auth: Define the `User` type

* gn3/auth/authentication.py -> gn3/auth/authentication/__init__.py: Convert
  module to package
* gn3/auth/authentication/users.py: Define the `User` type

2 files changed, 33 insertions, 0 deletions

diff --git a/gn3/auth/authentication/__init__.py b/gn3/auth/authentication/__init__.py
new file mode 100644
index 0000000..42ceacb
--- /dev/null
+++ b/gn3/auth/authentication/__init__.py
@@ -0,0 +1,24 @@
+"""Handle authentication requests"""
+
+import bcrypt
+
+def credentials_in_database(cursor, email: str, password: str) -> bool:
+    """Check whether credentials are in the database."""
+    if len(email.strip()) == 0 or len(password.strip()) == 0:
+        return False
+
+    cursor.execute(
+        ("SELECT "
+         "users.email, user_credentials.password "
+         "FROM users LEFT JOIN user_credentials "
+         "ON users.user_id = user_credentials.user_id "
+         "WHERE users.email = :email"),
+        {"email": email})
+    results = cursor.fetchall()
+    if len(results) == 0:
+        return False
+
+    assert len(results) == 1, "Expected one row."
+    row = results[0]
+    return (email == row[0] and
+            bcrypt.checkpw(password.encode("utf-8"), row[1]))
diff --git a/gn3/auth/authentication/users.py b/gn3/auth/authentication/users.py
new file mode 100644
index 0000000..4854d18
--- /dev/null
+++ b/gn3/auth/authentication/users.py
@@ -0,0 +1,9 @@
+"""User-specific code and data structures."""
+from uuid import UUID
+from typing import NamedTuple
+
+class User(NamedTuple):
+    """Class representing a user."""
+    user_id: UUID
+    email: str
+    name: str