package main

import (
	"context"
	"time"

	"github.com/lrstanley/go-ytdlp"
)

type DownloadOptions struct {
	EmbedThumbnail   bool
	IncludeSubtitles bool
}

type ProgressUpdate struct {
	Status   ytdlp.ProgressStatus
	Percent  string
	ETA      time.Duration
	Filename string
	Phase    string
}

func downloadVideo(out_dir, url string, opts DownloadOptions, progressChan chan<- ProgressUpdate) {
	defer close(progressChan)

	var lastPhase string

	dl := ytdlp.New().
		SetWorkDir(out_dir).
		FormatSort("res,ext:mp4:m4a").
		RecodeVideo("mp4").
		ProgressFunc(100*time.Millisecond, func(prog ytdlp.ProgressUpdate) {
			// Detect phase transition -- differentiate "downloading" as the main download
			// and "post processing" when the file name changes, preventing it from appearing "reset"
			phase := "downloading"
			if prog.Status == ytdlp.ProgressStatusDownloading && prog.Percent() == 0.0 {
				// If we already had progress, it's likely post-processing
				if lastPhase == "downloading" {
					phase = "post-processing"
				}
			} else if prog.Status != ytdlp.ProgressStatusDownloading {
				phase = "post-processing"
			}

			lastPhase = phase

			progressChan <- ProgressUpdate{
				Status:   prog.Status,
				Percent:  prog.PercentString(),
				ETA:      prog.ETA(),
				Filename: prog.Filename,
				Phase:    phase,
			}
		}).
		Output("%(title)s.%(ext)s")

	if opts.EmbedThumbnail {
		dl = dl.EmbedThumbnail()
	}

	if opts.IncludeSubtitles {
		dl = dl.CompatOptions("no-keep-subs")
		dl = dl.EmbedSubs()
		dl = dl.SubLangs("en,en*")
		dl = dl.WriteAutoSubs()
		dl = dl.WriteSubs()
	}

	_, err := dl.Run(context.TODO(), url)
	if err != nil {
		panic(err)
	}
}