"""ProjectMember model for cross-department project collaboration.

This model tracks explicit project membership, allowing users from different
departments to be granted access to projects they wouldn't normally have
access to based on department isolation rules.
"""
import uuid
from sqlalchemy import Column, String, ForeignKey, DateTime, UniqueConstraint
from sqlalchemy.sql import func
from sqlalchemy.orm import relationship
from app.core.database import Base


class ProjectMember(Base):
    """
    Represents a user's membership in a project.

    This enables cross-department collaboration by explicitly granting
    project access to users regardless of their department.

    Roles:
    - member: Can view and edit tasks
    - admin: Can manage project settings and add other members
    """
    __tablename__ = "pjctrl_project_members"

    id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
    project_id = Column(
        String(36),
        ForeignKey("pjctrl_projects.id", ondelete="CASCADE"),
        nullable=False,
        index=True
    )
    user_id = Column(
        String(36),
        ForeignKey("pjctrl_users.id", ondelete="CASCADE"),
        nullable=False,
        index=True
    )
    role = Column(String(50), nullable=False, default="member")
    added_by = Column(
        String(36),
        ForeignKey("pjctrl_users.id"),
        nullable=False
    )
    created_at = Column(DateTime, server_default=func.now(), nullable=False)

    # Unique constraint to prevent duplicate memberships
    __table_args__ = (
        UniqueConstraint('project_id', 'user_id', name='uq_project_member'),
    )

    # Relationships
    project = relationship("Project", back_populates="members")
    user = relationship("User", foreign_keys=[user_id], back_populates="project_memberships")
    added_by_user = relationship("User", foreign_keys=[added_by])