from __future__ import annotations

from datetime import UTC, datetime

from sqlalchemy import DateTime, Index, Integer, String, Text, text
from sqlalchemy.orm import Mapped, mapped_column

from deerflow.persistence.base import Base


class ScheduledTaskRunRow(Base):
    __tablename__ = "scheduled_task_runs"

    id: Mapped[str] = mapped_column(String(64), primary_key=True)
    task_id: Mapped[str] = mapped_column(String(64), index=True)
    thread_id: Mapped[str] = mapped_column(String(64), index=True)
    run_id: Mapped[str | None] = mapped_column(String(64), nullable=True)
    scheduled_for: Mapped[datetime] = mapped_column(DateTime(timezone=True))
    trigger: Mapped[str] = mapped_column(String(16))
    status: Mapped[str] = mapped_column(String(16), index=True)
    error: Mapped[str | None] = mapped_column(Text, nullable=True)
    lease_owner: Mapped[str | None] = mapped_column(String(128), nullable=True)
    lease_expires_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    attempt_count: Mapped[int] = mapped_column(Integer, default=0, server_default="0")
    started_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    finished_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=lambda: datetime.now(UTC))

    __table_args__ = (
        # At most one non-terminal (queued/launching/running) occurrence per
        # task. Queued occurrences are deliberately durable; ``launching`` is
        # a short lease-fenced claim used so multiple gateway instances cannot
        # launch the same row. Sibling of the ``runs`` table's
        # ``uq_runs_thread_active``
        # (PR #4003); that one keys on ``thread_id`` and does not cover the
        # default ``fresh_thread_per_run`` context (every dispatch gets a new
        # thread), which is why the scheduled-task run row needs its own guard.
        #
        # Must live in ORM ``__table_args__`` (not just the migration) because
        # the empty-DB bootstrap path runs ``create_all`` + ``stamp head`` and
        # never executes the migration that also defines this index.
        Index(
            "uq_scheduled_task_run_active",
            "task_id",
            unique=True,
            sqlite_where=text("status IN ('queued', 'launching', 'running')"),
            postgresql_where=text("status IN ('queued', 'launching', 'running')"),
        ),
    )