Support for retrieving messages via REST.

Support for retrieving messages via HTTP rather than websockets.

// FREEBIE

java/src/main/java/org/whispersystems/textsecure/api/TextSecureMessageReceiver.java

@@ -19,15 +19,19 @@ package org.whispersystems.textsecure.api;
 import org.whispersystems.libaxolotl.InvalidMessageException;
 import org.whispersystems.textsecure.api.crypto.AttachmentCipherInputStream;
 import org.whispersystems.textsecure.api.messages.TextSecureAttachmentPointer;
+import org.whispersystems.textsecure.api.messages.TextSecureEnvelope;
 import org.whispersystems.textsecure.api.push.TrustStore;
 import org.whispersystems.textsecure.api.util.CredentialsProvider;
 import org.whispersystems.textsecure.internal.push.PushServiceSocket;
+import org.whispersystems.textsecure.internal.push.TextSecureEnvelopeEntity;
 import org.whispersystems.textsecure.internal.util.StaticCredentialsProvider;
 import org.whispersystems.textsecure.internal.websocket.WebSocketConnection;
 
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.LinkedList;
+import java.util.List;
 
 /**
  * The primary interface for receiving TextSecure messages.
@@ -102,4 +106,38 @@ public class TextSecureMessageReceiver {
     return new TextSecureMessagePipe(webSocket, credentialsProvider);
   }
 
+  public List<TextSecureEnvelope> retrieveMessages() throws IOException {
+    return retrieveMessages(new NullMessageReceivedCallback());
+  }
+
+  public List<TextSecureEnvelope> retrieveMessages(MessageReceivedCallback callback)
+      throws IOException
+  {
+    List<TextSecureEnvelope>       results  = new LinkedList<>();
+    List<TextSecureEnvelopeEntity> entities = socket.getMessages();
+
+    for (TextSecureEnvelopeEntity entity : entities) {
+      TextSecureEnvelope envelope =  new TextSecureEnvelope(entity.getType(), entity.getSource(),
+                                                            entity.getSourceDevice(), entity.getRelay(),
+                                                            entity.getTimestamp(), entity.getMessage());
+
+      callback.onMessage(envelope);
+      results.add(envelope);
+
+      socket.acknowledgeMessage(entity.getSource(), entity.getTimestamp());
+    }
+
+    return results;
+  }
+
+
+  public interface MessageReceivedCallback {
+    public void onMessage(TextSecureEnvelope envelope);
+  }
+
+  public static class NullMessageReceivedCallback implements MessageReceivedCallback {
+    @Override
+    public void onMessage(TextSecureEnvelope envelope) {}
+  }
+
 }

java/src/main/java/org/whispersystems/textsecure/internal/push/PushServiceSocket.java

@@ -90,6 +90,7 @@ public class PushServiceSocket {
   private static final String DIRECTORY_TOKENS_PATH     = "/v1/directory/tokens";
   private static final String DIRECTORY_VERIFY_PATH     = "/v1/directory/%s";
   private static final String MESSAGE_PATH              = "/v1/messages/%s";
+  private static final String ACKNOWLEDGE_MESSAGE_PATH  = "/v1/messages/%s/%d";
   private static final String RECEIPT_PATH              = "/v1/receipt/%s/%d";
   private static final String ATTACHMENT_PATH           = "/v1/attachments/%s";
 
@@ -162,6 +163,15 @@ public class PushServiceSocket {
     }
   }
 
+  public List<TextSecureEnvelopeEntity> getMessages() throws IOException {
+    String responseText = makeRequest(String.format(MESSAGE_PATH, ""), "GET", null);
+    return JsonUtil.fromJson(responseText, TextSecureEnvelopeEntityList.class).getMessages();
+  }
+
+  public void acknowledgeMessage(String sender, long timestamp) throws IOException {
+    makeRequest(String.format(ACKNOWLEDGE_MESSAGE_PATH, sender, timestamp), "DELETE", null);
+  }
+
   public void registerPreKeys(IdentityKey identityKey,
                               PreKeyRecord lastResortKey,
                               SignedPreKeyRecord signedPreKey,

java/src/main/java/org/whispersystems/textsecure/internal/push/TextSecureEnvelopeEntity.java

@@ -0,0 +1,50 @@
+package org.whispersystems.textsecure.internal.push;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+public class TextSecureEnvelopeEntity {
+  
+  @JsonProperty
+  private int type;
+
+  @JsonProperty
+  private String relay;
+
+  @JsonProperty
+  private long timestamp;
+
+  @JsonProperty
+  private String source;
+
+  @JsonProperty
+  private int sourceDevice;
+
+  @JsonProperty
+  private byte[] message;
+
+  public TextSecureEnvelopeEntity() {}
+
+  public int getType() {
+    return type;
+  }
+
+  public String getRelay() {
+    return relay;
+  }
+
+  public long getTimestamp() {
+    return timestamp;
+  }
+
+  public String getSource() {
+    return source;
+  }
+
+  public int getSourceDevice() {
+    return sourceDevice;
+  }
+
+  public byte[] getMessage() {
+    return message;
+  }
+}

java/src/main/java/org/whispersystems/textsecure/internal/push/TextSecureEnvelopeEntityList.java

@@ -0,0 +1,16 @@
+package org.whispersystems.textsecure.internal.push;
+
+import org.whispersystems.textsecure.api.messages.TextSecureEnvelope;
+
+import java.util.List;
+
+public class TextSecureEnvelopeEntityList {
+
+  private List<TextSecureEnvelopeEntity> messages;
+
+  public TextSecureEnvelopeEntityList() {}
+
+  public List<TextSecureEnvelopeEntity> getMessages() {
+    return messages;
+  }
+}