package main

import (
		"fmt"
	"github.com/cavaliercoder/grab"
	"time"
)

func download(dst string,urls ...string)  {
	n:=len(urls)
	re,err:=grab.GetBatch(n,dst,urls...)
	if err!=nil {
		fmt.Print(err)
		return
	}

	t:=time.NewTicker(time.Millisecond*10)
	complete:=0
	progress:=0
	responses:=make([]*grab.Response,0)
	for complete<n {
		select {
		case r:=<-re:
			responses=append(responses,r)
		case <-t.C:
			progress=0
			for k,v:=range responses{
				if v!=nil {
					if v.IsComplete() {
						if v.Err()==nil {
							fmt.Printf("%s %s/%s %d%%\n",v.Filename,ShowBytes(float64(v.BytesComplete())),ShowBytes(float64(v.Size)),int(v.Progress()*100))
						} else {
							fmt.Printf("%s:%s\n",v.Filename,v.Err())
						}
						responses[k]=nil
						complete++
					} else {
						fmt.Printf("%s %s/%s %d%%\n",v.Filename,ShowBytes(float64(v.BytesComplete())),ShowBytes(float64(v.Size)),int(v.Progress()*100))
						progress++
					}
				}
			}
			if progress>0 {
				fmt.Printf("%d downloading\n",progress)
			}
		}
	}
	t.Stop()
}

func ShowBytes(bytesnum float64) string {
	if bytesnum<1024 {
		return fmt.Sprintf("%.2fB",bytesnum)
	} else if bytesnum<1024*1024 {
		return fmt.Sprintf("%.2fKB",bytesnum/1024.0)
	} else if bytesnum<1024*1024*1024 {
		return fmt.Sprintf("%.2fMB",bytesnum/1024.0/1024.0)
	} else {
		return fmt.Sprintf("%.2fGB",bytesnum/1024.0/1024.0/1024.0)
	}
}

func main()  {
	urls:=[]string{
		"https://rpic.douyucdn.cn/live-cover/appCovers/2018/08/31/3279944_20180831104533_small.jpg",
		"https://rpic.douyucdn.cn/live-cover/roomCover/2018/11/06/0a699f47dc4fc55deaa82402cc0876ea_big.png",
		"https://rpic.douyucdn.cn/live-cover/appCovers/2018/10/19/5230163_20181019161115_small.jpg",
	}
	download("download",urls...)
}