package mssql

import (
	"context"
	"database/sql"
	"fmt"
	"net"
	"strings"
	"time"

	mssqlDriver "github.com/denisenkom/go-mssqldb"
	"github.com/shadow1ng/fscan/common"
	"github.com/shadow1ng/fscan/plugins/base"
)

// MSSQLProxyDialer 自定义MSSQL代理拨号器
type MSSQLProxyDialer struct {
	timeout time.Duration
}

// DialContext 实现mssql.Dialer接口，支持socks代理
func (d *MSSQLProxyDialer) DialContext(ctx context.Context, network, addr string) (net.Conn, error) {
	return common.WrapperTcpWithContext(ctx, network, addr)
}

// MSSQLConnection MSSQL连接包装器
type MSSQLConnection struct {
	db     *sql.DB
	target string
	info   string
}

// MSSQLConnector MSSQL连接器实现
type MSSQLConnector struct{}

// NewMSSQLConnector 创建MSSQL连接器
func NewMSSQLConnector() *MSSQLConnector {
	return &MSSQLConnector{}
}

// Connect 连接到MSSQL服务器（不进行认证）
func (c *MSSQLConnector) Connect(ctx context.Context, info *common.HostInfo) (interface{}, error) {
	target := fmt.Sprintf("%s:%s", info.Host, info.Ports)
	timeout := time.Duration(common.Timeout) * time.Second
	
	// 尝试建立连接但不进行认证，使用空凭据进行连接尝试
	db, dbInfo, err := c.createConnection(ctx, info.Host, info.Ports, "", "", timeout)
	if err != nil {
		// 检查是否是MSSQL服务相关错误
		if c.isMSSQLError(err) {
			// 即使连接失败，但可以识别为MSSQL服务
			return &MSSQLConnection{
				db:     nil,
				target: target,
				info:   "Microsoft SQL Server (Service Detected)",
			}, nil
		}
		return nil, err
	}
	
	return &MSSQLConnection{
		db:     db,
		target: target,
		info:   dbInfo,
	}, nil
}

// Authenticate 使用凭据进行认证
func (c *MSSQLConnector) Authenticate(ctx context.Context, conn interface{}, cred *base.Credential) error {
	mssqlConn, ok := conn.(*MSSQLConnection)
	if !ok {
		return fmt.Errorf("invalid connection type")
	}
	
	// 解析目标地址
	parts := strings.Split(mssqlConn.target, ":")
	if len(parts) != 2 {
		return fmt.Errorf("invalid target format")
	}
	
	host := parts[0]
	port := parts[1]
	timeout := time.Duration(common.Timeout) * time.Second
	
	// 使用提供的凭据创建新连接
	db, info, err := c.createConnection(ctx, host, port, cred.Username, cred.Password, timeout)
	if err != nil {
		return err
	}
	
	// 更新连接信息
	if mssqlConn.db != nil {
		mssqlConn.db.Close()
	}
	mssqlConn.db = db
	mssqlConn.info = info
	
	return nil
}

// Close 关闭连接
func (c *MSSQLConnector) Close(conn interface{}) error {
	if mssqlConn, ok := conn.(*MSSQLConnection); ok && mssqlConn.db != nil {
		return mssqlConn.db.Close()
	}
	return nil
}

// createConnection 创建MSSQL数据库连接
func (c *MSSQLConnector) createConnection(ctx context.Context, host, port, username, password string, timeout time.Duration) (*sql.DB, string, error) {
	// 构造连接字符串
	connStr := fmt.Sprintf(
		"server=%s;user id=%s;password=%s;port=%s;encrypt=disable;timeout=%d",
		host, username, password, port, int(timeout.Seconds()),
	)
	
	var db *sql.DB
	var err error
	
	// 检查是否需要使用socks代理
	if common.Socks5Proxy != "" {
		connector, connErr := mssqlDriver.NewConnector(connStr)
		if connErr != nil {
			return nil, "", connErr
		}
		
		connector.Dialer = &MSSQLProxyDialer{
			timeout: timeout,
		}
		
		db = sql.OpenDB(connector)
	} else {
		db, err = sql.Open("mssql", connStr)
		if err != nil {
			return nil, "", err
		}
	}
	
	// 设置连接参数
	db.SetConnMaxLifetime(timeout)
	db.SetConnMaxIdleTime(timeout)
	db.SetMaxIdleConns(0)
	db.SetMaxOpenConns(1)
	
	// 创建ping上下文
	pingCtx, pingCancel := context.WithTimeout(ctx, timeout)
	defer pingCancel()
	
	// 执行ping测试连接
	err = db.PingContext(pingCtx)
	if err != nil {
		db.Close()
		return nil, "", err
	}
	
	// 获取数据库信息
	info := c.getDatabaseInfo(db)
	return db, info, nil
}

// getDatabaseInfo 获取数据库版本信息
func (c *MSSQLConnector) getDatabaseInfo(db *sql.DB) string {
	query := "SELECT @@VERSION"
	var version string
	
	err := db.QueryRow(query).Scan(&version)
	if err != nil {
		return "Microsoft SQL Server"
	}
	
	// 提取版本信息的关键部分
	if strings.Contains(version, "Microsoft SQL Server") {
		lines := strings.Split(version, "\n")
		if len(lines) > 0 {
			return strings.TrimSpace(lines[0])
		}
	}
	
	return fmt.Sprintf("Microsoft SQL Server - %s", version)
}

// isMSSQLError 检查是否是MSSQL相关错误
func (c *MSSQLConnector) isMSSQLError(err error) bool {
	if err == nil {
		return false
	}
	
	errorStr := strings.ToLower(err.Error())
	mssqlErrorIndicators := []string{
		"login failed",
		"cannot open database",
		"invalid object",
		"mssql:",
		"sql server",
		"sqlserver:",
		"database",
		"authentication failed",
		"server principal",
		"user does not have permission",
		"the login is from an untrusted domain",
	}
	
	for _, indicator := range mssqlErrorIndicators {
		if strings.Contains(errorStr, indicator) {
			return true
		}
	}
	
	return false
}