"""ORM models for the background job queue.

Tables:
- musehub_background_jobs: Durable job queue — web process enqueues, worker process executes
"""

from __future__ import annotations

from datetime import datetime, timezone

from sqlalchemy import DateTime, ForeignKey, Index, Integer, String, Text
from sqlalchemy.orm import Mapped, mapped_column
from sqlalchemy.dialects.postgresql import JSONB

from musehub.db.database import Base
from musehub.types.json_types import JSONObject, JSONValue  # JSONValue needed for ForwardRef resolution in Mapped[]


def _utc_now() -> datetime:
    return datetime.now(tz=timezone.utc)


class MusehubBackgroundJob(Base):
    """A durable background job enqueued by the web process and processed by the worker.

    The web process (uvicorn) never executes job logic directly — it only
    inserts a row here.  A separate worker process polls this table, claims
    rows with ``FOR UPDATE SKIP LOCKED``, and runs the work outside the web
    server's memory space so a crash in the worker cannot affect request handling.

    Supported job_type values:
        ``intel.code``        — rebuild code intelligence for a repo.
            payload: {"head": "<commit_id>"}
        ``intel.structural``  — compute cross-domain structural intelligence.
            payload: {"head": "<commit_id>"}
        ``gc``                — prune commits and snapshots unreachable from any branch.
            payload: {}

    Status lifecycle:
        pending → running → done
                          → failed  (attempt < max_attempts)
                         └→ pending (retried by worker after transient failure)
    """

    __tablename__ = "musehub_background_jobs"
    __table_args__ = (
        Index("ix_musehub_background_jobs_status_created", "status", "created_at"),
    )

    job_id: Mapped[str] = mapped_column(String(128), primary_key=True)
    repo_id: Mapped[str] = mapped_column(
        String(128),
        ForeignKey("musehub_repos.repo_id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    job_type: Mapped[str] = mapped_column(String(64), nullable=False)
    payload: Mapped[JSONObject] = mapped_column(JSONB, nullable=False, default=dict)
    status: Mapped[str] = mapped_column(String(16), nullable=False, default="pending", server_default="pending", index=True)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, default=_utc_now
    )
    claimed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    done_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    attempt: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
    error: Mapped[str | None] = mapped_column(Text, nullable=True)
    quarantine_reason: Mapped[str | None] = mapped_column(Text, nullable=True)