"""文档 API：POST /api/v1/documents 异步入库 + 任务查询 + 文档管理（列表/详情/删除）"""

from typing import Any

import structlog
from fastapi import APIRouter, Query
from fastapi.responses import JSONResponse

from app.api.response import ApiError, ok
from app.config import Settings
from app.core.ingest_tasks import IngestTaskManager
from app.core.ingestion import Ingester
from app.models.document import DocumentInput
from app.services.qdrant import QdrantService
from app.services.redis import RedisCache, get_cache

logger = structlog.get_logger()

router = APIRouter(prefix="/api/v1", tags=["document"])

# 模块级懒加载单例，避免每请求重建 Ingester 及其下游依赖
_ingester: Ingester | None = None
_qdrant: QdrantService | None = None
_task_manager: IngestTaskManager | None = None


def _get_ingester() -> Ingester:
    global _ingester
    if _ingester is None:
        _ingester = Ingester()
    return _ingester


def _get_qdrant() -> QdrantService:
    global _qdrant
    if _qdrant is None:
        _qdrant = QdrantService()
    return _qdrant


def _get_task_manager() -> IngestTaskManager:
    """入库任务管理器懒加载单例

    Redis 沿用全局缓存单例（RedisCache 读写全容错，不可用时镜像写失败仅告警）；
    获取缓存实例异常时传 None，退化为纯内存模式。
    """
    global _task_manager
    if _task_manager is None:
        try:
            redis: RedisCache | None = get_cache()
        except Exception:
            logger.warning("Redis 缓存不可用，入库任务状态仅保留在内存", exc_info=True)
            redis = None
        _task_manager = IngestTaskManager(ingester=_get_ingester(), redis=redis, settings=Settings())
    return _task_manager


@router.post("/documents")
async def ingest_document(doc: DocumentInput) -> JSONResponse:
    """文档入库入口：登记异步任务并返回 202 + task_id，入库结果经任务查询端点获取"""
    if not doc.text.strip():
        raise ApiError(1001, "文档内容不能为空")
    task_id = await _get_task_manager().submit(doc)
    return JSONResponse(status_code=202, content=ok({"task_id": task_id, "status": "pending"}))


@router.get("/documents/tasks/{task_id}")
async def get_ingest_task(task_id: str) -> dict[str, Any]:
    """查询入库任务状态：含 task_id/status/created_at/updated_at，done 附 result，failed 附 error"""
    task = await _get_task_manager().get(task_id)
    if task is None:
        raise ApiError(1004, "任务不存在")
    return ok(task)


@router.get("/documents")
async def list_documents(
    limit: int = Query(default=20, ge=1, le=100),
    offset: str | None = None,
) -> dict[str, Any]:
    """分页列出文档（L1 摘要），返回 items 与下一页游标 next_offset"""
    try:
        items, next_offset = await _get_qdrant().scroll_l1(limit=limit, offset=offset)
    except Exception as exc:
        logger.error("文档列表查询失败", error=str(exc))
        raise ApiError(2000, f"文档列表查询失败: {exc}") from exc
    return ok({"items": items, "next_offset": next_offset})


@router.get("/documents/{doc_id}")
async def get_document(doc_id: str) -> dict[str, Any]:
    """获取文档详情：L1 记录 + L2/L3 节点 + chunks 数量"""
    try:
        detail = await _get_qdrant().get_doc_detail(doc_id)
    except Exception as exc:
        logger.error("文档详情查询失败", doc_id=doc_id, error=str(exc))
        raise ApiError(2000, f"文档详情查询失败: {exc}") from exc
    if detail is None:
        raise ApiError(1004, "文档不存在")
    return ok(detail)


@router.delete("/documents/{doc_id}")
async def delete_document(doc_id: str) -> dict[str, Any]:
    """删除文档：四层集合中该 doc_id 的所有点；幂等，不存在也返回成功（删除数全 0）"""
    try:
        deleted = await _get_qdrant().delete_by_doc_id(doc_id)
    except Exception as exc:
        logger.error("文档删除失败", doc_id=doc_id, error=str(exc))
        raise ApiError(2000, f"文档删除失败: {exc}") from exc
    return ok({"doc_id": doc_id, "deleted": deleted, "deleted_total": sum(deleted.values())})