"""FastAPI application: upload documents, list/manage them, and chat over them."""
from __future__ import annotations

import uuid
from pathlib import Path

from fastapi import FastAPI, File, HTTPException, UploadFile
from fastapi.responses import FileResponse
from fastapi.staticfiles import StaticFiles

from . import db, vector_store
from .config import get_settings
from .embeddings import embed_texts
from .ingestion import process_document
from .models import ChatRequest, ChatResponse, DocumentSummary, IngestResponse

app = FastAPI(
    title="Document Intelligence & Chat Assistant",
    description="RAG over your uploaded documents: OCR + MongoDB + Qdrant + Claude.",
    version="1.0.0",
)

STATIC_DIR = Path(__file__).resolve().parent.parent / "static"


@app.on_event("startup")
def _startup() -> None:
    # Best-effort: create the Qdrant collection up front. Never block startup —
    # if Qdrant is briefly unreachable the collection is created lazily on the
    # first upload instead, so the server still binds and the UI loads.
    try:
        vector_store.ensure_collection()
    except Exception as exc:  # noqa: BLE001
        print(f"[startup] Qdrant not ready yet, will retry on first upload: {exc}")


def _to_summary(doc: dict) -> DocumentSummary:
    return DocumentSummary(
        id=doc["_id"],
        filename=doc["filename"],
        content_type=doc["content_type"],
        num_chunks=doc["num_chunks"],
        num_chars=doc["num_chars"],
        ocr_used=doc["ocr_used"],
        created_at=doc["created_at"],
    )


@app.get("/health")
def health() -> dict:
    status = {"status": "ok"}
    try:
        db.ping()
        status["mongodb"] = "ok"
    except Exception as exc:  # noqa: BLE001
        status["mongodb"] = f"error: {exc}"
    try:
        vector_store.get_client().get_collections()
        status["qdrant"] = "ok"
    except Exception as exc:  # noqa: BLE001
        status["qdrant"] = f"error: {exc}"
    status["llm_key_configured"] = bool(get_settings().openrouter_api_key)
    return status


@app.post("/documents/upload", response_model=IngestResponse)
async def upload_document(file: UploadFile = File(...)) -> IngestResponse:
    settings = get_settings()
    data = await file.read()
    if not data:
        raise HTTPException(status_code=400, detail="Uploaded file is empty.")

    chunks, ocr_used, num_chars = process_document(
        file.filename, file.content_type or "", data,
        settings.chunk_size, settings.chunk_overlap,
    )
    if not chunks:
        raise HTTPException(
            status_code=422,
            detail="No text could be extracted from this document.",
        )

    document_id = str(uuid.uuid4())
    vectors = embed_texts(chunks)
    vector_store.ensure_collection()  # lazy create if startup couldn't reach Qdrant
    vector_store.upsert_chunks(document_id, file.filename, chunks, vectors)
    doc = db.save_document(
        document_id=document_id,
        filename=file.filename,
        content_type=file.content_type or "",
        num_chunks=len(chunks),
        num_chars=num_chars,
        ocr_used=ocr_used,
    )

    return IngestResponse(
        document=_to_summary(doc),
        message=f"Indexed {len(chunks)} chunks" + (" (OCR used)" if ocr_used else ""),
    )


@app.get("/documents", response_model=list[DocumentSummary])
def list_documents() -> list[DocumentSummary]:
    return [_to_summary(d) for d in db.list_documents()]


@app.get("/documents/{document_id}", response_model=DocumentSummary)
def get_document(document_id: str) -> DocumentSummary:
    doc = db.get_document(document_id)
    if not doc:
        raise HTTPException(status_code=404, detail="Document not found.")
    return _to_summary(doc)


@app.delete("/documents/{document_id}")
def delete_document(document_id: str) -> dict:
    if not db.get_document(document_id):
        raise HTTPException(status_code=404, detail="Document not found.")
    vector_store.delete_document(document_id)
    db.delete_document(document_id)
    return {"deleted": document_id}


@app.post("/chat", response_model=ChatResponse)
def chat(request: ChatRequest) -> ChatResponse:
    from . import rag

    try:
        return rag.answer_question(
            question=request.question,
            document_ids=request.document_ids,
            top_k=request.top_k,
        )
    except RuntimeError as exc:
        raise HTTPException(status_code=503, detail=str(exc))
    except Exception as exc:  # noqa: BLE001 — always return JSON so the UI can show it
        import traceback
        traceback.print_exc()
        raise HTTPException(status_code=502, detail=f"{type(exc).__name__}: {exc}")


# --- Minimal web UI (served at /) ---
if STATIC_DIR.exists():
    app.mount("/ui", StaticFiles(directory=str(STATIC_DIR), html=True), name="ui")

    @app.get("/")
    def root() -> FileResponse:
        return FileResponse(str(STATIC_DIR / "index.html"))