Initial work for recommendations

app/src/main/java/musicbot/Listeners.java

@@ -13,6 +13,8 @@ public class Listeners extends ListenerAdapter {
 
     @Override
     public void onReady(@NotNull final ReadyEvent event) {
+        //final Guild guildId = event.getJDA().getGuildById(1197770092243599431L);
+
         event.getJDA().upsertCommand("music", "find music to play").addOptions(
                 new OptionData(
                         OptionType.STRING,
@@ -25,5 +27,14 @@ public class Listeners extends ListenerAdapter {
                         "The artist of the song",
                         true)
         ).queue();
+
+        event.getJDA().upsertCommand("recommend", "find recommendations for music").addOptions(
+                new OptionData(
+                        OptionType.STRING,
+                        "artist",
+                        "The name of artist you like",
+                        true
+                )
+        ).queue();
     }
 }

app/src/main/java/musicbot/Main.java

@@ -1,6 +1,7 @@
 package musicbot;
 
 import musicbot.commands.MusicVideo;
+import musicbot.commands.Recommend;
 import net.dv8tion.jda.api.JDA;
 import net.dv8tion.jda.api.JDABuilder;
 
@@ -11,5 +12,6 @@ public class Main {
                 .build();
         jda.addEventListener(new Listeners());
         jda.addEventListener(new MusicVideo());
+        jda.addEventListener(new Recommend());
     }
 }

app/src/main/java/musicbot/SpotifyClient.java

@@ -0,0 +1,87 @@
+package musicbot;
+
+import com.google.common.collect.ImmutableList;
+import com.neovisionaries.i18n.CountryCode;
+import org.apache.hc.core5.http.ParseException;
+import se.michaelthelin.spotify.SpotifyApi;
+import se.michaelthelin.spotify.exceptions.SpotifyWebApiException;
+import se.michaelthelin.spotify.model_objects.credentials.ClientCredentials;
+import se.michaelthelin.spotify.model_objects.special.SearchResult;
+import se.michaelthelin.spotify.model_objects.specification.Artist;
+import se.michaelthelin.spotify.model_objects.specification.Paging;
+import se.michaelthelin.spotify.model_objects.specification.Recommendations;
+import se.michaelthelin.spotify.model_objects.specification.Track;
+import se.michaelthelin.spotify.requests.authorization.client_credentials.ClientCredentialsRequest;
+import se.michaelthelin.spotify.requests.data.browse.GetRecommendationsRequest;
+import se.michaelthelin.spotify.requests.data.search.SearchItemRequest;
+import se.michaelthelin.spotify.requests.data.search.simplified.SearchArtistsRequest;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+public class SpotifyClient {
+    private static final SpotifyApi SPOTIFY_API = new SpotifyApi.Builder()
+                .setClientId(Token.SPOTIFY_CLIENT_ID)
+                .setClientSecret(Token.SPOTIFY_CLIENT_SECRET)
+                .build();
+
+    private static final ClientCredentialsRequest CLIENT_CREDENTIALS_REQUEST = SPOTIFY_API
+            .clientCredentials()
+            .build();
+
+    public SpotifyClient() {
+        clientCredentialsSync();
+    }
+
+    public Optional<Artist> findArtist(final String artist) {
+        final SearchArtistsRequest searchItemRequest = SPOTIFY_API.searchArtists(artist)
+                .market(CountryCode.US)
+                .limit(1)
+                .build();
+
+        try {
+            final SearchArtistsRequest searchArtistsRequest = SPOTIFY_API.searchArtists(artist)
+                    .limit(1)
+                    .build();
+
+            final Paging<Artist> artists  = searchArtistsRequest.execute();
+            return Arrays.stream(artists.getItems()).findFirst();
+        } catch (SpotifyWebApiException | ParseException | IOException exception) {
+            return Optional.empty();
+        }
+    }
+
+    public List<Track> findRecommendations(final String artistId) {
+        System.out.println("getting recommendations");
+        final GetRecommendationsRequest recommendationsRequest = SPOTIFY_API.getRecommendations()
+                .seed_artists(artistId)
+                .limit(5)
+                .build();
+
+        try {
+            final Recommendations recommendations = recommendationsRequest.execute();
+            System.out.println("Length: " + recommendations.getTracks().length);
+
+            return Arrays.stream(recommendations.getTracks()).collect(Collectors.toList());
+        } catch (IOException | SpotifyWebApiException | ParseException e) {
+            System.out.println("Error: " + e.getMessage());
+            return ImmutableList.of();
+        }
+    }
+
+    private static void clientCredentialsSync() {
+        try {
+            final ClientCredentials clientCredentials = CLIENT_CREDENTIALS_REQUEST.execute();
+
+            // Set access token for further "spotifyApi" object usage
+            SPOTIFY_API.setAccessToken(clientCredentials.getAccessToken());
+
+            System.out.println("Expires in: " + clientCredentials.getExpiresIn());
+        } catch (final IOException | SpotifyWebApiException | ParseException e) {
+            System.out.println("Error: " + e.getMessage());
+        }
+    }
+}

app/src/main/java/musicbot/commands/Recommend.java

@@ -0,0 +1,38 @@
+package musicbot.commands;
+
+import musicbot.SpotifyClient;
+import net.dv8tion.jda.api.events.interaction.command.SlashCommandInteractionEvent;
+import net.dv8tion.jda.api.utils.MiscUtil;
+import net.dv8tion.jda.api.hooks.ListenerAdapter;
+import net.dv8tion.jda.api.utils.messages.MessageCreateData;
+import org.jetbrains.annotations.NotNull;
+import se.michaelthelin.spotify.model_objects.specification.Artist;
+import se.michaelthelin.spotify.model_objects.specification.Recommendations;
+import se.michaelthelin.spotify.model_objects.specification.Track;
+
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+public class Recommend extends ListenerAdapter {
+
+    @Override
+    public void onSlashCommandInteraction(@NotNull final SlashCommandInteractionEvent event) {
+        if (!event.getName().equals("recommend")) return;
+
+        final String artist = Objects.requireNonNull(event.getOption("artist")).getAsString();
+        final SpotifyClient spotifyClient = new SpotifyClient();
+        final Optional<Artist> maybeArtist = spotifyClient.findArtist(artist);
+
+        if (maybeArtist.isPresent()) {
+            final String artistId = maybeArtist.get().getId();
+            final List<String> tracks = spotifyClient.findRecommendations(artistId).stream().map(track -> track.getName()).collect(Collectors.toList());
+            final String message = String.join(", ", tracks);/**/
+
+            event.reply(message).queue();
+        } else {
+            event.reply("Sorry, I can't find any recommendations.").queue();
+        }
+    }
+}