package parser

import (
	"encoding/base64"
	"encoding/json"
	"fmt"
	"strconv"
	"strings"

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

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

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

// VMessConfig VMess配置结构
type VMessConfig struct {
	V    string `json:"v"`    // 版本
	PS   string `json:"ps"`   // 备注
	Add  string `json:"add"`  // 服务器地址
	Port string `json:"port"` // 服务器端口
	ID   string `json:"id"`   // 用户ID
	Aid  string `json:"aid"`  // 额外ID (alterId)
	Net  string `json:"net"`  // 传输协议
	Type string `json:"type"` // 伪装类型
	Host string `json:"host"` // 主机名/域名
	Path string `json:"path"` // 路径
	TLS  string `json:"tls"`  // TLS加密
}

// Parse 解析VMess配置
// 支持标准Base64编码格式
func (p *VMessParser) Parse(input string) (*ProxyConfig, error) {
	p.logger.Debugf("Parsing VMess configuration")

	lower := strings.ToLower(input)
	if strings.HasPrefix(lower, "vmess1://") {
		input = "vmess://" + input[len("vmess1://"):]
	}

	// 去除前缀
	input = strings.TrimPrefix(input, "vmess://")

	// 解码Base64
	decoded, err := base64.StdEncoding.DecodeString(input)
	if err != nil {
		// 尝试URL安全的Base64解码
		decoded, err = base64.URLEncoding.DecodeString(input)
		if err != nil {
			return nil, fmt.Errorf("failed to decode VMess configuration: %v", err)
		}
	}

	// 解析JSON配置
	var vmessConfig VMessConfig
	if err := json.Unmarshal(decoded, &vmessConfig); err != nil {
		return nil, fmt.Errorf("failed to parse VMess JSON configuration: %v", err)
	}

	// 验证必要字段
	if vmessConfig.Add == "" || vmessConfig.Port == "" || vmessConfig.ID == "" {
		return nil, fmt.Errorf("invalid VMess configuration: missing required fields")
	}

	config := &ProxyConfig{
		Type:     "vmess",
		Protocol: "vmess",
		Server:   vmessConfig.Add,
	}

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

	// 设置备注
	if vmessConfig.PS != "" {
		config.Name = vmessConfig.PS
	} else {
		config.Name = fmt.Sprintf("vmess-%s:%d", config.Server, config.Port)
	}

	// 创建设置映射
	settings := map[string]interface{}{
		"uuid":    vmessConfig.ID,
		"alterId": p.parseAlterId(vmessConfig.Aid),
		"network": p.parseNetwork(vmessConfig.Net),
		"tls":     p.parseTLS(vmessConfig.TLS),
		"udp":     true,
	}

	// 添加网络特定配置
	switch vmessConfig.Net {
	case "ws":
		settings["wsSettings"] = map[string]interface{}{
			"path": p.parsePath(vmessConfig.Path),
			"headers": map[string]string{
				"Host": p.parseHost(vmessConfig.Host),
			},
		}
	case "http":
		settings["httpSettings"] = map[string]interface{}{
			"path": p.parsePath(vmessConfig.Path),
			"host": []string{p.parseHost(vmessConfig.Host)},
		}
	case "quic":
		settings["quicSettings"] = map[string]interface{}{
			"security": p.parseType(vmessConfig.Type),
			"key":      p.parseHost(vmessConfig.Host),
			"header": map[string]string{
				"type": p.parseType(vmessConfig.Type),
			},
		}
	case "grpc":
		settings["grpcSettings"] = map[string]interface{}{
			"serviceName": p.parsePath(vmessConfig.Path),
			"multiMode":   false,
		}
	}

	config.Settings = settings
	config.UDP = true

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

// parseAlterId 解析额外ID
func (p *VMessParser) parseAlterId(aid string) int {
	if aid == "" {
		return 0
	}
	alterId, err := strconv.Atoi(aid)
	if err != nil {
		p.logger.Warnf("Invalid alterId: %s, using default 0", aid)
		return 0
	}
	return alterId
}

// parseNetwork 解析网络协议
func (p *VMessParser) parseNetwork(net string) string {
	switch net {
	case "tcp", "kcp", "ws", "http", "quic", "grpc":
		return net
	default:
		p.logger.Warnf("Unknown network type: %s, using tcp", net)
		return "tcp"
	}
}

// parseTLS 解析TLS配置
func (p *VMessParser) parseTLS(tls string) string {
	switch tls {
	case "tls", "1", "true":
		return "tls"
	default:
		return "none"
	}
}

// parseType 解析伪装类型
func (p *VMessParser) parseType(typ string) string {
	if typ == "" {
		return "none"
	}
	return typ
}

// parseHost 解析主机名
func (p *VMessParser) parseHost(host string) string {
	if host == "" {
		return ""
	}
	return host
}

// parsePath 解析路径
func (p *VMessParser) parsePath(path string) string {
	if path == "" {
		return "/"
	}
	return path
}

// Validate 验证VMess配置
func (p *VMessParser) Validate(config *ProxyConfig) error {
	p.logger.Debugf("Validating VMess 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)
	}

	uuid := p.getUUID(config)
	if uuid == "" {
		return fmt.Errorf("UUID is required")
	}

	// 验证UUID格式
	if err := p.validateUUID(uuid); err != nil {
		return err
	}

	// 验证网络协议
	network := p.getNetwork(config)
	if err := p.validateNetwork(network); err != nil {
		return err
	}

	// 验证额外ID
	alterId := p.getAlterId(config)
	if err := p.validateAlterId(alterId); err != nil {
		return err
	}

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

// validateUUID 验证UUID格式
func (p *VMessParser) validateUUID(uuid string) error {
	// 简单的UUID格式验证
	if len(uuid) != 36 {
		return fmt.Errorf("invalid UUID length: %d", len(uuid))
	}

	if strings.Count(uuid, "-") != 4 {
		return fmt.Errorf("invalid UUID format: incorrect hyphen count")
	}

	return nil
}

// validateNetwork 验证网络协议
func (p *VMessParser) validateNetwork(network string) error {
	supportedNetworks := []string{"tcp", "kcp", "ws", "http", "quic", "grpc"}

	for _, supported := range supportedNetworks {
		if network == supported {
			return nil
		}
	}

	return fmt.Errorf("unsupported network type: %s", network)
}

// validateAlterId 验证额外ID
func (p *VMessParser) validateAlterId(alterId int) error {
	if alterId < 0 {
		return fmt.Errorf("alterId cannot be negative: %d", alterId)
	}

	if alterId > 65535 {
		return fmt.Errorf("alterId too large: %d", alterId)
	}

	return nil
}

// getUUID 从配置中获取UUID
func (p *VMessParser) getUUID(config *ProxyConfig) string {
	if uuid, exists := config.Settings["uuid"]; exists {
		if uuidStr, ok := uuid.(string); ok {
			return uuidStr
		}
	}
	return ""
}

// getNetwork 从配置中获取网络协议
func (p *VMessParser) getNetwork(config *ProxyConfig) string {
	if network, exists := config.Settings["network"]; exists {
		if networkStr, ok := network.(string); ok {
			return networkStr
		}
	}
	return "tcp"
}

// getAlterId 从配置中获取额外ID
func (p *VMessParser) getAlterId(config *ProxyConfig) int {
	if alterId, exists := config.Settings["alterId"]; exists {
		if alterIdInt, ok := alterId.(int); ok {
			return alterIdInt
		}
		if alterIdFloat, ok := alterId.(float64); ok {
			return int(alterIdFloat)
		}
	}
	return 0
}

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