"""User model for authentication and authorization

Represents an authenticated reader with account credentials.
Aligns with data-model.md User entity specification.
"""
from datetime import datetime
from uuid import UUID, uuid4
from sqlalchemy import Column, String, TIMESTAMP
from sqlalchemy.dialects.postgresql import UUID as PGUUID
from sqlalchemy.orm import relationship

from src.config.database import Base


class User(Base):
    """User model for authentication

    Attributes:
        id: Unique user identifier (UUID)
        email: User's email address (unique)
        password_hash: Hashed password (managed by auth service)
        created_at: Account creation timestamp
        updated_at: Last account modification timestamp
    """

    __tablename__ = "users"

    id = Column(
        PGUUID(as_uuid=True),
        primary_key=True,
        default=uuid4,
        server_default="gen_random_uuid()"
    )
    email = Column(String(255), unique=True, nullable=False, index=True)
    password_hash = Column(String(255), nullable=False)
    created_at = Column(TIMESTAMP, nullable=False, default=datetime.utcnow, server_default="NOW()")
    updated_at = Column(TIMESTAMP, nullable=False, default=datetime.utcnow, onupdate=datetime.utcnow, server_default="NOW()")

    # Relationships
    sessions = relationship("Session", back_populates="user", cascade="all, delete-orphan")
    chat_messages = relationship("ChatMessage", back_populates="user", cascade="all, delete-orphan")

    def __repr__(self) -> str:
        return f"<User(id={self.id}, email={self.email})>"