package examples

import (
	"encoding/json"
	"fmt"
	"log"
	"math/rand"
	"net"
	"os"
	"path"
	"regexp"
	"strconv"
	"strings"
	"time"

	ffmpeg "github.com/u2takey/ffmpeg-go"
)

// ExampleShowProgress is an example of using the ffmpeg `-progress` option with a
//    unix-domain socket to report progress
func ExampleShowProgress(inFileName, outFileName string) {
	a, err := ffmpeg.Probe(inFileName)
	if err != nil {
		panic(err)
	}
	totalDuration, err := probeDuration(a)
	if err != nil {
		panic(err)
	}

	err = ffmpeg.Input(inFileName).
		Output(outFileName, ffmpeg.KwArgs{"c:v": "libx264", "preset": "veryslow"}).
		GlobalArgs("-progress", "unix://"+TempSock(totalDuration)).
		OverWriteOutput().
		Run()
	if err != nil {
		panic(err)
	}
}

func TempSock(totalDuration float64) string {
	// serve

	rand.Seed(time.Now().Unix())
	sockFileName := path.Join(os.TempDir(), fmt.Sprintf("%d_sock", rand.Int()))
	l, err := net.Listen("unix", sockFileName)
	if err != nil {
		panic(err)
	}

	go func() {
		re := regexp.MustCompile(`out_time_ms=(\d+)`)
		fd, err := l.Accept()
		if err != nil {
			log.Fatal("accept error:", err)
		}
		buf := make([]byte, 16)
		data := ""
		progress := ""
		for {
			_, err := fd.Read(buf)
			if err != nil {
				return
			}
			data += string(buf)
			a := re.FindAllStringSubmatch(data, -1)
			cp := ""
			if len(a) > 0 && len(a[len(a)-1]) > 0 {
				c, _ := strconv.Atoi(a[len(a)-1][len(a[len(a)-1])-1])
				cp = fmt.Sprintf("%.2f", float64(c)/totalDuration/1000000)
			}
			if strings.Contains(data, "progress=end") {
				cp = "done"
			}
			if cp == "" {
				cp = ".0"
			}
			if cp != progress {
				progress = cp
				fmt.Println("progress: ", progress)
			}
		}
	}()

	return sockFileName
}

type probeFormat struct {
	Duration string `json:"duration"`
}

type probeData struct {
	Format probeFormat `json:"format"`
}

func probeDuration(a string) (float64, error) {
	pd := probeData{}
	err := json.Unmarshal([]byte(a), &pd)
	if err != nil {
		return 0, err
	}
	f, err := strconv.ParseFloat(pd.Format.Duration, 64)
	if err != nil {
		return 0, err
	}
	return f, nil
}