"""Toy-model acceptance pins — hand-checked, like every study must have.

Every number here was computed by hand before it was pinned. When you
replace the toy domain, replace these with hand-checks of YOUR math;
the in-notebook verification gate is the second layer, not a substitute.
"""

from __future__ import annotations

import pytest

from studylib import model as m


def test_contracted_overlays_verbatim():
    assert m.anchor("platform_annual") == 500_000          # signed contract
    assert m.ANCHOR_VERBATIM["platform_annual"] == 600_000  # pitch record intact
    assert m.anchor("baseline_annual") == m.ANCHOR_VERBATIM["baseline_annual"]


def test_ramp_mechanics():
    assert m.platform_costs_by_year() == {2026: 300_000, 2027: 600_000,
                                          2028: 600_000}
    assert m.platform_costs_by_year(12)[2026] == 0.0
    assert m.platform_costs_by_year(0)[2026] == 600_000.0
    assert m.platform_costs_by_year(annual=m.anchor("platform_annual")) == \
        {2026: 250_000, 2027: 500_000, 2028: 500_000}


def test_benefits_phase_on_the_schedule():
    ben = m.benefits_by_year()
    assert ben[2026] == 0.0                                 # nothing lands in year 1
    assert ben[2027] == pytest.approx(900_000 * 6 / 18)     # months 19-24
    assert ben[2028] == pytest.approx(900_000 * 12 / 18)
    assert sum(ben.values()) == pytest.approx(m.anchor("benefit_3yr"))


def _frame(annual):
    plat = m.platform_costs_by_year(annual=annual)
    total = {y: m.current_costs_by_year()[y] + plat[y] + m.services_by_year()[y]
             for y in m.YEARS}
    return m.case_flows(total, m.benefits_by_year())


def test_contracted_frame_kpis():
    inc, net = _frame(m.anchor("platform_annual"))
    assert sum(net.values()) == pytest.approx(400_000)
    kpi = m.case_kpis(inc, net)
    assert kpi["roi"] == pytest.approx(0.8)
    assert kpi["npv"] == pytest.approx(206_612, abs=1)      # @10%, hand-checked
    assert kpi["payback"] == "32 months (~Aug 2028)"


def test_vendor_frame_kpis():
    inc, net = _frame(None)                                 # verbatim pitch rate
    assert sum(net.values()) == pytest.approx(150_000)
    assert m.case_kpis(inc, net)["payback"] == "35 months (~Nov 2028)"


def test_payback_edges():
    assert m.payback_label({2026: 1.0, 2027: 0.0, 2028: 0.0}) == "immediate"
    assert m.payback_label({2026: -1.0, 2027: -1.0, 2028: -1.0}) == "beyond 2028"