Implement support for password change and logout

Note the hack.

snikket_web/user/__init__.py

@@ -0,0 +1,66 @@
+import quart.flask_patch
+
+from quart import Blueprint, render_template, request, redirect, url_for
+import quart.exceptions
+from flask_wtf import FlaskForm
+import wtforms
+
+from snikket_web.prosodyclient import client
+
+user_bp = Blueprint('user', __name__, url_prefix="/user")
+
+
+class ChangePasswordForm(FlaskForm):
+    current_password = wtforms.PasswordField(
+        validators=[wtforms.validators.InputRequired()]
+    )
+
+    new_password = wtforms.PasswordField(
+        validators=[wtforms.validators.InputRequired()]
+    )
+
+    new_password_confirm = wtforms.PasswordField(
+        validators=[wtforms.validators.InputRequired(),
+                    wtforms.validators.EqualTo("new_password")]
+    )
+
+
+class LogoutForm(FlaskForm):
+    pass
+
+
+@user_bp.route("/")
+async def index():
+    user_info = await client.get_user_info()
+    return await render_template("user_home.html", user_info=user_info)
+
+
+@user_bp.route('/passwd', methods=["GET", "POST"])
+async def change_pw():
+    form = ChangePasswordForm()
+    if form.validate_on_submit():
+        try:
+            await client.change_password(
+                form.current_password.data,
+                form.new_password.data,
+            )
+        except quart.exceptions.Unauthorized:
+            # server refused current password, set an appropriate error
+            form.errors.setdefault(form.current_password.name, []).append(
+                # TODO(i18n)
+                "Incorrect password",
+            )
+        else:
+            return redirect(url_for("user.change_pw"))
+
+    return await render_template("user_passwd.html", form=form)
+
+
+@user_bp.route("/logout", methods=["GET", "POST"])
+async def logout():
+    form = LogoutForm()
+    if form.validate_on_submit():
+        await client.logout()
+        return redirect(url_for("home"))
+
+    return await render_template("user_logout.html", form=form)