add recommend definition (#18)

internal/functions/definitions.go

@@ -0,0 +1,47 @@
+package functions
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/zmb3/spotify/v2"
+)
+
+const (
+	RecommendCount = 5
+)
+
+func Recommend(ctx context.Context, client *spotify.Client, genres string) (string, error) {
+	// genres length needs to be less than 5
+	if len(genres) > 5 {
+		genres = genres[:5]
+	}
+	genresSlice := strings.Split(genres, ",")
+
+	seeds := spotify.Seeds{
+		Genres: genresSlice,
+	}
+
+	trackAttrib := spotify.NewTrackAttributes()
+
+	recommendations, err := client.GetRecommendations(ctx, seeds, trackAttrib, spotify.Limit(RecommendCount))
+	if err != nil {
+		return "", fmt.Errorf("fail to get recommendations: %v", err)
+	}
+
+	var output string
+	for i, track := range recommendations.Tracks {
+		output += fmt.Sprintf("[%d]\n", i+1)
+		output += fmt.Sprintf("album: %s\n", track.Album.Name)
+		var artists []string
+		for _, artist := range track.Artists {
+			artists = append(artists, artist.Name)
+		}
+		output += fmt.Sprintf("artists: %s\n", strings.Join(artists, ","))
+		output += fmt.Sprintf("url: %s\n", track.ExternalURLs["spotify"])
+		output += "\n"
+	}
+
+	return output, nil
+}