"""PR-Worker-Pool-Registry-1B: /internal/worker/* 5 endpoint 실 구현.

worker-pool-policy §B.2 invariant 매핑:
  - inv 2: drain = heartbeat INSERT only (advisory). claim 거부 = Notebook-Pilot-1.
  - inv 3: /result result = raw JSONB only. canonical promote 0.
  - inv 4: ProcessingQueue 무변경 — worker_jobs 별 table.
  - inv 5: 운영 자동 분기 변경 0 — heartbeat alive 판정 SQL 부재, classify_worker/queue_consumer touch 0.

사용자 review 정정 5개 (2026-05-19):
  - #1: worker_jobs.user_id = job owner (실 사용자). worker 인증은 worker_id + JWT 별도.
  - #2: /result 소유권 검증 (WHERE id AND worker_id AND status='processing'). 매칭 0건 → 404.
  - #3: explicit failed 재시도 (attempts<max → pending 복귀, attempts>=max → final failed).
  - #4: /claim 204 = Response(status_code=204) body 0.
  - #5: mig 275 status CHECK ('pending','processing','completed','failed').
"""

from datetime import datetime, timezone
from typing import Annotated, Any

from fastapi import APIRouter, Depends, HTTPException, Response, status
from pydantic import BaseModel
from sqlalchemy import select, update
from sqlalchemy.dialects.postgresql import insert as pg_insert
from sqlalchemy.ext.asyncio import AsyncSession

from core.auth import require_worker_user
from core.database import get_session
from models.worker_pool import WorkerCapability, WorkerHeartbeat, WorkerJob

router = APIRouter()


# ─── Pydantic schemas ───


class WorkerRegisterRequest(BaseModel):
    worker_id: str
    device_label: str
    worker_class: str
    tier: str
    capabilities: list[str] = []
    models_loaded: list[str] = []
    endpoint: str | None = None


class WorkerHeartbeatRequest(BaseModel):
    worker_id: str
    status: str  # starting/available/busy/draining
    current_job_id: int | None = None
    battery: str | None = None
    thermal: str | None = None
    raw_payload: dict[str, Any] = {}


class WorkerClaimRequest(BaseModel):
    worker_id: str
    job_type: str


class WorkerClaimResponse(BaseModel):
    id: int
    job_type: str
    payload: dict[str, Any]
    attempts: int


class WorkerResultRequest(BaseModel):
    job_id: int
    worker_id: str  # 정정 #2 — 소유권 검증
    status: str  # completed | failed
    result: dict[str, Any] | None = None
    error_message: str | None = None


class WorkerDrainRequest(BaseModel):
    worker_id: str
    reason: str | None = None


# ─── 엔드포인트 ───


@router.post("/register")
async def register(
    body: WorkerRegisterRequest,
    user: Annotated[Any, Depends(require_worker_user)],
    session: Annotated[AsyncSession, Depends(get_session)],
):
    """worker_capabilities UPSERT — register 또는 capability 갱신."""
    now = datetime.now(timezone.utc)
    stmt = pg_insert(WorkerCapability).values(
        worker_id=body.worker_id,
        user_id=user.id,
        device_label=body.device_label,
        worker_class=body.worker_class,
        tier=body.tier,
        capabilities=body.capabilities,
        models_loaded=body.models_loaded,
        endpoint=body.endpoint,
        created_at=now,
        last_registered_at=now,
    ).on_conflict_do_update(
        index_elements=["worker_id"],
        set_={
            "device_label": body.device_label,
            "worker_class": body.worker_class,
            "tier": body.tier,
            "capabilities": body.capabilities,
            "models_loaded": body.models_loaded,
            "endpoint": body.endpoint,
            "last_registered_at": now,
        },
    )
    await session.execute(stmt)
    await session.commit()
    return {"ok": True, "worker_id": body.worker_id}


@router.post("/heartbeat")
async def heartbeat(
    body: WorkerHeartbeatRequest,
    user: Annotated[Any, Depends(require_worker_user)],
    session: Annotated[AsyncSession, Depends(get_session)],
):
    """worker_heartbeats append-only INSERT.

    inv 5 강제: alive 판정 SQL 부재. 본 endpoint 는 row 추가 + ok 반환만.
    """
    hb = WorkerHeartbeat(
        worker_id=body.worker_id,
        status=body.status,
        current_job_id=body.current_job_id,
        battery=body.battery,
        thermal=body.thermal,
        raw_payload=body.raw_payload,
    )
    session.add(hb)
    await session.commit()
    return {"ok": True}


@router.post(
    "/claim",
    responses={
        200: {"model": WorkerClaimResponse},
        204: {"description": "queue empty"},
    },
)
async def claim(
    body: WorkerClaimRequest,
    user: Annotated[Any, Depends(require_worker_user)],
    session: Annotated[AsyncSession, Depends(get_session)],
):
    """SELECT FOR UPDATE SKIP LOCKED 로 pending job 1건 claim.

    정정 #4: miss → Response(status_code=204) body 0. WorkerClaimResponse | None 회피.
    """
    now = datetime.now(timezone.utc)
    stmt = (
        select(WorkerJob)
        .where(WorkerJob.status == "pending", WorkerJob.job_type == body.job_type)
        .order_by(WorkerJob.created_at)
        .limit(1)
        .with_for_update(skip_locked=True)
    )
    result = await session.execute(stmt)
    job = result.scalar_one_or_none()
    if job is None:
        await session.commit()  # FOR UPDATE 트랜잭션 해제
        return Response(status_code=204)

    job.status = "processing"
    job.worker_id = body.worker_id
    job.claimed_at = now
    job.attempts = job.attempts + 1
    await session.commit()

    return WorkerClaimResponse(
        id=job.id,
        job_type=job.job_type,
        payload=job.payload,
        attempts=job.attempts,
    )


@router.post("/result")
async def result(
    body: WorkerResultRequest,
    user: Annotated[Any, Depends(require_worker_user)],
    session: Annotated[AsyncSession, Depends(get_session)],
):
    """job 결과 제출. 정정 #2 (소유권) + #3 (재시도) 강제.

    소유권 검증: WHERE id AND worker_id AND status='processing'. 매칭 0건 → 404.
    completed: status='completed' + result + completed_at.
    failed:
      attempts < max_attempts → status='pending' (worker_id/claimed_at/completed_at NULL).
      attempts >= max_attempts → status='failed' final + completed_at.
      result 컬럼 절대 갱신 X — request.result 무시 (failed 시 partial result 저장 차단).
    """
    if body.status not in ("completed", "failed"):
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="status must be 'completed' or 'failed'",
        )

    stmt = select(WorkerJob).where(
        WorkerJob.id == body.job_id,
        WorkerJob.worker_id == body.worker_id,
        WorkerJob.status == "processing",
    )
    res = await session.execute(stmt)
    job = res.scalar_one_or_none()
    if job is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="job not found or not owned by this worker (or not in processing)",
        )

    now = datetime.now(timezone.utc)
    if body.status == "completed":
        job.status = "completed"
        job.result = body.result  # raw JSONB (inv 3 — canonical promote 0)
        job.completed_at = now
        job.error_message = None
    else:  # failed
        job.error_message = body.error_message
        # 정정 #3 정책: result 컬럼 절대 갱신 X (request.result 무시)
        if job.attempts < job.max_attempts:
            job.status = "pending"
            job.worker_id = None
            job.claimed_at = None
            job.completed_at = None
        else:
            job.status = "failed"
            job.completed_at = now

    await session.commit()
    return {"ok": True, "status": job.status, "attempts": job.attempts}


@router.post("/drain")
async def drain(
    body: WorkerDrainRequest,
    user: Annotated[Any, Depends(require_worker_user)],
    session: Annotated[AsyncSession, Depends(get_session)],
):
    """drain = heartbeat INSERT status='draining' (advisory/audit only, inv 2).

    claim 거부 로직 부재 = Notebook-Pilot-1 영역.
    """
    payload: dict[str, Any] = {}
    if body.reason:
        payload["reason"] = body.reason
    hb = WorkerHeartbeat(
        worker_id=body.worker_id,
        status="draining",
        raw_payload=payload,
    )
    session.add(hb)
    await session.commit()
    return {"ok": True}