JWTConfig      `mapstructure:"jwt"`
	Storage  StorageConfig  `mapstructure:"storage"`
	Backup   BackupConfig   `mapstructure:"backup"`
}

// BackupConfig 备份工具配置
type BackupConfig struct {
	// MySQL
	MysqlDumpPath string `mapstructure:"mysqldump_path"`
	MysqlPath     string `mapstructure:"mysql_path"`
	// PostgreSQL
	PgDumpPath string `mapstructure:"pgdump_path"`
	PsqlPath   string `mapstructure:"psql_path"`
	// SQL Server
	SqlCmdPath string `mapstructure:"sqlcmd_path"`
}

// ServerConfig 服务器配置
type ServerConfig struct {
	Port      int    `mapstructure:"port"`
	Mode      string `mapstructure:"mode"`        // debug / release
	PublicURL string `mapstructure:"public_url"`  // 公网访问地址, 如 http://files.example.com
}

// DatabaseConfig 数据库配置
type DatabaseConfig struct {
	Type     string `mapstructure:"type"`     // 数据库类型: mysql / sqlserver / postgres
	Host     string `mapstructure:"host"`
	Port     int    `mapstructure:"port"`
	Username string `mapstructure:"username"`
	Password string `mapstructure:"password"`
	DBName   string `mapstructure:"dbname"`
}

// DSN 返回数据库连接字符串(根据类型生成不同格式)
func (d *DatabaseConfig) DSN() string {
	switch d.Type {
	case "sqlserver":
		// SQL Server: sqlserver://user:pass@host:port?database=db名
		return fmt.Sprintf("sqlserver://%s:%s@%s:%d?database=%s",
			d.Username, d.Password, d.Host, d.Port, d.DBName)
	case "postgres":
		// PostgreSQL: host=localhost port=5432 user=x password=x dbname=x sslmode=disable
		return fmt.Sprintf("host=%s port=%d user=%s password=%s dbname=%s sslmode=disable TimeZone=Asia/Shanghai",
			d.Host, d.Port, d.Username, d.Password, d.DBName)
	default:
		// MySQL: user:pass@tcp(host:port)/dbname?charset=utf8mb4&parseTime=True&loc=Local
		return fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=utf8mb4&parseTime=True&loc=Local",
			d.Username, d.Password, d.Host, d.Port, d.DBName)
	}
}

// JWTConfig JWT配置
type JWTConfig struct {
	Secret     string `mapstructure:"secret"`
	Expiration int    `mapstructure:"expiration"` // 过期时间(小时)
}

// StorageConfig 存储配置
type StorageConfig struct {
	DefaultPolicyID uint   `mapstructure:"default_policy_id"`
	LocalBasePath   string `mapstructure:"local_base_path"`
	CDNHost         string `mapstructure:"cdn_host"` // CDN地址, 如 http://localhost:3090
	CDNPathPrefix   string `mapstructure:"cdn_path_prefix"` // CDN路径前缀, 如 /public
}

// Load 加载配置文件
// 配置文件搜索路径: ./config.yaml, ./config/config.yaml
// 支持环境变量覆盖: SERVER_PORT, SERVER_MODE, DB_HOST, DB_PORT, DB_PASSWORD, DB_NAME 等
func Load() (*Config, error) {
	viper.SetConfigName("config")
	viper.SetConfigType("yaml")
	viper.AddConfigPath(".")
	viper.AddConfigPath("./config")
	viper.AddConfigPath("./server")

	// 设置默认值
	setDefaults()

	// 读取配置文件
	if err := viper.ReadInConfig(); err != nil {
		if _, ok := err.(viper.ConfigFileNotFoundError); !ok {
			return nil, fmt.Errorf("读取配置文件失败: %w", err)
		}
		log.Println("未找到配置文件, 使用默认配置")
	}

	// 支持环境变量覆盖(优先级: 环境变量 > 配置文件 > 默认值)
	viper.SetEnvPrefix("FS")
	viper.AutomaticEnv()

	// 环境变量映射
	viper.BindEnv("server.port", "FS_SERVER_PORT")
	viper.BindEnv("server.mode", "FS_SERVER_MODE")
	viper.BindEnv("server.public_url", "FS_PUBLIC_URL")
	viper.BindEnv("database.type", "FS_DB_TYPE")
	viper.BindEnv("database.host", "FS_DB_HOST")
	viper.BindEnv("database.port", "FS_DB_PORT")
	viper.BindEnv("database.username", "FS_DB_USER")
	viper.BindEnv("database.password", "FS_DB_PASSWORD")
	viper.BindEnv("database.dbname", "FS_DB_NAME")
	viper.BindEnv("jwt.secret", "FS_JWT_SECRET")

	AppConfig = &Config{}
	if err := viper.Unmarshal(AppConfig); err != nil {
		return nil, fmt.Errorf("解析配置失败: %w", err)
	}

	return AppConfig, nil
}

// setDefaults 设置配置默认值
func setDefaults() {
	// 服务器默认配置
	viper.SetDefault("server.port", 8080)
	viper.SetDefault("server.mode", "debug")

	// 数据库默认配置
	viper.SetDefault("database.type", "mysql")
	viper.SetDefault("database.host", "127.0.0.1")
	viper.SetDefault("database.port", 3306)
	viper.SetDefault("database.username", "root")
	viper.SetDefault("database.password", "root")
	viper.SetDefault("database.dbname", "seeyon_fs")

	// JWT默认配置
	viper.SetDefault("jwt.secret", "seeyon-filesystem-jwt-secret-key-2024")
	viper.SetDefault("jwt.expiration", 24)

	// 存储默认配置
	viper.SetDefault("storage.default_policy_id", 1)
	viper.SetDefault("storage.local_base_path", "./data/storage")
	viper.SetDefault("storage.cdn_host", "")
	viper.SetDefault("storage.cdn_path_prefix", "/public")
}