"""Scenario pins — hand-checked composite results per scenario, clamp
behaviour, and copy semantics."""

import pytest

from teicalc import (
    BENEFITS_VERBATIM,
    COSTS_VERBATIM,
    SCENARIOS,
    apply_scenario,
    compute_summary,
)


def _summary(scenario):
    return compute_summary(
        apply_scenario(BENEFITS_VERBATIM, scenario),
        apply_scenario(COSTS_VERBATIM, scenario),
        0.10,
    )


def test_scenario_definitions():
    assert SCENARIOS == {
        "conservative": {"adoption": 0.80, "risk_delta": 0.10},
        "moderate": {"adoption": 1.00, "risk_delta": 0.00},
        "aggressive": {"adoption": 1.15, "risk_delta": -0.05},
    }


def test_moderate_is_identity():
    got = _summary("moderate")
    want = compute_summary(BENEFITS_VERBATIM, COSTS_VERBATIM, 0.10)
    assert got["benefits_pv"] == pytest.approx(want["benefits_pv"], abs=0.01)
    assert got["costs_pv"] == pytest.approx(want["costs_pv"], abs=0.01)


def test_conservative_pins():
    s = _summary("conservative")
    assert s["benefits_pv"] == pytest.approx(71_672_867.65, abs=1)
    assert s["costs_pv"] == pytest.approx(17_437_916.34, abs=1)
    assert s["npv"] == pytest.approx(54_234_951.31, abs=1)
    assert s["roi_pct"] == pytest.approx(311.02, abs=0.01)
    assert s["payback_months"] == pytest.approx(0.763, abs=0.001)


def test_aggressive_pins():
    s = _summary("aggressive")
    assert s["benefits_pv"] == pytest.approx(123_911_705.40, abs=1)
    assert s["costs_pv"] == pytest.approx(27_682_368.61, abs=1)
    assert s["npv"] == pytest.approx(96_229_336.79, abs=1)
    assert s["roi_pct"] == pytest.approx(347.62, abs=0.01)
    assert s["payback_months"] == pytest.approx(0.705, abs=0.001)


def test_risk_delta_clamps_at_zero():
    """Conservative subtracts 0.10 from cost risk; usage (0.05) clamps to 0."""
    rows = apply_scenario(COSTS_VERBATIM, "conservative")
    usage = next(r for r in rows if r["field_key"] == "amazon_connect_usage")
    assert usage["risk_adjustment"] == 0.0
    impl = next(r for r in rows if r["field_key"] == "implementation_migration")
    assert impl["risk_adjustment"] == pytest.approx(0.0)          # 0.10 − 0.10
    assert impl["initial"] == pytest.approx(1_087_500 * 0.80)     # adoption scales initial


def test_unknown_scenario_raises():
    with pytest.raises(KeyError):
        apply_scenario(BENEFITS_VERBATIM, "wildly_optimistic")


def test_inputs_not_mutated():
    apply_scenario(BENEFITS_VERBATIM, "aggressive")
    apply_scenario(COSTS_VERBATIM, "conservative")
    assert BENEFITS_VERBATIM[0]["year_values"]["1"] == 13_911_040
    assert COSTS_VERBATIM[1]["initial"] == 1_087_500