[add] like a post

Author: SimCoderYoutube

.gitignore

@@ -40,4 +40,10 @@ app.*.symbols
 # Obfuscation related
 app.*.map.json
 /frontend/android/app/google-services.json
-/frontend/build
+/frontend/build
+/backend/functions/.eslintrc.js
+/backend/functions/package-lock.json
+/backend/.firebaserc
+/backend/.gitignore
+/backend/firebase.json
+/backend/functions/package.json

backend/functions/.gitignore

@@ -0,0 +1 @@
+node_modules/

backend/functions/index.js

@@ -0,0 +1,28 @@
+const functions = require("firebase-functions");
+
+const admin = require('firebase-admin');
+admin.initializeApp();
+
+const db = admin.firestore();
+
+exports.addLike = functions.firestore.document('/posts/{postId}/likes/{userId}')
+.onCreate((snap, context) => {
+    return db
+    .collection("posts")
+    .doc(context.params.postId)
+    .update(
+        {
+            likesCount: admin.firestore.FieldValue.increment(1)
+        })
+})
+
+exports.deleteLike = functions.firestore.document('/posts/{postId}/likes/{userId}')
+.onDelete((snap, context) => {
+    return db
+    .collection("posts")
+    .doc(context.params.postId)
+    .update(
+        {
+            likesCount: admin.firestore.FieldValue.increment(-1)
+        })
+})

frontend/lib/models/post.dart

@@ -5,6 +5,8 @@ class PostModel {
   final String creator;
   final String text;
   final Timestamp timestamp;
+  int likesCount;
 
-  PostModel({this.id, this.creator, this.text, this.timestamp});
+  PostModel(
+      {this.id, this.creator, this.text, this.timestamp, this.likesCount});
 }

frontend/lib/screens/main/posts/list.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
 import 'package:twitter/models/post.dart';
 import 'package:twitter/models/user.dart';
+import 'package:twitter/services/posts.dart';
 import 'package:twitter/services/user.dart';
 
 class ListPosts extends StatefulWidget {
@@ -13,6 +14,7 @@ class ListPosts extends StatefulWidget {
 
 class _ListPostsState extends State<ListPosts> {
   UserService _userService = UserService();
+  PostService _postService = PostService();
   @override
   Widget build(BuildContext context) {
     final posts = Provider.of<List<PostModel>>(context) ?? [];
@@ -23,44 +25,69 @@ class _ListPostsState extends State<ListPosts> {
         final post = posts[index];
         return StreamBuilder(
             stream: _userService.getUserInfo(post.creator),
-            builder: (BuildContext context, AsyncSnapshot<UserModel> snapshot) {
-              if (!snapshot.hasData) {
+            builder:
+                (BuildContext context, AsyncSnapshot<UserModel> snapshotUser) {
+              if (!snapshotUser.hasData) {
                 return Center(child: CircularProgressIndicator());
               }
-              return ListTile(
-                title: Padding(
-                  padding: EdgeInsets.fromLTRB(0, 15, 0, 15),
-                  child: Row(
-                    children: [
-                      snapshot.data.profileImageUrl != ''
-                          ? CircleAvatar(
-                              radius: 20,
-                              backgroundImage:
-                                  NetworkImage(snapshot.data.profileImageUrl))
-                          : Icon(Icons.person, size: 40),
-                      SizedBox(width: 10),
-                      Text(snapshot.data.name)
-                    ],
-                  ),
-                ),
-                subtitle: Column(
-                  crossAxisAlignment: CrossAxisAlignment.start,
-                  children: [
-                    Padding(
-                      padding: EdgeInsets.fromLTRB(0, 15, 0, 15),
-                      child: Column(
+
+              //stream builder to get user like
+              return StreamBuilder(
+                  stream: _postService.getCurrentUserLike(post),
+                  builder:
+                      (BuildContext context, AsyncSnapshot<bool> snapshotLike) {
+                    if (!snapshotLike.hasData) {
+                      return Center(child: CircularProgressIndicator());
+                    }
+
+                    return ListTile(
+                      title: Padding(
+                        padding: EdgeInsets.fromLTRB(0, 15, 0, 15),
+                        child: Row(
+                          children: [
+                            snapshotUser.data.profileImageUrl != ''
+                                ? CircleAvatar(
+                                    radius: 20,
+                                    backgroundImage: NetworkImage(
+                                        snapshotUser.data.profileImageUrl))
+                                : Icon(Icons.person, size: 40),
+                            SizedBox(width: 10),
+                            Text(snapshotUser.data.name)
+                          ],
+                        ),
+                      ),
+                      subtitle: Column(
                         crossAxisAlignment: CrossAxisAlignment.start,
                         children: [
-                          Text(post.text),
-                          SizedBox(height: 20),
-                          Text(post.timestamp.toDate().toString())
+                          Padding(
+                            padding: EdgeInsets.fromLTRB(0, 15, 0, 15),
+                            child: Column(
+                              crossAxisAlignment: CrossAxisAlignment.start,
+                              children: [
+                                Text(post.text),
+                                SizedBox(height: 20),
+                                Text(post.timestamp.toDate().toString()),
+                                SizedBox(height: 20),
+                                IconButton(
+                                    icon: new Icon(
+                                        snapshotLike.data
+                                            ? Icons.favorite
+                                            : Icons.favorite_border,
+                                        color: Colors.blue,
+                                        size: 30.0),
+                                    onPressed: () {
+                                      _postService.likePost(
+                                          post, snapshotLike.data);
+                                    }),
+                                Text(post.likesCount.toString())
+                              ],
+                            ),
+                          ),
+                          Divider(),
                         ],
                       ),
-                    ),
-                    Divider(),
-                  ],
-                ),
-              );
+                    );
+                  });
             });
       },
     );

frontend/lib/services/posts.dart

@@ -14,6 +14,7 @@ class PostService {
         text: doc.data()['text'] ?? '',
         creator: doc.data()['creator'] ?? '',
         timestamp: doc.data()['timestamp'] ?? 0,
+        likesCount: doc.data()['likesCount'] ?? 0,
       );
     }).toList();
   }
@@ -26,6 +27,41 @@ class PostService {
     });
   }
 
+  Future likePost(PostModel post, bool current) async {
+    print(post.id);
+    if (current) {
+      post.likesCount = post.likesCount - 1;
+      await FirebaseFirestore.instance
+          .collection("posts")
+          .doc(post.id)
+          .collection("likes")
+          .doc(FirebaseAuth.instance.currentUser.uid)
+          .delete();
+    }
+    if (!current) {
+      post.likesCount = post.likesCount + 1;
+
+      await FirebaseFirestore.instance
+          .collection("posts")
+          .doc(post.id)
+          .collection("likes")
+          .doc(FirebaseAuth.instance.currentUser.uid)
+          .set({});
+    }
+  }
+
+  Stream<bool> getCurrentUserLike(PostModel post) {
+    return FirebaseFirestore.instance
+        .collection("posts")
+        .doc(post.id)
+        .collection("likes")
+        .doc(FirebaseAuth.instance.currentUser.uid)
+        .snapshots()
+        .map((snapshot) {
+      return snapshot.exists;
+    });
+  }
+
   Stream<List<PostModel>> getPostsByUser(uid) {
     return FirebaseFirestore.instance
         .collection("posts")