"""System B passes only when electric/thermal ledgers stay separate and scenarios cover the shortfall honestly."""

from __future__ import annotations

import math
import sys
from pathlib import Path

import pytest

ROOT = Path(__file__).resolve().parents[1]
sys.path.insert(0, str(ROOT))

from system_b_ledger import (  # noqa: E402
    RETIRED_COMPOSITE_MW,
    SystemBLedger,
    build_ledger,
)


@pytest.fixture
def ledger() -> SystemBLedger:
    return build_ledger()


def test_retired_composite_is_not_firm_electric(ledger: SystemBLedger) -> None:
    """The old 895 MW figure mixed 145 MWth into MW — it must not be the firm headline."""
    assert RETIRED_COMPOSITE_MW == 895
    assert ledger.firm_headline_mw != RETIRED_COMPOSITE_MW
    assert RETIRED_COMPOSITE_MW not in ledger.accreditation_mw.values()


def test_thermal_mwth_never_enters_electric_sum(ledger: SystemBLedger) -> None:
    """Electric firm = BESS + DSM + intertie + hub_net_electric — never hub_thermal_mwth."""
    full = ledger.accreditation_mw["full"]
    parts = (
        ledger.bess_mw
        + ledger.dsm_mw
        + ledger.intertie_mw
        + ledger.hub_net_electric_mw
    )
    assert full == parts
    assert ledger.hub_thermal_mwth not in (
        ledger.bess_mw,
        ledger.dsm_mw,
        ledger.intertie_mw,
        ledger.hub_net_electric_mw,
    )
    # Explicit anti-pattern: adding the full thermal build (effluent + contingent
    # compute reject) would recreate the retired 895 composite
    from regulator_paper_assumptions import v as _v
    hub_all_th = ledger.hub_thermal_mwth + _v("hub_contingent_thermal_mwth")
    mixed = ledger.bess_mw + hub_all_th + ledger.dsm_mw + ledger.intertie_mw
    assert mixed == RETIRED_COMPOSITE_MW
    assert full != mixed


def test_reference_and_full_cover_shortfall(ledger: SystemBLedger) -> None:
    assert ledger.covers_shortfall("conservative") is False
    assert ledger.covers_shortfall("reference") is True
    assert ledger.covers_shortfall("full") is True
    assert ledger.margin_mw("reference") == ledger.accreditation_mw["reference"] - ledger.shortfall_mw
    assert ledger.margin_mw("full") == ledger.accreditation_mw["full"] - ledger.shortfall_mw


def test_cost_per_kw_uses_electric_denominator(ledger: SystemBLedger) -> None:
    ref_net = ledger.cost_per_kw_hybrid_net("reference")
    full_net = ledger.cost_per_kw_hybrid_net("full")
    gas = ledger.cost_per_kw_gas_derate()
    assert ref_net < gas
    assert full_net < gas
    # Must not match the invalid $1,676/kW that used 895 as denominator
    invalid = ledger.hybrid_capex_net_b * 1e9 / (RETIRED_COMPOSITE_MW * 1000)
    assert not math.isclose(ref_net, invalid, rel_tol=1e-6)
    assert not math.isclose(full_net, invalid, rel_tol=1e-6)


def test_twenty_year_bands_do_not_overlap(ledger: SystemBLedger) -> None:
    assert ledger.hybrid_20yr_high_b < ledger.gas_20yr_low_b
    lo, hi = ledger.savings_band_b
    assert lo == pytest.approx(ledger.gas_20yr_low_b - ledger.hybrid_20yr_high_b)
    assert hi == pytest.approx(ledger.gas_20yr_high_b - ledger.hybrid_20yr_low_b)
    assert lo > 0 and hi > lo


def test_dual_ledgers_expose_thermal_and_electric(ledger: SystemBLedger) -> None:
    assert ledger.thermal_ledger_mwth["hub_total"] == ledger.hub_thermal_mwth
    assert ledger.electric_ledger_mw["hub_net"] == ledger.hub_net_electric_mw
    assert ledger.electric_ledger_mw["hub_net"] < ledger.thermal_ledger_mwth["hub_total"]


def test_system_b_pass_report_is_all_green(ledger: SystemBLedger) -> None:
    report = ledger.pass_report()
    assert report["passed"] is True
    assert all(report["gates"].values())
    assert "895" not in report["headline"]
    assert "413" in report["headline"] or "688" in report["headline"] or "788" in report["headline"]


def test_peak_shave_profile_uses_net_electric_hub(ledger: SystemBLedger) -> None:
    """Hourly electric peak shave credits hub as net electric MW, not MWth."""
    profile = ledger.peak_shave_mw_by_hour()
    assert len(profile) == 24
    # Off-peak hours: hub net electric only
    assert profile[3] == ledger.hub_net_electric_mw
    # Morning peak window: hub + BESS + DSM
    assert profile[8] == ledger.hub_net_electric_mw + ledger.bess_mw + ledger.dsm_mw