music-dl/main.go

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"log"
	"music-downloader/monochrome"
	"net/http"
	"os"
	"path"
	"strconv"
	"sync"

	"go.senan.xyz/taglib"
)

func sendJSON(w http.ResponseWriter, data any, status int) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	if err := json.NewEncoder(w).Encode(data); err != nil {
		http.Error(w, err.Error(), 500)
	}
}

func main() {
	mClient := monochrome.NewClient(monochrome.ClientConfig{
		ApiURL: "https://api.monochrome.tf",
	})

	mux := http.NewServeMux()

	mux.HandleFunc("GET /search", func(w http.ResponseWriter, r *http.Request) {
		q := r.URL.Query().Get("q")

		results, err := mClient.SearchAlbum(q)
		if err != nil {
			http.Error(w, err.Error(), 404)
			return
		}

		sendJSON(w, results, 200)
	})

	mux.HandleFunc("GET /download-album/{id}", func(w http.ResponseWriter, r *http.Request) {
		id, err := strconv.Atoi(r.PathValue("id"))
		if err != nil {
			http.Error(w, err.Error(), 500)
			return
		}

		album, err := mClient.AlbumInfo(id)
		if err != nil {
			http.Error(w, err.Error(), 404)
			return
		}

		if album == nil {
			http.Error(w, "album not found for some reason", 404)
			return
		}

		albumCoverImg, err := mClient.AlbumCoverImage(album.CoverID)
		if err != nil {
			log.Printf("failed to download album cover: %v\n", err)
		}

		if err := os.Mkdir("./Music/"+album.Title, 0777); err != nil {
			http.Error(w, fmt.Sprintf("failed to create album directory: %v", err), 500)
			return
		}

		type Response struct {
			sync.Mutex
			count int
		}
		response := new(Response)

		var wg sync.WaitGroup
		for _, track := range album.Items {
			wg.Go(func() {
				info, err := mClient.TrackInfo(track.Item.ID, track.Item.AudioQuality)
				if err != nil {
					log.Printf("failed to get track info: %v\n", err)
					return
				}

				manifest, err := mClient.DecodeManifest(info.Manifest)
				if err != nil {
					log.Printf("failed to decode track manifest: %v\n", err)
					return
				}

				if manifest.EncryptionType != monochrome.TrackManifestEncryptionNone {
					log.Println("file is encrypted; can't download")
					return
				}

				if len(manifest.URLs) == 0 {
					log.Println("track manifest doesn't have urls array")
					return
				}

				resp, err := http.Get(manifest.URLs[0])
				if err != nil {
					log.Printf("failed to download track data: %v\n", err)
					return
				}
				defer resp.Body.Close()

				data, err := io.ReadAll(resp.Body)
				if err != nil {
					log.Printf("failed to read track data: %v\n", err)
					return
				}

				fPath := path.Join("./Music/", album.Title, track.Item.Title+".flac")
				if err := os.WriteFile(fPath, data, 0644); err != nil {
					log.Printf("failed to save track file: %v\n", err)
					return
				}

				artists := []string{}
				for _, artist := range album.Artists {
					artists = append(artists, artist.Name)
				}

				if err := taglib.WriteTags(fPath, map[string][]string{
					taglib.Artist:      {album.Artist.Name},
					taglib.Artists:     artists,
					taglib.AlbumArtist: artists,
					taglib.TrackNumber: {strconv.Itoa(track.Item.TrackNumber)},
					taglib.Album:       {album.Title},
					taglib.Title:       {track.Item.Title},
					taglib.ReleaseDate: {album.ReleaseDate},
				}, 0); err != nil {
					log.Printf("failed to add metadata tags to track file: %v\n", err)
				}

				if err := taglib.WriteImage(fPath, albumCoverImg); err != nil {
					log.Printf("failed to add album cover to track metadata: %v\n", err)
				}

				response.Lock()
				response.count++
				response.Unlock()
			})
		}

		wg.Wait()

		sendJSON(w, struct {
			DownloadedFilesCount int `json:"downloadedFilesCount"`
			TotalFilesCount      int `json:"totalFilesCount"`
		}{
			DownloadedFilesCount: response.count,
			TotalFilesCount:      len(album.Items),
		}, 200)
	})

	log.Println("starting http server")
	if err := http.ListenAndServe(":5000", mux); err != nil {
		log.Fatalf("failed to start http server: %v\n", err)
	}
}