sign in system pretty much

app.py

@@ -1,4 +1,6 @@
-from flask import Flask, render_template, redirect, request, url_for
+from functools import wraps
+
+from flask import Flask, render_template, redirect, request, url_for, session, flash
 from flask_sqlalchemy import SQLAlchemy
 from werkzeug.security import generate_password_hash, check_password_hash
 
@@ -19,6 +21,16 @@ with app.app_context():
     db.create_all()
 
 
+def login_required(view_func):
+    @wraps(view_func)
+    def wrapped(*args, **kwargs):
+        if 'user_id' not in session:
+            flash('Please sign in to view that page.')
+            return redirect(url_for('signin'))
+        return view_func(*args, **kwargs)
+    return wrapped
+
+
 @app.route('/submit-form', methods=['POST'])
 def handle_submission():
     form_username = request.form.get('username')
@@ -41,21 +53,21 @@ def handle_submission():
 
 
 @app.route('/users')
+@login_required
 def view_users():
     all_users = User.query.all()
-    
 
     html_output = "<h2>Registered Accounts</h2><table border='1' cellpadding='10'>"
     html_output += "<tr><th>ID</th><th>Username</th><th>Email</th></tr>"
-    
+
     for user in all_users:
-        html_output += f"<tr><td>{user.id}</td><td>{user.username}</td><td>{user.email}</td><td>{user.password_hash}</td></tr>"
-        
+        html_output += f"<tr><td>{user.id}</td><td>{user.username}</td><td>{user.email}</td></tr>"
+
     html_output += "</table>"
-    
+
     if not all_users:
         return "<h3>No accounts found in the database yet.</h3>"
-        
+
     return html_output
 
 
@@ -71,15 +83,36 @@ def bivariate():
 def about():
     return render_template('about.html')
 
-@app.route('/signin')
+@app.route('/signin', methods=['GET', 'POST'])
 def signin():
+    if request.method == 'POST':
+        form_username = request.form.get('username')
+        form_password = request.form.get('password')
+
+        user = User.query.filter_by(username=form_username).first()
+
+        if user is None or not check_password_hash(user.password_hash, form_password):
+            flash('Incorrect username or password.')
+            return render_template('signin.html'), 401
+
+        session['user_id'] = user.id
+        session['username'] = user.username
+        return redirect(url_for('home'))
+
     return render_template('signin.html')
 
+
+@app.route('/logout')
+def logout():
+    session.clear()
+    return redirect(url_for('home'))
+
 @app.route('/signup')
 def signup():
     return render_template('signup.html')
 
 @app.route('/all_users')
+@login_required
 def all_users():
     return render_template('all_users.html')