from datetime import datetime, timezone
from enum import Enum

from sqlalchemy import Column, Boolean, ForeignKey, UniqueConstraint, Enum as SQLEnum, DateTime
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy.orm import relationship

from .base import Base, TimestampMixin, UUIDMixin


class EventManagerRole(str, Enum):
    OWNER = "owner"
    ADMIN = "admin"
    MODERATOR = "moderator"
    VIEWER = "viewer"


class EventManager(Base, UUIDMixin, TimestampMixin):
    __tablename__ = 'event_managers'

    # Foreign Keys
    user_id = Column(UUID(as_uuid=True), ForeignKey('users.id'), nullable=False)
    event_id = Column(UUID(as_uuid=True), ForeignKey('events.id'), nullable=False)
    assigned_by = Column(UUID(as_uuid=True), ForeignKey('users.id'), nullable=False)

    # Role using Enum
    role = Column(SQLEnum(EventManagerRole), nullable=False)

    # Explicit permissions
    can_edit = Column(Boolean, default=False, nullable=False)
    can_invite = Column(Boolean, default=False, nullable=False)
    can_manage_gifts = Column(Boolean, default=False, nullable=False)
    can_send_updates = Column(Boolean, default=False, nullable=False)
    can_view_analytics = Column(Boolean, default=False, nullable=False)

    assigned_at = Column(DateTime(timezone=True), default=lambda: datetime.now(timezone.utc), nullable=False)

    # Relationships
    user = relationship("User", back_populates="managed_events", foreign_keys=[user_id])
    event = relationship("Event", back_populates="managers")
    assigner = relationship("User", foreign_keys=[assigned_by])

    __table_args__ = (
        UniqueConstraint('user_id', 'event_id', name='uq_user_event_manager'),
    )

    def __repr__(self):
        return f"<EventManager user_id={self.user_id} event_id={self.event_id} role={self.role.value}>"

    @property
    def permissions(self):
        """Get permissions based on role"""
        return ROLE_PERMISSIONS[self.role]

    def has_permission(self, permission: str) -> bool:
        """Check if manager has specific permission"""
        return getattr(self, permission, False) or self.permissions.get(permission, False)


# Define default permissions for each role
ROLE_PERMISSIONS = {
    EventManagerRole.OWNER: {
        'can_edit': True,
        'can_invite': True,
        'can_manage_gifts': True,
        'can_send_updates': True,
        'can_view_analytics': True,
        'can_manage_managers': True,  # Special permission for owners
    },
    EventManagerRole.ADMIN: {
        'can_edit': True,
        'can_invite': True,
        'can_manage_gifts': True,
        'can_send_updates': True,
        'can_view_analytics': True,
        'can_manage_managers': False,
    },
    EventManagerRole.MODERATOR: {
        'can_edit': False,
        'can_invite': True,
        'can_manage_gifts': True,
        'can_send_updates': True,
        'can_view_analytics': True,
        'can_manage_managers': False,
    },
    EventManagerRole.VIEWER: {
        'can_edit': False,
        'can_invite': False,
        'can_manage_gifts': False,
        'can_send_updates': False,
        'can_view_analytics': True,
        'can_manage_managers': False,
    }
}


def init_event_owner(user_id: UUID, event_id: UUID) -> EventManager:
    """Helper function to create an owner manager for a new event"""
    return EventManager(
        user_id=user_id,
        event_id=event_id,
        assigned_by=user_id,  # Owner is self-assigned
        role=EventManagerRole.OWNER,
        can_edit=True,
        can_invite=True,
        can_manage_gifts=True,
        can_send_updates=True,
        can_view_analytics=True
    )