"""Documents API endpoints — async upload with background processing."""
from fastapi import APIRouter, Depends, UploadFile, File, Form, HTTPException, status, BackgroundTasks
from pydantic import BaseModel
from sqlalchemy.orm import Session
from app.database import get_db
from app.auth import get_current_user
from app.models import User, Document
from app.application.document_service import DocumentService
from app.dependencies import get_document_service
from app.config import get_settings
from typing import Optional
import logging

logger = logging.getLogger(__name__)
router = APIRouter(prefix="/documents", tags=["documents"])
settings = get_settings()


class MoveDocumentRequest(BaseModel):
    folder_id: Optional[str] = None


def _doc_response(doc: Document) -> dict:
    return {
        "id": doc.id,
        "name": doc.name,
        "size": doc.size,
        "chunks": doc.chunks,
        "status": doc.status,
        "error_message": doc.error_message,
        "folder_id": doc.folder_id,
        "created_at": doc.created_at.isoformat(),
    }


@router.post("/upload", status_code=status.HTTP_202_ACCEPTED)
async def upload_document(
    background_tasks: BackgroundTasks,
    file: UploadFile = File(...),
    folder_id: Optional[str] = Form(None),
    document_service: DocumentService = Depends(get_document_service),
    current_user: User = Depends(get_current_user),
):
    """
    Accept a file upload and return immediately (202 Accepted).
    Processing (text extraction, embedding, vector storage) runs in the background.
    Poll GET /documents/{id}/status to track progress.
    """
    try:
        content = await file.read()
        file_size = len(content)

        if file_size > settings.MAX_FILE_SIZE:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail=f"File too large. Max: {settings.MAX_FILE_SIZE // 1024 // 1024}MB",
            )

        # Persist document record immediately (status = "processing")
        document = await document_service.accept_upload(
            file_data=content,
            filename=file.filename,
            file_size=file_size,
            user=current_user,
            folder_id=folder_id,
        )

        # Schedule heavy work as a background task — does NOT block the response
        background_tasks.add_task(
            document_service.process_document_background,
            document.id,
        )

        return _doc_response(document)

    except ValueError as e:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=str(e))
    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Upload error: {e}", exc_info=True)
        raise HTTPException(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail=str(e))


@router.get("/{document_id}/status")
async def get_document_status(
    document_id: str,
    document_service: DocumentService = Depends(get_document_service),
    current_user: User = Depends(get_current_user),
):
    """
    Poll processing status for a document.
    Returns: { status: 'processing' | 'done' | 'error', chunks, error_message }
    """
    try:
        doc = await document_service.get_document_status(document_id, current_user)
        return _doc_response(doc)
    except ValueError as e:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail=str(e))


@router.get("/")
async def list_documents(
    folder_id: Optional[str] = None,
    root_only: bool = False,
    document_service: DocumentService = Depends(get_document_service),
    current_user: User = Depends(get_current_user),
):
    """
    List documents.
    - GET /documents/                    → all documents
    - GET /documents/?folder_id=X        → documents in folder X
    - GET /documents/?root_only=true     → only documents with no folder (root level)
    """
    documents = await document_service.list_documents(current_user, folder_id, root_only)
    return [_doc_response(doc) for doc in documents]


@router.patch("/{document_id}/move")
async def move_document(
    document_id: str,
    request: MoveDocumentRequest,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Move a document to a folder or root."""
    document = db.query(Document).filter(
        Document.id == document_id,
        Document.org_id == current_user.org_id,
    ).first()
    if not document:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Document not found")

    if request.folder_id:
        from app.models import Folder
        folder = db.query(Folder).filter(
            Folder.id == request.folder_id,
            Folder.org_id == current_user.org_id,
        ).first()
        if not folder:
            raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Folder not found")

    document.folder_id = request.folder_id
    db.commit()
    return _doc_response(document)


@router.delete("/{document_id}")
async def delete_document(
    document_id: str,
    document_service: DocumentService = Depends(get_document_service),
    current_user: User = Depends(get_current_user),
):
    """Delete a document."""
    try:
        await document_service.delete_document(document_id, current_user)
        return {"message": "Document deleted successfully"}
    except ValueError as e:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail=str(e))


@router.get("/{document_id}/download")
async def get_download_url(
    document_id: str,
    document_service: DocumentService = Depends(get_document_service),
    current_user: User = Depends(get_current_user),
):
    """Get download URL."""
    try:
        url = await document_service.get_download_url(document_id, current_user)
        return {"download_url": url}
    except ValueError as e:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail=str(e))