"""Conversion and climate study book. Not the winter resource stack."""

from __future__ import annotations

from pathlib import Path

import yaml

STUDY_YAML = Path(__file__).with_name("heat_pump_study.yaml")


def load_study(path: Path = STUDY_YAML) -> dict:
    data = yaml.safe_load(path.read_text())
    return {k: v for k, v in data.items() if not str(k).startswith("_")}


def sv(key: str, path: Path = STUDY_YAML):
    return load_study(path)[key]["value"]


def unmanaged_peak_mw(n_dwellings: float, share: float, kw_per_home: float) -> float:
    return float(n_dwellings) * float(share) * float(kw_per_home) / 1000.0


def dual_fuel_extra_mw(n_dwellings: float, share: float, kw_per_home: float) -> float:
    del n_dwellings, share, kw_per_home
    return 0.0


def identity_verdict(
    computed_mw: tuple[float, ...],
    registry_mw: float = 675.0,
    tol_mw: float = 25.0,
) -> dict:
    lo, hi = min(computed_mw), max(computed_mw)
    status = (
        "confirm"
        if abs(lo - registry_mw) <= tol_mw and abs(hi - registry_mw) <= tol_mw
        else "fence"
    )
    return {
        "status": status,
        "range_mw": (lo, hi),
        "round_identity_mw": unmanaged_peak_mw(300_000, 0.15, 15.0),
        "registry_mw": registry_mw,
        "do_not_add_to_shortfall": True,
    }


def organic_peak_2030_mw(record_mw: float, years: int, rate: float) -> float:
    return float(record_mw) * (1.0 + float(rate)) ** int(years)


def shortfall_reconstruction(
    organic_2030_mw: float,
    record_mw: float,
    stated_shortfall_mw: float = 600.0,
) -> dict:
    growth = float(organic_2030_mw) - float(record_mw)
    return {
        "organic_2030_mw": float(organic_2030_mw),
        "organic_growth_mw": growth,
        "stated_shortfall_mw": float(stated_shortfall_mw),
        "verdict": "keep_pd",
        "reason": (
            "600 is a drought firm-supply gap, not organic load growth from the "
            "2025 record peak. Firm hydro MW is not in the main registry. Keep "
            "shortfall_2030_mw as PD."
        ),
        "do_not_replace_shortfall": True,
        "do_not_add_to_675": True,
    }


def load_daily_mins(path: Path) -> list[float]:
    import csv

    with path.open() as f:
        return [float(row["min_c"]) for row in csv.DictReader(f)]


def count_extremes(
    temps: list[float], thresholds: tuple[float, ...] = (-30.0, -35.0)
) -> dict:
    return {t: sum(1 for x in temps if x <= t) for t in thresholds}


def apply_warming_bands(count_at_minus_35: float, low: float, high: float) -> dict:
    return {
        "low": float(count_at_minus_35) * float(low),
        "high": float(count_at_minus_35) * float(high),
    }


def climate_forecast_or_observations_only(
    atlas_factors: dict | None, observed_count: float
) -> dict:
    if not atlas_factors:
        return {"mode": "observations_only", "observed_count": observed_count}
    return {
        "mode": "c_plus",
        "observed_count": observed_count,
        "forecast": apply_warming_bands(
            observed_count, atlas_factors["low"], atlas_factors["high"]
        ),
    }


def rollout_share(n: float, annual_installs: float, years: int) -> float:
    return (float(annual_installs) * int(years)) / float(n)


def household_book_cad(installs: float, net_cost_per_home: float) -> float:
    return float(installs) * float(net_cost_per_home)


def utility_peak_capital_b(
    extra_mw: float, gas_capex_b: float, gas_nameplate_mw: float
) -> float:
    if extra_mw <= 0:
        return 0.0
    return float(extra_mw) / float(gas_nameplate_mw) * float(gas_capex_b)


def combined_forbidden(household_cad: float, utility_b: float) -> None:
    raise ValueError("never add household $ to utility peak $")


def render_study_note() -> str:
    nrcan_n = float(sv("nrcan_mb_gas_heating_stock"))
    share = float(sv("conversion_share"))
    kw = float(sv("kw_resistance_at_design"))
    households = float(sv("mb_private_households_ref"))
    cer_n = households * float(sv("cer_mb_gas_share"))
    nrcan_mw = unmanaged_peak_mw(nrcan_n, share, kw)
    cer_mw = unmanaged_peak_mw(cer_n, share, kw)
    verdict = identity_verdict((nrcan_mw, cer_mw), 675.0, 25.0)
    from regulator_paper_assumptions import v

    organic = organic_peak_2030_mw(
        float(v("peak_record_mw")),
        int(sv("years_record_to_2030")),
        float(sv("organic_growth_rate")),
    )
    rec = shortfall_reconstruction(organic, float(v("peak_record_mw")), 600.0)
    installs_2030 = float(sv("annual_installs_e")) * int(sv("years_to_2030"))
    share_2030 = rollout_share(
        nrcan_n, float(sv("annual_installs_e")), int(sv("years_to_2030"))
    )
    share_2040 = rollout_share(
        nrcan_n, float(sv("annual_installs_e")), int(sv("years_to_2040"))
    )
    hh = household_book_cad(installs_2030, float(sv("net_cost_per_home_cad")))
    util = utility_peak_capital_b(
        nrcan_mw, float(v("gas_capex_b")), float(v("gas_nameplate_mw"))
    )
    return (
        "# Heat-pump rollout and peak study\n\n"
        "Separate book. Never add Hydro’s 600 MW shortfall to the 675 MW conversion "
        "stress. Never add either to the winter resource stack.\n\n"
        "## Chapter 1 — Is 600 real?\n\n"
        f"Organic peak in 2030 from the 2025 record at 1.2%/yr is "
        f"**{organic:.0f} MW** (growth **{rec['organic_growth_mw']:.0f} MW**). "
        "That is not 600. Verdict: **keep_pd**. 600 is a drought firm-supply gap. "
        "Do not replace `shortfall_2030_mw`. Do not add it to 675.\n\n"
        "## Chapter 2 — Is 675 real?\n\n"
        f"NRCan 2021 gas heating stock **{nrcan_n:,.0f}** × 15% × 15 kW = "
        f"**{nrcan_mw:.1f} MW**. CER 51% of {households:,.0f} households = "
        f"**{cer_n:,.0f}** → **{cer_mw:.1f} MW**. The live **675 MW** is the "
        "round identity 300,000 × 15% × 15 kW. Sources disagree. "
        f"Verdict: **{verdict['status']}**. Do not add to the shortfall.\n\n"
        "## Chapter 1b — Is −35 °C real?\n\n"
        "Registry already splits the 20 January 2025 peak at **−32.7 °C** from "
        "the **−35 °C** design hour. Fixture counts are in "
        "`research/data/climate_fixtures/`. Climate Atlas factors are **E** "
        "placeholders until pasted; missing Atlas → observations only.\n\n"
        "## Chapter 3 — Rollout\n\n"
        f"At {float(sv('annual_installs_e')):,.0f} homes/year (E), 2030 share of NRCan "
        f"stock is **{share_2030:.1%}** — below 15%. 2040 tail is **{share_2040:.1%}**. "
        f"Household book (2030 installs): **${hh:,.0f}**. Utility book on the "
        f"NRCan furnace-out peak: **${util:.2f}B** of Brandon-like capital. "
        "Never add the two books. Dual-fuel extra coincident MW at the design "
        "hour is **0**.\n"
    )


if __name__ == "__main__":
    note = render_study_note()
    out = Path(__file__).resolve().parent / "dist" / "heat-pump-rollout-study.md"
    out.write_text(note)
    print(out)