package internal

import (
	"encoding/json"
	"errors"
	"fmt"
	"math/rand"
	"os"
	"sync"
	"time"

	"mongo.games.com/goserver/core/broker"
	"mongo.games.com/goserver/core/broker/rabbitmq"
	"mongo.games.com/goserver/core/logger"
)

/*
 在发布功能上加上异步发送消息和发送失败备份到本地文件的功能
*/

var ErrClosed = errors.New("publisher is closed")

type item struct {
	topic string
	msg   interface{}
	opts  []broker.PublishOption
}

type RabbitMQPublisher struct {
	broker.Broker
	exchange rabbitmq.Exchange
	url      string
	que      chan *item
	closed   chan struct{}
	wg       sync.WaitGroup
}

func NewRabbitMQPublisher(url string, exchange rabbitmq.Exchange, queueSize int, opts ...broker.Option) *RabbitMQPublisher {
	if queueSize <= 0 {
		queueSize = 1
	}
	mq := &RabbitMQPublisher{
		url:      url,
		exchange: exchange,
		que:      make(chan *item, queueSize),
		closed:   make(chan struct{}),
	}
	options := []broker.Option{
		broker.Addrs(url), rabbitmq.ExchangeName(exchange.Name),
	}
	if exchange.Durable {
		options = append(options, rabbitmq.DurableExchange())
	}
	if len(opts) > 0 {
		options = append(options, opts...)
	}
	mq.Broker = rabbitmq.NewBroker(options...)
	mq.Broker.Init()
	return mq
}

// 发布消息，同步
func (p *RabbitMQPublisher) publish(topic string, msg interface{}, opts ...broker.PublishOption) (err error) {
	defer func() {
		e := recover()
		if e != nil {
			logger.Logger.Errorf("RabbitMQPublisher.public() topic:%v message:%v recover:%v", topic, msg, e)
		}
		if err != nil || e != nil {
			p.backup(topic, msg, err)
		}
	}()

	var buf []byte
	switch d := msg.(type) {
	case []byte:
		buf = d
	case string:
		buf = []byte(d)
	default:
		buf, err = json.Marshal(msg)
		if err != nil {
			return err
		}
	}

	err = p.Publish(topic, &broker.Message{Body: buf}, opts...)
	if err != nil {
		logger.Logger.Errorf("RabbitMQPublisher.publish() topic:%v message:%v err:%v", topic, msg, err)
		return
	}
	return nil
}

func (p *RabbitMQPublisher) publishRoutine() {
	p.wg.Add(1)
	defer p.wg.Done()

	for {
		select {
		case item, ok := <-p.que:
			if ok {
				p.publish(item.topic, item.msg, item.opts...)
			} else {
				return
			}
		case <-p.closed:
			return
		}
	}
}

func (p *RabbitMQPublisher) Start() (err error) {
	if ok, _ := PathExists(BackupPath); !ok {
		err = os.MkdirAll(BackupPath, os.ModePerm)
		if err != nil {
			return
		}
	}

	if err = p.Connect(); err != nil {
		return err
	}

	logger.Logger.Infof("RabbitMQPublisher.Start() url:%s exchange:%s", p.url, p.exchange.Name)

	go p.publishRoutine()

	return nil
}

func (p *RabbitMQPublisher) Stop() error {
	logger.Logger.Infof("RabbitMQPublisher.Stop() url:%s exchange:%s", p.url, p.exchange.Name)
	select {
	case <-p.closed:
		return ErrClosed
	default:
	}

	close(p.closed)
	close(p.que)
	for item := range p.que {
		p.publish(item.topic, item.msg, item.opts...)
	}

	//等待所有投递出去的任务全部完成
	p.wg.Wait()

	return p.Disconnect()
}

// Send 发布消息，异步
func (p *RabbitMQPublisher) Send(topic string, msg interface{}, opts ...broker.PublishOption) (err error) {
	select {
	case <-p.closed:
		return ErrClosed
	default:
	}

	i := &item{topic: topic, msg: msg, opts: opts}
	select {
	case p.que <- i:
	default:
		//会不会情况更糟糕
		go func() {
			p.wg.Add(1)
			defer p.wg.Done()
			p.publish(topic, msg)
		}()
	}
	return nil
}

func (p *RabbitMQPublisher) backup(topic string, msg interface{}, err error) {
	buf, er := json.Marshal(msg)
	if er != nil {
		return
	}
	tNow := time.Now()
	filePath := fmt.Sprintf(FilePathFormat, BackupPath, topic, tNow.Format(TimeFormat), tNow.Nanosecond(), rand.Int31n(10000))
	f, er := os.Create(filePath)
	if er != nil {
		logger.Logger.Errorf("RabbitMQPublisher.public() topic:%v message:%v err:%v", topic, msg, er)
		return
	}
	defer f.Close()
	var reason string
	if err != nil {
		reason = err.Error()
	}
	f.WriteString("reason:" + reason + "\n")
	f.WriteString("data:" + string(buf) + "\n")
}