likes

app/src/main/java/com/dowerx/quack/fragment/PostRecyclerViewAdapter.java

@@ -4,6 +4,7 @@ import androidx.annotation.NonNull;
 import androidx.recyclerview.widget.RecyclerView;
 
 import android.annotation.SuppressLint;
+import android.graphics.Color;
 import android.view.LayoutInflater;
 import android.view.ViewGroup;
 import android.widget.Button;
@@ -35,7 +36,26 @@ public class PostRecyclerViewAdapter extends RecyclerView.Adapter<PostRecyclerVi
         holder.mItem = mValues.get(position);
         holder.username.setText(holder.mItem.getUser().getUsername());
         holder.content.setText(holder.mItem.getContent());
-        holder.like.setText("Likes " + holder.mItem.getLikes());
+        holder.like.setText((holder.mItem.isLiked() ? "Liked " : "Likes ") + holder.mItem.getLikes());
+        holder.like.setBackgroundColor(holder.mItem.isLiked() ? Color.rgb(36, 166, 71) : Color.rgb(173, 33, 61));
+        holder.like.setOnClickListener(v -> {
+            PostService.ToggleLike task = new PostService.ToggleLike(
+                    ()->{
+                        holder.mItem.setLikes(holder.mItem.getLikes()+1);
+                        holder.like.setText("Liked " + holder.mItem.getLikes());
+                        holder.like.setBackgroundColor(Color.rgb(36, 166, 71));
+                        return null;
+                    },
+                    ()->{
+                        holder.mItem.setLikes(holder.mItem.getLikes()-1);
+                        holder.like.setText("Likes " + holder.mItem.getLikes());
+                        holder.like.setBackgroundColor(Color.rgb(173, 33, 61));
+                        return null;
+                    },
+                    v.getContext());
+            task.execute(holder.mItem.getId(), AuthService.getId());
+        });
+
         if (!AuthService.getId().equals(holder.mItem.getUser().getId())) {
             holder.remove.setAlpha(0.5f);
             holder.remove.setClickable(false);

app/src/main/java/com/dowerx/quack/service/PostService.java

@@ -18,6 +18,7 @@ import com.google.android.gms.tasks.Task;
 import com.google.android.gms.tasks.Tasks;
 import com.google.firebase.auth.FirebaseAuth;
 import com.google.firebase.firestore.CollectionReference;
+import com.google.firebase.firestore.DocumentReference;
 import com.google.firebase.firestore.DocumentSnapshot;
 import com.google.firebase.firestore.Filter;
 import com.google.firebase.firestore.FirebaseFirestore;
@@ -52,12 +53,24 @@ public class PostService {
                     String username = user.get("username", String.class);
                     String email = user.get("email", String.class);
                     String id = user.get("id", String.class);
+
+                    QuerySnapshot likes = Tasks.await(
+                            db.collection("like")
+                                .where(Filter.equalTo("post", post.getReference()))
+                                .get());
+
+                    boolean liked = false;
+                    for (DocumentSnapshot like : likes) {
+                        if (Tasks.await(like.getDocumentReference("user").get()).getString("id").equals(AuthService.getId()))
+                            liked = true;
+                    }
+
                     posts.add(new Post(
                             new User(username, email, id),
                             post.get("content", String.class),
                             post.get("image", String.class),
-                            0,
+                            likes.size(),
-                            false,
+                            liked,
                             post.getId()
                     ));
                 }
@@ -96,12 +109,24 @@ public class PostService {
                     String username = user.get("username", String.class);
                     String email = user.get("email", String.class);
                     String id = user.get("id", String.class);
+
+                    QuerySnapshot likes = Tasks.await(
+                            db.collection("like")
+                                    .where(Filter.equalTo("post", post.getReference()))
+                                    .get());
+
+                    boolean liked = false;
+                    for (DocumentSnapshot like : likes) {
+                        if (Tasks.await(like.getDocumentReference("user").get()).getString("id").equals(AuthService.getId()))
+                            liked = true;
+                    }
+
                     posts.add(new Post(
                             new User(username, email, id),
                             post.get("content", String.class),
                             post.get("image", String.class),
-                            0,
+                            likes.size(),
-                            false,
+                            liked,
                             post.getId()
                     ));
                 }
@@ -200,4 +225,85 @@ public class PostService {
             }
         }
     }
+
+    // post_id, user_id
+    public static class ToggleLike extends AsyncTask<String, Void, Integer> {
+
+        private static final Integer LIKED = 0;
+        private static final Integer DISLIKED = 1;
+        private static final Integer ERROR = -1;
+
+        private final Callable<Void> callback_liked;
+        private final Callable<Void> callback_disliked;
+
+        private final Context context;
+
+        public ToggleLike(Callable<Void> callback_liked, Callable<Void> callback_disliked, Context context) {
+            this.callback_liked = callback_liked;
+            this.callback_disliked = callback_disliked;
+            this.context = context;
+        }
+
+        @Override
+        protected Integer doInBackground(String... strings) {
+            FirebaseFirestore db = FirebaseFirestore.getInstance();
+
+            try {
+                DocumentReference post = db.document("/post/" + strings[0]);
+                DocumentReference user = Tasks.await(
+                    db.collection("user")
+                        .where(Filter.equalTo("id", strings[1]))
+                        .get())
+                        .getDocuments().get(0).getReference();
+
+                QuerySnapshot result = Tasks.await(
+                    db.collection("like")
+                        .where(Filter.equalTo("post", post))
+                        .where(Filter.equalTo("user", user))
+                        .get());
+
+                // not liked yet, like it
+                if (result.isEmpty())  {
+                    HashMap<String, Object> data = new HashMap<>();
+                    data.put("post", post);
+                    data.put("user", user);
+                    Tasks.await(db.collection("like").add(data));
+                    return LIKED;
+                }
+                // already liked, remove the like
+                else {
+                    for (DocumentSnapshot doc : result) {
+                        Tasks.await(doc.getReference().delete());
+                    }
+                    return DISLIKED;
+                }
+            } catch (ExecutionException | InterruptedException e) {
+                return ERROR;
+            }
+        }
+
+        @Override
+        protected void onPostExecute(Integer result) {
+            try {
+                if (result == LIKED)
+                    this.callback_liked.call();
+                else if (result == DISLIKED)
+                    this.callback_disliked.call();
+                else {
+                    Log.e(this.getClass().getName(), "failed to toggle like");
+                    Toast toast = new Toast(context);
+                    toast.setText("failed to toggle likes");
+                    toast.setDuration(Toast.LENGTH_LONG);
+                    toast.show();
+                }
+            } catch (Exception e) {
+                Log.e(this.getClass().getName(), "failed in callbacks while attempting to toggle like");
+                Toast toast = new Toast(context);
+                toast.setText("failed to toggle likes");
+                toast.setDuration(Toast.LENGTH_LONG);
+                toast.show();
+            }
+
+        }
+    }
 }