add user signup flow

app/auth.py

@@ -4,6 +4,7 @@ from argon2 import PasswordHasher
 from functools import wraps
 import secrets
 import time
+import re
 
 ph = PasswordHasher()
 
@@ -44,6 +45,15 @@ def create_session(user_id, temporary=False):
         'expires_at': int(time.time()) + (expires_days * 24 * 60 * 60),
     })
 
+def parse_username(username: str) -> Tuple[str, str]:
+    if len(username) < 3:
+        raise ValueError
+    invalid_regex = r'[^a-zA-Z0-9_-]'
+    return username, re.sub(invalid_regex, '_', username.lower())[:20]
+
+def is_password_valid(password: str) -> bool:
+    return re.match(r'^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[\W_])(?!.*\s).{10,255}$', password) is not None
+
 # annotations
 def login_required(view_func):
     @wraps(view_func)

app/routes/users.py

@@ -1,8 +1,10 @@
 from flask import Blueprint, redirect, url_for, render_template, request, session
 from functools import wraps
+import time
 
-from ..auth import digest, verify, create_session, is_logged_in
+from ..auth import digest, verify, create_session, is_logged_in, parse_username, is_password_valid
 from ..models import Users
+from ..constants import PermissionLevel
 
 bp = Blueprint('users', __name__, url_prefix='/users/')
 
@@ -39,10 +41,53 @@ def log_in_post():
         session.permanent = True
     return redirect(request.form.get('return_to', default=url_for('topics.all_topics')))
 
-@bp.get('/sign-up')
+@bp.get('/sign-up/')
 @redirect_if_logged_in()
 def sign_up():
-    return 'stub'
+    return render_template('users/sign_up.html')
+
+@bp.post('/sign-up/')
+@redirect_if_logged_in()
+def sign_up_post():
+    generic_error_page = redirect(url_for('.sign_up', error='The username or password you entered is invalid.'))
+    user_exists_error_page = redirect(url_for('.sign_up', error='This username is already taken. Please pick another.'))
+    passwords_error_page = redirect(url_for('.sign_up', error='The passwords do not match.'))
+    username = request.form.get('username', default='')
+    if not username:
+        return generic_error_page
+    if request.form.get('password', default=None) is None:
+        return generic_error_page
+    if len(request.form.getlist('password')) != 2:
+        return passwords_error_page
+    username_pair = parse_username(username)
+    potential_user = Users.find({'username': username})
+    if potential_user:
+        return user_exists_error_page
+
+    if request.form.getlist('password')[0] != request.form.getlist('password')[1]:
+        return passwords_error_page
+
+    password_hash = digest(request.form.get('password'))
+
+    user = Users.create({
+        'username': username_pair[0],
+        'password_hash': password_hash,
+        'permission': PermissionLevel.GUEST.value,
+        'created_at': int(time.time()),
+    })
+
+    if username_pair[0] != username_pair[1]:
+        user.update({
+            'display_name': username_pair[1]
+        })
+
+    session['remember'] = request.form.get('remember') == 'on'
+    sess = create_session(user.id, not session['remember'])
+    session['pyrom_session_key'] = sess.key
+    if session['remember']:
+        session.permanent = True
+
+    return redirect(url_for('topics.all_topics'))
 
 @bp.get('/<username>')
 def user_page(username):

app/templates/common/topnav.html

@@ -13,7 +13,7 @@
     {%- endif %}
   </ul>
   {%- endwith -%}
-  {%- else -%}
+  {%- elif request.path != url_for('users.sign_up') and request.path != url_for('users.log_in') -%}
   <form class="horizontal wrap" method="POST" action="{{url_for('users.log_in_post')}}">
     <input type="hidden" name="return_to" value="{{request.path}}">
     <input type="text" placeholder="Username" name="username" autocomplete="username" required>

app/templates/users/sign_up.html

@@ -0,0 +1,24 @@
+{% from 'common/macros.html' import subheader %}
+{%- extends 'base.html' -%}
+{%- block title -%}sign up{%- endblock -%}
+{%- block content -%}
+{%- set welcome -%}
+Please read the rules etc. stub
+{%- endset -%}
+{{ subheader('Sign up', welcome)}}
+{%- if request.args.get('error') -%}
+<div class="infobox plank critical">
+  {{request.args.get('error')}}
+</div>
+{%- endif -%}
+<form class="plank primary-bg full-width" method="POST">
+  <label for="username">Username</label>
+  <input type="text" id="username" name="username" pattern="[a-zA-Z0-9_\-]{3,20}" title="3-20 characters. Only upper and lowercase letters, digits, hyphens, and underscores" autocomplete="username" required>
+  <label for="password">Create password</label>
+  <input type="password" id="password" name="password" pattern="(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[\W_])(?!.*\s).{10,255}" title="10+ chars with: 1 uppercase, 1 lowercase, 1 number, 1 special char, and no spaces" autocomplete="new-password" required>
+  <label for="password2">Confirm password</label>
+  <input type="password" id="password2" name="password" pattern="(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[\W_])(?!.*\s).{10,255}" title="10+ chars with: 1 uppercase, 1 lowercase, 1 number, 1 special char, and no spaces" autocomplete="new-password" required>
+  <span><input type="checkbox" name="remember" id="remember"> <label for="remember">Remember me</label></span>
+  <input type="submit" value="Sign up">
+</form>
+{%- endblock -%}