plexbrainz/main.go

package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"os"
	"strconv"
	"strings"
	"time"
)

var lbToken string
var plexUsername string
var plexLibsStr string
var listen = ":9102"

func main() {

	lbToken = os.Getenv("PB_LISTENBRAINZ_USER_TOKEN")
	plexUsername = os.Getenv("PB_PLEX_USERNAME")
	plexLibsStr = os.Getenv("PB_PLEX_LIBRARIES")
	debug, _ := strconv.ParseBool(os.Getenv("PB_DEBUG"))

	if lbToken == "" {
		slog.Error("you must set PB_LISTENBRAINZ_USER_TOKEN - see https://listenbrainz.org/settings/")
		os.Exit(1)
	}

	if plexUsername == "" {
		slog.Error("you must set PB_PLEX_USERNAME to the user who's listens will be recorded")
		os.Exit(1)
	}

	if plexLibsStr == "" {
		slog.Error("you must set PB_PLEX_LIBRARIES to a comma separated list of plex libraries which will be scrobbled")
		os.Exit(1)
	}

	if debug {
		slog.SetLogLoggerLevel(slog.LevelDebug)
	}

	plexLibs := strings.Split(plexLibsStr, ",")

	http.HandleFunc("POST /plex", func(w http.ResponseWriter, r *http.Request) {
		err := r.ParseMultipartForm(1 * 1024 * 1024)
		if err != nil {
			slog.Error("error parsing multipart form", "error", err.Error())
			return
		}

		pl := r.FormValue("payload")
		event := webhookEvent{}
		err = json.Unmarshal([]byte(pl), &event)

		if err != nil {
			slog.Error("error parsing JSON", "error", err.Error())
			w.WriteHeader(400)
			w.Write([]byte("could not parse your JSON"))
			return
		}

		slog.Debug("received event", "event", event)
		// slog.Printf("account name: %s", event.Account.Title)
		// slog.Printf("title: %s", event.Metadata.Title)
		// slog.Printf("album: %s", event.Metadata.ParentTitle)
		// slog.Printf("artist: %s", event.Metadata.GrandparentTitle)
		// slog.Printf("library: %s", event.Metadata.LibrarySectionTitle)

		// 2025/10/19 09:21:31 event: media.play
		// 2025/10/19 09:21:31 account name: username
		// 2025/10/19 09:21:31 title: Face to Face (Cosmo Vitelli remix)
		// 2025/10/19 09:21:31 album: Daft Club
		// 2025/10/19 09:21:31 artist: Daft Punk
		// 2025/10/19 09:21:31 library: Music
		if event.Account.Title != plexUsername {
			slog.Error("not scrobbling for this user", "user", event.Account.Title)
			w.WriteHeader(200)
			w.Write([]byte("ok"))
			return
		}

		if event.Event == "media.scrobble" {
			found := false
			for i := range plexLibs {
				if event.Metadata.LibrarySectionTitle == plexLibs[i] {
					found = true
					break
				}
			}
			if !found {
				slog.Debug("not scrobbling for this library", "library", event.Metadata.LibrarySectionTitle)
				slog.Debug("does not match a configured library", "libraries", plexLibsStr)
				w.WriteHeader(200)
				w.Write([]byte("ok"))
				return
			}

			err = lbSubmit(event.Metadata.Title, event.Metadata.GrandparentTitle, event.Metadata.ParentTitle)
			if err != nil {
				slog.Error("error submitting to listenbrainz", "error", err.Error())
				w.WriteHeader(400)
				w.Write([]byte("could not submit to listenbrainz"))
				return
			} else {
				slog.Info("scrobbled play", "grandparent", event.Metadata.GrandparentTitle, "title", event.Metadata.Title)
				w.WriteHeader(200)
				w.Write([]byte("ok"))
				return
			}
		} else {
			slog.Debug("non scrobble event", "event", event.Event)
			w.WriteHeader(200)
			w.Write([]byte("ok"))
			return
		}

	})
	slog.Info("starting web server", "listen", listen)
	slog.Error(http.ListenAndServe(listen, nil).Error())
	os.Exit(1)
}

func lbSubmit(title, artist, album string) error {
	c := http.Client{}

	c.Timeout = time.Second * 10
	url := "https://api.listenbrainz.org/1/submit-listens"

	b := bytes.Buffer{}
	pl := lbListen{
		ListenType: "single",
		Payload: []lbListenPayload{{
			ListenedAt: time.Now().Unix(),
			TrackMetadata: lbTrackMetadata{
				ArtistName:  artist,
				TrackName:   title,
				ReleaseName: album,
			},
		}},
	}

	err := json.NewEncoder(&b).Encode(pl)
	if err != nil {
		return err
	}

	req, err := http.NewRequest("POST", url, bytes.NewBuffer(b.Bytes()))
	if err != nil {
		return err
	}
	req.Header.Set("Authorization", fmt.Sprintf("Token %s", lbToken))
	req.Header.Set("Content-Type", "application/json")

	res, err := c.Do(req)
	if err != nil {
		return err
	}
	defer res.Body.Close()

	if res.StatusCode != 200 {
		errB := bytes.Buffer{}
		io.Copy(&errB, res.Body)
		return fmt.Errorf("got non-200 response: %d - body: %s", res.StatusCode, errB.String())
	}

	// happy path
	resB := bytes.Buffer{}
	io.Copy(&resB, res.Body)
	slog.Debug("listenbrainz OK", "response", resB.String())

	return nil
}