3 files changed, 107 insertions, 0 deletions
diff --git a/gn_auth/auth/authentication/oauth2/grants/__init__.py b/gn_auth/auth/authentication/oauth2/grants/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/grants/__init__.py
diff --git a/gn_auth/auth/authentication/oauth2/grants/authorisation_code_grant.py b/gn_auth/auth/authentication/oauth2/grants/authorisation_code_grant.py
new file mode 100644
index 0000000..f80d02e
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/grants/authorisation_code_grant.py
@@ -0,0 +1,85 @@
+"""Classes and function for Authorisation Code flow."""
+import uuid
+import string
+import random
+from typing import Optional
+from datetime import datetime
+
+from flask import current_app as app
+from authlib.oauth2.rfc6749 import grants
+from authlib.oauth2.rfc7636 import create_s256_code_challenge
+
+from gn3.auth import db
+from gn3.auth.db_utils import with_db_connection
+from gn3.auth.authentication.users import User
+
+from ..models.oauth2client import OAuth2Client
+from ..models.authorization_code import (
+    AuthorisationCode, authorisation_code, save_authorisation_code)
+
+class AuthorisationCodeGrant(grants.AuthorizationCodeGrant):
+    """Implement the 'Authorisation Code' grant."""
+    TOKEN_ENDPOINT_AUTH_METHODS: list[str] = [
+        "client_secret_basic", "client_secret_post"]
+    AUTHORIZATION_CODE_LENGTH: int = 48
+    TOKEN_ENDPOINT_HTTP_METHODS = ['POST']
+    GRANT_TYPE = "authorization_code"
+    RESPONSE_TYPES = {'code'}
+
+    def save_authorization_code(self, code, request):
+        """Persist the authorisation code to database."""
+        client = request.client
+        nonce = "".join(random.sample(string.ascii_letters + string.digits,
+                                      k=self.AUTHORIZATION_CODE_LENGTH))
+        return __save_authorization_code__(AuthorisationCode(
+            uuid.uuid4(), code, client, request.redirect_uri, request.scope,
+            nonce, int(datetime.now().timestamp()),
+            create_s256_code_challenge(app.config["SECRET_KEY"]),
+            "S256", request.user))
+
+    def query_authorization_code(self, code, client):
+        """Retrieve the code from the database."""
+        return __query_authorization_code__(code, client)
+
+    def delete_authorization_code(self, authorization_code):# pylint: disable=[no-self-use]
+        """Delete the authorisation code."""
+        with db.connection(app.config["AUTH_DB"]) as conn:
+            with db.cursor(conn) as cursor:
+                cursor.execute(
+                    "DELETE FROM authorisation_code WHERE code_id=?",
+                    (str(authorization_code.code_id),))
+
+    def authenticate_user(self, authorization_code) -> Optional[User]:
+        """Authenticate the user who own the authorisation code."""
+        query = (
+            "SELECT users.* FROM authorisation_code LEFT JOIN users "
+            "ON authorisation_code.user_id=users.user_id "
+            "WHERE authorisation_code.code=?")
+        with db.connection(app.config["AUTH_DB"]) as conn:
+            with db.cursor(conn) as cursor:
+                cursor.execute(query, (str(authorization_code.code),))
+                res = cursor.fetchone()
+                if res:
+                    return User(
+                        uuid.UUID(res["user_id"]), res["email"], res["name"])
+
+        return None
+
+def __query_authorization_code__(
+        code: str, client: OAuth2Client) -> AuthorisationCode:
+    """A helper function that creates a new database connection.
+
+    This is found to be necessary since the `AuthorizationCodeGrant` class(es)
+    do not have a way to pass the database connection."""
+    def __auth_code__(conn) -> str:
+        the_code = authorisation_code(conn, code, client)
+        return the_code.maybe(None, lambda cde: cde) # type: ignore[misc, arg-type, return-value]
+
+    return with_db_connection(__auth_code__)
+
+def __save_authorization_code__(code: AuthorisationCode) -> AuthorisationCode:
+    """A helper function that creates a new database connection.
+
+    This is found to be necessary since the `AuthorizationCodeGrant` class(es)
+    do not have a way to pass the database connection."""
+    return with_db_connection(lambda conn: save_authorisation_code(conn, code))
diff --git a/gn_auth/auth/authentication/oauth2/grants/password_grant.py b/gn_auth/auth/authentication/oauth2/grants/password_grant.py
new file mode 100644
index 0000000..3233877
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/grants/password_grant.py
@@ -0,0 +1,22 @@
+"""Allows users to authenticate directly."""
+
+from flask import current_app as app
+from authlib.oauth2.rfc6749 import grants
+
+from gn3.auth import db
+from gn3.auth.authentication.users import valid_login, user_by_email
+
+from gn3.auth.authorisation.errors import NotFoundError
+
+class PasswordGrant(grants.ResourceOwnerPasswordCredentialsGrant):
+    """Implement the 'Password' grant."""
+    TOKEN_ENDPOINT_AUTH_METHODS = ["client_secret_basic", "client_secret_post"]
+
+    def authenticate_user(self, username, password):
+        "Authenticate the user with their username and password."
+        with db.connection(app.config["AUTH_DB"]) as conn:
+            try:
+                user = user_by_email(conn, username)
+                return user if valid_login(conn, user, password) else None
+            except NotFoundError as _nfe:
+                return None