package rule

import (
	"encoding/json"
	"github.com/streadway/amqp"
	"sparrow/pkg/server"
)

type ExternalConsumer interface {
	AddMessageHandle(msg *TaskLifecycleMessage) error
	RemoveMessageHandle(msg *TaskLifecycleMessage) error
	UpdateMessageHandle(msg *TaskLifecycleMessage) error
	SnapMessageHandle(msg *TaskLifecycleMessage) error
	StartMessageHandle(msg *TaskLifecycleMessage) error
	StopMessageHandle(msg *TaskLifecycleMessage) error
}

const TaskLifecycleExchange = "task_lifecycle_exchange"
const TaskExchange = "task_exchange"

type TaskLifecycleConsumer struct {
	ch          *amqp.Channel
	ec          ExternalConsumer
	stopChan    chan struct{}
	messageChan chan []byte
}

func NewTaskLifecycleConsumer(ch *amqp.Channel) *TaskLifecycleConsumer {
	return &TaskLifecycleConsumer{
		ch:          ch,
		stopChan:    make(chan struct{}),
		messageChan: make(chan []byte, 10),
	}
}

func (a *TaskLifecycleConsumer) SetExternalConsumer(ec ExternalConsumer) {
	a.ec = ec
}

func (a *TaskLifecycleConsumer) Stop() {
	close(a.stopChan)
}

func (a *TaskLifecycleConsumer) Start() error {
	go func() {
		for {
			select {
			case <-a.stopChan:
				return
			case msg := <-a.messageChan:
				a.handleMessage(msg)
			}
		}
	}()
	return nil
}

func (a *TaskLifecycleConsumer) handleMessage(msg []byte) {
	if a.ec == nil {
		server.Log.Errorf("TaskLifecycleConsumer is unset")
		return
	}
	var tm TaskLifecycleMessage
	err := json.Unmarshal(msg, &tm)
	if err != nil {
		server.Log.Errorf("handle lifecycle message error :%v", err)
		return
	}
	switch tm.Action {
	case "add":
		err = a.ec.AddMessageHandle(&tm)
	case "remove":
		err = a.ec.RemoveMessageHandle(&tm)
	case "update":
		err = a.ec.UpdateMessageHandle(&tm)
	case "snap":
		err = a.ec.SnapMessageHandle(&tm)
	case "start":
		err = a.ec.StartMessageHandle(&tm)
	case "stop":
		err = a.ec.StopMessageHandle(&tm)
	}
}

func (a *TaskLifecycleConsumer) Init() error {
	err := a.ch.ExchangeDeclare(
		TaskLifecycleExchange, // name
		"fanout",              // type
		true,                  // durable
		false,                 // auto-deleted
		false,                 // internal
		false,                 // no-wait
		nil,                   // arguments
	)
	if err != nil {
		return err
	}
	//绑定queue到交换机
	q, err := a.ch.QueueDeclare(
		"",    // name
		false, // durable
		false, // delete when unused
		true,  // exclusive
		false, // no-wait
		nil,   // arguments
	)
	if err != nil {
		return err
	}
	err = a.ch.QueueBind(
		q.Name, // queue name
		"",     // routing key
		TaskLifecycleExchange,
		false,
		nil,
	)
	if err != nil {
		return err
	}
	// creat consumer
	msg, err := a.ch.Consume(q.Name, "", true, false, false, false, nil)
	if err != nil {
		return err
	}
	go func() {
		for {
			select {
			case <-a.stopChan:
				return
			case d := <-msg:
				a.messageChan <- d.Body
			}
		}
	}()
	return nil
}