package lastfm
import (
"context"
"crypto/md5"
"encoding/hex"
"encoding/json"
"fmt"
"net/http"
"net/url"
"slices"
"sort"
"strconv"
"strings"
"time"
"github.com/navidrome/navidrome/log"
)
const (
apiBaseUrl = "https://ws.audioscrobbler.com/2.0/"
)
type lastFMError struct {
Code int
Message string
}
func (e *lastFMError) Error() string {
return fmt.Sprintf("last.fm error(%d): %s", e.Code, e.Message)
}
type httpDoer interface {
Do(req *http.Request) (*http.Response, error)
}
func newClient(apiKey string, secret string, hc httpDoer) *client {
return &client{apiKey, secret, hc}
}
type client struct {
apiKey string
secret string
hc httpDoer
}
func (c *client) albumGetInfo(ctx context.Context, name string, artist string, mbid string, lang string) (*Album, error) {
params := url.Values{}
params.Add("method", "album.getInfo")
params.Add("album", name)
params.Add("artist", artist)
params.Add("mbid", mbid)
params.Add("lang", lang)
response, err := c.makeRequest(ctx, http.MethodGet, params, false)
if err != nil {
return nil, err
}
return &response.Album, nil
}
func (c *client) artistGetInfo(ctx context.Context, name string, lang string) (*Artist, error) {
params := url.Values{}
params.Add("method", "artist.getInfo")
params.Add("artist", name)
params.Add("lang", lang)
response, err := c.makeRequest(ctx, http.MethodGet, params, false)
if err != nil {
return nil, err
}
return &response.Artist, nil
}
func (c *client) artistGetSimilar(ctx context.Context, name string, limit int) (*SimilarArtists, error) {
params := url.Values{}
params.Add("method", "artist.getSimilar")
params.Add("artist", name)
params.Add("limit", strconv.Itoa(limit))
response, err := c.makeRequest(ctx, http.MethodGet, params, false)
if err != nil {
return nil, err
}
return &response.SimilarArtists, nil
}
func (c *client) artistGetTopTracks(ctx context.Context, name string, limit int) (*TopTracks, error) {
params := url.Values{}
params.Add("method", "artist.getTopTracks")
params.Add("artist", name)
params.Add("limit", strconv.Itoa(limit))
response, err := c.makeRequest(ctx, http.MethodGet, params, false)
if err != nil {
return nil, err
}
return &response.TopTracks, nil
}
func (c *client) trackGetSimilar(ctx context.Context, name, artist string, limit int) (*SimilarTracks, error) {
params := url.Values{}
params.Add("method", "track.getSimilar")
params.Add("track", name)
params.Add("artist", artist)
params.Add("limit", strconv.Itoa(limit))
response, err := c.makeRequest(ctx, http.MethodGet, params, false)
if err != nil {
return nil, err
}
return &response.SimilarTracks, nil
}
func (c *client) GetToken(ctx context.Context) (string, error) {
params := url.Values{}
params.Add("method", "auth.getToken")
c.sign(params)
response, err := c.makeRequest(ctx, http.MethodGet, params, true)
if err != nil {
return "", err
}
return response.Token, nil
}
func (c *client) getSession(ctx context.Context, token string) (string, error) {
params := url.Values{}
params.Add("method", "auth.getSession")
params.Add("token", token)
response, err := c.makeRequest(ctx, http.MethodGet, params, true)
if err != nil {
return "", err
}
return response.Session.Key, nil
}
type ScrobbleInfo struct {
artist string
track string
album string
trackNumber int
mbid string
duration int
albumArtist string
timestamp time.Time
}
func (c *client) updateNowPlaying(ctx context.Context, sessionKey string, info ScrobbleInfo) error {
params := url.Values{}
params.Add("method", "track.updateNowPlaying")
params.Add("artist", info.artist)
params.Add("track", info.track)
params.Add("album", info.album)
params.Add("trackNumber", strconv.Itoa(info.trackNumber))
params.Add("mbid", info.mbid)
params.Add("duration", strconv.Itoa(info.duration))
params.Add("albumArtist", info.albumArtist)
params.Add("sk", sessionKey)
resp, err := c.makeRequest(ctx, http.MethodPost, params, true)
if err != nil {
return err
}
if resp.NowPlaying.IgnoredMessage.Code != "0" {
log.Warn(ctx, "LastFM: NowPlaying was ignored", "code", resp.NowPlaying.IgnoredMessage.Code,
"text", resp.NowPlaying.IgnoredMessage.Text)
}
return nil
}
func (c *client) scrobble(ctx context.Context, sessionKey string, info ScrobbleInfo) error {
params := url.Values{}
params.Add("method", "track.scrobble")
params.Add("timestamp", strconv.FormatInt(info.timestamp.Unix(), 10))
params.Add("artist", info.artist)
params.Add("track", info.track)
params.Add("album", info.album)
params.Add("trackNumber", strconv.Itoa(info.trackNumber))
params.Add("mbid", info.mbid)
params.Add("duration", strconv.Itoa(info.duration))
params.Add("albumArtist", info.albumArtist)
params.Add("sk", sessionKey)
resp, err := c.makeRequest(ctx, http.MethodPost, params, true)
if err != nil {
return err
}
if resp.Scrobbles.Scrobble.IgnoredMessage.Code != "0" {
log.Warn(ctx, "LastFM: scrobble was ignored", "code", resp.Scrobbles.Scrobble.IgnoredMessage.Code,
"text", resp.Scrobbles.Scrobble.IgnoredMessage.Text, "info", info)
}
if resp.Scrobbles.Attr.Accepted != 1 {
log.Warn(ctx, "LastFM: scrobble was not accepted", "code", resp.Scrobbles.Scrobble.IgnoredMessage.Code,
"text", resp.Scrobbles.Scrobble.IgnoredMessage.Text, "info", info)
}
return nil
}
func (c *client) makeRequest(ctx context.Context, method string, params url.Values, signed bool) (*Response, error) {
params.Add("format", "json")
params.Add("api_key", c.apiKey)
if signed {
c.sign(params)
}
var req *http.Request
if method == http.MethodPost {
body := strings.NewReader(params.Encode())
req, _ = http.NewRequestWithContext(ctx, method, apiBaseUrl, body)
req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
} else {
req, _ = http.NewRequestWithContext(ctx, method, apiBaseUrl, nil)
req.URL.RawQuery = params.Encode()
}
log.Trace(ctx, fmt.Sprintf("Sending Last.fm %s request", req.Method), "url", req.URL)
resp, err := c.hc.Do(req)
if err != nil {
return nil, err
}
defer resp.Body.Close()
decoder := json.NewDecoder(resp.Body)
var response Response
jsonErr := decoder.Decode(&response)
if resp.StatusCode != 200 && jsonErr != nil {
return nil, fmt.Errorf("last.fm http status: (%d)", resp.StatusCode)
}
if jsonErr != nil {
return nil, jsonErr
}
if response.Error != 0 {
return &response, &lastFMError{Code: response.Error, Message: response.Message}
}
return &response, nil
}
func (c *client) sign(params url.Values) {
keys := make([]string, 0, len(params))
for k := range params {
if slices.Contains([]string{"format", "callback"}, k) {
continue
}
keys = append(keys, k)
}
sort.Strings(keys)
msg := strings.Builder{}
for _, k := range keys {
msg.WriteString(k)
msg.WriteString(params[k][0])
}
msg.WriteString(c.secret)
hash := md5.Sum([]byte(msg.String()))
params.Add("api_sig", hex.EncodeToString(hash[:]))
}
