package queue

import (
	"os"
	"os/signal"
	"syscall"
)

// 工作对象封装
type ChanWorker struct {
	ID         int                   // 工作对象编号
	WorkerPool chan chan interface{} // 工作管道池，实例化时由调度器传入
	JobChannel chan interface{}      // 工作管道
	quit       chan bool             // 退出消息
}

func NewChanWorker(workerId, capacity int, workerPool chan chan interface{}) *ChanWorker {
	var jobChannel chan interface{}
	if capacity < 0 {
		jobChannel = make(chan interface{})
	} else {
		jobChannel = make(chan interface{}, capacity)
	}

	return &ChanWorker{
		ID:         workerId,
		WorkerPool: workerPool,
		JobChannel: jobChannel,
		quit:       make(chan bool),
	}
}

func (w *ChanWorker) Start(callback func(workerId int, msg interface{})) {
	go func(w *ChanWorker, callback func(workerId int, msg interface{})) {
		for {
			// 新工作管道加入工作管道池
			w.WorkerPool <- w.JobChannel

			select {
			case msg := <-w.JobChannel:
				callback(w.ID, msg)
			case <-w.quit:
				return
			}
		}
	}(w, callback)

	go w.closeWait()
}

func (w *ChanWorker) Stop() {
	go func(w *ChanWorker) {
		w.quit <- true
	}(w)
}

func (w *ChanWorker) closeWait() {
	var c chan os.Signal
	c = make(chan os.Signal, 1)
	signal.Notify(c, syscall.SIGQUIT, syscall.SIGTERM, syscall.SIGINT)
	for {
		select {
		case <-c:
			w.Stop()
		}
	}
}

// 调度对象
type ChanDispatcher struct {
	MsgQueue   chan interface{}      // 消息输入管道
	WorkerPool chan chan interface{} // 工作管道池
	maxWorkers int                   // 最大工作对象数
	capacity   int                   // 工作管道消息缓冲大小
}

func NewChanDispatcher(msgQueue chan interface{}, maxWorkers int) *ChanDispatcher {
	return &ChanDispatcher{
		MsgQueue:   msgQueue,
		WorkerPool: make(chan chan interface{}, maxWorkers),
		maxWorkers: maxWorkers,
		capacity:   -1,
	}
}

func NewChanDispatcherWithCapacity(msgQueue chan interface{}, maxWorkers, capacity int) *ChanDispatcher {
	return &ChanDispatcher{
		MsgQueue:   msgQueue,
		WorkerPool: make(chan chan interface{}, maxWorkers),
		maxWorkers: maxWorkers,
		capacity:   capacity,
	}
}

func (d *ChanDispatcher) Run(callback func(workerId int, msg interface{})) {
	for i := 0; i < d.maxWorkers; i++ {
		worker := NewChanWorker(i, d.capacity, d.WorkerPool)
		worker.Start(callback)
	}

	go d.dispatch()
}

func (d *ChanDispatcher) dispatch() {
	for {
		select {
		case msg := <-d.MsgQueue:
			go func(d *ChanDispatcher, msg interface{}) {
				// 从工作管道池中尝试取出一个空闲（未阻塞）的工作管道，无空闲工作管道时阻塞
				jobChannel := <-d.WorkerPool

				// 将一条消息发送给当前工作管道
				jobChannel <- msg
			}(d, msg)
		}
	}
}