from __future__ import annotations

from collections.abc import Callable
from dataclasses import dataclass

from sqlalchemy import inspect, text

from .extensions import db


@dataclass(frozen=True)
class Migration:
    version: str
    upgrade: Callable[[], None]


MIGRATIONS: tuple[Migration, ...] = ()

def ensure_migration_table() -> None:
    inspector = inspect(db.engine)
    if inspector.has_table("schema_migration"):
        return

    db.session.execute(text("""
        CREATE TABLE schema_migration (
            version VARCHAR(100) PRIMARY KEY,
            applied_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
        )
    """))
    db.session.commit()


def migrate_database() -> list[str]:
    """Uruchamia wyłącznie niewykonane migracje."""
    ensure_migration_table()

    applied = {
        row[0]
        for row in db.session.execute(text("SELECT version FROM schema_migration"))
    }
    completed: list[str] = []

    for migration in MIGRATIONS:
        if migration.version in applied:
            continue

        try:
            migration.upgrade()
            db.session.execute(
                text("INSERT INTO schema_migration (version) VALUES (:version)"),
                {"version": migration.version},
            )
            db.session.commit()
            completed.append(migration.version)
        except Exception:
            db.session.rollback()
            raise

    return completed


def main() -> None:
    from . import create_app

    app = create_app()
    with app.app_context():
        applied = migrate_database()

    if applied:
        print("Wykonane migracje: " + ", ".join(applied))
    else:
        print("Brak nowych migracji.")


if __name__ == "__main__":
    main()