package parser

import (
	"fmt"
	"net/url"
	"strconv"
	"strings"

	"github.com/subconverter-go/internal/logging"
)

// Socks5Parser Socks5协议解析器
// 实现Socks5代理配置的解析功能
type Socks5Parser struct {
	logger *logging.Logger
}

// NewSocks5Parser 创建新的Socks5解析器
// 返回初始化好的Socks5Parser实例
func NewSocks5Parser(logger *logging.Logger) *Socks5Parser {
	return &Socks5Parser{
		logger: logger,
	}
}

// Parse 解析Socks5配置
// 支持标准URL格式
func (p *Socks5Parser) Parse(input string) (*ProxyConfig, error) {
	p.logger.Debugf("Parsing Socks5 configuration")

	normalized, err := p.normalizeInput(input)
	if err != nil {
		return nil, err
	}

	// 去除前缀
	trimmed := strings.TrimPrefix(normalized, "socks5://")

	// 解析URL
	parsedURL, err := url.Parse("socks5://" + trimmed)
	if err != nil {
		return nil, fmt.Errorf("failed to parse Socks5 URL: %v", err)
	}

	config := &ProxyConfig{
		Type:     "socks5",
		Protocol: "socks5",
		Server:   parsedURL.Hostname(),
	}

	// 解析端口
	port, err := strconv.Atoi(parsedURL.Port())
	if err != nil {
		return nil, fmt.Errorf("invalid port number: %v", err)
	}
	config.Port = port

	// 解析用户名和密码
	var username, password string
	if parsedURL.User != nil {
		username = parsedURL.User.Username()
		password, _ = parsedURL.User.Password()
	}

	// 解析备注
	if parsedURL.Fragment != "" {
		config.Name = parsedURL.Fragment
	} else {
		config.Name = fmt.Sprintf("socks5-%s:%d", config.Server, config.Port)
	}

	// 创建设置映射
	settings := map[string]interface{}{
		"udp": true,
	}

	// 添加认证信息
	if username != "" {
		settings["username"] = username
		if password != "" {
			settings["password"] = password
		}
	}

	config.Settings = settings
	config.UDP = true

	p.logger.Infof("Successfully parsed Socks5 configuration for server: %s:%d", config.Server, config.Port)
	return config, nil
}

func (p *Socks5Parser) normalizeInput(input string) (string, error) {
	trimmed := strings.TrimSpace(input)
	if trimmed == "" {
		return "", fmt.Errorf("empty socks proxy string")
	}

	lower := strings.ToLower(trimmed)

	switch {
	case strings.HasPrefix(lower, "socks5://"):
		return trimmed, nil
	case strings.HasPrefix(lower, "socks://"):
		return "socks5://" + trimmed[len("socks://"):], nil
	case strings.HasPrefix(lower, "tg://socks"), strings.HasPrefix(lower, "https://t.me/socks"):
		return p.normalizeTelegramLink(trimmed)
	default:
		return trimmed, nil
	}
}

func (p *Socks5Parser) normalizeTelegramLink(link string) (string, error) {
	parsed, err := url.Parse(link)
	if err != nil {
		return "", fmt.Errorf("failed to parse Telegram socks link: %w", err)
	}

	values := parsed.Query()
	host := values.Get("server")
	if host == "" {
		host = values.Get("host")
	}
	port := values.Get("port")
	if port == "" {
		return "", fmt.Errorf("missing port in Telegram socks link")
	}

	username := values.Get("user")
	if username == "" {
		username = values.Get("username")
	}
	password := values.Get("pass")
	if password == "" {
		password = values.Get("password")
	}

	if host == "" {
		return "", fmt.Errorf("missing server in Telegram socks link")
	}

	credentials := ""
	if username != "" {
		var userInfo *url.Userinfo
		if password != "" {
			userInfo = url.UserPassword(username, password)
		} else {
			userInfo = url.User(username)
		}
		credentials = userInfo.String() + "@"
	}

	fragment := parsed.Fragment
	if fragment != "" {
		fragment = "#" + fragment
	}

	return fmt.Sprintf("socks5://%s%s:%s%s", credentials, host, port, fragment), nil
}

// Validate 验证Socks5配置
func (p *Socks5Parser) Validate(config *ProxyConfig) error {
	p.logger.Debugf("Validating Socks5 configuration")

	// 检查必要字段
	if config.Server == "" {
		return fmt.Errorf("server address is required")
	}

	if config.Port <= 0 || config.Port > 65535 {
		return fmt.Errorf("invalid port number: %d", config.Port)
	}

	// 验证认证信息
	username := p.getUsername(config)
	password := p.getPassword(config)

	// 如果提供了用户名，验证密码是否也提供
	if username != "" && password == "" {
		p.logger.Warn("Username provided but password is empty")
	}

	// 如果没有提供用户名，确保也没有密码
	if username == "" && password != "" {
		return fmt.Errorf("password provided without username")
	}

	p.logger.Debug("Socks5 configuration validation passed")
	return nil
}

// getUsername 从配置中获取用户名
func (p *Socks5Parser) getUsername(config *ProxyConfig) string {
	if username, exists := config.Settings["username"]; exists {
		if usernameStr, ok := username.(string); ok {
			return usernameStr
		}
	}
	return ""
}

// getPassword 从配置中获取密码
func (p *Socks5Parser) getPassword(config *ProxyConfig) string {
	if password, exists := config.Settings["password"]; exists {
		if passwordStr, ok := password.(string); ok {
			return passwordStr
		}
	}
	return ""
}

// GetSupportedProtocols 获取支持的协议
func (p *Socks5Parser) GetSupportedProtocols() []string {
	return []string{"socks5"}
}