import pytest

from app.services.data_service import _run_dcf_explicit_build


_APPROX = pytest.approx


def test_run_dcf_explicit_build_two_year_reference_scenario() -> None:
    # Given
    base_revenue = 1_000.0

    # When
    result = _run_dcf_explicit_build(
        base_revenue=base_revenue,
        revenue_growth=[0.10, 0.05],
        ebitda_margin=[0.30, 0.32],
        dna_pct_revenue=[0.05, 0.05],
        capex_pct_revenue=[0.07, 0.07],
        nwc_chg_pct_delta_rev=[0.02, 0.02],
        tax_rate=[0.25, 0.25],
        wacc=0.10,
        terminal_growth=0.03,
        shares_outstanding=100.0,
        total_debt=50.0,
        cash=10.0,
        preferred_equity=5.0,
        minority_interest=3.0,
        projection_years=2,
    )

    # Then
    assert result["available"] is True
    assert result["base_fcf"] == _APPROX(184.25)
    assert result["fcf_pv_sum"] == _APPROX(357.42928814344134)
    assert result["terminal_value_pv"] == _APPROX(2_674.37743224556)
    assert result["enterprise_value"] == _APPROX(3_031.8067203890014)
    assert result["net_debt"] == 40.0
    assert result["equity_value"] == _APPROX(2_983.8067203890014)
    assert result["intrinsic_value_per_share"] == _APPROX(29.838067203890013)
    assert result["wacc"] == 0.10
    assert result["terminal_growth"] == 0.03
    assert result["projection_years"] == 2


def test_run_dcf_explicit_build_terminal_growth_at_wacc_returns_error() -> None:
    # Given / When
    result = _run_dcf_explicit_build(
        base_revenue=1_000.0,
        revenue_growth=[0.05],
        ebitda_margin=[0.30],
        dna_pct_revenue=[0.05],
        capex_pct_revenue=[0.07],
        nwc_chg_pct_delta_rev=[0.02],
        tax_rate=[0.25],
        wacc=0.10,
        terminal_growth=0.10,
        shares_outstanding=100.0,
        total_debt=0.0,
        cash=0.0,
        preferred_equity=0.0,
        minority_interest=0.0,
        projection_years=1,
    )

    # Then
    assert result["available"] is True
    assert "Terminal growth" in result["error"]
    assert "intrinsic_value_per_share" not in result


def test_run_dcf_explicit_build_zero_wacc_returns_error() -> None:
    # Given / When
    result = _run_dcf_explicit_build(
        base_revenue=1_000.0,
        revenue_growth=[0.05],
        ebitda_margin=[0.30],
        dna_pct_revenue=[0.05],
        capex_pct_revenue=[0.07],
        nwc_chg_pct_delta_rev=[0.02],
        tax_rate=[0.25],
        wacc=0.0,
        terminal_growth=0.03,
        shares_outstanding=100.0,
        total_debt=0.0,
        cash=0.0,
        preferred_equity=0.0,
        minority_interest=0.0,
        projection_years=1,
    )

    # Then
    assert result["available"] is True
    assert "WACC" in result["error"]
    assert "intrinsic_value_per_share" not in result


@pytest.mark.parametrize("shares_outstanding", [0.0, -1.0])
def test_run_dcf_explicit_build_nonpositive_shares_return_error(shares_outstanding: float) -> None:
    # Given / When
    result = _run_dcf_explicit_build(
        base_revenue=1_000.0,
        revenue_growth=[0.05],
        ebitda_margin=[0.30],
        dna_pct_revenue=[0.05],
        capex_pct_revenue=[0.07],
        nwc_chg_pct_delta_rev=[0.02],
        tax_rate=[0.25],
        wacc=0.10,
        terminal_growth=0.03,
        shares_outstanding=shares_outstanding,
        total_debt=0.0,
        cash=0.0,
        preferred_equity=0.0,
        minority_interest=0.0,
        projection_years=1,
    )

    # Then
    assert result["available"] is True
    assert "Shares outstanding" in result["error"]
    assert "intrinsic_value_per_share" not in result


def test_run_dcf_explicit_build_zero_base_revenue_returns_error() -> None:
    # Given / When
    result = _run_dcf_explicit_build(
        base_revenue=0.0,
        revenue_growth=[0.05],
        ebitda_margin=[0.30],
        dna_pct_revenue=[0.05],
        capex_pct_revenue=[0.07],
        nwc_chg_pct_delta_rev=[0.02],
        tax_rate=[0.25],
        wacc=0.10,
        terminal_growth=0.03,
        shares_outstanding=100.0,
        total_debt=0.0,
        cash=0.0,
        preferred_equity=0.0,
        minority_interest=0.0,
        projection_years=1,
    )

    # Then
    assert result["available"] is True
    assert "Base revenue" in result["error"]
    assert "intrinsic_value_per_share" not in result