feat: implement user and role models with password hashing, and add tests for user functionality

models/user.py

@@ -0,0 +1,168 @@
+from __future__ import annotations
+
+from datetime import datetime
+from typing import List, Optional
+
+from passlib.context import CryptContext
+from sqlalchemy import (
+    Boolean,
+    DateTime,
+    ForeignKey,
+    Integer,
+    String,
+    Text,
+    UniqueConstraint,
+)
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+from sqlalchemy.sql import func
+
+from config.database import Base
+
+# Configure password hashing strategy. Argon2 provides strong resistance against
+# GPU-based cracking attempts, aligning with the security plan.
+password_context = CryptContext(schemes=["argon2"], deprecated="auto")
+
+
+class User(Base):
+    """Authenticated platform user with optional elevated privileges."""
+
+    __tablename__ = "users"
+    __table_args__ = (
+        UniqueConstraint("email", name="uq_users_email"),
+        UniqueConstraint("username", name="uq_users_username"),
+    )
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    email: Mapped[str] = mapped_column(String(255), nullable=False)
+    username: Mapped[str] = mapped_column(String(128), nullable=False)
+    password_hash: Mapped[str] = mapped_column(String(255), nullable=False)
+    is_active: Mapped[bool] = mapped_column(
+        Boolean, nullable=False, default=True)
+    is_superuser: Mapped[bool] = mapped_column(
+        Boolean, nullable=False, default=False)
+    last_login_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True), nullable=True
+    )
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now(), onupdate=func.now()
+    )
+
+    role_assignments: Mapped[List["UserRole"]] = relationship(
+        "UserRole",
+        back_populates="user",
+        cascade="all, delete-orphan",
+        foreign_keys="UserRole.user_id",
+    )
+    roles: Mapped[List["Role"]] = relationship(
+        "Role",
+        secondary="user_roles",
+        primaryjoin="User.id == UserRole.user_id",
+        secondaryjoin="Role.id == UserRole.role_id",
+        viewonly=True,
+        back_populates="users",
+    )
+
+    def set_password(self, raw_password: str) -> None:
+        """Hash and store a password for the user."""
+
+        self.password_hash = self.hash_password(raw_password)
+
+    @staticmethod
+    def hash_password(raw_password: str) -> str:
+        """Return the Argon2 hash for a clear-text password."""
+
+        return password_context.hash(raw_password)
+
+    def verify_password(self, candidate_password: str) -> bool:
+        """Validate a password against the stored hash."""
+
+        if not self.password_hash:
+            return False
+        return password_context.verify(candidate_password, self.password_hash)
+
+    def __repr__(self) -> str:  # pragma: no cover - helpful for debugging
+        return f"User(id={self.id!r}, email={self.email!r})"
+
+
+class Role(Base):
+    """Role encapsulating a set of permissions."""
+
+    __tablename__ = "roles"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    name: Mapped[str] = mapped_column(String(64), nullable=False, unique=True)
+    display_name: Mapped[str] = mapped_column(String(128), nullable=False)
+    description: Mapped[str | None] = mapped_column(Text, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now(), onupdate=func.now()
+    )
+
+    assignments: Mapped[List["UserRole"]] = relationship(
+        "UserRole",
+        back_populates="role",
+        cascade="all, delete-orphan",
+        foreign_keys="UserRole.role_id",
+    )
+    users: Mapped[List["User"]] = relationship(
+        "User",
+        secondary="user_roles",
+        primaryjoin="Role.id == UserRole.role_id",
+        secondaryjoin="User.id == UserRole.user_id",
+        viewonly=True,
+        back_populates="roles",
+    )
+
+    def __repr__(self) -> str:  # pragma: no cover - helpful for debugging
+        return f"Role(id={self.id!r}, name={self.name!r})"
+
+
+class UserRole(Base):
+    """Association between users and roles with assignment metadata."""
+
+    __tablename__ = "user_roles"
+    __table_args__ = (
+        UniqueConstraint("user_id", "role_id", name="uq_user_roles_user_role"),
+    )
+
+    user_id: Mapped[int] = mapped_column(
+        Integer,
+        ForeignKey("users.id", ondelete="CASCADE"),
+        primary_key=True,
+    )
+    role_id: Mapped[int] = mapped_column(
+        Integer,
+        ForeignKey("roles.id", ondelete="CASCADE"),
+        primary_key=True,
+    )
+    granted_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )
+    granted_by: Mapped[Optional[int]] = mapped_column(
+        Integer,
+        ForeignKey("users.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+
+    user: Mapped["User"] = relationship(
+        "User",
+        foreign_keys=[user_id],
+        back_populates="role_assignments",
+    )
+    role: Mapped["Role"] = relationship(
+        "Role",
+        foreign_keys=[role_id],
+        back_populates="assignments",
+    )
+    granted_by_user: Mapped[Optional["User"]] = relationship(
+        "User",
+        foreign_keys=[granted_by],
+    )
+
+    def __repr__(self) -> str:  # pragma: no cover - debugging helper
+        return f"UserRole(user_id={self.user_id!r}, role_id={self.role_id!r})"