package video

import (
	"encoding/json"
	"fmt"
	"os"
	"path"
	"strconv"

	"arimelody.space/live-vod-uploader/youtube"
	ffmpeg "github.com/u2takey/ffmpeg-go"
)

type (
	probeFormat struct {
		Duration string `json:"duration"`
	}
	probeData struct {
		Format probeFormat `json:"format"`
	}
)

func ConcatVideo(video *youtube.Video, vodFiles []string, verbose bool) (int64, error) {
	fileListPath := path.Join(
		path.Dir(video.Filename),
		"files.txt",
	)

	totalDuration := float64(0.0)
	fileListString := ""
	for _, file := range vodFiles {
		fileListString += fmt.Sprintf("file '%s'\n", file)
		jsonProbe, err := ffmpeg.Probe(path.Join(path.Dir(video.Filename), file))
		if err != nil {
			return 0, fmt.Errorf("failed to probe file `%s`: %v", file, err)
		}
		probe := probeData{}
		json.Unmarshal([]byte(jsonProbe), &probe)
		duration, err := strconv.ParseFloat(probe.Format.Duration, 64)
		if err != nil {
			return 0, fmt.Errorf("failed to parse duration of file `%s`: %v", file, err)
		}
		totalDuration += duration
	}
	err := os.WriteFile(
		fileListPath,
		[]byte(fileListString),
		0644,
	)
	if err != nil {
		return 0, fmt.Errorf("failed to write file list: %v", err)
	}

	stream := ffmpeg.Input(fileListPath, ffmpeg.KwArgs{
		"f": "concat",
		"safe": "0",
	}).Output(video.Filename, ffmpeg.KwArgs{
		"c": "copy",
	}).OverWriteOutput()
	if verbose { stream = stream.ErrorToStdOut() }
	err = stream.Run()

	if err != nil {
		return 0, fmt.Errorf("ffmpeg error: %v", err)
	}

	fileInfo, err := os.Stat(video.Filename)
	if err != nil { return 0, fmt.Errorf("failed to read output file: %v", err) }

	return fileInfo.Size(), nil
}