Introduce APIs for RTT calls (part 1)

Add signaling methods and data pipes for handling real-time text during
a call.

Change-Id: I876827c448252c5f786d7a4919c47891acb03877
Test: manual, through telecom testapps
diff --git a/telecomm/java/android/telecom/Call.java b/telecomm/java/android/telecom/Call.java
index c69b7c2..d67a0d6 100644
--- a/telecomm/java/android/telecom/Call.java
+++ b/telecomm/java/android/telecom/Call.java
@@ -16,12 +16,21 @@
 
 package android.telecom;
 
+import android.annotation.IntDef;
+import android.annotation.Nullable;
 import android.annotation.SystemApi;
 import android.net.Uri;
 import android.os.Bundle;
 import android.os.Handler;
+import android.os.ParcelFileDescriptor;
 
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
 import java.lang.String;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -828,6 +837,142 @@
          * @param extras Extras associated with the connection event.
          */
         public void onConnectionEvent(Call call, String event, Bundle extras) {}
+
+        /**
+         * Invoked when the RTT mode changes for this call.
+         * @param call The call whose RTT mode has changed.
+         * @param mode the new RTT mode, one of
+         * {@link RttCall#RTT_MODE_FULL}, {@link RttCall#RTT_MODE_HCO},
+         *             or {@link RttCall#RTT_MODE_VCO}
+         */
+        public void onRttModeChanged(Call call, int mode) {}
+
+        /**
+         * Invoked when the call's RTT status changes, either from off to on or from on to off.
+         * @param call The call whose RTT status has changed.
+         * @param enabled whether RTT is now enabled or disabled
+         * @param rttCall the {@link RttCall} object to use for reading and writing if RTT is now
+         *                on, null otherwise.
+         */
+        public void onRttStatusChanged(Call call, boolean enabled, RttCall rttCall) {}
+
+        /**
+         * Invoked when the remote end of the connection has requested that an RTT communication
+         * channel be opened. A response to this should be sent via {@link #respondToRttRequest}
+         * with the same ID that this method is invoked with.
+         * @param call The call which the RTT request was placed on
+         * @param id The ID of the request.
+         */
+        public void onRttRequest(Call call, int id) {}
+    }
+
+    /**
+     * A class that holds the state that describes the state of the RTT channel to the remote
+     * party, if it is active.
+     */
+    public static final class RttCall {
+        @Retention(RetentionPolicy.SOURCE)
+        @IntDef({RTT_MODE_INVALID, RTT_MODE_FULL, RTT_MODE_HCO, RTT_MODE_VCO})
+        public @interface RttAudioMode {}
+
+        /**
+         * For metrics use. Default value in the proto.
+         * @hide
+         */
+        public static final int RTT_MODE_INVALID = 0;
+
+        /**
+         * Indicates that there should be a bidirectional audio stream between the two parties
+         * on the call.
+         */
+        public static final int RTT_MODE_FULL = 1;
+
+        /**
+         * Indicates that the local user should be able to hear the audio stream from the remote
+         * user, but not vice versa. Equivalent to muting the microphone.
+         */
+        public static final int RTT_MODE_HCO = 2;
+
+        /**
+         * Indicates that the remote user should be able to hear the audio stream from the local
+         * user, but not vice versa. Equivalent to setting the volume to zero.
+         */
+        public static final int RTT_MODE_VCO = 3;
+
+        private static final int READ_BUFFER_SIZE = 1000;
+
+        private InputStreamReader mReceiveStream;
+        private OutputStreamWriter mTransmitStream;
+        private int mRttMode;
+        private final InCallAdapter mInCallAdapter;
+        private char[] mReadBuffer = new char[READ_BUFFER_SIZE];
+
+        /**
+         * @hide
+         */
+        public RttCall(InputStreamReader receiveStream, OutputStreamWriter transmitStream,
+                int mode, InCallAdapter inCallAdapter) {
+            mReceiveStream = receiveStream;
+            mTransmitStream = transmitStream;
+            mRttMode = mode;
+            mInCallAdapter = inCallAdapter;
+        }
+
+        /**
+         * Returns the current RTT audio mode.
+         * @return Current RTT audio mode. One of {@link #RTT_MODE_FULL}, {@link #RTT_MODE_VCO}, or
+         * {@link #RTT_MODE_HCO}.
+         */
+        public int getRttAudioMode() {
+            return mRttMode;
+        }
+
+        /**
+         * Sets the RTT audio mode. The requested mode change will be communicated through
+         * {@link Callback#onRttModeChanged(Call, int)}.
+         * @param mode The desired RTT audio mode, one of {@link #RTT_MODE_FULL},
+         * {@link #RTT_MODE_VCO}, or {@link #RTT_MODE_HCO}.
+         */
+        public void setRttMode(@RttAudioMode int mode) {
+            mInCallAdapter.setRttMode(mode);
+        }
+
+        /**
+         * Writes the string {@param input} into the outgoing text stream for this RTT call. Since
+         * RTT transmits text in real-time, this method should be called once for each character
+         * the user enters into the device.
+         *
+         * This method is not thread-safe -- calling it from multiple threads simultaneously may
+         * lead to interleaved text.
+         * @param input The message to send to the remote user.
+         */
+        public void write(String input) throws IOException {
+            mTransmitStream.write(input);
+            mTransmitStream.flush();
+        }
+
+        /**
+         * Reads a string from the remote user, blocking if there is no data available. Returns
+         * {@code null} if the RTT conversation has been terminated and there is no further data
+         * to read.
+         *
+         * This method is not thread-safe -- calling it from multiple threads simultaneously may
+         * lead to interleaved text.
+         * @return A string containing text sent by the remote user, or {@code null} if the
+         * conversation has been terminated or if there was an error while reading.
+         */
+        public String read() {
+            try {
+                int numRead = mReceiveStream.read(mReadBuffer, 0, READ_BUFFER_SIZE);
+                if (numRead < 0) {
+                    return null;
+                }
+                return new String(mReadBuffer, 0, numRead);
+            } catch (IOException e) {
+                Log.w(this, "Exception encountered when reading from InputStreamReader: %s", e);
+                return null;
+            }
+        }
     }
 
     /**
@@ -856,6 +1001,7 @@
     private String mCallingPackage;
     private String mRemainingPostDialSequence;
     private VideoCallImpl mVideoCallImpl;
+    private RttCall mRttCall;
     private Details mDetails;
     private Bundle mExtras;
 
@@ -1054,6 +1200,34 @@
     }
 
     /**
+     * Sends an RTT upgrade request to the remote end of the connection. Success is not
+     * guaranteed, and notification of success will be via the
+     * {@link Callback#onRttStatusChanged(Call, boolean, RttCall)} callback.
+     */
+    public void sendRttRequest() {
+        mInCallAdapter.sendRttRequest();
+    }
+
+    /**
+     * Responds to an RTT request received via the {@link Callback#onRttRequest(Call, int)} )}
+     * callback.
+     * The ID used here should be the same as the ID that was received via the callback.
+     * @param id The request ID received via {@link Callback#onRttRequest(Call, int)}
+     * @param accept {@code true} if the RTT request should be accepted, {@code false} otherwise.
+     */
+    public void respondToRttRequest(int id, boolean accept) {
+        mInCallAdapter.respondToRttRequest(id, accept);
+    }
+
+    /**
+     * Terminate the RTT session on this call. The resulting state change will be notified via
+     * the {@link Callback#onRttStatusChanged(Call, boolean, RttCall)} callback.
+     */
+    public void stopRtt() {
+        mInCallAdapter.stopRtt();
+    }
+
+    /**
      * Adds some extras to this {@link Call}.  Existing keys are replaced and new ones are
      * added.
      * <p>
@@ -1233,6 +1407,23 @@
     }
 
     /**
+     * Returns this call's RttCall object. The {@link RttCall} instance is used to send and
+     * receive RTT text data, as well as to change the RTT mode.
+     * @return A {@link Call.RttCall}. {@code null} if there is no active RTT connection.
+     */
+    public @Nullable RttCall getRttCall() {
+        return mRttCall;
+    }
+
+    /**
+     * Returns whether this call has an active RTT connection.
+     * @return true if there is a connection, false otherwise.
+     */
+    public boolean isRttActive() {
+        return mRttCall != null;
+    }
+
+    /**
      * Registers a callback to this {@code Call}.
      *
      * @param callback A {@code Callback}.
@@ -1426,6 +1617,32 @@
             fireConferenceableCallsChanged();
         }
 
+        boolean isRttChanged = false;
+        boolean rttModeChanged = false;
+        if (parcelableCall.getParcelableRttCall() != null && parcelableCall.getIsRttCallChanged()) {
+            ParcelableRttCall parcelableRttCall = parcelableCall.getParcelableRttCall();
+            InputStreamReader receiveStream = new InputStreamReader(
+                    new ParcelFileDescriptor.AutoCloseInputStream(
+                            parcelableRttCall.getReceiveStream()),
+                    StandardCharsets.UTF_8);
+            OutputStreamWriter transmitStream = new OutputStreamWriter(
+                    new ParcelFileDescriptor.AutoCloseOutputStream(
+                            parcelableRttCall.getTransmitStream()),
+                    StandardCharsets.UTF_8);
+            RttCall newRttCall = new Call.RttCall(
+                    receiveStream, transmitStream, parcelableRttCall.getRttMode(), mInCallAdapter);
+            if (mRttCall == null) {
+                isRttChanged = true;
+            } else if (mRttCall.getRttAudioMode() != newRttCall.getRttAudioMode()) {
+                rttModeChanged = true;
+            }
+            mRttCall = newRttCall;
+        } else if (mRttCall != null && parcelableCall.getParcelableRttCall() == null
+                && parcelableCall.getIsRttCallChanged()) {
+            isRttChanged = true;
+            mRttCall = null;
+        }
+
         // Now we fire updates, ensuring that any client who listens to any of these notifications
         // gets the most up-to-date state.
 
@@ -1447,6 +1664,12 @@
         if (childrenChanged) {
             fireChildrenChanged(getChildren());
         }
+        if (isRttChanged) {
+            fireOnIsRttChanged(mRttCall != null, mRttCall);
+        }
+        if (rttModeChanged) {
+            fireOnRttModeChanged(mRttCall.getRttAudioMode());
+        }
 
         // If we have transitioned to DISCONNECTED, that means we need to notify clients and
         // remove ourselves from the Phone. Note that we do this after completing all state updates
@@ -1477,6 +1700,15 @@
         fireOnConnectionEvent(event, extras);
     }
 
+    /** {@hide} */
+    final void internalOnRttUpgradeRequest(final int requestId) {
+        for (CallbackRecord<Callback> record : mCallbackRecords) {
+            final Call call = this;
+            final Callback callback = record.getCallback();
+            record.getHandler().post(() -> callback.onRttRequest(call, requestId));
+        }
+    }
+
     private void fireStateChanged(final int newState) {
         for (CallbackRecord<Callback> record : mCallbackRecords) {
             final Call call = this;
@@ -1645,6 +1877,32 @@
     }
 
     /**
+     * Notifies listeners of an RTT on/off change
+     *
+     * @param enabled True if RTT is now enabled, false otherwise
+     */
+    private void fireOnIsRttChanged(final boolean enabled, final RttCall rttCall) {
+        for (CallbackRecord<Callback> record : mCallbackRecords) {
+            final Call call = this;
+            final Callback callback = record.getCallback();
+            record.getHandler().post(() -> callback.onRttStatusChanged(call, enabled, rttCall));
+        }
+    }
+
+    /**
+     * Notifies listeners of a RTT mode change
+     *
+     * @param mode The new RTT mode
+     */
+    private void fireOnRttModeChanged(final int mode) {
+        for (CallbackRecord<Callback> record : mCallbackRecords) {
+            final Call call = this;
+            final Callback callback = record.getCallback();
+            record.getHandler().post(() -> callback.onRttModeChanged(call, mode));
+        }
+    }
+
+    /**
      * Determines if two bundles are equal.
      *
      * @param bundle The original bundle.