package utl

import (
	"fmt"
	"time"
)

// WorkPool Options
type WorkPoolOption func(*WorkPool)

// size of pool
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 {
	chPool   TJobPool
	size     int
	lifetime time.Duration
}

// constructor. return a WorkPool instance by options
func NewWorkPool(options ...WorkPoolOption) *WorkPool {
	wp := &WorkPool{}

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

	wp.chPool = make(TJobPool, wp.size)

	return wp
}

func (wp *WorkPool) Put(job *Job) {
	for len(wp.chPool) > 0 {
		jobChan := <-wp.chPool
		if jobChan == nil {
			continue
		}
		select {
		case <-jobChan:
		default:
			jobChan <- job
			return
		}
	} // for

	jobChan := make(TJobChan, 1)
	jobChan <- job
	go wp.do(jobChan)
}

// in goroutine
func (wp *WorkPool) do(one TJobChan) {
	defer func() {
		if e := recover(); e != nil {
			fmt.Println("WorkPool error:", e)
		}
	}()

	timer := time.NewTimer(wp.lifetime)
	defer timer.Stop()

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