package handler

import (
	"context"
	"log"
	"sync"
	"time"

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

type DataEvent struct {
	Action    string        `json:"action"`
	Schema    string        `json:"schema"`
	Table     string        `json:"table"`
	Timestamp time.Time     `json:"timestamp"`
	Data      []interface{} `json:"data"`
	OldData   []interface{} `json:"old_data,omitempty"`
}

type EventHandler struct {
	canal.DummyEventHandler
	eventChan chan *DataEvent
	batchSize int
	workers   int
	wg        sync.WaitGroup
	ctx       context.Context
	cancel    context.CancelFunc
}

func NewEventHandler(batchSize, workers int) *EventHandler {
	ctx, cancel := context.WithCancel(context.Background())
	handler := &EventHandler{
		eventChan: make(chan *DataEvent, 1000),
		batchSize: batchSize,
		workers:   workers,
		ctx:       ctx,
		cancel:    cancel,
	}

	handler.startWorkers()
	return handler
}

func (h *EventHandler) startWorkers() {
	for i := 0; i < h.workers; i++ {
		h.wg.Add(1)
		go h.worker(i)
	}
}

func (h *EventHandler) worker(id int) {
	defer h.wg.Done()

	var batch []*DataEvent
	batchTimer := time.NewTimer(100 * time.Millisecond)
	defer batchTimer.Stop()

	for {
		select {
		case event, ok := <-h.eventChan:
			if !ok {
				// 通道关闭，处理剩余数据
				if len(batch) > 0 {
					h.processBatch(batch)
				}
				return
			}

			batch = append(batch, event)

			if len(batch) >= h.batchSize {
				h.processBatch(batch)
				batch = nil
				batchTimer.Reset(100 * time.Millisecond)
			}

		case <-batchTimer.C:
			if len(batch) > 0 {
				h.processBatch(batch)
				batch = nil
			}
			batchTimer.Reset(100 * time.Millisecond)

		case <-h.ctx.Done():
			if len(batch) > 0 {
				h.processBatch(batch)
			}
			return
		}
	}
}

func (h *EventHandler) processBatch(events []*DataEvent) {
	// 这里实现数据同步逻辑
	// 可以同步到其他数据库、消息队列、ES等

	log.Printf("处理批次: %d 个事件", len(events))
	for _, event := range events {
		// 示例：打印事件信息
		log.Printf("同步事件: %s.%s %s", event.Schema, event.Table, event.Action)

		// 实际应用中，这里可以同步到：
		// 1. 其他MySQL数据库
		// 2. Elasticsearch
		// 3. Redis缓存
		// 4. Kafka消息队列
		// 5. 其他数据存储
	}
}

func (h *EventHandler) OnRow(e *canal.RowsEvent) error {
	var event *DataEvent

	switch e.Action {
	case "insert":
		for _, row := range e.Rows {
			event = &DataEvent{
				Action:    "insert",
				Schema:    e.Table.Schema,
				Table:     e.Table.Name,
				Timestamp: time.Now(),
				Data:      row,
			}
			h.eventChan <- event
		}

	case "update":
		for i := 0; i < len(e.Rows); i += 2 {
			event = &DataEvent{
				Action:    "update",
				Schema:    e.Table.Schema,
				Table:     e.Table.Name,
				Timestamp: time.Now(),
				OldData:   e.Rows[i],
				Data:      e.Rows[i+1],
			}
			h.eventChan <- event
		}

	case "delete":
		for _, row := range e.Rows {
			event = &DataEvent{
				Action:    "delete",
				Schema:    e.Table.Schema,
				Table:     e.Table.Name,
				Timestamp: time.Now(),
				Data:      row,
			}
			h.eventChan <- event
		}
	}

	return nil
}

func (h *EventHandler) OnPosSynced(pos mysql.Position, force bool) error {
	log.Printf("位置已同步: %s, force: %t", pos, force)
	return nil
}

func (h *EventHandler) Close() {
	h.cancel()
	close(h.eventChan)
	h.wg.Wait()
}