refactors

backend/models/associations.py

@@ -0,0 +1,36 @@
+from sqlalchemy import Column, Enum, ForeignKey, Integer, Table
+
+from database import Base
+
+from .enums import Permission
+
+# Association table: Role <-> Permission (many-to-many)
+role_permissions = Table(
+    "role_permissions",
+    Base.metadata,
+    Column(
+        "role_id",
+        Integer,
+        ForeignKey("roles.id", ondelete="CASCADE"),
+        primary_key=True,
+    ),
+    Column("permission", Enum(Permission), primary_key=True),
+)
+
+# Association table: User <-> Role (many-to-many)
+user_roles = Table(
+    "user_roles",
+    Base.metadata,
+    Column(
+        "user_id",
+        Integer,
+        ForeignKey("users.id", ondelete="CASCADE"),
+        primary_key=True,
+    ),
+    Column(
+        "role_id",
+        Integer,
+        ForeignKey("roles.id", ondelete="CASCADE"),
+        primary_key=True,
+    ),
+)