Register: Fix behaviour on email conflict, add password suggestion

app/blueprints/users/account.py

@@ -23,8 +23,10 @@ from wtforms import *
 from wtforms.validators import *
 
 from app.models import *
-from app.tasks.emails import sendVerifyEmail
+from app.tasks.emails import sendVerifyEmail, sendEmailRaw
 from app.utils import randomString, make_flask_login_password, is_safe_url, check_password_hash
+from passlib.pwd import genphrase
+
 from . import bp
 
 
@@ -102,24 +104,29 @@ class RegisterForm(FlaskForm):
 def register():
 	form = RegisterForm(request.form)
 	if form.validate_on_submit():
-		user = User(form.username.data, False, form.email.data, make_flask_login_password(form.password.data))
-		db.session.add(user)
+		user = User.query.filter_by(email=form.email.data).first()
+		if user:
+			sendEmailRaw([form.email.data], "Email already in use",
+					"We were unable to create the account as the email is already in use by {}. Try a different email address.".format(user.display_name))
+		else:
+			user = User(form.username.data, False, form.email.data, make_flask_login_password(form.password.data))
+			db.session.add(user)
 
-		token = randomString(32)
+			token = randomString(32)
 
-		ver = UserEmailVerification()
-		ver.user = user
-		ver.token = token
-		ver.email = form.email.data
-		db.session.add(ver)
-		db.session.commit()
+			ver = UserEmailVerification()
+			ver.user = user
+			ver.token = token
+			ver.email = form.email.data
+			db.session.add(ver)
+			db.session.commit()
 
-		sendVerifyEmail.delay(form.email.data, token)
+			sendVerifyEmail.delay(form.email.data, token)
 
 		flash("Check your email address to verify your account", "success")
 		return redirect(url_for("homepage.home"))
 
-	return render_template("users/register.html", form=form)
+	return render_template("users/register.html", form=form, suggested_password=genphrase(entropy=52, wordset="bip39"))
 
 
 class ForgotPassword(FlaskForm):

app/tasks/emails.py

@@ -41,11 +41,11 @@ def sendVerifyEmail(newEmail, token):
 	mail.send(msg)
 
 @celery.task()
-def sendEmailRaw(to, subject, text, html):
+def sendEmailRaw(to, subject, text, html=None):
 	from flask_mail import Message
 	msg = Message(subject, recipients=to)
 
-	msg.body = text or html
+	msg.body = text
 	html = html or text
 	msg.html = render_template("emails/base.html", subject=subject, content=html)
 	mail.send(msg)

app/templates/users/register.html

@@ -20,6 +20,11 @@ Register
 		<p>
 			Must be at least 8 characters long.
 		</p>
+		<p>
+			Password suggestion
+			(<a href="https://xkcd.com/936/">Why?</a>):
+			<code>{{ suggested_password }}</code>
+		</p>
 
 		{# Submit button #}
 		<p>