from __future__ import annotations

from datetime import datetime
from uuid import UUID, uuid4

from sqlalchemy import CheckConstraint, UniqueConstraint
from sqlmodel import Field

from app.core.time import utcnow
from app.models.tenancy import TenantScoped


class TaskDependency(TenantScoped, table=True):
    __tablename__ = "task_dependencies"
    __table_args__ = (
        UniqueConstraint(
            "task_id",
            "depends_on_task_id",
            name="uq_task_dependencies_task_id_depends_on_task_id",
        ),
        CheckConstraint(
            "task_id <> depends_on_task_id",
            name="ck_task_dependencies_no_self",
        ),
    )

    id: UUID = Field(default_factory=uuid4, primary_key=True)
    board_id: UUID = Field(foreign_key="boards.id", index=True)
    task_id: UUID = Field(foreign_key="tasks.id", index=True)
    depends_on_task_id: UUID = Field(foreign_key="tasks.id", index=True)
    created_at: datetime = Field(default_factory=utcnow)