from datetime import date

from app.fitness.charts import (
    _resolve_chart_range,
    build_fitness_charts,
    linear_regression,
    week_start,
)


def test_week_start_monday():
    assert week_start(date(2026, 6, 13)) == date(2026, 6, 8)


def test_linear_regression_increasing():
    points = [(0.0, 1.0), (1.0, 2.0), (2.0, 3.0)]
    fit = linear_regression(points)
    assert fit is not None
    assert abs(fit["slope"] - 1.0) < 1e-9
    assert abs(fit["intercept"] - 1.0) < 1e-9


def test_linear_regression_requires_two_points():
    assert linear_regression([(0.0, 5.0)]) is None
    assert linear_regression([]) is None


def test_resolve_chart_range_auto_no_data():
    weeks, granularity, lookback, label, span = _resolve_chart_range(0, date(2026, 6, 18), None)
    assert weeks == 4
    assert granularity == "day"
    assert lookback == 7
    assert label == "7 дней"
    assert span == 0


def test_resolve_chart_range_auto_short_span():
    first = date(2026, 6, 1)
    end = date(2026, 6, 18)
    weeks, granularity, lookback, label, span = _resolve_chart_range(0, end, first)
    assert granularity == "day"
    assert span == 18
    assert lookback == 18
    assert "дн." in label


def test_resolve_chart_range_auto_long_span():
    first = date(2026, 1, 1)
    end = date(2026, 6, 18)
    weeks, granularity, lookback, label, span = _resolve_chart_range(0, end, first)
    assert granularity == "week"
    assert weeks >= 20
    assert "нед." in label
    assert span > 35


def test_build_fitness_charts_auto_granularity():
    from datetime import datetime, timezone

    from sqlalchemy import create_engine
    from sqlalchemy.orm import Session, sessionmaker

    from app.db.models import Base, FoodLog, User

    engine = create_engine("sqlite:///:memory:")
    Base.metadata.create_all(engine)
    SessionLocal = sessionmaker(bind=engine)
    with Session(engine) as db:
        user = User(username="charts", api_token_hash="h")
        db.add(user)
        db.commit()
        uid = user.id
        day = date(2026, 6, 10)
        db.add(
            FoodLog(
                user_id=uid,
                description="lunch",
                calories=500,
                logged_at=datetime.combine(day, datetime.min.time(), tzinfo=timezone.utc),
            )
        )
        db.commit()
        result = build_fitness_charts(db, uid, weeks=0, end_day=day)
    assert result["granularity"] == "day"
    assert result["range_label"]
    assert result["daily_series"] is not None