from datetime import datetime
from zoneinfo import ZoneInfo

from app.analysis.vwap import build_vwap_level
from app.bars.models import Bar, Timeframe

EASTERN = ZoneInfo("America/New_York")


def at(year: int, month: int, day: int, hour: int, minute: int = 0) -> int:
    return int(datetime(year, month, day, hour, minute, tzinfo=EASTERN).timestamp())


def minute(t: int, price: float, volume: int) -> Bar:
    return Bar(Timeframe.M1, t, price, price, price, price, volume, True, "ES=F", "test")


def test_vwap_is_volume_weighted_not_a_simple_mean():
    bars = [minute(at(2026, 8, 10, 19), 100, 1), minute(at(2026, 8, 10, 20), 200, 3)]

    level = build_vwap_level(bars)[0]

    assert level.anchor_p == (100 * 1 + 200 * 3) / 4  # 175, not 150


def test_prior_session_bars_are_excluded():
    bars = [
        # Before Monday's 18:00 open, so part of the previous session.
        minute(at(2026, 8, 10, 17), 500, 10),
        minute(at(2026, 8, 10, 19), 100, 1),
        minute(at(2026, 8, 10, 20), 200, 1),
    ]

    level = build_vwap_level(bars)[0]

    assert level.anchor_p == 150
    assert level.first_t == at(2026, 8, 10, 19)


def test_zero_volume_minutes_do_not_divide_by_zero():
    bars = [minute(at(2026, 8, 10, 19), 100, 0), minute(at(2026, 8, 10, 20), 200, 2)]

    level = build_vwap_level(bars)[0]

    assert level.anchor_p == 200
    # The zero-volume minute contributes no point rather than a NaN.
    assert len(level.points) == 1


def test_no_volume_at_all_yields_no_level():
    assert build_vwap_level([minute(at(2026, 8, 10, 19), 100, 0)]) == []


def test_side_tracks_price_relative_to_vwap():
    bars = [minute(at(2026, 8, 10, 19), 100, 1), minute(at(2026, 8, 10, 20), 200, 1)]
    # Last close 200 sits above VWAP 150, so VWAP is support beneath price.
    assert build_vwap_level(bars)[0].side.value == "support"