package utl

import (
	"time"
)

type WorkPoolOption func(*WorkPool)

func WithWorkPoolSize(size int) WorkPoolOption {
	return func(wp *WorkPool) {
		if size < 1 {
			size = 64
		}
		wp.size = size
	}
}

func WithWorkPoolLifetime(lifetime time.Duration) WorkPoolOption {
	if lifetime < 1*time.Second {
		lifetime = 1 * time.Second
	}
	return func(wp *WorkPool) {
		wp.lifetime = lifetime
	}
}

type WorkPool struct {
	goChan   chan chan func(*time.Timer)
	size     int
	lifetime time.Duration
}

func NewWorkPool(options ...WorkPoolOption) *WorkPool {
	wp := &WorkPool{}

	for _, opt := range options {
		opt(wp)
	}

	wp.goChan = make(chan chan func(*time.Timer), wp.size)

	return wp
}

func (wp *WorkPool) Put(f func(*time.Timer)) {
	for len(wp.goChan) > 0 {
		goRun := <-wp.goChan
		if goRun == nil {
			continue
		}
		select {
		case <-goRun:
		default:
			goRun <- f
			return
		}
	}
	goRun := make(chan func(*time.Timer), 1)
	goRun <- f
	go wp.do(goRun)
}

// in goroutine
func (wp *WorkPool) do(one chan func(*time.Timer)) {
	defer func() {
		if e := recover(); e != nil {
		}
	}()
	timer := time.NewTimer(time.Second * 1)
	defer timer.Stop()

	for {
		select {
		case <-timer.C:
			close(one)
			f, ok := <-one
			if !ok {
				return
			}
			f(timer)
			return
		case f, ok := <-one:
			if !ok {
				return // one 可能关闭
			}
			f(timer)
			timer.Reset(time.Second * 10)
		}
		// reuse
		if len(wp.goChan) < wp.size {
			wp.goChan <- one
		}
	} //for
}