from sqlalchemy import text
from sqlalchemy.engine import Engine

VIEWS: dict[str, str] = {
    "v_balance_history": """
        SELECT t.booking_date AS day, a.name AS account,
               SUM(SUM(t.amount)) OVER (PARTITION BY a.id
                                        ORDER BY t.booking_date) AS balance
        FROM transactions t JOIN accounts a ON a.id = t.account_id
        WHERE t.status = 'confirmed'
        GROUP BY a.id, a.name, t.booking_date""",
    "v_balance_total": """
        SELECT booking_date AS day,
               SUM(SUM(amount)) OVER (ORDER BY booking_date) AS balance
        FROM transactions WHERE status = 'confirmed' GROUP BY booking_date""",
    "v_monthly_by_category": """
        SELECT date_trunc('month', t.booking_date) AS month,
               COALESCE(c.name, 'unkategorisiert') AS category,
               SUM(t.amount) AS total
        FROM transactions t LEFT JOIN categories c ON c.id = t.category_id
        WHERE t.status = 'confirmed' GROUP BY 1, 2""",
    "v_projection": """
        SELECT s.name AS scenario, p.day, p.balance
        FROM projection_points p JOIN scenarios s ON s.id = p.scenario_id""",
}


def create_views(engine: Engine) -> None:
    if engine.dialect.name != "postgresql":
        return
    with engine.begin() as conn:
        for name, body in VIEWS.items():
            conn.execute(text(f"CREATE OR REPLACE VIEW {name} AS {body}"))