Adds Lyrics Support to Subsonic API (#1379)

* Add function 'isSynced' that identifies if lyrics are synced or not and add tests for the same

* implement 'getLyrics' which returns lyrics if they exist

Signed-off-by: Dheeraj Lalwani <lalwanidheeraj1234@gmail.com>

* remove timestamps frorom the the lyrics if they are synced, fix filters & clean up code

Signed-off-by: Dheeraj Lalwani <lalwanidheeraj1234@gmail.com>

* add snapshot tests for the 'Lyrics' response & add some clean up

Signed-off-by: Dheeraj Lalwani <lalwanidheeraj1234@gmail.com>

* add tests for 'GetLyrics' function

Signed-off-by: Dheeraj Lalwani <lalwanidheeraj1234@gmail.com>

* update the snapshot test & the test for 'GetLyrics' function

Signed-off-by: Dheeraj Lalwani <lalwanidheeraj1234@gmail.com>

server/subsonic/media_retrieval.go

@@ -3,6 +3,7 @@ package subsonic
 import (
 	"io"
 	"net/http"
+	"regexp"
 
 	"github.com/navidrome/navidrome/conf"
 	"github.com/navidrome/navidrome/consts"
@@ -10,6 +11,7 @@ import (
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/resources"
+	"github.com/navidrome/navidrome/server/subsonic/filter"
 	"github.com/navidrome/navidrome/server/subsonic/responses"
 	"github.com/navidrome/navidrome/utils"
 	"github.com/navidrome/navidrome/utils/gravatar"
@@ -78,3 +80,42 @@ func (c *MediaRetrievalController) GetCoverArt(w http.ResponseWriter, r *http.Re
 
 	return nil, err
 }
+
+const TIMESTAMP_REGEX string = `(\[([0-9]{1,2}:)?([0-9]{1,2}:)([0-9]{1,2})(\.[0-9]{1,2})?\])`
+
+func isSynced(rawLyrics string) bool {
+	r := regexp.MustCompile(TIMESTAMP_REGEX)
+	// Eg: [04:02:50.85]
+	// [02:50.85]
+	// [02:50]
+	return r.MatchString(rawLyrics)
+}
+
+func (c *MediaRetrievalController) GetLyrics(w http.ResponseWriter, r *http.Request) (*responses.Subsonic, error) {
+	artist := utils.ParamString(r, "artist")
+	title := utils.ParamString(r, "title")
+	response := newResponse()
+	lyrics := responses.Lyrics{}
+	response.Lyrics = &lyrics
+	media_files, err := c.ds.MediaFile(r.Context()).GetAll(filter.SongsWithLyrics(artist, title))
+
+	if err != nil {
+		return nil, err
+	}
+
+	if len(media_files) == 0 {
+		return response, nil
+	}
+
+	lyrics.Artist = artist
+	lyrics.Title = title
+
+	if isSynced(media_files[0].Lyrics) {
+		r := regexp.MustCompile(TIMESTAMP_REGEX)
+		lyrics.Value = r.ReplaceAllString(media_files[0].Lyrics, "")
+	} else {
+		lyrics.Value = media_files[0].Lyrics
+	}
+
+	return response, nil
+}