Files
gonic/server/lastfm/lastfm.go
2020-05-07 03:24:50 +01:00

115 lines
2.9 KiB
Go

package lastfm
import (
"crypto/md5"
"encoding/hex"
"encoding/xml"
"errors"
"fmt"
"net/http"
"net/url"
"sort"
"strconv"
"go.senan.xyz/gonic/server/db"
)
const (
baseURL = "https://ws.audioscrobbler.com/2.0/"
)
var (
ErrLastFM = errors.New("last.fm error")
)
// TODO: remove this package's dependency on models/db
func getParamSignature(params url.Values, secret string) string {
// the parameters must be in order before hashing
paramKeys := make([]string, 0, len(params))
for k := range params {
paramKeys = append(paramKeys, k)
}
sort.Strings(paramKeys)
toHash := ""
for _, k := range paramKeys {
toHash += k
toHash += params[k][0]
}
toHash += secret
hash := md5.Sum([]byte(toHash))
return hex.EncodeToString(hash[:])
}
func makeRequest(method string, params url.Values) (LastFM, error) {
req, _ := http.NewRequest(method, baseURL, nil)
req.URL.RawQuery = params.Encode()
resp, err := http.DefaultClient.Do(req)
if err != nil {
return LastFM{}, fmt.Errorf("get: %w", err)
}
defer resp.Body.Close()
decoder := xml.NewDecoder(resp.Body)
lastfm := LastFM{}
if err = decoder.Decode(&lastfm); err != nil {
return LastFM{}, fmt.Errorf("decoding: %w", err)
}
if lastfm.Error.Code != 0 {
return LastFM{}, fmt.Errorf("%v: %w", lastfm.Error.Value, ErrLastFM)
}
return lastfm, nil
}
func GetSession(apiKey, secret, token string) (string, error) {
params := url.Values{}
params.Add("method", "auth.getSession")
params.Add("api_key", apiKey)
params.Add("token", token)
params.Add("api_sig", getParamSignature(params, secret))
resp, err := makeRequest("GET", params)
if err != nil {
return "", fmt.Errorf("making session GET: %w", err)
}
return resp.Session.Key, nil
}
type ScrobbleOptions struct {
Track *db.Track
StampMili int
Submission bool
}
func Scrobble(apiKey, secret, session string, opts ScrobbleOptions) error {
params := url.Values{}
if opts.Submission {
params.Add("method", "track.Scrobble")
// last.fm wants the timestamp in seconds
params.Add("timestamp", strconv.Itoa(opts.StampMili/1e3))
} else {
params.Add("method", "track.updateNowPlaying")
}
params.Add("api_key", apiKey)
params.Add("sk", session)
params.Add("artist", opts.Track.TagTrackArtist)
params.Add("track", opts.Track.TagTitle)
params.Add("trackNumber", strconv.Itoa(opts.Track.TagTrackNumber))
params.Add("album", opts.Track.Album.TagTitle)
params.Add("mbid", opts.Track.TagBrainzID)
params.Add("albumArtist", opts.Track.Artist.Name)
params.Add("api_sig", getParamSignature(params, secret))
_, err := makeRequest("POST", params)
return err
}
func ArtistGetInfo(apiKey string, artist *db.Artist) (Artist, error) {
params := url.Values{}
params.Add("method", "artist.getInfo")
params.Add("api_key", apiKey)
params.Add("artist", artist.Name)
resp, err := makeRequest("GET", params)
if err != nil {
return Artist{}, fmt.Errorf("making artist GET: %w", err)
}
return resp.Artist, nil
}