import uuid
from datetime import datetime, timezone
from typing import Optional, TYPE_CHECKING
from sqlalchemy import String, Text, DateTime, ForeignKey, Boolean, Integer, UniqueConstraint
from sqlalchemy.orm import Mapped, mapped_column, relationship
from sqlalchemy.dialects.postgresql import UUID
from app.core.database import Base

if TYPE_CHECKING:
    from app.models.tree import Tree
    from app.models.team import Team
    from app.models.account import Account
    from app.models.user import User


class TreeCategory(Base):
    """Admin-managed categories for organizing trees.

    Categories can be:
    - Global (team_id=NULL): Created by ResolutionFlow admins, visible to all
    - Team-specific (team_id set): Created by team admins, visible to team members
    """
    __tablename__ = "tree_categories"
    __table_args__ = (
        UniqueConstraint('slug', 'team_id', name='uq_tree_categories_slug_team'),
    )

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        primary_key=True,
        default=uuid.uuid4
    )
    name: Mapped[str] = mapped_column(String(100), nullable=False)
    slug: Mapped[str] = mapped_column(String(100), nullable=False, index=True)
    description: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
    team_id: Mapped[Optional[uuid.UUID]] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("teams.id", ondelete="CASCADE"),
        nullable=True,
        index=True
    )
    account_id: Mapped[Optional[uuid.UUID]] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("accounts.id", ondelete="CASCADE"),
        nullable=True,
        index=True
    )
    display_order: Mapped[int] = mapped_column(Integer, nullable=False, default=0, index=True)
    is_active: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)
    created_by: Mapped[Optional[uuid.UUID]] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("users.id", ondelete="SET NULL"),
        nullable=True
    )
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        default=lambda: datetime.now(timezone.utc)
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        default=lambda: datetime.now(timezone.utc),
        onupdate=lambda: datetime.now(timezone.utc)
    )

    # Relationships
    team: Mapped[Optional["Team"]] = relationship("Team", back_populates="categories")
    account: Mapped[Optional["Account"]] = relationship("Account", foreign_keys=[account_id], back_populates="categories")
    creator: Mapped[Optional["User"]] = relationship("User", foreign_keys=[created_by])
    trees: Mapped[list["Tree"]] = relationship("Tree", back_populates="category_rel")

    @property
    def is_global(self) -> bool:
        """Returns True if this is a global category (not team or account-specific)."""
        return self.team_id is None and self.account_id is None