from __future__ import annotations

from datetime import date
from decimal import Decimal

from app.extensions import db
from app.models import Month


def test_auto_creates_missing_month(app):
    service = app.extensions["saldo.month_service"]
    month = service.ensure_month(date(2026, 5, 1))
    assert month.label == "2026-05"
    assert month.auto_created is True


def test_copy_previous_month_keeps_values(app):
    service = app.extensions["saldo.month_service"]
    april = Month.query.filter_by(label="2026-04").first()
    copied = service.copy_month(april, 2026, 6, auto_created=False)
    db.session.commit()
    assert copied.label == "2026-06"
    assert len(copied.entry_values) == len(april.entry_values)
    assert copied.incomes[0].amount == april.incomes[0].amount


def test_remainder_calculation(app):
    service = app.extensions["saldo.month_service"]
    month = Month.query.filter_by(label="2026-04").first()
    summary = service.compute_summary(month)
    assert summary.total_income == Decimal("5550.00")
    assert summary.remainder == summary.total_income - summary.total_costs