import math
from typing import Any


def _is_female(sex: str) -> bool:
    return sex.lower() in ("f", "female", "ж", "женский", "woman")


def _cm_to_inches(cm: float) -> float:
    return cm / 2.54


def _clamp_bf(value: float) -> float:
    return round(max(3.0, min(50.0, value)), 1)


def navy_body_fat_pct(
    *,
    sex: str,
    height_cm: float,
    neck_cm: float,
    waist_cm: float,
    hip_cm: float | None = None,
) -> float | None:
    if height_cm <= 0 or neck_cm <= 0 or waist_cm <= 0:
        return None

    height_in = _cm_to_inches(height_cm)
    neck_in = _cm_to_inches(neck_cm)
    waist_in = _cm_to_inches(waist_cm)

    if _is_female(sex):
        if hip_cm is None or hip_cm <= 0:
            return None
        hip_in = _cm_to_inches(hip_cm)
        sum_in = waist_in + hip_in - neck_in
        if sum_in <= 0:
            return None
        denom = (
            1.29579
            - 0.35004 * math.log10(sum_in)
            + 0.22100 * math.log10(height_in)
        )
    else:
        diff_in = waist_in - neck_in
        if diff_in <= 0:
            return None
        denom = (
            1.0324
            - 0.19077 * math.log10(diff_in)
            + 0.15456 * math.log10(height_in)
        )

    if denom <= 0:
        return None

    return _clamp_bf(495.0 / denom - 450.0)


def whr(waist_cm: float, hip_cm: float) -> float | None:
    if waist_cm <= 0 or hip_cm <= 0:
        return None
    return round(waist_cm / hip_cm, 2)


def lean_body_mass(weight_kg: float, body_fat_pct: float) -> float:
    return round(weight_kg * (1.0 - body_fat_pct / 100.0), 1)


def ffmi(weight_kg: float, height_cm: float, body_fat_pct: float) -> float | None:
    if height_cm <= 0:
        return None
    height_m = height_cm / 100.0
    lbm = weight_kg * (1.0 - body_fat_pct / 100.0)
    raw = lbm / (height_m * height_m)
    normalized = raw + 6.1 * (1.8 - height_m)
    return round(normalized, 1)


def compute_body_composition(
    *,
    sex: str,
    height_cm: float,
    weight_kg: float,
    neck_cm: float | None = None,
    waist_cm: float | None = None,
    hip_cm: float | None = None,
    body_fat_pct: float | None = None,
) -> dict[str, Any]:
    warnings: list[str] = []
    result: dict[str, Any] = {
        "body_fat_pct": None,
        "body_fat_method": None,
        "whr": None,
        "lbm_kg": None,
        "ffmi": None,
        "warnings": warnings,
    }

    bf = body_fat_pct
    method: str | None = "manual" if bf is not None else None

    if bf is None and neck_cm and waist_cm:
        navy_bf = navy_body_fat_pct(
            sex=sex,
            height_cm=height_cm,
            neck_cm=neck_cm,
            waist_cm=waist_cm,
            hip_cm=hip_cm,
        )
        if navy_bf is not None:
            bf = navy_bf
            method = "navy"
        elif _is_female(sex) and not hip_cm:
            warnings.append("Для Navy у женщин нужен обхват бёдер (hip_cm).")
        elif neck_cm and waist_cm and waist_cm <= neck_cm:
            warnings.append("Обхват талии должен быть больше шеи для Navy.")

    if bf is not None:
        result["body_fat_pct"] = round(float(bf), 1)
        result["body_fat_method"] = method
        result["lbm_kg"] = lean_body_mass(weight_kg, float(bf))
        result["ffmi"] = ffmi(weight_kg, height_cm, float(bf))

    if waist_cm and hip_cm:
        result["whr"] = whr(waist_cm, hip_cm)

    return result