package main

import (
	"flag"
	"fmt"
	"log"
	"strings"

	"github.com/go-mysql-org/go-mysql/canal"
	"github.com/go-mysql-org/go-mysql/mysql"
)

// 自定义事件处理结构体
type MyEventHandler struct {
	canal.DummyEventHandler
}

// 处理行事件
func (h *MyEventHandler) OnRow(e *canal.RowsEvent) error {
	table := e.Table
	sql := ""

	switch e.Action {
	case canal.InsertAction:
		// 处理插入事件
		columns := make([]string, len(table.Columns))
		for i, col := range table.Columns {
			columns[i] = col.Name
		}

		values := make([]string, len(e.Rows[0]))
		for i, val := range e.Rows[0] {
			values[i] = formatValue(val)
		}

		sql = fmt.Sprintf("INSERT INTO `%s`.`%s` (%s) VALUES (%s);",
			table.Schema, table.Name,
			strings.Join(columns, ", "),
			strings.Join(values, ", "))

	case canal.UpdateAction:
		// 处理更新事件
		oldRow := e.Rows[0]
		newRow := e.Rows[1]

		sets := make([]string, 0)
		wheres := make([]string, 0)

		for i, col := range table.Columns {
			if oldRow[i] != newRow[i] {
				sets = append(sets, fmt.Sprintf("`%s` = %s", col.Name, formatValue(newRow[i])))
			}
			wheres = append(wheres, fmt.Sprintf("`%s` = %s", col.Name, formatValue(oldRow[i])))
		}

		sql = fmt.Sprintf("UPDATE `%s`.`%s` SET %s WHERE %s;",
			table.Schema, table.Name,
			strings.Join(sets, ", "),
			strings.Join(wheres, " AND "))

	case canal.DeleteAction:
		// 处理删除事件
		wheres := make([]string, len(table.Columns))
		for i, col := range table.Columns {
			wheres[i] = fmt.Sprintf("`%s` = %s", col.Name, formatValue(e.Rows[0][i]))
		}

		sql = fmt.Sprintf("DELETE FROM `%s`.`%s` WHERE %s;",
			table.Schema, table.Name,
			strings.Join(wheres, " AND "))
	}

	if sql != "" {
		fmt.Println(sql)
	}

	return nil
}

// string
func (h *MyEventHandler) String() string { return "MyEventHandler" }

// 处理DDL事件
// func (h *MyEventHandler) OnDDL(nextPos mysql.Position, queryEvent *replication.QueryEvent) error {
// 	sql := string(queryEvent.Query)
// 	if sql != "" {
// 		fmt.Println(sql + ";")
// 	}
// 	return nil
// }

// 格式化值为SQL表示形式
func formatValue(value interface{}) string {
	if value == nil {
		return "NULL"
	}

	switch v := value.(type) {
	case int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, float32, float64:
		return fmt.Sprintf("%v", v)
	case []byte:
		// 处理二进制数据
		return fmt.Sprintf("X'%x'", v)
	case string:
		// 转义单引号
		return fmt.Sprintf("'%s'", strings.ReplaceAll(v, "'", "''"))
	default:
		return fmt.Sprintf("'%v'", v)
	}
}

func main() {
	// 解析命令行参数
	host := flag.String("host", "localhost", "MySQL主机地址")
	port := flag.Uint("port", 3306, "MySQL端口")
	user := flag.String("user", "root", "MySQL用户名")
	password := flag.String("password", "", "MySQL密码")
	serverID := flag.Uint("server-id", 1001, "客户端服务器ID")
	flavor := flag.String("flavor", "mysql", "数据库类型 (mysql或mariadb)")
	startFile := flag.String("start-file", "", "开始读取的binlog文件名")
	startPos := flag.Uint("start-pos", 4, "开始读取的位置")

	flag.Parse()

	// 创建canal配置
	cfg := canal.NewDefaultConfig()
	cfg.Addr = fmt.Sprintf("%s:%d", *host, *port)
	cfg.User = *user
	cfg.Password = *password
	cfg.ServerID = uint32(*serverID)
	cfg.Flavor = *flavor

	// 设置需要监听的数据库和表，默认监听所有
	// cfg.Dump.TableDB = "test_db"
	// cfg.Dump.Tables = []string{"test_table"}

	// 创建canal实例
	c, err := canal.NewCanal(cfg)
	if err != nil {
		log.Fatalf("创建canal实例失败: %v", err)
	}

	// 设置事件处理器
	c.SetEventHandler(&MyEventHandler{})

	// 设置起始位置
	var pos mysql.Position
	if *startFile != "" {
		pos = mysql.Position{Name: *startFile, Pos: uint32(*startPos)}
	} else {
		// 如果未指定，从当前位置开始
		pos, err = c.GetMasterPos()
		if err != nil {
			log.Fatalf("获取主库位置失败: %v", err)
		}
		fmt.Printf("从binlog位置 %s:%d 开始读取\n", pos.Name, pos.Pos)
	}

	// 开始同步
	err = c.RunFrom(pos)
	if err != nil {
		log.Fatalf("同步失败: %v", err)
	}
}