auth: Implement "Authorization Code Flow" auth/implement-authorization-code-flow

Implement the "Authorization Code Flow" for the authentication of users.

* gn3/auth/authentication/oauth2/grants/authorisation_code_grant.py: query and
  save the authorisation code.
* gn3/auth/authentication/oauth2/models/authorization_code.py: Implement the
  `AuthorisationCode` model
* gn3/auth/authentication/oauth2/models/oauth2client.py: Fix typo
* gn3/auth/authentication/oauth2/server.py: Register the
  `AuthorisationCodeGrant` grant with the server.
* gn3/auth/authentication/oauth2/views.py: Implement `/authorise` endpoint
* gn3/templates/base.html: New HTML Templates of authorisation UI
* gn3/templates/common-macros.html: New HTML Templates of authorisation UI
* gn3/templates/oauth2/authorise-user.html: New HTML Templates of
  authorisation UI
* main.py: Allow both "code" and "token" response types.

1 files changed, 50 insertions, 2 deletions

diff --git a/gn3/auth/authentication/oauth2/views.py b/gn3/auth/authentication/oauth2/views.py
index 3a14a48..48a97da 100644
--- a/gn3/auth/authentication/oauth2/views.py
+++ b/gn3/auth/authentication/oauth2/views.py
@@ -1,14 +1,28 @@
 """Endpoints for the oauth2 server"""
 import uuid
+import traceback
 
-from flask import Response, Blueprint, current_app as app
+from email_validator import validate_email, EmailNotValidError
+from flask import (
+    flash,
+    request,
+    url_for,
+    redirect,
+    Response,
+    Blueprint,
+    render_template,
+    current_app as app)
 
+from gn3.auth import db
+from gn3.auth.db_utils import with_db_connection
 from gn3.auth.authorisation.errors import ForbiddenAccess
 
 from .resource_server import require_oauth
 from .endpoints.revocation import RevocationEndpoint
 from .endpoints.introspection import IntrospectionEndpoint
 
+from ..users import valid_login, NotFoundError, user_by_email
+
 auth = Blueprint("auth", __name__)
 
 @auth.route("/register-client", methods=["GET", "POST"])
@@ -24,7 +38,41 @@ def delete_client(client_id: uuid.UUID):
 @auth.route("/authorise", methods=["GET", "POST"])
 def authorise():
     """Authorise a user"""
-    return "WOULD AUTHORISE THE USER."
+    server = app.config["OAUTH2_SERVER"]
+    client_id = uuid.UUID(request.args.get("client_id", str(uuid.uuid4())))
+    client = server.query_client(client_id)
+    if not bool(client):
+        flash("Invalid OAuth2 client.", "alert-error")
+    if request.method == "GET":
+        client = server.query_client(request.args.get("client_id"))
+        return render_template(
+            "oauth2/authorise-user.html",
+            client=client,
+            scope=client.scope,
+            response_type="code")
+
+    form = request.form
+    def __authorise__(conn: db.DbConnection) -> Response:
+        email_passwd_msg = "Email or password is invalid!"
+        redirect_response = redirect(url_for("oauth2.auth.authorise",
+                                             client_id=client_id))
+        try:
+            email = validate_email(form.get("user:email"))
+            user = user_by_email(conn, email["email"])
+            if valid_login(conn, user, form.get("user:password", "")):
+                return server.create_authorization_response(request=request, grant_user=user)
+            flash(email_passwd_msg, "alert-error")
+            return redirect_response # type: ignore[return-value]
+        except EmailNotValidError as _enve:
+            app.logger.debug(traceback.format_exc())
+            flash(email_passwd_msg, "alert-error")
+            return redirect_response # type: ignore[return-value]
+        except NotFoundError as _nfe:
+            app.logger.debug(traceback.format_exc())
+            flash(email_passwd_msg, "alert-error")
+            return redirect_response # type: ignore[return-value]
+
+    return with_db_connection(__authorise__)
 
 @auth.route("/token", methods=["POST"])
 def token():