"""
Batch utilities.

- run_batch: generic batch concurrency runner
- BatchTask: SSE task manager for admin batch operations
"""

import asyncio
import time
import uuid
from typing import Any, Awaitable, Callable, Dict, List, Optional, TypeVar

from app.core.logger import logger

T = TypeVar("T")


async def run_batch(
    items: List[str],
    worker: Callable[[str], Awaitable[T]],
    *,
    batch_size: int = 50,
    task: Optional["BatchTask"] = None,
    on_item: Optional[Callable[[str, Dict[str, Any]], Awaitable[None]]] = None,
    should_cancel: Optional[Callable[[], bool]] = None,
) -> Dict[str, Dict[str, Any]]:
    """
    分批并发执行，单项失败不影响整体

    Args:
        items: 待处理项列表
        worker: 异步处理函数
        batch_size: 每批大小

    Returns:
        {item: {"ok": bool, "data": ..., "error": ...}}
    """
    try:
        batch_size = int(batch_size)
    except Exception:
        batch_size = 50

    batch_size = max(1, batch_size)

    async def _one(item: str) -> tuple[str, dict]:
        if (should_cancel and should_cancel()) or (task and task.cancelled):
            return item, {"ok": False, "error": "cancelled", "cancelled": True}
        try:
            data = await worker(item)
            result = {"ok": True, "data": data}
            if task:
                task.record(True)
            if on_item:
                try:
                    await on_item(item, result)
                except Exception:
                    pass
            return item, result
        except Exception as e:
            logger.warning(f"Batch item failed: {item[:16]}... - {e}")
            result = {"ok": False, "error": str(e)}
            if task:
                task.record(False, error=str(e))
            if on_item:
                try:
                    await on_item(item, result)
                except Exception:
                    pass
            return item, result

    results: Dict[str, dict] = {}

    # 分批执行，避免一次性创建所有 task
    for i in range(0, len(items), batch_size):
        if (should_cancel and should_cancel()) or (task and task.cancelled):
            break
        chunk = items[i : i + batch_size]
        pairs = await asyncio.gather(*(_one(x) for x in chunk))
        results.update(dict(pairs))

    return results


class BatchTask:
    def __init__(self, total: int):
        self.id = uuid.uuid4().hex
        self.total = int(total)
        self.processed = 0
        self.ok = 0
        self.fail = 0
        self.status = "running"
        self.warning: Optional[str] = None
        self.result: Optional[Dict[str, Any]] = None
        self.error: Optional[str] = None
        self.created_at = time.time()
        self._queues: List[asyncio.Queue] = []
        self._final_event: Optional[Dict[str, Any]] = None
        self.cancelled = False

    def snapshot(self) -> Dict[str, Any]:
        return {
            "task_id": self.id,
            "status": self.status,
            "total": self.total,
            "processed": self.processed,
            "ok": self.ok,
            "fail": self.fail,
            "warning": self.warning,
        }

    def attach(self) -> asyncio.Queue:
        q: asyncio.Queue = asyncio.Queue(maxsize=200)
        self._queues.append(q)
        return q

    def detach(self, q: asyncio.Queue) -> None:
        if q in self._queues:
            self._queues.remove(q)

    def _publish(self, event: Dict[str, Any]) -> None:
        for q in list(self._queues):
            try:
                q.put_nowait(event)
            except Exception:
                # Drop if queue is full or closed
                pass

    def record(
        self, ok: bool, *, item: Any = None, detail: Any = None, error: str = ""
    ) -> None:
        self.processed += 1
        if ok:
            self.ok += 1
        else:
            self.fail += 1
        event: Dict[str, Any] = {
            "type": "progress",
            "task_id": self.id,
            "total": self.total,
            "processed": self.processed,
            "ok": self.ok,
            "fail": self.fail,
        }
        if item is not None:
            event["item"] = item
        if detail is not None:
            event["detail"] = detail
        if error:
            event["error"] = error
        self._publish(event)

    def finish(self, result: Dict[str, Any], *, warning: Optional[str] = None) -> None:
        self.status = "done"
        self.result = result
        self.warning = warning
        event = {
            "type": "done",
            "task_id": self.id,
            "total": self.total,
            "processed": self.processed,
            "ok": self.ok,
            "fail": self.fail,
            "warning": self.warning,
            "result": result,
        }
        self._final_event = event
        self._publish(event)

    def fail_task(self, error: str) -> None:
        self.status = "error"
        self.error = error
        event = {
            "type": "error",
            "task_id": self.id,
            "total": self.total,
            "processed": self.processed,
            "ok": self.ok,
            "fail": self.fail,
            "error": error,
        }
        self._final_event = event
        self._publish(event)

    def cancel(self) -> None:
        self.cancelled = True

    def finish_cancelled(self) -> None:
        self.status = "cancelled"
        event = {
            "type": "cancelled",
            "task_id": self.id,
            "total": self.total,
            "processed": self.processed,
            "ok": self.ok,
            "fail": self.fail,
        }
        self._final_event = event
        self._publish(event)

    def final_event(self) -> Optional[Dict[str, Any]]:
        return self._final_event


_TASKS: Dict[str, BatchTask] = {}


def create_task(total: int) -> BatchTask:
    task = BatchTask(total)
    _TASKS[task.id] = task
    return task


def get_task(task_id: str) -> Optional[BatchTask]:
    return _TASKS.get(task_id)


def delete_task(task_id: str) -> None:
    _TASKS.pop(task_id, None)


async def expire_task(task_id: str, delay: int = 300) -> None:
    await asyncio.sleep(delay)
    delete_task(task_id)


__all__ = [
    "run_batch",
    "BatchTask",
    "create_task",
    "get_task",
    "delete_task",
    "expire_task",
]