from datetime import date
from decimal import Decimal

from sqlalchemy import inspect
from sqlalchemy.orm import Session

from src.models.b4w import CategoryDb
from src.models.category_budget import CategoryBudgetDb


def test_category_budget_schema(db_session: Session):
    inspector = inspect(db_session.get_bind())
    columns = {c["name"]: c for c in inspector.get_columns("category_budget")}

    assert set(columns) == {
        "id",
        "category_id",
        "amount_eur",
        "valid_from",
        "valid_to",
    }
    assert columns["id"]["nullable"] is False
    assert columns["category_id"]["nullable"] is False
    assert columns["amount_eur"]["nullable"] is False
    assert columns["valid_from"]["nullable"] is True
    assert columns["valid_to"]["nullable"] is True
    assert str(columns["amount_eur"]["type"]) == "NUMERIC(12, 2)"

    foreign_keys = inspector.get_foreign_keys("category_budget")
    assert len(foreign_keys) == 1
    assert foreign_keys[0]["constrained_columns"] == ["category_id"]
    assert foreign_keys[0]["referred_table"] == "category"


def test_category_budget_defaults_null_dates(db_session: Session):
    category = CategoryDb(name="Lebenshaltung")
    db_session.add(category)
    db_session.flush()

    budget = CategoryBudgetDb(category_id=category.id, amount_eur=Decimal("150.00"))
    db_session.add(budget)
    db_session.commit()
    db_session.refresh(budget)

    assert budget.id is not None
    assert budget.category_id == category.id
    assert budget.amount_eur == Decimal("150.00")
    # Null means unbounded in either direction.
    assert budget.valid_from is None
    assert budget.valid_to is None


def test_category_budget_date_window(db_session: Session):
    category = CategoryDb(name="Freizeit")
    db_session.add(category)
    db_session.flush()

    budget = CategoryBudgetDb(
        category_id=category.id,
        amount_eur=Decimal("200.50"),
        valid_from=date(2026, 10, 1),
        valid_to=date(2026, 10, 31),
    )
    db_session.add(budget)
    db_session.commit()
    db_session.refresh(budget)

    assert budget.valid_from == date(2026, 10, 1)
    assert budget.valid_to == date(2026, 10, 31)


def test_category_budget_relationship_both_ways(db_session: Session):
    category = CategoryDb(name="Beruf")
    db_session.add(category)
    db_session.flush()

    budget = CategoryBudgetDb(category_id=category.id, amount_eur=Decimal("1.00"))
    db_session.add(budget)
    db_session.commit()

    # Force re-read from the database so the relationship is loaded, not
    # just resolved from the session identity map.
    db_session.expire_all()
    assert [b.id for b in category.budgets] == [budget.id]
    assert budget.category.id == category.id


def test_category_has_multiple_budgets(db_session: Session):
    category = CategoryDb(name="Wohnen")
    db_session.add(category)
    db_session.flush()

    budgets = [
        CategoryBudgetDb(
            category_id=category.id,
            amount_eur=Decimal("1200.00"),
            valid_from=date(2026, 10, 1),
            valid_to=date(2026, 10, 31),
        ),
        CategoryBudgetDb(
            category_id=category.id,
            amount_eur=Decimal("1300.00"),
            valid_from=date(2026, 11, 1),
            valid_to=date(2026, 11, 30),
        ),
    ]
    for budget in budgets:
        db_session.add(budget)
    db_session.commit()
    db_session.expire_all()

    assert [b.id for b in category.budgets] == [b.id for b in budgets]