package services

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

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

type SMTPPlugin struct {
	plugins.BasePlugin
}

func NewSMTPPlugin() *SMTPPlugin {
	return &SMTPPlugin{
		BasePlugin: plugins.NewBasePlugin("smtp"),
	}
}



func (p *SMTPPlugin) Scan(ctx context.Context, info *common.HostInfo) *plugins.Result {
	target := fmt.Sprintf("%s:%s", info.Host, info.Ports)

	if common.DisableBrute {
		return p.identifyService(ctx, info)
	}

	// 首先测试匿名访问（最重要！）
	if p.testCredential(ctx, info, plugins.Credential{Username: "", Password: ""}) {
		common.LogSuccess(fmt.Sprintf("SMTP服务 %s 允许匿名访问", target))
		return &plugins.Result{
			Success: true,
			Service: "smtp",
			Banner:  "允许匿名访问",
		}
	}

	// 检查开放中继
	if result := p.testOpenRelay(ctx, info); result != nil && result.Success {
		common.LogSuccess(fmt.Sprintf("SMTP %s 开放中继", target))
		return result
	}

	credentials := plugins.GenerateCredentials("smtp")
	if len(credentials) == 0 {
		return &plugins.Result{
			Success: false,
			Service: "smtp",
			Error:   fmt.Errorf("没有可用的测试凭据"),
		}
	}

	for _, cred := range credentials {
		// 检查上下文是否已取消
		select {
		case <-ctx.Done():
			return &plugins.Result{
				Success: false,
				Service: "smtp",
				Error:   ctx.Err(),
			}
		default:
		}

		if p.testCredential(ctx, info, cred) {
			common.LogSuccess(fmt.Sprintf("SMTP %s %s:%s", target, cred.Username, cred.Password))
			return &plugins.Result{
				Success:  true,
				Service:  "smtp",
				Username: cred.Username,
				Password: cred.Password,
			}
		}
	}

	return &plugins.Result{
		Success: false,
		Service: "smtp",
		Error:   fmt.Errorf("未发现弱密码"),
	}
}


func (p *SMTPPlugin) testOpenRelay(ctx context.Context, info *common.HostInfo) *plugins.Result {
	target := fmt.Sprintf("%s:%s", info.Host, info.Ports)
	
	// 检查发包限制
	if canSend, reason := common.CanSendPacket(); !canSend {
		common.LogError(fmt.Sprintf("SMTP连接 %s 受限: %s", target, reason))
		return nil
	}
	
	// 设置超时的Dialer
	dialer := &net.Dialer{
		Timeout: time.Duration(common.Timeout) * time.Second,
	}
	
	conn, err := dialer.DialContext(ctx, "tcp", target)
	if err == nil {
		common.IncrementTCPSuccessPacketCount()
	} else {
		common.IncrementTCPFailedPacketCount()
	}
	if err != nil {
		return nil
	}
	defer conn.Close()
	
	client, err := smtp.NewClient(conn, info.Host)
	if err != nil {
		return nil
	}
	defer client.Quit()

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

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

	if err := client.Rcpt("external@example.com"); err != nil {
		return nil
	}

	return &plugins.Result{
		Success: true,
		Service: "smtp",
		Banner:  "开放中继",
	}
}

func (p *SMTPPlugin) testCredential(ctx context.Context, info *common.HostInfo, cred plugins.Credential) bool {
	target := fmt.Sprintf("%s:%s", info.Host, info.Ports)
	timeout := time.Duration(common.Timeout) * time.Second
	
	common.LogDebug(fmt.Sprintf("SMTP测试凭据: %s:%s", cred.Username, cred.Password))
	
	// 检查发包限制
	if canSend, reason := common.CanSendPacket(); !canSend {
		common.LogError(fmt.Sprintf("SMTP凭据测试 %s 受限: %s", target, reason))
		return false
	}

	// 设置连接超时
	dialer := &net.Dialer{
		Timeout: timeout,
	}
	
	conn, err := dialer.DialContext(ctx, "tcp", target)
	if err == nil {
		common.IncrementTCPSuccessPacketCount()
	} else {
		common.IncrementTCPFailedPacketCount()
	}
	if err != nil {
		common.LogDebug(fmt.Sprintf("SMTP连接失败: %v", err))
		return false
	}
	defer conn.Close()
	
	// 设置读写超时
	conn.SetDeadline(time.Now().Add(timeout))
	
	client, err := smtp.NewClient(conn, info.Host)
	if err != nil {
		common.LogDebug(fmt.Sprintf("SMTP客户端创建失败: %v", err))
		return false
	}
	defer client.Close()

	// 如果有用户名密码，则尝试认证
	if cred.Username != "" {
		auth := smtp.PlainAuth("", cred.Username, cred.Password, info.Host)
		if err := client.Auth(auth); err != nil {
			common.LogDebug(fmt.Sprintf("SMTP认证失败 %s:%s - %v", cred.Username, cred.Password, err))
			return false
		}
	}

	// 尝试发送邮件测试权限（仿照原版）
	if err := client.Mail("test@test.com"); err != nil {
		common.LogDebug(fmt.Sprintf("SMTP Mail命令失败 %s:%s - %v", cred.Username, cred.Password, err))
		return false
	}

	common.LogDebug(fmt.Sprintf("SMTP认证成功: %s:%s", cred.Username, cred.Password))
	return true
}


func (p *SMTPPlugin) getServerInfo(ctx context.Context, info *common.HostInfo) string {
	target := fmt.Sprintf("%s:%s", info.Host, info.Ports)
	
	// 使用统一TCP包装器
	conn, err := common.SafeTCPDial(target, time.Duration(common.Timeout)*time.Second)
	if err != nil {
		return ""
	}
	defer conn.Close()

	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
}

func (p *SMTPPlugin) identifyService(ctx context.Context, info *common.HostInfo) *plugins.Result {
	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 {
		// 使用统一TCP包装器进行简单连接测试
		conn, err := common.SafeTCPDial(target, time.Duration(common.Timeout)*time.Second)
		if err != nil {
			return &plugins.Result{
				Success: false,
				Service: "smtp",
				Error:   err,
			}
		}
		defer conn.Close()
		banner = "SMTP邮件服务"
	}

	common.LogSuccess(fmt.Sprintf("SMTP %s %s", target, banner))

	return &plugins.Result{
		Success: true,
		Service: "smtp",
		Banner:  banner,
	}
}

func init() {
	plugins.RegisterWithPorts("smtp", func() plugins.Plugin {
		return NewSMTPPlugin()
	}, []int{25, 465, 587, 2525})
}