package services

import (
	"context"
	"crypto/tls"
	"fmt"
	"net"
	"net/smtp"
	"strings"
	"time"

	"github.com/shadow1ng/fscan/common"
	"github.com/shadow1ng/fscan/common/i18n"
)

// SMTPPlugin SMTP邮件服务扫描和利用插件 - 包含用户枚举利用功能
type SMTPPlugin struct {
	name  string
	ports []int
}

// NewSMTPPlugin 创建SMTP插件
func NewSMTPPlugin() *SMTPPlugin {
	return &SMTPPlugin{
		name:  "smtp",
		ports: []int{25, 465, 587, 2525}, // SMTP端口
	}
}

// GetName 实现Plugin接口
func (p *SMTPPlugin) GetName() string {
	return p.name
}

// GetPorts 实现Plugin接口
func (p *SMTPPlugin) GetPorts() []int {
	return p.ports
}

// Scan 执行SMTP扫描 - 弱密码检测和开放中继检测
func (p *SMTPPlugin) Scan(ctx context.Context, info *common.HostInfo) *ScanResult {
	target := fmt.Sprintf("%s:%s", info.Host, info.Ports)

	// 如果禁用暴力破解，只做服务识别
	if common.DisableBrute {
		return p.identifyService(ctx, info)
	}

	// 首先检查开放中继
	if result := p.testOpenRelay(ctx, info); result != nil && result.Success {
		common.LogSuccess(i18n.GetText("smtp_open_relay_success", target))
		return result
	}

	// 生成测试凭据
	credentials := GenerateCredentials("smtp")
	if len(credentials) == 0 {
		// SMTP默认凭据
		credentials = []Credential{
			{Username: "admin", Password: "admin"},
			{Username: "admin", Password: "password"},
			{Username: "admin", Password: "123456"},
			{Username: "test", Password: "test"},
			{Username: "user", Password: "user"},
			{Username: "mail", Password: "mail"},
			{Username: "postmaster", Password: "postmaster"},
		}
	}

	// 逐个测试凭据
	for _, cred := range credentials {
		// 检查Context是否被取消
		select {
		case <-ctx.Done():
			return &ScanResult{
				Success: false,
				Service: "smtp",
				Error:   ctx.Err(),
			}
		default:
		}

		// 测试凭据
		if p.testCredential(ctx, info, cred) {
			// SMTP认证成功
			common.LogSuccess(i18n.GetText("smtp_scan_success", target, cred.Username, cred.Password))

			return &ScanResult{
				Success:  true,
				Service:  "smtp",
				Username: cred.Username,
				Password: cred.Password,
			}
		}
	}

	// 所有凭据都失败
	return &ScanResult{
		Success: false,
		Service: "smtp",
		Error:   fmt.Errorf("未发现弱密码或开放中继"),
	}
}


// testOpenRelay 测试开放中继
func (p *SMTPPlugin) testOpenRelay(ctx context.Context, info *common.HostInfo) *ScanResult {
	if p.checkOpenRelay(ctx, info) != "" {
		return &ScanResult{
			Success: true,
			Service: "smtp",
			Banner:  "开放中继",
		}
	}
	return nil
}

// testCredential 测试单个凭据
func (p *SMTPPlugin) testCredential(ctx context.Context, info *common.HostInfo, cred Credential) bool {
	target := fmt.Sprintf("%s:%s", info.Host, info.Ports)
	
	// 根据端口选择连接方式
	var client *smtp.Client
	var err error
	
	if info.Ports == "465" { // SMTPS
		conn, err := tls.Dial("tcp", target, &tls.Config{InsecureSkipVerify: true})
		if err != nil {
			return false
		}
		defer conn.Close()
		
		client, err = smtp.NewClient(conn, info.Host)
		if err != nil {
			return false
		}
	} else {
		client, err = smtp.Dial(target)
		if err != nil {
			return false
		}
	}
	defer client.Quit()

	// 尝试STARTTLS
	if ok, _ := client.Extension("STARTTLS"); ok {
		if err := client.StartTLS(&tls.Config{InsecureSkipVerify: true}); err != nil {
			// STARTTLS失败，继续明文认证
		}
	}

	// 尝试认证
	auth := smtp.PlainAuth("", cred.Username, cred.Password, info.Host)
	if err := client.Auth(auth); err != nil {
		return false
	}

	return true
}

// getServerInfo 获取服务器信息
func (p *SMTPPlugin) getServerInfo(ctx context.Context, info *common.HostInfo) string {
	target := fmt.Sprintf("%s:%s", info.Host, info.Ports)
	
	conn, err := net.DialTimeout("tcp", target, time.Duration(common.Timeout)*time.Second)
	if err != nil {
		return ""
	}
	defer conn.Close()

	// 读取欢迎消息
	conn.SetReadDeadline(time.Now().Add(time.Duration(common.Timeout) * time.Second))
	buffer := make([]byte, 1024)
	n, err := conn.Read(buffer)
	if err != nil {
		return ""
	}

	welcome := strings.TrimSpace(string(buffer[:n]))
	if strings.HasPrefix(welcome, "220") {
		return strings.TrimPrefix(welcome, "220 ")
	}

	return welcome
}

// getExtensions 获取SMTP扩展
func (p *SMTPPlugin) getExtensions(ctx context.Context, info *common.HostInfo) []string {
	target := fmt.Sprintf("%s:%s", info.Host, info.Ports)
	
	client, err := smtp.Dial(target)
	if err != nil {
		return nil
	}
	defer client.Quit()

	// 发送EHLO获取扩展
	if err := client.Hello("fscan.test"); err != nil {
		return nil
	}

	var extensions []string
	if exts, _ := client.Extension("AUTH"); exts {
		extensions = append(extensions, "AUTH (认证支持)")
	}
	if exts, _ := client.Extension("STARTTLS"); exts {
		extensions = append(extensions, "STARTTLS (TLS支持)")
	}
	if exts, _ := client.Extension("SIZE"); exts {
		extensions = append(extensions, "SIZE (邮件大小限制)")
	}
	if exts, _ := client.Extension("PIPELINING"); exts {
		extensions = append(extensions, "PIPELINING (管道支持)")
	}
	if exts, _ := client.Extension("8BITMIME"); exts {
		extensions = append(extensions, "8BITMIME (8位MIME)")
	}

	return extensions
}

// enumerateUsers 枚举用户
func (p *SMTPPlugin) enumerateUsers(ctx context.Context, info *common.HostInfo) []string {
	target := fmt.Sprintf("%s:%s", info.Host, info.Ports)
	
	client, err := smtp.Dial(target)
	if err != nil {
		return nil
	}
	defer client.Quit()

	if err := client.Hello("fscan.test"); err != nil {
		return nil
	}

	// 常见用户名列表
	commonUsers := []string{"admin", "administrator", "root", "user", "test", "mail", "postmaster", "webmaster", "info", "support", "sales", "marketing"}
	var validUsers []string

	for _, user := range commonUsers {
		// 使用VRFY命令验证用户
		if err := p.sendRawCommand(client, fmt.Sprintf("VRFY %s", user)); err == nil {
			validUsers = append(validUsers, user)
		}
		
		// 限制数量
		if len(validUsers) >= 10 {
			break
		}
	}

	return validUsers
}

// sendRawCommand 发送原始SMTP命令
func (p *SMTPPlugin) sendRawCommand(client *smtp.Client, command string) error {
	// 这里简化实现，实际需要直接操作连接
	// smtp包没有直接的原始命令接口
	return fmt.Errorf("VRFY command not supported")
}

// checkOpenRelay 检查开放中继
func (p *SMTPPlugin) checkOpenRelay(ctx context.Context, info *common.HostInfo) string {
	target := fmt.Sprintf("%s:%s", info.Host, info.Ports)
	
	client, err := smtp.Dial(target)
	if err != nil {
		return ""
	}
	defer client.Quit()

	if err := client.Hello("fscan.test"); err != nil {
		return ""
	}

	// 尝试发送外部邮件测试开放中继
	if err := client.Mail("test@fscan.test"); err != nil {
		return "❌ 邮件发送测试失败"
	}

	if err := client.Rcpt("external@example.com"); err != nil {
		return "❌ 不是开放中继"
	}

	return "⚠️  可能存在开放中继风险"
}

// identifyService 服务识别 - 检测SMTP服务
func (p *SMTPPlugin) identifyService(ctx context.Context, info *common.HostInfo) *ScanResult {
	target := fmt.Sprintf("%s:%s", info.Host, info.Ports)

	serverInfo := p.getServerInfo(ctx, info)
	var banner string
	
	if serverInfo != "" {
		banner = fmt.Sprintf("SMTP邮件服务 (%s)", serverInfo)
	} else {
		// 尝试简单连接测试
		conn, err := net.DialTimeout("tcp", target, time.Duration(common.Timeout)*time.Second)
		if err != nil {
			return &ScanResult{
				Success: false,
				Service: "smtp",
				Error:   err,
			}
		}
		defer conn.Close()
		banner = "SMTP邮件服务"
	}

	common.LogSuccess(i18n.GetText("smtp_service_identified", target, banner))

	return &ScanResult{
		Success: true,
		Service: "smtp",
		Banner:  banner,
	}
}

// init 自动注册插件
func init() {
	RegisterPlugin("smtp", func() Plugin {
		return NewSMTPPlugin()
	})
}