package config

import (
	"fmt"
	"os"
	"path/filepath"
	"sync"

	"gopkg.in/yaml.v2"
)

// Config 应用配置
type Config struct {
	Database DBConfig `yaml:"database"`
	Auth     Auth     `yaml:"auth"`
	Service  Service  `yaml:"service"`
}

// DBConfig 数据库配置
type DBConfig struct {
	Type            string `yaml:"type"`
	Host            string `yaml:"host"`
	Port            int    `yaml:"port"`
	Username        string `yaml:"username"`
	Password        string `yaml:"password"`
	Database        string `yaml:"database"`
	MaxOpenConns    int    `yaml:"max_open_conns"`
	MaxIdleConns    int    `yaml:"max_idle_conns"`
	ConnMaxLifetime int    `yaml:"conn_max_lifetime"` // 单位：秒
}

// Auth 认证配置
type Auth struct {
	Token string `yaml:"token"`
}

// Service 微服务配置
type Service struct {
	ReadTimeout  int `yaml:"read_timeout"`
	WriteTimeout int `yaml:"write_timeout"`
	IdleTimeout  int `yaml:"idle_timeout"`
}

// 导出接口，防止外部修改
type IConfig interface {
	GetDatabase() DBConfig
	GetAuth() Auth
	GetService() Service
	IsDatabaseConfigured() bool
}

// 实现接口的具体类型
type configWrapper struct {
	config *Config
}

func (cw *configWrapper) GetDatabase() DBConfig {
	return cw.config.Database
}

func (cw *configWrapper) GetAuth() Auth {
	return cw.config.Auth
}

func (cw *configWrapper) GetService() Service {
	return cw.config.Service
}

func (cw *configWrapper) IsDatabaseConfigured() bool {
	return cw.config.Database.Type != "" &&
		cw.config.Database.Host != "" &&
		cw.config.Database.Port > 0 &&
		cw.config.Database.Username != "" &&
		cw.config.Database.Database != ""
}

func (cw *configWrapper) IsAuthConfigured() bool {
	return cw.config.Auth.Token != ""
}

func (cw *configWrapper) IsServiceConfigured() bool {
	return cw.config.Service.ReadTimeout > 0 &&
		cw.config.Service.WriteTimeout > 0 &&
		cw.config.Service.IdleTimeout > 0

}

var (
	instance IConfig
	once     sync.Once
	initErr  error
)

// GetConfig 获取配置单例实例
func GetConfig() IConfig {
	once.Do(func() {
		config, err := loadConfig()
		if err != nil {
			initErr = err
			// 创建一个空的配置实例，避免nil指针
			instance = &configWrapper{config: &Config{}}
			return
		}
		instance = &configWrapper{config: config}
	})
	return instance
}

// GetInitError 获取初始化错误（如果有）
func GetInitError() error {
	return initErr
}

// loadConfig 加载配置文件
func loadConfig() (*Config, error) {
	configFile, err := findConfigFile()
	if err != nil {
		return nil, err
	}

	fmt.Printf("✅ Using config file: %s\n", configFile)

	// 读取配置文件
	data, err := os.ReadFile(configFile)
	if err != nil {
		return nil, fmt.Errorf("failed to read config file %s: %v", configFile, err)
	}

	var config Config
	err = yaml.Unmarshal(data, &config)
	if err != nil {
		return nil, fmt.Errorf("failed to parse config file: %v", err)
	}

	return &config, nil
}

// findConfigFile 查找配置文件
func findConfigFile() (string, error) {
	// 1. 首先尝试可执行文件同目录
	exePath, err := os.Executable()
	if err == nil {
		exeDir := filepath.Dir(exePath)
		configFile := filepath.Join(exeDir, "db.yaml")
		if _, err := os.Stat(configFile); err == nil {
			return configFile, nil
		}
	}

	// 2. 尝试环境变量指定的路径
	envConfigPath := os.Getenv("DB_CONFIG_PATH")
	if envConfigPath != "" {
		if _, err := os.Stat(envConfigPath); err == nil {
			return envConfigPath, nil
		}
		return "", fmt.Errorf("DB_CONFIG_PATH file not found: %s", envConfigPath)
	}

	// 3. 如果都没有找到，返回错误
	exeDir := "unknown"
	if exePath, err := os.Executable(); err == nil {
		exeDir = filepath.Dir(exePath)
	}

	return "", fmt.Errorf(`No configuration file found!

Tried locations:
1. Executable directory: %s/db.yaml
2. Environment variable: DB_CONFIG_PATH

Solutions:
- Place db.yaml in the same directory as the executable
- Or set DB_CONFIG_PATH environment variable to config file path

Example:
  export DB_CONFIG_PATH=/path/to/your/db.yaml`, exeDir)
}