from datetime import datetime
from zoneinfo import ZoneInfo

import pytest

from app.bars.models import Timeframe
from app.bars.session import (
    FUTURE_SLOT_COUNT,
    bucket_duration,
    bucket_start,
    future_bucket_starts,
    next_bucket_start,
)

UTC = ZoneInfo("UTC")
ET = ZoneInfo("America/New_York")


def epoch(value: str, zone=UTC) -> int:
    return int(datetime.fromisoformat(value).replace(tzinfo=zone).timestamp())


@pytest.mark.parametrize(
    ("value", "tf", "expected"),
    [
        ("2026-08-09T22:00:00", Timeframe.D1, "2026-08-09T22:00:00"),
        ("2026-08-10T16:37:00", Timeframe.D1, "2026-08-09T22:00:00"),
        ("2026-08-14T20:59:00", Timeframe.D1, "2026-08-13T22:00:00"),
        ("2026-08-10T21:30:00", Timeframe.D1, "2026-08-09T22:00:00"),
        ("2026-08-10T22:00:00", Timeframe.D1, "2026-08-10T22:00:00"),
    ],
)
def test_session_boundaries(value, tf, expected):
    assert bucket_start(epoch(value), tf) == epoch(expected)


def test_intraday_buckets_use_utc_boundaries():
    assert bucket_start(epoch("2026-08-10T12:37:45"), Timeframe.M15) == epoch(
        "2026-08-10T12:30:00"
    )


@pytest.mark.parametrize(
    ("local_value", "expected_local"),
    [
        ("2026-03-08T18:00:00", "2026-03-08T18:00:00"),
        ("2026-11-01T18:00:00", "2026-11-01T18:00:00"),
    ],
)
def test_sunday_open_across_dst(local_value, expected_local):
    assert bucket_start(epoch(local_value, ET), Timeframe.D1) == epoch(expected_local, ET)


@pytest.mark.parametrize(
    ("value_utc", "expected_open_utc"),
    [
        ("2026-01-13T04:00:00", "2026-01-12T23:00:00"),
        ("2026-07-14T03:00:00", "2026-07-13T22:00:00"),
        ("2026-11-01T22:59:00", "2026-10-31T22:00:00"),
        ("2026-11-01T23:00:00", "2026-11-01T23:00:00"),
    ],
)
def test_daily_open_tracks_eastern_dst_in_utc(value_utc, expected_open_utc):
    assert bucket_start(epoch(value_utc), Timeframe.D1) == epoch(expected_open_utc)


def test_daily_geometry_excludes_the_settlement_halt():
    start = epoch("2026-08-10T18:00:00", ET)

    assert bucket_duration(start, Timeframe.D1) == 23 * 3600


def test_daily_future_geometry_skips_the_weekend_and_opens_at_1800_eastern():
    thursday = epoch("2026-08-13T18:00:00", ET)
    sunday = epoch("2026-08-16T18:00:00", ET)

    assert next_bucket_start(thursday, Timeframe.D1) == sunday


def test_intraday_future_geometry_skips_the_settlement_halt():
    monday_last = epoch("2026-08-10T16:55:00", ET)
    monday_reopen = epoch("2026-08-10T18:00:00", ET)

    assert next_bucket_start(monday_last, Timeframe.M5) == monday_reopen


def test_intraday_future_geometry_skips_the_weekend():
    friday_last = epoch("2026-08-14T16:55:00", ET)
    sunday_reopen = epoch("2026-08-16T18:00:00", ET)

    assert next_bucket_start(friday_last, Timeframe.M5) == sunday_reopen


def test_future_geometry_uses_the_shared_180_slot_horizon():
    start = epoch("2026-08-13T18:00:00", ET)
    future = future_bucket_starts(start, Timeframe.D1)

    assert len(future) == FUTURE_SLOT_COUNT == 180
    assert all(datetime.fromtimestamp(value, ET).weekday() in {6, 0, 1, 2, 3} for value in future)