// Package event ...
//
// Description : event ...
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 2024-06-25 16:06
package event

import (
	"context"
	"errors"
	"fmt"
	"git.zhangdeman.cn/zhangdeman/consts"
	"git.zhangdeman.cn/zhangdeman/event/abstract"
	"git.zhangdeman.cn/zhangdeman/event/define"
	"git.zhangdeman.cn/zhangdeman/serialize"
	"git.zhangdeman.cn/zhangdeman/wrapper"
	"github.com/redis/go-redis/v9"
	"time"
)

var (
	RedisEventPubSubClient abstract.IEvent
)

// InitRedisPubSubEvent 初始化redis事件驱动, 基于 pub / sub 指令
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 16:24 2024/6/25
func InitRedisPubSubEvent(redisClient *redis.Client, pubSubConfig *define.RedisEventPubSubConfig) {
	instance := &RedisEventPubSub{
		base: &base{
			panicCallback:     define.DefaultPanicCallback,
			parseFailCallback: define.DefaultParseFailCallbackFunc,
		},
		redisClient:  redisClient,
		pubSubConfig: pubSubConfig,
	}
	instance.SetRedisClient(redisClient, pubSubConfig)
	instance.StartConsumer() // 启动消费者
	RedisEventPubSubClient = instance
}

// RedisEventPubSub 基于redis的事件驱动
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 16:07 2024/6/25
type RedisEventPubSub struct {
	*base
	redisClient       *redis.Client                   // redis客户端
	pubSubConfig      *define.RedisEventPubSubConfig  // 事件配置
	messageChan       chan *define.EventData          // 消息队列
	stopConsumer      chan bool                       // 停止消费者
	isStop            bool                            // 是否已停止
	parseFailCallback abstract.EventParseFailCallback // 数据解析失败回调
}

// SendEvent 发布时间
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 10:58 2024/6/27
func (r *RedisEventPubSub) SendEvent(ctx context.Context, eventData *define.EventData) (*define.SendResult, error) {
	partition := int(wrapper.String(eventData.Key).HashNumber().Value % uint64(r.pubSubConfig.PartitionNum))
	realTopic := fmt.Sprintf("%v_%v", r.pubSubConfig.Topic, partition)
	res := r.redisClient.Publish(ctx, realTopic, eventData)
	if nil == res {
		return nil, errors.New("can not get send event result")
	}
	return &define.SendResult{
		Data:       eventData,
		Partition:  partition,
		Topic:      realTopic,
		IsSuccess:  res.Err() == nil,
		FailReason: wrapper.TernaryOperator.String(res.Err() == nil, "success", wrapper.String(res.Err().Error())).Value(),
		Extension:  nil,
	}, res.Err()
}

// SendEventAsync 异步发送事件
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 11:29 2024/6/27
func (r *RedisEventPubSub) SendEventAsync(ctx context.Context, eventData *define.EventData, sendSuccessCallback abstract.SendSuccessCallback, sendFailCallback abstract.SendFailCallback) {
	go func() {
		if nil == sendFailCallback {
			sendFailCallback = define.DefaultSendFailCallback
		}
		if nil == sendSuccessCallback {
			sendSuccessCallback = define.DefaultSendSuccessCallback
		}
		var (
			sendResult *define.SendResult
			handlerErr error
		)
		defer func() {
			if panicErr := recover(); nil != panicErr {
				r.panicCallback(panicErr, eventData, map[string]any{
					"send_result": sendResult,
				})
			}
		}()
		if sendResult, handlerErr = r.SendEvent(ctx, eventData); nil != handlerErr {
			sendFailCallback(ctx, eventData, sendResult, handlerErr)
		} else {
			sendSuccessCallback(ctx, sendResult)
		}
	}()
}

// GetConsumeEventChan 获取消息channel, 自行实现消费
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 17:13 2024/6/26
func (r *RedisEventPubSub) GetConsumeEventChan() (<-chan *define.EventData, error) {
	if r.isStop {
		return nil, errors.New("event instance has stop")
	}
	return r.messageChan, nil
}

// ConsumeEvent 获取数据消费实例
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 17:06 2024/6/26
func (r *RedisEventPubSub) ConsumeEvent(handler abstract.EventHandler, successCallback abstract.ConsumeSuccessCallback, failureCallback abstract.ConsumeFailCallbackHandler) error {
	if nil == handler {
		return errors.New("handler is nil")
	}
	var (
		messageChan <-chan *define.EventData
		err         error
	)

	if messageChan, err = r.GetConsumeEventChan(); nil != err {
		return err
	}
	if nil == failureCallback {
		failureCallback = define.DefaultFailCallbackHandler
	}
	if nil == successCallback {
		successCallback = define.DefaultSuccessCallbackHandler
	}

	for eventData := range messageChan {
		handlerResult, handleErr := handler(eventData)
		if nil != handleErr {
			failureCallback(eventData, handlerResult, err)
		} else {
			successCallback(eventData, handlerResult)
		}
	}

	return nil
}

// StartConsumer 启动消费者
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 18:36 2024/6/27
func (r *RedisEventPubSub) StartConsumer() {
	for partition := 0; partition < r.pubSubConfig.PartitionNum; partition++ {
		go func(realPartition int) {
			defer func() {
				if panicErr := recover(); nil != panicErr {
					r.panicCallback(panicErr, nil, nil)
				}
			}()
			// 启动消费者
			realTopic := fmt.Sprintf("%v_%v", r.pubSubConfig.Topic, realPartition)
			messageChannel := r.redisClient.Subscribe(context.Background(), realTopic).Channel()
			for message := range messageChannel {
				var (
					eventData define.EventData
					err       error
				)

				if err = serialize.JSON.UnmarshalWithNumber([]byte(message.Payload), &eventData); nil != err {
					// TODO : 事件数据解析失败的回调
					continue
				}
				r.messageChan <- &eventData
			}
		}(partition)
	}
}

// Destroy 销毁事件实例
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 15:42 2024/6/26
func (r *RedisEventPubSub) Destroy() {
	if r.isStop {
		// 已停止
		return
	}
	r.stopConsumer <- true // 停止消费者
	messageChan := make(chan bool, 1)
	go func() {
		for {
			if len(r.messageChan) == 0 {
				messageChan <- true
				return
			}
		}
	}()
	select {
	case <-time.After(time.Millisecond * time.Duration(r.pubSubConfig.CloseMaxWaitTime)):
		// 定时器到期
		return
	case <-messageChan:
		// 没有待消费数据
		return
	}
}

func (r *RedisEventPubSub) DriverType() string {
	return consts.EventDriverRedis
}

// SetRedisClient 设置redis客户端
//
// Author : go_developer@163.com<白茶清欢>
//
// Date : 16:30 2024/6/25
func (r *RedisEventPubSub) SetRedisClient(redisClient *redis.Client, pubSubConfig *define.RedisEventPubSubConfig) {
	if nil == pubSubConfig {
		pubSubConfig = &define.RedisEventPubSubConfig{
			Topic:             "",
			PartitionNum:      0,
			MessageBufferSize: 0,
		}
	}
	if len(pubSubConfig.Topic) == 0 {
		pubSubConfig.Topic = define.DefaultRedisTopic
	}
	if pubSubConfig.PartitionNum <= 0 {
		pubSubConfig.PartitionNum = define.DefaultRedisPartitionNum
	}
	if pubSubConfig.MessageBufferSize <= 0 {
		r.pubSubConfig.MessageBufferSize = define.DefaultRedisMessageBufferSize
	}
	if pubSubConfig.CloseMaxWaitTime <= 0 {
		r.pubSubConfig.CloseMaxWaitTime = define.DefaultRedisCloseMaxWaitTime
	}
	r.redisClient = redisClient
	r.pubSubConfig = pubSubConfig
	r.stopConsumer = make(chan bool, 1)
	r.messageChan = make(chan *define.EventData, r.pubSubConfig.MessageBufferSize)
}