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AblyEventStreamHandler.java
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AblyEventStreamHandler.java
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package io.ably.flutter.plugin;
import android.content.Context;
import android.os.Handler;
import android.os.Looper;
import android.util.Log;
import java.util.Map;
import io.ably.flutter.plugin.generated.PlatformConstants;
import io.ably.lib.realtime.Channel;
import io.ably.lib.realtime.ChannelStateListener;
import io.ably.lib.realtime.ConnectionStateListener;
import io.ably.lib.realtime.Presence;
import io.ably.lib.types.AblyException;
import io.ably.lib.types.ChannelOptions;
import io.ably.lib.types.Message;
import io.ably.lib.types.PresenceMessage;
import io.flutter.plugin.common.EventChannel;
/**
* Dart side can listen to Event Streams by pushing data to eventSink available in onListen method.
* Event listening can be cancelled when stream subscription is cancelled on dart side
* <p>
* ref: https://api.flutter.dev/javadoc/io/flutter/plugin/common/EventChannel.StreamHandler.html
*/
public class AblyEventStreamHandler implements EventChannel.StreamHandler {
private static final String TAG = AblyEventStreamHandler.class.getName();
/**
* Creating an ablyLibrary instance.
* As ablyLibrary is a singleton,
* all ably object instance will be accessible
*/
private final AblyLibrary ablyLibrary;
public AblyEventStreamHandler(Context applicationContext) {
ablyLibrary = AblyLibrary.getInstance(applicationContext);
}
/**
* Refer to the comments on AblyMethodCallHandler.MethodResultWrapper
* on why this customized EventSink is required
*/
private static class MainThreadEventSink implements EventChannel.EventSink {
private EventChannel.EventSink eventSink;
private Handler handler;
MainThreadEventSink(EventChannel.EventSink eventSink) {
this.eventSink = eventSink;
handler = new Handler(Looper.getMainLooper());
}
@Override
public void success(final Object o) {
handler.post(() -> eventSink.success(o)); //lambda for new Runnable
}
@Override
public void error(final String s, final String s1, final Object o) {
handler.post(() -> eventSink.error(s, s1, o));
}
@Override
public void endOfStream() {
}
}
// Listeners
private PluginConnectionStateListener connectionStateListener;
private PluginChannelStateListener channelStateListener;
private PluginChannelMessageListener channelMessageListener;
private PluginChannelPresenceMessageListener channelPresenceMessageListener;
void handleAblyException(EventChannel.EventSink eventSink, AblyException ablyException) {
eventSink.error(ablyException.errorInfo.message, null, ablyException.errorInfo);
}
static private class Listener {
EventChannel.EventSink eventSink;
Listener(EventChannel.EventSink eventSink) {
this.eventSink = eventSink;
}
}
static private class PluginConnectionStateListener extends Listener implements ConnectionStateListener {
PluginConnectionStateListener(EventChannel.EventSink eventSink) {
super(eventSink);
}
public void onConnectionStateChanged(ConnectionStateChange stateChange) {
eventSink.success(stateChange);
}
}
static private class PluginChannelStateListener extends Listener implements ChannelStateListener {
PluginChannelStateListener(EventChannel.EventSink eventSink) {
super(eventSink);
}
public void onChannelStateChanged(ChannelStateChange stateChange) {
eventSink.success(stateChange);
}
}
static private class PluginChannelMessageListener extends Listener implements Channel.MessageListener {
PluginChannelMessageListener(EventChannel.EventSink eventSink) {
super(eventSink);
}
public void onMessage(Message message) {
eventSink.success(message);
}
}
static private class PluginChannelPresenceMessageListener extends Listener implements Presence.PresenceListener {
PluginChannelPresenceMessageListener(EventChannel.EventSink eventSink) {
super(eventSink);
}
public void onPresenceMessage(PresenceMessage message) {
eventSink.success(message);
}
}
// Casting stream creation arguments from `Object` into `AblyFlutterMessage<AblyEventMessage>`
private AblyFlutterMessage<AblyEventMessage<Object>> getMessage(Object message) {
return (AblyFlutterMessage<AblyEventMessage<Object>>) message;
}
@Override
public void onListen(Object object, EventChannel.EventSink uiThreadEventSink) {
MainThreadEventSink eventSink = new MainThreadEventSink(uiThreadEventSink);
final AblyFlutterMessage<AblyEventMessage<Object>> ablyMessage = getMessage(object);
final AblyEventMessage<Object> eventMessage = ablyMessage.message;
final String eventName = eventMessage.eventName;
final Map<String, Object> eventPayload = (eventMessage.message == null) ? null : (Map<String, Object>) eventMessage.message;
try {
switch (eventName) {
case PlatformConstants.PlatformMethod.onRealtimeConnectionStateChanged:
connectionStateListener = new PluginConnectionStateListener(eventSink);
ablyLibrary.getRealtime(ablyMessage.handle).connection.on(connectionStateListener);
break;
case PlatformConstants.PlatformMethod.onRealtimeChannelStateChanged:
assert eventPayload != null : "event message is missing";
channelStateListener = new PluginChannelStateListener(eventSink);
ablyLibrary
.getRealtime(ablyMessage.handle)
.channels
.get((String) eventPayload.get(PlatformConstants.TxTransportKeys.channelName))
.on(channelStateListener);
break;
case PlatformConstants.PlatformMethod.onRealtimeChannelMessage:
assert eventPayload != null : "event message is missing";
try {
channelMessageListener = new PluginChannelMessageListener(eventSink);
ablyLibrary
.getRealtime(ablyMessage.handle)
.channels
.get((String) eventPayload.get(PlatformConstants.TxTransportKeys.channelName))
.subscribe(channelMessageListener);
} catch (AblyException ablyException) {
handleAblyException(eventSink, ablyException);
}
break;
case PlatformConstants.PlatformMethod.onRealtimePresenceMessage:
assert eventPayload != null : "event message is missing";
try {
channelPresenceMessageListener = new PluginChannelPresenceMessageListener(eventSink);
ablyLibrary
.getRealtime(ablyMessage.handle)
.channels
.get((String) eventPayload.get(PlatformConstants.TxTransportKeys.channelName))
.presence.subscribe(channelPresenceMessageListener);
} catch (AblyException ablyException) {
handleAblyException(eventSink, ablyException);
}
break;
default:
eventSink.error("unhandled event", eventName, null);
}
} catch (AssertionError assertionError) {
eventSink.error(assertionError.getMessage(), null, null);
}
}
@Override
public void onCancel(Object object) {
if (object == null) {
Log.w(TAG, "onCancel cannot decode null");
return;
}
final AblyFlutterMessage<AblyEventMessage<Object>> ablyMessage = getMessage(object);
final AblyEventMessage<Object> eventMessage = ablyMessage.message;
final String eventName = eventMessage.eventName;
final Map<String, Object> eventPayload = (eventMessage.message == null) ? null : (Map<String, Object>) eventMessage.message;
switch (eventName) {
case PlatformConstants.PlatformMethod.onRealtimeConnectionStateChanged:
ablyLibrary.getRealtime(ablyMessage.handle).connection.off(connectionStateListener);
break;
case PlatformConstants.PlatformMethod.onRealtimeChannelStateChanged:
// Note: this and all other assert statements in this onCancel method are
// left as is as there is no way of propagating this error to flutter side
assert eventPayload != null : "event message is missing";
ablyLibrary
.getRealtime(ablyMessage.handle)
.channels
.get((String) eventPayload.get(PlatformConstants.TxTransportKeys.channelName))
.off(channelStateListener);
break;
case PlatformConstants.PlatformMethod.onRealtimeChannelMessage:
assert eventPayload != null : "event message is missing";
ablyLibrary
.getRealtime(ablyMessage.handle)
.channels
.get((String) eventPayload.get(PlatformConstants.TxTransportKeys.channelName))
.unsubscribe(channelMessageListener);
break;
case PlatformConstants.PlatformMethod.onRealtimePresenceMessage:
assert eventPayload != null : "event message is missing";
ablyLibrary
.getRealtime(ablyMessage.handle)
.channels
.get((String) eventPayload.get(PlatformConstants.TxTransportKeys.channelName))
.presence
.unsubscribe(channelPresenceMessageListener);
break;
}
}
}