# app/deps.py
"""FastAPI dependency providers."""
from __future__ import annotations

import sqlite3
from dataclasses import dataclass
from pathlib import Path
from typing import Generator

from fastapi import Depends, Request

from app.config import DATA_DIR, LOCAL_USER_ID
from app.services.bm25_index import BM25Index


@dataclass
class UserCtx:
    """Per-request context routing DB paths and BM25 to the right user."""

    user_id: str
    db_path: str
    vec_db_path: str
    data_dir: Path
    watch_dir: Path
    bm25: BM25Index


_user_startup_done: set[str] = set()


def _run_user_startup(user_id: str, user_dir: Path) -> None:
    """Run migrations and vec schema check once per process lifetime per user."""
    if user_id in _user_startup_done:
        return
    _user_startup_done.add(user_id)
    from app.config import VEC_DIMENSIONS
    from app.startup import apply_migrations, check_and_rebuild_vec_schema
    apply_migrations(str(user_dir / "pagepiper.db"))
    check_and_rebuild_vec_schema(
        str(user_dir / "pagepiper_vecs.db"), VEC_DIMENSIONS, str(user_dir / "pagepiper.db")
    )


def get_user_ctx(request: Request) -> UserCtx:
    """Resolve the per-user data directory, DB paths, and BM25 instance for this request."""
    import app.main as _main
    from app.cloud_session import CLOUD_MODE

    if CLOUD_MODE:
        from app.cloud_session import resolve_authenticated_user
        from app.config import user_data_dir
        user_id = resolve_authenticated_user(request)
        user_dir = user_data_dir(user_id)
        _run_user_startup(user_id, user_dir)
        watch_dir = user_dir / "books"
        watch_dir.mkdir(parents=True, exist_ok=True)
    else:
        from app.config import WATCH_DIR
        user_id = LOCAL_USER_ID
        user_dir = DATA_DIR
        watch_dir = WATCH_DIR

    return UserCtx(
        user_id=user_id,
        db_path=str(user_dir / "pagepiper.db"),
        vec_db_path=str(user_dir / "pagepiper_vecs.db"),
        data_dir=user_dir,
        watch_dir=watch_dir,
        bm25=_main._get_bm25_for(user_id),
    )


def get_db(ctx: UserCtx = Depends(get_user_ctx)) -> Generator[sqlite3.Connection, None, None]:
    conn = sqlite3.connect(ctx.db_path, check_same_thread=False)
    conn.execute("PRAGMA foreign_keys = ON")
    conn.execute("PRAGMA journal_mode = WAL")
    conn.row_factory = sqlite3.Row
    try:
        yield conn
    finally:
        conn.close()