package main

import (
	"bufio"
	"fmt"
	"log"
	"os"
	"regexp"
	"strings"
	"sync"
	//"path/filepath"

	"github.com/gosuri/uiprogress"
	. "github.com/kkdai/youtube"
)

type Batch struct {
	batchfile, destDir string
}

func NewBatch(batchFile, destinationDir string) *Batch {
	return &Batch{batchfile: batchFile, destDir: destinationDir}
}

func (b *Batch) Start() {
	//Start downloading all videos
	log.Println("Start downloading...")
	//open the file containing yt links
	linkfile, err := os.Open(b.batchfile)
	if err != nil {
		log.Fatal(err)
	}
	defer linkfile.Close()

	//Create scanner to go line by line through the file
	//This scanner allows 65536 characters per line.
	//That should be enough for yt links.
	scanner := bufio.NewScanner(linkfile)

	//Start rendering for progressbar
	//This is the initialization the actual bars
	//will be instantiated in the go routines
	uiprogress.Start()

	var wg sync.WaitGroup

	for scanner.Scan() {
		//Call download
		//add go routine to wait for
		if strings.TrimSpace(scanner.Text()) != "" {
			wg.Add(1)
			log.Println(scanner.Text())
			go downloadVideo(b.destDir, strings.TrimSpace(scanner.Text()), &wg)
		} else {
			log.Println("Ignoring blank line")
		}
	}

	//wait for all go routines to finish
	wg.Wait()
	log.Println("All downloads finished")
	if err := scanner.Err(); err != nil {
		log.Fatal(err)
	}
}

func downloadVideo(destDir, url string, wg *sync.WaitGroup) {
	// NewYoutube(debug) if debug parameter will set true we can log of messages
	//defer Done() so that WaitGroup knows when the routine finishes
	defer wg.Done()
	y := NewYoutube(false)
	y.DecodeURL(url)
	re := regexp.MustCompile("(mp4|webm|3gpp)")
	fileext := re.FindString(y.StreamList[0]["type"])
	filename := fmt.Sprintf("%s/%s.%s", destDir, y.StreamList[0]["title"], fileext)
	filenameRune := []rune(y.StreamList[0]["title"])
	shortFilename := string(filenameRune[0:20]) + "..."

	go func() {
		bar := uiprogress.AddBar(100).AppendCompleted()

		//Custom decorator (the short name in front of the bar)
		bar.PrependFunc(func(b *uiprogress.Bar) string {
			return shortFilename
		})

		var i int64 = 0
		for i < 100 {
			i = <-y.DownloadPercent
			bar.Set(int(i))
		}
	}()

	//start the actual download
	err := y.StartDownload(filename)
	if err != nil {
		log.Println("Failed to download", url)
		log.Println("Message:", err.Error())
	}
}