package memcached

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

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

// MemcachedConnection Memcached连接包装器
type MemcachedConnection struct {
	client net.Conn
	target string
}

// MemcachedConnector Memcached连接器实现
type MemcachedConnector struct {
	host string
	port string
}

// NewMemcachedConnector 创建Memcached连接器
func NewMemcachedConnector() *MemcachedConnector {
	return &MemcachedConnector{}
}

// Connect 连接到Memcached服务
func (c *MemcachedConnector) Connect(ctx context.Context, info *common.HostInfo) (interface{}, error) {
	c.host = info.Host
	c.port = info.Ports
	
	target := fmt.Sprintf("%s:%s", c.host, c.port)
	timeout := time.Duration(common.Timeout) * time.Second
	
	// 建立TCP连接
	client, err := common.WrapperTcpWithTimeout("tcp", target, timeout)
	if err != nil {
		return nil, fmt.Errorf("Memcached连接失败: %v", err)
	}
	
	return &MemcachedConnection{
		client: client,
		target: target,
	}, nil
}

// Authenticate 认证 - Memcached通常无认证，检查未授权访问
func (c *MemcachedConnector) Authenticate(ctx context.Context, conn interface{}, cred *base.Credential) error {
	memcachedConn, ok := conn.(*MemcachedConnection)
	if !ok {
		return fmt.Errorf("无效的连接类型")
	}
	
	// 在goroutine中进行操作，支持Context取消
	resultChan := make(chan error, 1)
	
	go func() {
		// 设置操作超时
		timeout := time.Duration(common.Timeout) * time.Second
		if err := memcachedConn.client.SetDeadline(time.Now().Add(timeout)); err != nil {
			resultChan <- fmt.Errorf("设置超时失败: %v", err)
			return
		}
		
		// 发送stats命令测试连接
		if _, err := memcachedConn.client.Write([]byte("stats\n")); err != nil {
			resultChan <- fmt.Errorf("发送命令失败: %v", err)
			return
		}
		
		// 读取响应
		buffer := make([]byte, 1024)
		n, err := memcachedConn.client.Read(buffer)
		if err != nil {
			resultChan <- fmt.Errorf("读取响应失败: %v", err)
			return
		}
		
		// 检查响应是否包含Memcached统计信息
		response := string(buffer[:n])
		if strings.Contains(response, "STAT") {
			// 未授权访问成功
			resultChan <- nil
			return
		}
		
		resultChan <- fmt.Errorf("Memcached服务无响应或不可访问")
	}()
	
	// 等待操作结果或Context取消
	select {
	case err := <-resultChan:
		return err
	case <-ctx.Done():
		return fmt.Errorf("Memcached操作超时: %v", ctx.Err())
	}
}

// Close 关闭连接
func (c *MemcachedConnector) Close(conn interface{}) error {
	if memcachedConn, ok := conn.(*MemcachedConnection); ok && memcachedConn.client != nil {
		return memcachedConn.client.Close()
	}
	return nil
}