from sqlalchemy import Column, Integer, String, Boolean, DateTime, Enum, ForeignKey
from sqlalchemy.orm import relationship
from sqlalchemy.sql import func
import enum

from app.db.base import Base


class Priority(str, enum.Enum):
    LOW = "low"
    MEDIUM = "medium"
    HIGH = "high"


class Todo(Base):
    __tablename__ = "todos"

    id = Column(Integer, primary_key=True, index=True)
    title = Column(String(200), nullable=False)
    description = Column(String(500), nullable=True)
    completed = Column(Boolean, default=False)
    priority = Column(Enum(Priority), default=Priority.MEDIUM)
    project_id = Column(Integer, ForeignKey("projects.id"), nullable=True)
    category_id = Column(Integer, ForeignKey("categories.id"), nullable=True)
    parent_id = Column(Integer, ForeignKey("todos.id"), nullable=True)
    created_at = Column(DateTime(timezone=True), server_default=func.now())
    updated_at = Column(DateTime(timezone=True), onupdate=func.now())

    # Relationship to project
    project = relationship("Project", back_populates="todos")

    # Relationship to category
    category = relationship("Category", back_populates="todos")

    # Many-to-many relationship with tags
    tags = relationship("Tag", secondary="todo_tags", back_populates="todos")

    # Self-referential relationship for subtasks
    parent = relationship("Todo", remote_side=[id], back_populates="children")
    children = relationship(
        "Todo", back_populates="parent", cascade="all, delete-orphan"
    )

    @property
    def is_subtask(self) -> bool:
        """Check if this todo is a subtask of another todo."""
        return self.parent_id is not None