import tempfile
import unittest
from pathlib import Path
from unittest import mock

import pandas as pd

from factor_attribution import load_external_us_factors


class ExternalFactorLoaderTests(unittest.TestCase):
    def test_load_external_us_factors_parses_percent_values_and_dates(self):
        csv_text = (
            "This line is ignored\n"
            ",Mkt-RF,SMB,HML,RMW,CMA,RF\n"
            "20260102,1.00,0.50,-0.25,0.10,-0.05,0.02\n"
            "20260105,-0.20,0.10,0.30,-0.15,0.05,0.02\n"
            "\n"
        )

        with tempfile.TemporaryDirectory() as tmpdir:
            with mock.patch(
                "factor_attribution._download_kf_zip_bytes",
                return_value=csv_text.encode("utf-8"),
            ):
                factors = load_external_us_factors(cache_dir=Path(tmpdir))

        self.assertListEqual(
            list(factors.columns),
            ["MKT_RF", "SMB", "HML", "RMW", "CMA", "RF"],
        )
        self.assertAlmostEqual(factors.iloc[0]["MKT_RF"], 0.01)
        self.assertAlmostEqual(factors.iloc[0]["RF"], 0.0002)
        self.assertEqual(str(factors.index[0].date()), "2026-01-02")

    def test_load_external_us_factors_falls_back_to_cache_when_download_fails(self):
        cached = pd.DataFrame(
            {
                "MKT_RF": [0.01],
                "SMB": [0.0],
                "HML": [0.0],
                "RMW": [0.0],
                "CMA": [0.0],
                "RF": [0.0001],
            },
            index=pd.to_datetime(["2026-01-02"]),
        )

        with tempfile.TemporaryDirectory() as tmpdir:
            cache_dir = Path(tmpdir)
            cached.to_csv(cache_dir / "ff5_us_daily.csv")
            with mock.patch(
                "factor_attribution._download_kf_zip_bytes",
                side_effect=RuntimeError("boom"),
            ):
                factors = load_external_us_factors(cache_dir=cache_dir)

        self.assertEqual(len(factors), 1)
        self.assertAlmostEqual(factors.iloc[0]["MKT_RF"], 0.01)