from datetime import UTC, datetime
from pathlib import Path

import pandas as pd
import pytest

from multi_swarm.data.ohlcv_loader import OHLCVLoader, OHLCVRequest


@pytest.fixture
def sample_ohlcv_rows():
    base_ts = int(datetime(2024, 1, 1, tzinfo=UTC).timestamp() * 1000)
    rows = []
    for i in range(48):
        rows.append(
            [base_ts + i * 3600 * 1000, 40000 + i, 40100 + i, 39900 + i, 40050 + i, 100.0 + i]
        )
    return rows


def test_loader_fetches_and_caches(tmp_path: Path, mocker, sample_ohlcv_rows):
    fake_exchange = mocker.MagicMock()
    fake_exchange.fetch_ohlcv.return_value = sample_ohlcv_rows
    mocker.patch("multi_swarm.data.ohlcv_loader.ccxt.binance", return_value=fake_exchange)

    loader = OHLCVLoader(cache_dir=tmp_path)
    req = OHLCVRequest(
        symbol="BTC/USDT",
        timeframe="1h",
        start=datetime(2024, 1, 1, tzinfo=UTC),
        end=datetime(2024, 1, 3, tzinfo=UTC),
    )
    df = loader.load(req)

    assert isinstance(df, pd.DataFrame)
    assert list(df.columns) == ["open", "high", "low", "close", "volume"]
    assert len(df) == 48
    assert df.index.is_monotonic_increasing
    cache_files = list(tmp_path.glob("*.parquet"))
    assert len(cache_files) == 1


def test_loader_uses_cache_on_second_call(tmp_path: Path, mocker, sample_ohlcv_rows):
    fake_exchange = mocker.MagicMock()
    fake_exchange.fetch_ohlcv.return_value = sample_ohlcv_rows
    mocker.patch("multi_swarm.data.ohlcv_loader.ccxt.binance", return_value=fake_exchange)

    loader = OHLCVLoader(cache_dir=tmp_path)
    req = OHLCVRequest(
        symbol="BTC/USDT",
        timeframe="1h",
        start=datetime(2024, 1, 1, tzinfo=UTC),
        end=datetime(2024, 1, 3, tzinfo=UTC),
    )
    df1 = loader.load(req)
    df2 = loader.load(req)

    assert fake_exchange.fetch_ohlcv.call_count == 1  # 48 < limit, single batch
    pd.testing.assert_frame_equal(df1, df2)
    # Seconda chiamata legge da cache, non chiama exchange
    fake_exchange.fetch_ohlcv.reset_mock()
    df3 = loader.load(req)
    assert fake_exchange.fetch_ohlcv.call_count == 0
    pd.testing.assert_frame_equal(df1, df3)