from datetime import date, timedelta

from sqlalchemy import func, select

from app.config import get_settings
from app.models.tables import ProjectionPoint, ProjectionResult, Scenario
from app.services.projection_service import refresh_stale_projections, run_projection

TODAY = date(2026, 9, 28)


def _scenario(db, name):
    sc = Scenario(name=name, description="", include_recurring=False,
                  include_planned=False)
    db.add(sc)
    db.commit()
    return sc


def _first_day(db, sid):
    return db.execute(select(func.min(ProjectionPoint.day))
                      .where(ProjectionPoint.scenario_id == sid)).scalar()


def _count(db, sid):
    return db.execute(select(func.count()).select_from(ProjectionPoint)
                      .where(ProjectionPoint.scenario_id == sid)).scalar()


def test_veraltetes_szenario_wird_ab_heute_neu_gerechnet(db):
    sc = _scenario(db, "Alt")
    run_projection(db, sc, 10, TODAY - timedelta(days=5))
    assert _first_day(db, sc.id) == TODAY - timedelta(days=4)
    assert refresh_stale_projections(db, TODAY) == 1
    assert _first_day(db, sc.id) == TODAY + timedelta(days=1)
    assert _count(db, sc.id) == get_settings().horizon_days


def test_gestern_gerechnet_gilt_als_veraltet(db):
    sc = _scenario(db, "Gestern")
    run_projection(db, sc, 10, TODAY - timedelta(days=1))
    assert refresh_stale_projections(db, TODAY) == 1


def test_heute_gerechnet_bleibt_unveraendert(db):
    sc = _scenario(db, "Heute")
    run_projection(db, sc, 10, TODAY)
    before = db.get(ProjectionResult, sc.id).computed_at
    assert refresh_stale_projections(db, TODAY) == 0
    assert _count(db, sc.id) == 10
    assert db.get(ProjectionResult, sc.id).computed_at == before


def test_nie_gerechnetes_szenario_bleibt_ohne_ergebnis(db):
    sc = _scenario(db, "Nie")
    assert refresh_stale_projections(db, TODAY) == 0
    assert db.get(ProjectionResult, sc.id) is None
    assert _count(db, sc.id) == 0


def test_refresh_ist_idempotent(db):
    sc = _scenario(db, "Zweimal")
    run_projection(db, sc, 10, TODAY - timedelta(days=3))
    assert refresh_stale_projections(db, TODAY) == 1
    assert refresh_stale_projections(db, TODAY) == 0
    assert _count(db, sc.id) == get_settings().horizon_days