from fastapi import APIRouter, UploadFile, File, HTTPException, Request
from fastapi.responses import FileResponse
from pathlib import Path
import uuid
import os
import aiofiles
from app.core.config import settings
from app.core.limiter import limiter
from app.ingestion.pipeline import IngestionPipeline

router = APIRouter(prefix="/api/documents", tags=["Documents"])
pipeline = IngestionPipeline()

MAX_FILE_SIZE = 50 * 1024 * 1024

@router.post("/upload")
async def upload_document(file: UploadFile = File(...)):
    if not file.filename:
        raise HTTPException(400, "No filename provided")

    ext = Path(file.filename).suffix.lower()
    if ext not in (".pdf", ".txt", ".md"):
        raise HTTPException(400, f"Unsupported file type: {ext}")

    upload_dir = Path(settings.upload_dir)
    upload_dir.mkdir(exist_ok=True)
    file_id = str(uuid.uuid4())
    save_path = upload_dir / f"{file_id}{ext}"

    size = 0
    async with aiofiles.open(save_path, "wb") as f:
        while True:
            chunk = await file.read(8 * 1024 * 1024)
            if not chunk:
                break
            size += len(chunk)
            if size > MAX_FILE_SIZE:
                raise HTTPException(400, "File too large (max 50MB)")
            await f.write(chunk)

    result = await pipeline.process_file(save_path, file_id)
    return {
        "document_id": result["document_id"],
        "filename": file.filename,
        "chunks": result["chunks"],
        "pages": result["pages"],
        "status": "processed",
    }

@router.get("/")
@limiter.limit("30/minute")
async def list_documents(request: Request):
    from app.vectorstore.factory import get_vector_store
    store = get_vector_store(settings.vector_store)
    collections = store.list_collections()
    return {"documents": collections}

@router.get("/{document_id}/download")
@limiter.limit("30/minute")
async def download_document(request: Request, document_id: str):
    upload_dir = Path(settings.upload_dir)
    for ext in (".pdf", ".txt", ".md"):
        path = upload_dir / f"{document_id}{ext}"
        if path.exists():
            return FileResponse(
                path,
                filename=f"{document_id}{ext}",
                media_type="application/octet-stream",
                headers={"Content-Disposition": f"attachment; filename=\"{document_id}{ext}\""},
            )
    raise HTTPException(404, "Document not found")

@router.delete("/{document_id}")
@limiter.limit("10/minute")
async def delete_document(request: Request, document_id: str):
    from app.vectorstore.factory import get_vector_store
    store = get_vector_store(settings.vector_store)
    store.delete_collection(document_id)
    return {"status": "deleted", "document_id": document_id}