Merge pull request #229 from ProximaEPFL/recursive-deletion

Recursive post deletion

lib/services/database/comment_repository_service.dart

@@ -7,6 +7,7 @@ import "package:proxima/models/database/post/post_data.dart";
 import "package:proxima/models/database/post/post_firestore.dart";
 import "package:proxima/models/database/post/post_id_firestore.dart";
 import "package:proxima/services/database/firestore_service.dart";
+import "package:proxima/services/database/upvote_repository_service.dart";
 
 /// This class is a service that allows to interact with the comments
 /// of the posts in the firestore database.
@@ -88,27 +89,84 @@ class CommentRepositoryService {
   Future<void> deleteComment(
     PostIdFirestore parentPostId,
     CommentIdFirestore commentId,
-  ) =>
-      _firestore.runTransaction(
-        (transaction) async {
-          final commentRef =
-              _commentsSubCollection(parentPostId).doc(commentId.value);
-
-          final commentDoc = await transaction.get(commentRef);
-
-          if (!commentDoc.exists) {
-            throw Exception("Comment does not exist");
-          }
-
-          transaction.delete(commentRef);
-
-          final postDocRef = _postDocument(parentPostId);
-          transaction.update(
-            postDocRef,
-            {PostData.commentCountField: FieldValue.increment(-1)},
-          );
-        },
+  ) async {
+    final batch = _firestore.batch();
+
+    final commentUpvoteRepository =
+        UpvoteRepositoryService.commentUpvoteRepository(
+      _firestore,
+      parentPostId,
+    );
+
+    await _deleteCommentNoCountUpdate(
+      parentPostId,
+      commentId,
+      batch,
+      commentUpvoteRepository,
+    );
+
+    batch.update(
+      _postDocument(parentPostId),
+      {PostData.commentCountField: FieldValue.increment(-1)},
+    );
+
+    await batch.commit();
+  }
+
+  /// This method will delete all the comments of the post with id [parentPostId].
+  /// Helper method to delete a post. Adds all the deletions to the batch [batch].
+  Future<void> deleteAllComments(
+    PostIdFirestore parentPostId,
+    WriteBatch batch,
+  ) async {
+    final commentsRef = _commentsSubCollection(parentPostId);
+    final comments = await commentsRef.get();
+    final commentUpvoteRepository =
+        UpvoteRepositoryService.commentUpvoteRepository(
+      _firestore,
+      parentPostId,
+    );
+
+    for (final comment in comments.docs) {
+      await _deleteCommentNoCountUpdate(
+        parentPostId,
+        CommentIdFirestore(value: comment.id),
+        batch,
+        commentUpvoteRepository,
+        checkExists: false,
       );
+    }
+
+    batch.update(_postDocument(parentPostId), {PostData.commentCountField: 0});
+  }
+
+  /// Helper method to delete a comment. Adds all the deletions to the batch [batch].
+  /// Does not update the comment count of the post. That should be done separately.
+  /// If [checkExists] is true, the method will check if the comment exists before
+  /// deleting it. If it does not exist, the method will throw an error.
+  Future<void> _deleteCommentNoCountUpdate(
+    PostIdFirestore parentPostId,
+    CommentIdFirestore commentId,
+    WriteBatch batch,
+    UpvoteRepositoryService<CommentIdFirestore> commentUpvoteRepository, {
+    bool checkExists = true,
+  }) async {
+    final commentRef =
+        _commentsSubCollection(parentPostId).doc(commentId.value);
+
+    if (checkExists) {
+      final comment = await commentRef.get();
+      if (!comment.exists) {
+        throw Exception("Comment does not exist");
+      }
+    }
+
+    await commentUpvoteRepository.deleteAllUpvotes(
+      commentId,
+      batch,
+    );
+    batch.delete(commentRef);
+  }
 }
 
 final commentRepositoryProvider = Provider<CommentRepositoryService>(

lib/services/database/post_repository_service.dart

@@ -6,15 +6,24 @@ import "package:proxima/models/database/post/post_firestore.dart";
 import "package:proxima/models/database/post/post_id_firestore.dart";
 import "package:proxima/models/database/post/post_location_firestore.dart";
 import "package:proxima/models/database/user/user_id_firestore.dart";
+import "package:proxima/services/database/comment_repository_service.dart";
 import "package:proxima/services/database/firestore_service.dart";
+import "package:proxima/services/database/upvote_repository_service.dart";
 
 /// This repository service is responsible for managing the posts in the database
 class PostRepositoryService {
-  final CollectionReference _collectionRef;
+  final FirebaseFirestore _firestore;
+  final CollectionReference<Map<String, dynamic>> _collectionRef;
+  final CommentRepositoryService _commentRepository;
+  final UpvoteRepositoryService<PostIdFirestore> _upvoteRepository;
 
   PostRepositoryService({
     required FirebaseFirestore firestore,
-  }) : _collectionRef = firestore.collection(PostFirestore.collectionName);
+  })  : _firestore = firestore,
+        _collectionRef = firestore.collection(PostFirestore.collectionName),
+        _commentRepository = CommentRepositoryService(firestore: firestore),
+        _upvoteRepository =
+            UpvoteRepositoryService.postUpvoteRepository(firestore);
 
   /// This method creates a new post that has for data [postData]
   /// and that is located at [position] and adds it to the database
@@ -29,9 +38,17 @@ class PostRepositoryService {
     return PostIdFirestore(value: reference.id);
   }
 
-  /// This method deletes the post with id [postId] from the database
+  /// This method deletes the post with id [postId] from the database.
+  /// This means removing the corresponding document, and all the
+  /// subcollections.
   Future<void> deletePost(PostIdFirestore postId) async {
-    await _collectionRef.doc(postId.value).delete();
+    final batch = _firestore.batch();
+
+    await _commentRepository.deleteAllComments(postId, batch);
+    await _upvoteRepository.deleteAllUpvotes(postId, batch);
+    batch.delete(_collectionRef.doc(postId.value));
+
+    await batch.commit();
   }
 
   /// This method returns true if the post with id [postId] exists in the database

lib/services/database/upvote_repository_service.dart

@@ -133,4 +133,18 @@ class UpvoteRepositoryService<ParentIdFirestore extends IdFirestore> {
       );
     });
   }
+
+  /// Deletes all the upvotes of the parent with id [parentId]. Should not be
+  /// used on its own but rather as part of the deletion of the parent. Adds all
+  /// the deletions to the batch [batch].
+  Future<void> deleteAllUpvotes(
+    ParentIdFirestore parentId,
+    WriteBatch batch,
+  ) async {
+    final upvotes = await _votersCollection(parentId).get();
+    for (final upvote in upvotes.docs) {
+      batch.delete(upvote.reference);
+    }
+    batch.update(_parentDocument(parentId), {_voteScoreField: 0});
+  }
 }

test/services/database/comment_repository_test.dart

@@ -7,12 +7,15 @@ import "package:proxima/models/database/comment/comment_id_firestore.dart";
 import "package:proxima/models/database/post/post_data.dart";
 import "package:proxima/models/database/post/post_firestore.dart";
 import "package:proxima/models/database/post/post_id_firestore.dart";
+import "package:proxima/models/database/vote/upvote_state.dart";
 import "package:proxima/services/database/comment_repository_service.dart";
 import "package:proxima/services/database/firestore_service.dart";
+import "package:proxima/services/database/upvote_repository_service.dart";
 
 import "../../mocks/data/comment_data.dart";
 import "../../mocks/data/firestore_comment.dart";
 import "../../mocks/data/firestore_post.dart";
+import "../../mocks/data/firestore_user.dart";
 import "../../mocks/data/geopoint.dart";
 
 void main() {
@@ -26,6 +29,8 @@ void main() {
     late CommentFirestoreGenerator commentGenerator;
     late CommentDataGenerator commentDataGenerator;
 
+    late UpvoteRepositoryService<CommentIdFirestore> commentUpvoteRepository;
+
     /// The setup add a single post with no comments
     setUp(() async {
       fakeFirestore = FakeFirebaseFirestore();
@@ -57,6 +62,11 @@ void main() {
 
       commentGenerator = CommentFirestoreGenerator();
       commentDataGenerator = CommentDataGenerator();
+
+      commentUpvoteRepository = UpvoteRepositoryService.commentUpvoteRepository(
+        fakeFirestore,
+        postId,
+      );
     });
 
     group("getting comments", () {
@@ -180,12 +190,26 @@ void main() {
 
         final commentId = comment.first.id;
 
+        // Add an upvote to the comment to later check that it is deleted
+        commentUpvoteRepository.setUpvoteState(
+          testingUserFirestoreId,
+          commentId,
+          UpvoteState.upvoted,
+        );
+
         await commentRepository.deleteComment(postId, commentId);
 
         // Check that the comment was deleted
         final actualComments = await commentRepository.getComments(postId);
         expect(actualComments, isEmpty);
 
+        // Check that the upvote was deleted
+        final upvote = await commentUpvoteRepository.getUpvoteState(
+          testingUserFirestoreId,
+          commentId,
+        );
+        expect(upvote, UpvoteState.none);
+
         // Check that the comment count was updated correctly
         final postDoc = await postDocument.get();
         final post = PostFirestore.fromDb(postDoc);
@@ -248,6 +272,26 @@ void main() {
 
         expect(post.data.commentCount, equals(5));
       });
+
+      test("can delete all comments", () async {
+        await commentGenerator.addComments(
+          5,
+          postId,
+          commentRepository,
+        );
+
+        final batch = fakeFirestore.batch();
+        await commentRepository.deleteAllComments(postId, batch);
+        await batch.commit();
+
+        final actualComments = await commentRepository.getComments(postId);
+        expect(actualComments, isEmpty);
+
+        final postDoc = await postDocument.get();
+        final post = PostFirestore.fromDb(postDoc);
+
+        expect(post.data.commentCount, equals(0));
+      });
     });
   });
 }

test/services/database/post_repository_test.dart

@@ -1,13 +1,20 @@
 import "package:fake_cloud_firestore/fake_cloud_firestore.dart";
 import "package:flutter_test/flutter_test.dart";
 import "package:geoflutterfire_plus/geoflutterfire_plus.dart";
+import "package:proxima/models/database/comment/comment_firestore.dart";
 import "package:proxima/models/database/post/post_firestore.dart";
 import "package:proxima/models/database/post/post_id_firestore.dart";
 import "package:proxima/models/database/post/post_location_firestore.dart";
 import "package:proxima/models/database/user/user_id_firestore.dart";
+import "package:proxima/models/database/vote/upvote_state.dart";
+import "package:proxima/models/database/vote/vote_firestore.dart";
+import "package:proxima/services/database/comment_repository_service.dart";
 import "package:proxima/services/database/post_repository_service.dart";
+import "package:proxima/services/database/upvote_repository_service.dart";
 
+import "../../mocks/data/firestore_comment.dart";
 import "../../mocks/data/firestore_post.dart";
+import "../../mocks/data/firestore_user.dart";
 import "../../mocks/data/geopoint.dart";
 import "../../mocks/data/post_data.dart";
 
@@ -47,6 +54,41 @@ void main() {
       expect(actualPost.exists, false);
     });
 
+    test("Delete method deletes subcollections", () async {
+      await setPostFirestore(post, firestore);
+      final postRef =
+          firestore.collection(PostFirestore.collectionName).doc(post.id.value);
+      // Check that the post is in the db
+      final dbPost = await postRef.get();
+      expect(dbPost.exists, true);
+
+      final commentRepository = CommentRepositoryService(firestore: firestore);
+      await CommentFirestoreGenerator()
+          .addComments(4, post.id, commentRepository);
+
+      final upvoteRepository = UpvoteRepositoryService.postUpvoteRepository(
+        firestore,
+      );
+
+      await upvoteRepository.setUpvoteState(
+        testingUserFirestoreId,
+        post.id,
+        UpvoteState.upvoted,
+      );
+
+      await postRepository.deletePost(post.id);
+      final actualPost = await postRef.get();
+      expect(actualPost.exists, false);
+
+      final actualComments =
+          await postRef.collection(CommentFirestore.subCollectionName).get();
+      expect(actualComments.docs.length, 0);
+
+      final actualVoters =
+          await postRef.collection(VoteFirestore.votersSubCollectionName).get();
+      expect(actualVoters.size, 0);
+    });
+
     test("Get post correctly", () async {
       await setPostFirestore(post, firestore);