feat(cloud_firestore): Move Snapshot handling into a EventChannel

packages/cloud_firestore/cloud_firestore/android/src/main/java/io/flutter/plugins/firebase/firestore/FlutterFirebaseFirestoreException.java

@@ -8,7 +8,7 @@
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
-class FlutterFirebaseFirestoreException extends Exception {
+public class FlutterFirebaseFirestoreException extends Exception {
   private static final String ERROR_ABORTED =
       "The operation was aborted, typically due to a concurrency issue like transaction aborts, etc.";
   private static final String ERROR_ALREADY_EXISTS =
@@ -42,7 +42,8 @@ class FlutterFirebaseFirestoreException extends Exception {
   private final String code;
   private final String message;
 
-  FlutterFirebaseFirestoreException(FirebaseFirestoreException nativeException, Throwable cause) {
+  public FlutterFirebaseFirestoreException(
+      FirebaseFirestoreException nativeException, Throwable cause) {
     super(nativeException != null ? nativeException.getMessage() : "", cause);
 
     String code = null;

packages/cloud_firestore/cloud_firestore/android/src/main/java/io/flutter/plugins/firebase/firestore/FlutterFirebaseFirestoreTransactionResult.java

@@ -7,8 +7,9 @@
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
-class FlutterFirebaseFirestoreTransactionResult {
-  final @Nullable Exception exception;
+public class FlutterFirebaseFirestoreTransactionResult {
+
+  public final @Nullable Exception exception;
 
   private FlutterFirebaseFirestoreTransactionResult(@NonNull Exception failureException) {
     exception = failureException;
@@ -18,11 +19,11 @@ private FlutterFirebaseFirestoreTransactionResult() {
     exception = null;
   }
 
-  static FlutterFirebaseFirestoreTransactionResult failed(@NonNull Exception exception) {
+  public static FlutterFirebaseFirestoreTransactionResult failed(@NonNull Exception exception) {
     return new FlutterFirebaseFirestoreTransactionResult(exception);
   }
 
-  static FlutterFirebaseFirestoreTransactionResult complete() {
+  public static FlutterFirebaseFirestoreTransactionResult complete() {
     return new FlutterFirebaseFirestoreTransactionResult();
   }
 }

packages/cloud_firestore/cloud_firestore/android/src/main/java/io/flutter/plugins/firebase/firestore/streamhandler/DocumentSnapshotsStreamHandler.java

@@ -0,0 +1,54 @@
+package io.flutter.plugins.firebase.firestore.streamhandler;
+
+import static io.flutter.plugins.firebase.firestore.FlutterFirebaseFirestorePlugin.DEFAULT_ERROR_CODE;
+
+import com.google.firebase.firestore.DocumentReference;
+import com.google.firebase.firestore.ListenerRegistration;
+import com.google.firebase.firestore.MetadataChanges;
+import io.flutter.plugin.common.EventChannel.EventSink;
+import io.flutter.plugin.common.EventChannel.StreamHandler;
+import io.flutter.plugins.firebase.firestore.utils.ExceptionConverter;
+import java.util.Map;
+import java.util.Objects;
+
+public class DocumentSnapshotsStreamHandler implements StreamHandler {
+
+  ListenerRegistration listenerRegistration;
+
+  @Override
+  public void onListen(Object arguments, EventSink events) {
+    @SuppressWarnings("unchecked")
+    Map<String, Object> argumentsMap = (Map<String, Object>) arguments;
+
+    MetadataChanges metadataChanges =
+        (Boolean) Objects.requireNonNull(argumentsMap.get("includeMetadataChanges"))
+            ? MetadataChanges.INCLUDE
+            : MetadataChanges.EXCLUDE;
+
+    DocumentReference documentReference =
+        (DocumentReference) Objects.requireNonNull(argumentsMap.get("reference"));
+
+    listenerRegistration =
+        documentReference.addSnapshotListener(
+            metadataChanges,
+            (documentSnapshot, exception) -> {
+              if (exception != null) {
+                Map<String, String> exceptionDetails = ExceptionConverter.createDetails(exception);
+                events.error(DEFAULT_ERROR_CODE, exception.getMessage(), exceptionDetails);
+                events.endOfStream();
+
+                onCancel(null);
+              } else {
+                events.success(documentSnapshot);
+              }
+            });
+  }
+
+  @Override
+  public void onCancel(Object arguments) {
+    if (listenerRegistration != null) {
+      listenerRegistration.remove();
+      listenerRegistration = null;
+    }
+  }
+}

packages/cloud_firestore/cloud_firestore/android/src/main/java/io/flutter/plugins/firebase/firestore/streamhandler/OnTransactionResultListener.java

@@ -0,0 +1,8 @@
+package io.flutter.plugins.firebase.firestore.streamhandler;
+
+import java.util.Map;
+
+/** callback when a transaction result has been computed. */
+public interface OnTransactionResultListener {
+  void receiveTransactionResponse(Map<String, Object> result);
+}

packages/cloud_firestore/cloud_firestore/android/src/main/java/io/flutter/plugins/firebase/firestore/streamhandler/QuerySnapshotsStreamHandler.java

@@ -0,0 +1,58 @@
+package io.flutter.plugins.firebase.firestore.streamhandler;
+
+import static io.flutter.plugins.firebase.firestore.FlutterFirebaseFirestorePlugin.DEFAULT_ERROR_CODE;
+
+import com.google.firebase.firestore.ListenerRegistration;
+import com.google.firebase.firestore.MetadataChanges;
+import com.google.firebase.firestore.Query;
+import io.flutter.plugin.common.EventChannel.EventSink;
+import io.flutter.plugin.common.EventChannel.StreamHandler;
+import io.flutter.plugins.firebase.firestore.utils.ExceptionConverter;
+import java.util.Map;
+import java.util.Objects;
+
+public class QuerySnapshotsStreamHandler implements StreamHandler {
+
+  ListenerRegistration listenerRegistration;
+
+  @Override
+  public void onListen(Object arguments, EventSink events) {
+    @SuppressWarnings("unchecked")
+    Map<String, Object> argumentsMap = (Map<String, Object>) arguments;
+
+    MetadataChanges metadataChanges =
+        (Boolean) Objects.requireNonNull(argumentsMap.get("includeMetadataChanges"))
+            ? MetadataChanges.INCLUDE
+            : MetadataChanges.EXCLUDE;
+
+    Query query = (Query) argumentsMap.get("query");
+
+    if (query == null) {
+      throw new IllegalArgumentException(
+          "An error occurred while parsing query arguments, see native logs for more information. Please report this issue.");
+    }
+
+    listenerRegistration =
+        query.addSnapshotListener(
+            metadataChanges,
+            (querySnapshot, exception) -> {
+              if (exception != null) {
+                Map<String, String> exceptionDetails = ExceptionConverter.createDetails(exception);
+                events.error(DEFAULT_ERROR_CODE, exception.getMessage(), exceptionDetails);
+                events.endOfStream();
+
+                onCancel(null);
+              } else {
+                events.success(querySnapshot);
+              }
+            });
+  }
+
+  @Override
+  public void onCancel(Object arguments) {
+    if (listenerRegistration != null) {
+      listenerRegistration.remove();
+      listenerRegistration = null;
+    }
+  }
+}

packages/cloud_firestore/cloud_firestore/android/src/main/java/io/flutter/plugins/firebase/firestore/streamhandler/SnapshotsInSyncStreamHandler.java

@@ -0,0 +1,34 @@
+package io.flutter.plugins.firebase.firestore.streamhandler;
+
+import com.google.firebase.firestore.FirebaseFirestore;
+import com.google.firebase.firestore.ListenerRegistration;
+import io.flutter.plugin.common.EventChannel.EventSink;
+import io.flutter.plugin.common.EventChannel.StreamHandler;
+import java.util.Map;
+import java.util.Objects;
+
+public class SnapshotsInSyncStreamHandler implements StreamHandler {
+
+  ListenerRegistration listenerRegistration;
+
+  @Override
+  public void onListen(Object arguments, EventSink events) {
+    @SuppressWarnings("unchecked")
+    Map<String, Object> argumentsMap = (Map<String, Object>) arguments;
+
+    FirebaseFirestore firestore =
+        (FirebaseFirestore) Objects.requireNonNull(argumentsMap.get("firestore"));
+
+    Runnable snapshotsInSyncRunnable = () -> events.success(null);
+
+    listenerRegistration = firestore.addSnapshotsInSyncListener(snapshotsInSyncRunnable);
+  }
+
+  @Override
+  public void onCancel(Object arguments) {
+    if (listenerRegistration != null) {
+      listenerRegistration.remove();
+      listenerRegistration = null;
+    }
+  }
+}