Implemented follow/unfollow in webapp. Implemented deleteRows helper …

…method in webapp.

webapp/minitwit.js

@@ -232,6 +232,30 @@ app.get('/:username', async function(req, res) {
     });
 });
 
+app.get('/:username/follow', async function(req, res) {
+    const { username } = req.params;
+    if (!req.session.user_id)
+        res.status(401).send();
+    let whom = await selectOne('SELECT * FROM user WHERE username = ?',[username]);
+    if (!whom)
+        res.status(404).send();
+    await insertOne('INSERT INTO follower (who_id, whom_id) VALUES (?, ?)', [req.session.user_id, whom.user_id])
+
+    return res.redirect('/' + username);
+});
+
+app.get('/:username/unfollow', async function(req, res) {
+    const { username } = req.params;
+    if (!req.session.user_id)
+        res.status(401).send();
+    let whom = await selectOne('SELECT * FROM user WHERE username = ?',[username]);
+    if (!whom)
+        res.status(404).send();
+    await deleteRows('DELETE FROM follower WHERE who_id = ? AND whom_id = ?', [req.session.user_id, whom.user_id]);
+
+    return res.redirect('/' + username);
+});
+
 // Start application
 app.listen(8080);
 console.log('MiniTwit is running on port 8080..');
@@ -275,6 +299,20 @@ function insertOne(query, params) {
     });
 }
 
+// Delete row(s)
+function deleteRows(query, params) {
+    return new Promise((resolve, reject) => {
+        db.run(query, params, function(err) {
+            if (err) {
+                console.error(err.message);
+                reject();
+            }
+            // Return the deleted
+            resolve(this.changes);
+        });
+    });
+}
+
 // Lame password hash function
 // TODO Use proper hashing library, bcrypt maybe?
 String.prototype.lameHash = function() {