Support sending voice messages

src/main/java/net/dv8tion/jda/api/entities/Message.java

@@ -2253,6 +2253,13 @@ default MessageCreateAction replyFiles(@Nonnull Collection<? extends FileUpload>
      */
     boolean isSuppressedNotifications();
 
+    /**
+     * Whether this message is a voice message.
+     *
+     * @return True, if this is a voice message
+     */
+    boolean isVoiceMessage();
+
     /**
      * Returns a possibly {@code null} {@link ThreadChannel ThreadChannel} that was started from this message.
      * This can be {@code null} due to no ThreadChannel being started from it or the ThreadChannel later being deleted.

src/main/java/net/dv8tion/jda/api/utils/FileUpload.java

@@ -32,9 +32,11 @@
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.io.*;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.OpenOption;
 import java.nio.file.Path;
+import java.util.Base64;
 import java.util.function.Supplier;
 
 /**
@@ -51,6 +53,9 @@ public class FileUpload implements Closeable, AttachedFile
     private String name;
     private TypedBody<?> body;
     private String description;
+    private MediaType mediaType = Requester.MEDIA_TYPE_OCTET;
+    private byte[] waveform;
+    private double durationSeconds;
 
     protected FileUpload(InputStream resource, String name)
     {
@@ -358,6 +363,45 @@ public FileUpload setDescription(@Nullable String description)
         return this;
     }
 
+    /**
+     * Turns this attachment into a voice message with the provided waveform.
+     *
+     * @param  mediaType
+     *         The audio type for the attached audio file. Should be {@code audio/ogg} or similar.
+     * @param  waveform
+     *         The waveform of the audio, which is a low frequency sampling up to 256 bytes.
+     * @param  durationSeconds
+     *         The actual duration of the audio data in seconds.
+     *
+     * @throws IllegalArgumentException
+     *         If null is provided or the waveform is not between 1 and 256 bytes long.
+     *
+     * @return The same FileUpload instance configured as a voice message attachment
+     */
+    @Nonnull
+    public FileUpload asVoiceMessage(@Nonnull MediaType mediaType, @Nonnull byte[] waveform, double durationSeconds)
+    {
+        Checks.notNull(mediaType, "Media type");
+        Checks.notNull(waveform, "Waveform");
+        Checks.check(waveform.length > 0 && waveform.length <= 256, "Waveform must be between 1 and 256 bytes long");
+        Checks.check(Double.isFinite(durationSeconds), "Duration must be a finite number");
+        Checks.check(durationSeconds > 0, "Duration must be positive");
+        this.waveform = waveform;
+        this.durationSeconds = durationSeconds;
+        this.mediaType = mediaType;
+        return this;
+    }
+
+    /**
+     * Whether this attachment is a valid voice message attachment.
+     *
+     * @return True, if this is a voice message attachment.
+     */
+    public boolean isVoiceMessage()
+    {
+        return this.mediaType.type().equals("audio");
+    }
+
     /**
      * The filename for the file.
      *
@@ -425,17 +469,24 @@ public synchronized RequestBody getRequestBody(@Nonnull MediaType type)
     @SuppressWarnings("ConstantConditions")
     public synchronized void addPart(@Nonnull MultipartBody.Builder builder, int index)
     {
-        builder.addFormDataPart("files[" + index + "]", name, getRequestBody(Requester.MEDIA_TYPE_OCTET));
+        builder.addFormDataPart("files[" + index + "]", name, getRequestBody(mediaType));
     }
 
     @Nonnull
     @Override
     public DataObject toAttachmentData(int index)
     {
-        return DataObject.empty()
+        DataObject attachment = DataObject.empty()
                 .put("id", index)
                 .put("description", description == null ? "" : description)
+                .put("content_type", mediaType)
                 .put("filename", name);
+        if (waveform != null && durationSeconds > 0)
+        {
+            attachment.put("waveform", new String(Base64.getEncoder().encode(waveform), StandardCharsets.UTF_8));
+            attachment.put("duration_secs", durationSeconds);
+        }
+        return attachment;
     }
 
     @Override

src/main/java/net/dv8tion/jda/api/utils/messages/MessageCreateBuilder.java

@@ -24,6 +24,7 @@
 import net.dv8tion.jda.internal.utils.Checks;
 import net.dv8tion.jda.internal.utils.Helpers;
 import net.dv8tion.jda.internal.utils.IOUtil;
+import org.jetbrains.annotations.NotNull;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
@@ -181,7 +182,10 @@ public MessageCreateBuilder setFiles(@Nullable Collection<? extends FileUpload>
             Checks.noneNull(files, "Files");
         this.files.clear();
         if (files != null)
+        {
             this.files.addAll(files);
+            this.setVoiceMessageIfApplicable(files);
+        }
         return this;
     }
 
@@ -213,6 +217,7 @@ public MessageCreateBuilder addFiles(@Nonnull Collection<? extends FileUpload> f
     {
         Checks.noneNull(files, "Files");
         this.files.addAll(files);
+        this.setVoiceMessageIfApplicable(files);
         return this;
     }
 
@@ -228,13 +233,24 @@ public MessageCreateBuilder setTTS(boolean tts)
     @Override
     public MessageCreateBuilder setSuppressedNotifications(boolean suppressed)
     {
-        if(suppressed)
+        if (suppressed)
             messageFlags |= Message.MessageFlag.NOTIFICATIONS_SUPPRESSED.getValue();
         else
             messageFlags &= ~Message.MessageFlag.NOTIFICATIONS_SUPPRESSED.getValue();
         return this;
     }
 
+    @Nonnull
+    @Override
+    public MessageCreateBuilder setVoiceMessage(boolean voiceMessage)
+    {
+        if (voiceMessage)
+            messageFlags |= Message.MessageFlag.IS_VOICE_MESSAGE.getValue();
+        else
+            messageFlags &= ~Message.MessageFlag.IS_VOICE_MESSAGE.getValue();
+        return this;
+    }
+
     @Override
     public boolean isEmpty()
     {
@@ -291,4 +307,10 @@ public MessageCreateBuilder closeFiles()
         files.clear();
         return this;
     }
+
+    private void setVoiceMessageIfApplicable(@NotNull Collection<? extends FileUpload> files)
+    {
+        if (files.stream().anyMatch(FileUpload::isVoiceMessage))
+            this.setVoiceMessage(true);
+    }
 }

src/main/java/net/dv8tion/jda/api/utils/messages/MessageCreateData.java

@@ -270,13 +270,23 @@ public boolean isTTS()
     /**
      * Whether this message is silent.
      *
-     * @return True, if the message will not trigger push and desktop notifications
+     * @return True, if the message will not trigger push and desktop notifications.
      */
     public boolean isSuppressedNotifications()
     {
         return (flags & Message.MessageFlag.NOTIFICATIONS_SUPPRESSED.getValue()) != 0;
     }
 
+    /**
+     * Whether this message is intended as a voice message.
+     *
+     * @return True, if this message is intended as a voice message.
+     */
+    public boolean isVoiceMessage()
+    {
+        return (flags & Message.MessageFlag.IS_VOICE_MESSAGE.getValue()) != 0;
+    }
+
     /**
      * The IDs for users which are allowed to be mentioned, or an empty list.
      *

src/main/java/net/dv8tion/jda/api/utils/messages/MessageCreateRequest.java

@@ -25,6 +25,7 @@
 import net.dv8tion.jda.api.requests.RestAction;
 import net.dv8tion.jda.api.utils.FileUpload;
 import net.dv8tion.jda.internal.utils.Checks;
+import okhttp3.MediaType;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
@@ -339,11 +340,24 @@ default R addFiles(@Nonnull FileUpload... files)
      * @param  suppressed
      *         True, if this message should not trigger push/desktop notifications
      *
-     * @return The same reply action, for chaining convenience
+     * @return The same instance for chaining
      */
     @Nonnull
     R setSuppressedNotifications(boolean suppressed);
 
+    /**
+     * Whether this message should be considered a voice message.
+     * <br>Voice messages must upload a valid voice message attachment, using {@link FileUpload#asVoiceMessage(MediaType, byte[], double)}.
+     *
+     * @param  voiceMessage
+     *         True, if this message is a voice message.
+     *         Turned on automatically if attachment is a valid voice message attachment.
+     *
+     * @return The same instance for chaining
+     */
+    @Nonnull
+    R setVoiceMessage(boolean voiceMessage);
+
     /**
      * Applies the provided {@link MessageCreateData} to this request.
      *
@@ -372,6 +386,7 @@ default R applyData(@Nonnull MessageCreateData data)
                 .setTTS(data.isTTS())
                 .setSuppressEmbeds(data.isSuppressEmbeds())
                 .setSuppressedNotifications(data.isSuppressedNotifications())
+                .setVoiceMessage(data.isVoiceMessage())
                 .setComponents(layoutComponents)
                 .setPoll(data.getPoll())
                 .setFiles(data.getFiles());
@@ -390,6 +405,7 @@ default R applyMessage(@Nonnull Message message)
                 .setEmbeds(embeds)
                 .setTTS(message.isTTS())
                 .setSuppressedNotifications(message.isSuppressedNotifications())
+                .setVoiceMessage(message.isVoiceMessage())
                 .setComponents(message.getActionRows())
                 .setPoll(message.getPoll() != null ? MessagePollData.from(message.getPoll()) : null);
     }

src/main/java/net/dv8tion/jda/internal/entities/ReceivedMessage.java

@@ -933,6 +933,12 @@ public boolean isSuppressedNotifications()
         return (this.flags & MessageFlag.NOTIFICATIONS_SUPPRESSED.getValue()) != 0;
     }
 
+    @Override
+    public boolean isVoiceMessage()
+    {
+        return (this.flags & MessageFlag.IS_VOICE_MESSAGE.getValue()) != 0;
+    }
+
     @Nullable
     @Override
     public ThreadChannel getStartedThread()

src/main/java/net/dv8tion/jda/internal/utils/message/MessageCreateBuilderMixin.java

@@ -108,4 +108,12 @@ default R setSuppressedNotifications(boolean suppressed)
         getBuilder().setSuppressedNotifications(suppressed);
         return (R) this;
     }
+
+    @Nonnull
+    @Override
+    default R setVoiceMessage(boolean voiceMessage)
+    {
+        getBuilder().setVoiceMessage(voiceMessage);
+        return (R) this;
+    }
 }