import os
from fastapi import FastAPI, HTTPException, Response
from app import crud
from app.db import get_engine, make_session_factory, init_db
from app.schemas import ItemCreate, ItemUpdate, ItemOut


def create_app(session_factory=None) -> FastAPI:
    if session_factory is None:
        db_url = os.environ.get("CHORUS_DB_URL", "sqlite:///./chorus.db")
        engine = get_engine(db_url)
        init_db(engine)
        session_factory = make_session_factory(engine)

    app = FastAPI(title="Chorus API")

    @app.post("/items", response_model=ItemOut)
    def post_item(payload: ItemCreate, response: Response):
        session = session_factory()
        try:
            item, created = crud.create_item(session, **payload.model_dump())
            response.status_code = 201 if created else 200
            return item
        finally:
            session.close()

    @app.get("/items", response_model=list[ItemOut])
    def get_items(stage: str | None = None, modality: str | None = None,
                  include_done: bool = False):
        session = session_factory()
        try:
            return crud.list_items(session, stage=stage, modality=modality,
                                    include_done=include_done)
        finally:
            session.close()

    @app.get("/items/{item_id}", response_model=ItemOut)
    def get_item(item_id: int):
        session = session_factory()
        try:
            item = crud.get_item(session, item_id)
            if item is None:
                raise HTTPException(status_code=404, detail="Item not found")
            return item
        finally:
            session.close()

    @app.patch("/items/{item_id}", response_model=ItemOut)
    def patch_item(item_id: int, payload: ItemUpdate):
        session = session_factory()
        try:
            fields = {k: v for k, v in payload.model_dump().items() if v is not None}
            try:
                item = crud.update_item(session, item_id, **fields)
            except ValueError as exc:
                raise HTTPException(status_code=422, detail=str(exc))
            if item is None:
                raise HTTPException(status_code=404, detail="Item not found")
            return item
        finally:
            session.close()

    return app


app = create_app()