"""
Platform Worker
================
AwoooP Phase 4: SKIP LOCKED worker + stale run reaper（ADR-114）
2026-05-04 ogt + Claude Sonnet 4.6

功能：
1. Worker Loop：以 SKIP LOCKED 從 awooop_run_state 取 PENDING run 並執行
2. Stale Run Reaper：每 60 秒掃描 lease 過期的 RUNNING run
3. Shadow Mode Enforcer：所有 Phase 4 run 強制 is_shadow=True

Worker 設計：
- 啟動時以 asyncio.create_task 掛入 main.py lifespan
- 多個 worker 安全並行（SKIP LOCKED 保證每 run 只被一個 worker 取得）
- Heartbeat 每 15 秒更新 lease（防 stale reaper 誤殺）
- 優雅停機：收到 stop signal 後完成當前 run 再退出

與 legacy 的關係：
- 完全獨立，不碰任何既有 signal_worker.py / aider_event_processor.py
- 只處理 awooop_run_state 表（legacy signal 不寫入此表）
"""

from __future__ import annotations

import asyncio
from datetime import datetime, timezone

import structlog

from src.services.platform_runtime import shadow_execute
from src.services.run_state_machine import (
    HEARTBEAT_INTERVAL_SECONDS,
    STALE_REAPER_INTERVAL_SECONDS,
    acquire_pending_run,
    heartbeat,
    reap_stale_runs,
)

logger = structlog.get_logger(__name__)

# Phase 4 固定處理 awoooi 租戶（Phase 6+ 改為多租戶掃描）
_DEFAULT_PROJECT_ID = "awoooi"
_WORKER_POLL_INTERVAL_SECONDS = 5  # 無任務時的等待間隔
_WORKER_CONCURRENCY = 2            # 同時最多幾個 run 並行


class PlatformWorker:
    """
    Platform Worker：SKIP LOCKED + shadow execution + stale reaper。

    Usage（在 main.py lifespan 中）：
        worker = PlatformWorker()
        asyncio.create_task(worker.run_loop())
        asyncio.create_task(worker.reaper_loop())
    """

    def __init__(self, project_id: str = _DEFAULT_PROJECT_ID) -> None:
        self.project_id = project_id
        self._stop_event = asyncio.Event()
        self._active_runs: set[str] = set()

    def stop(self) -> None:
        """優雅停機信號"""
        self._stop_event.set()

    async def run_loop(self) -> None:
        """
        主 worker loop：
        1. 取一筆 PENDING run（SKIP LOCKED）
        2. 執行 shadow_execute（不產生 user response）
        3. Heartbeat（每 15 秒）
        4. 等待 5 秒後重新掃描
        """
        logger.info("platform_worker_started", project_id=self.project_id)
        while not self._stop_event.is_set():
            try:
                # 控制並行度
                if len(self._active_runs) >= _WORKER_CONCURRENCY:
                    await asyncio.sleep(1)
                    continue

                run = await acquire_pending_run(self.project_id)
                if run is None:
                    await asyncio.sleep(_WORKER_POLL_INTERVAL_SECONDS)
                    continue

                run_id_str = str(run.run_id)
                self._active_runs.add(run_id_str)

                # 每個 run 獨立 task，不阻塞 loop
                asyncio.create_task(
                    self._execute_with_heartbeat(run),
                    name=f"platform_run_{run_id_str[:8]}",
                )

            except asyncio.CancelledError:
                break
            except Exception as exc:
                logger.exception("platform_worker_loop_error", error=str(exc))
                await asyncio.sleep(_WORKER_POLL_INTERVAL_SECONDS)

        logger.info("platform_worker_stopped", project_id=self.project_id)

    async def _execute_with_heartbeat(self, run: object) -> None:
        """
        在 shadow_execute 執行期間，同步 heartbeat 防 stale reaper 誤殺。
        """
        from src.db.awooop_models import AwoooPRunState
        assert isinstance(run, AwoooPRunState)
        run_id_str = str(run.run_id)

        # Heartbeat task（每 15 秒更新 lease）
        heartbeat_task = asyncio.create_task(
            self._heartbeat_loop(run.run_id, self.project_id),
            name=f"heartbeat_{run_id_str[:8]}",
        )

        try:
            await shadow_execute(run)
        except Exception as exc:
            logger.exception(
                "platform_run_execution_error",
                run_id=run_id_str,
                error=str(exc),
            )
        finally:
            heartbeat_task.cancel()
            self._active_runs.discard(run_id_str)

    async def _heartbeat_loop(self, run_id: object, project_id: str) -> None:
        """每 HEARTBEAT_INTERVAL_SECONDS 秒更新 lease，直到被 cancel"""
        import uuid as _uuid
        while True:
            await asyncio.sleep(HEARTBEAT_INTERVAL_SECONDS)
            try:
                await heartbeat(run_id, project_id)  # type: ignore[arg-type]
            except Exception as exc:
                logger.warning(
                    "platform_heartbeat_failed",
                    run_id=str(run_id),
                    error=str(exc),
                )

    async def reaper_loop(self) -> None:
        """
        Stale run reaper：每 60 秒掃描 lease 過期的 RUNNING run。
        lease < NOW() + attempt < max → PENDING（retry）
        lease < NOW() + attempt >= max → FAILED(E-RUN-002)
        """
        logger.info("stale_run_reaper_started", project_id=self.project_id)
        while not self._stop_event.is_set():
            try:
                await asyncio.sleep(STALE_REAPER_INTERVAL_SECONDS)
                reaped = await reap_stale_runs(self.project_id)
                if reaped:
                    logger.info(
                        "stale_run_reaper_cycle",
                        project_id=self.project_id,
                        reaped=reaped,
                        ts=datetime.now(timezone.utc).isoformat(),
                    )
            except asyncio.CancelledError:
                break
            except Exception as exc:
                logger.exception("stale_run_reaper_error", error=str(exc))

        logger.info("stale_run_reaper_stopped", project_id=self.project_id)


# ─────────────────────────────────────────────────────────────────────────────
# Singleton（掛入 lifespan 用）
# ─────────────────────────────────────────────────────────────────────────────

_platform_worker: PlatformWorker | None = None


def get_platform_worker() -> PlatformWorker:
    global _platform_worker
    if _platform_worker is None:
        _platform_worker = PlatformWorker()
    return _platform_worker


async def start_platform_worker() -> None:
    """在 main.py lifespan 中呼叫此函數啟動 worker"""
    worker = get_platform_worker()
    asyncio.create_task(worker.run_loop(), name="platform_worker_run_loop")
    asyncio.create_task(worker.reaper_loop(), name="platform_worker_reaper_loop")
    logger.info("platform_worker_tasks_started")


async def stop_platform_worker() -> None:
    """在 main.py lifespan 關閉時呼叫"""
    worker = get_platform_worker()
    worker.stop()
    logger.info("platform_worker_stop_requested")