from __future__ import annotations
import fcntl
from contextlib import contextmanager
from pathlib import Path
from flask import Flask
from .database_init import initialize_database
from .database_migrations import migrate_database


@contextmanager
def _startup_lock(app: Flask):
    lock_path = Path(app.instance_path) / ".database-startup.lock"
    lock_path.parent.mkdir(parents=True, exist_ok=True)

    with lock_path.open("w") as lock_file:
        fcntl.flock(lock_file.fileno(), fcntl.LOCK_EX)
        try:
            yield
        finally:
            fcntl.flock(lock_file.fileno(), fcntl.LOCK_UN)


def prepare_database(app: Flask) -> list[str]:
    with app.app_context(), _startup_lock(app):
        initialize_database()
        applied = migrate_database()
        from .extensions import db
        from .models import FuelEntry
        from .settlement import freeze
        pending = FuelEntry.query.filter_by(settlement_frozen=False).all()
        for entry in pending:
            freeze(entry, source="Migracja istniejącego wpisu", migration_note="Warunki odtworzono z ustawień dostępnych podczas migracji; wymagają weryfikacji.")
        if pending:
            db.session.commit()
        return applied


__all__ = ["initialize_database", "migrate_database", "prepare_database"]