package queue

import (
	"git.aionnect.com/aionnect/go-common/utils"
	"os"
	"os/signal"
	"syscall"
)

// chan worker object
type ChanWorker struct {
	ID         int                   // worker ID
	WorkerPool chan chan interface{} // refer to chan worker pool
	JobChannel chan interface{}      // job message chan
	quit       chan bool             // quit chan
}

// NewChanWorker() get new chan worker object instance
func NewChanWorker(workerId int, workerPool chan chan interface{}) *ChanWorker {
	jobChannel := make(chan interface{})

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

// Start() worker handling
func (w *ChanWorker) Start(callback func(workerId int, msg interface{})) {
	go func(w *ChanWorker, callback func(workerId int, msg interface{})) {
		defer utils.DefaultGoroutineRecover(nil, `chan pool worker handling`)
		for {
			// job chan add to pool,when create or used
			w.WorkerPool <- w.JobChannel

			select {
			case msg, ok := <-w.JobChannel: // block when empty
				if ok {
					callback(w.ID, msg)
				}
			case <-w.quit:
				return
			}
		}
	}(w, callback)
}

// chan worker pool dispatcher object
type ChanDispatcher struct {
	MsgQueue   chan interface{}      // message input chan
	WorkerPool chan chan interface{} // worker chan pool
	maxWorkers int                   // max concurrent chan count
	workers    []*ChanWorker         // chan worker object list
}

// NewChanDispatcher() get new chan worker pool dispatcher object instance
func NewChanDispatcher(msgQueue chan interface{}, maxWorkers int) *ChanDispatcher {
	return &ChanDispatcher{
		MsgQueue:   msgQueue,
		WorkerPool: make(chan chan interface{}, maxWorkers),
		maxWorkers: maxWorkers,
	}
}

// Run() start concurrent message customers base on chan worker pool dispatcher
func (d *ChanDispatcher) Run(callback func(workerId int, msg interface{})) {
	for i := 0; i < d.maxWorkers; i++ {
		worker := NewChanWorker(i, d.WorkerPool)
		d.workers = append(d.workers, worker)
		worker.Start(callback)
	}
	d.closeWait()
	d.dispatch()
}

// dispatch() dispatch handling
func (d *ChanDispatcher) dispatch() {
	go func(d *ChanDispatcher) {
		defer utils.DefaultGoroutineRecover(nil, `chan pool dispatch handling`)
		for {
			select {
			case msg, ok := <-d.MsgQueue:
				if ok {
					// try to get a free worker chan from pool
					// (all worker chan in pool is free,because take it out when use,and put it back when used)
					// block when all worker channels are busy(pool is empty)
					jobChannel, isOpen := <-d.WorkerPool
					if isOpen {
						// send a message to job chan
						jobChannel <- msg
					}
				}
			}
		}
	}(d)
}

// closeWait() release dispatcher resource when signal close
func (d *ChanDispatcher) closeWait() {
	go func(d *ChanDispatcher) {
		defer utils.DefaultGoroutineRecover(nil, `chan池关闭`)
		var c chan os.Signal
		var s os.Signal
		c = make(chan os.Signal, 1)
		signal.Notify(c, syscall.SIGHUP, syscall.SIGINT, syscall.SIGTERM, syscall.SIGQUIT, syscall.SIGKILL)
		for {
			s = <-c
			switch s {
			case syscall.SIGHUP, syscall.SIGINT, syscall.SIGTERM, syscall.SIGQUIT, syscall.SIGKILL:
				if nil != d.workers && len(d.workers) > 0 {
					for i := 0; i < len(d.workers); i++ {
						d.workers[i].quit <- true
					}
				}
				return
			default:
				return
			}
		}
	}(d)
}