import uuid
import logging
from pathlib import Path

from fastapi import APIRouter, Depends, UploadFile, File, Form, HTTPException, BackgroundTasks
from pydantic import BaseModel
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select

from ..core.deps import get_db
from ..models.db import Workspace, File as FileRecord, Task
from ..services.rag import hybrid_search, rerank, generate_answer
from ..worker import process_file_task

logger = logging.getLogger(__name__)
router = APIRouter(prefix="/api/kb", tags=["知识库"])

UPLOAD_DIR = Path("/app/data/uploads")
UPLOAD_DIR.mkdir(parents=True, exist_ok=True)


class WorkspaceCreate(BaseModel):
    name: str
    description: str = ""
    domain: str = "general"


class QARequest(BaseModel):
    query: str
    workspace_id: str | None = None
    top_k: int = 5
    return_sources: bool = True


@router.post("/workspaces")
async def create_workspace(req: WorkspaceCreate, db: AsyncSession = Depends(get_db)):
    ws = Workspace(name=req.name, description=req.description, domain=req.domain)
    db.add(ws)
    await db.flush()
    return {"id": str(ws.id), "name": ws.name, "domain": ws.domain}


@router.post("/files/upload")
async def upload_file(
    background_tasks: BackgroundTasks,
    file: UploadFile = File(...),
    workspace_id: str = Form(default=""),
    db: AsyncSession = Depends(get_db),
):
    content = await file.read()
    file_id = str(uuid.uuid4())
    suffix = Path(file.filename or "doc").suffix
    save_path = UPLOAD_DIR / f"{file_id}{suffix}"
    save_path.write_bytes(content)

    file_record = FileRecord(
        id=uuid.UUID(file_id),
        filename=f"{file_id}{suffix}",
        original_name=file.filename or "unknown",
        file_type=suffix.lstrip("."),
        file_size=len(content),
        storage_path=str(save_path),
        workspace_id=uuid.UUID(workspace_id) if workspace_id else None,
        status="uploaded",
    )
    db.add(file_record)

    task = Task(
        task_type="parse_and_vectorize",
        status="pending",
        file_id=uuid.UUID(file_id),
        payload={"workspace_id": workspace_id},
    )
    db.add(task)
    await db.flush()

    # 异步触发 Celery 任务
    celery_task = process_file_task.delay(file_id, str(task.id), workspace_id)
    task.celery_task_id = celery_task.id
    await db.flush()

    return {"file_id": file_id, "task_id": str(task.id), "status": "processing"}


@router.get("/tasks/{task_id}")
async def get_task(task_id: str, db: AsyncSession = Depends(get_db)):
    result = await db.execute(select(Task).where(Task.id == uuid.UUID(task_id)))
    task = result.scalar_one_or_none()
    if not task:
        raise HTTPException(status_code=404, detail="任务不存在")
    return {
        "task_id": str(task.id),
        "status": task.status,
        "progress": task.progress,
        "file_id": str(task.file_id) if task.file_id else None,
        "error_msg": task.error_msg,
        "completed_at": task.completed_at.isoformat() if task.completed_at else None,
    }


@router.post("/qa")
async def qa(req: QARequest):
    chunks = await hybrid_search(req.query, workspace_id=req.workspace_id, top_k=req.top_k * 2)
    ranked = await rerank(req.query, chunks, top_k=req.top_k)
    result = await generate_answer(req.query, ranked)
    if not req.return_sources:
        result.pop("sources", None)
    return result


@router.post("/knowledge/retrieval")
async def retrieval(req: QARequest):
    chunks = await hybrid_search(req.query, workspace_id=req.workspace_id, top_k=req.top_k)
    return {"chunks": chunks, "total": len(chunks)}