package config

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

	"gopkg.in/yaml.v3"

	appErrors "nex/backend/pkg/errors"
)

// Config 应用配置
type Config struct {
	Server   ServerConfig   `yaml:"server"`
	Database DatabaseConfig `yaml:"database"`
	Log      LogConfig      `yaml:"log"`
}

// ServerConfig 服务器配置
type ServerConfig struct {
	Port         int           `yaml:"port"`
	ReadTimeout  time.Duration `yaml:"read_timeout"`
	WriteTimeout time.Duration `yaml:"write_timeout"`
}

// DatabaseConfig 数据库配置
type DatabaseConfig struct {
	Path            string        `yaml:"path"`
	MaxIdleConns    int           `yaml:"max_idle_conns"`
	MaxOpenConns    int           `yaml:"max_open_conns"`
	ConnMaxLifetime time.Duration `yaml:"conn_max_lifetime"`
}

// LogConfig 日志配置
type LogConfig struct {
	Level      string `yaml:"level"`
	Path       string `yaml:"path"`
	MaxSize    int    `yaml:"max_size"`
	MaxBackups int    `yaml:"max_backups"`
	MaxAge     int    `yaml:"max_age"`
	Compress   bool   `yaml:"compress"`
}

// DefaultConfig returns default config values
func DefaultConfig() *Config {
	// Use home dir for default paths
	homeDir, _ := os.UserHomeDir()
	nexDir := filepath.Join(homeDir, ".nex")

	return &Config{
		Server: ServerConfig{
			Port:         9826,
			ReadTimeout:  30 * time.Second,
			WriteTimeout: 30 * time.Second,
		},
		Database: DatabaseConfig{
			Path:            filepath.Join(nexDir, "config.db"),
			MaxIdleConns:    10,
			MaxOpenConns:    100,
			ConnMaxLifetime: 1 * time.Hour,
		},
		Log: LogConfig{
			Level:      "info",
			Path:       filepath.Join(nexDir, "log"),
			MaxSize:    100,
			MaxBackups: 10,
			MaxAge:     30,
			Compress:   true,
		},
	}
}

// GetConfigDir 获取配置目录路径（~/.nex/）
func GetConfigDir() (string, error) {
	homeDir, err := os.UserHomeDir()
	if err != nil {
		return "", err
	}
	configDir := filepath.Join(homeDir, ".nex")
	if err := os.MkdirAll(configDir, 0755); err != nil {
		return "", err
	}
	return configDir, nil
}

// GetDBPath 获取数据库文件路径
func GetDBPath() (string, error) {
	configDir, err := GetConfigDir()
	if err != nil {
		return "", err
	}
	return filepath.Join(configDir, "config.db"), nil
}

// GetConfigPath 获取配置文件路径
func GetConfigPath() (string, error) {
	configDir, err := GetConfigDir()
	if err != nil {
		return "", err
	}
	return filepath.Join(configDir, "config.yaml"), nil
}

// LoadConfig loads config from YAML file, creates default if not exists
func LoadConfig() (*Config, error) {
	configPath, err := GetConfigPath()
	if err != nil {
		return nil, appErrors.Wrap(appErrors.ErrInternal, err)
	}

	cfg := DefaultConfig()

	data, err := os.ReadFile(configPath)
	if err != nil {
		if os.IsNotExist(err) {
			// Create default config file
			if saveErr := SaveConfig(cfg); saveErr != nil {
				return nil, appErrors.WithMessage(appErrors.ErrInternal, "创建默认配置失败")
			}
			return cfg, nil
		}
		return nil, appErrors.Wrap(appErrors.ErrInternal, err)
	}

	if err := yaml.Unmarshal(data, cfg); err != nil {
		return nil, appErrors.Wrap(appErrors.ErrInternal, err)
	}

	return cfg, nil
}

// SaveConfig saves config to YAML file
func SaveConfig(cfg *Config) error {
	configPath, err := GetConfigPath()
	if err != nil {
		return appErrors.Wrap(appErrors.ErrInternal, err)
	}

	data, err := yaml.Marshal(cfg)
	if err != nil {
		return appErrors.Wrap(appErrors.ErrInternal, err)
	}

	// Ensure directory exists
	dir := filepath.Dir(configPath)
	if err := os.MkdirAll(dir, 0755); err != nil {
		return appErrors.Wrap(appErrors.ErrInternal, err)
	}

	return os.WriteFile(configPath, data, 0644)
}

// Validate validates the config
func (c *Config) Validate() error {
	if c.Server.Port < 1 || c.Server.Port > 65535 {
		return appErrors.WithMessage(appErrors.ErrInvalidRequest, fmt.Sprintf("无效的端口号: %d", c.Server.Port))
	}

	validLevels := map[string]bool{"debug": true, "info": true, "warn": true, "error": true}
	if !validLevels[c.Log.Level] {
		return appErrors.WithMessage(appErrors.ErrInvalidRequest, fmt.Sprintf("无效的日志级别: %s", c.Log.Level))
	}

	if c.Database.Path == "" {
		return appErrors.WithMessage(appErrors.ErrInvalidRequest, "数据库路径不能为空")
	}

	return nil
}