"""WESP-политики расчёта на базе GfE 2001 (отличия от zootech Excel — осознанные)."""

from __future__ import annotations

from dataclasses import dataclass
from typing import Literal

FeedGroup = Literal["rough", "succulent", "concentrate", "other", "unknown"]

# --- GfE 2001 константы (формулы не меняем) ---
NEL_Q_COEFF = 0.004
NEL_Q_REF_PCT = 57.0
NEL_BASE = 0.6

GE_CP = 0.0239
GE_FAT = 0.0398
GE_FIBER = 0.0201
GE_NFE = 0.0175

ME_FAT = 0.0312
ME_FIBER = 0.0136
ME_OR_RESIDUE = 0.0147
ME_CP = 0.00234

USP_FAT_THRESHOLD_G_PER_KG_DM = 70.0  # 7% СЖ/кг СВ

# DCAB (Na+K)-(Cl+S), мэкв при минералах в г/кг СВ
DCAB_NA = 43.5
DCAB_K = 25.6
DCAB_CL = 28.2
DCAB_S = 62.4

# Дефолты переваримости при пустых коэфф. (Excel legacy, кроме ОВ)
DEFAULT_CP_DIGEST_PCT = 86.0
DEFAULT_FAT_DIGEST_PCT = 75.0
DEFAULT_FIBER_DIGEST_PCT = 86.0
DEFAULT_NFE_DIGEST_PCT = 94.0
DEFAULT_INSOLUBLE_PROTEIN_PCT = 15.0
DEFAULT_PROTEIN_FRACTION_PCT = 18.9

# WESP: дефолт ВРХ орг. вещ. при пустом поле — по классу корма
DEFAULT_OMD_ROUGH_PCT = 65.0
DEFAULT_OMD_SUCCULENT_PCT = 72.0
DEFAULT_OMD_CONCENTRATE_PCT = 91.0


@dataclass(frozen=True)
class DeriveContext:
    feed_group: FeedGroup = "unknown"
    is_main_feed: bool = False

    @classmethod
    def from_cells(cls, *, main_feed_g: float = 0.0, feed_group: FeedGroup = "unknown") -> DeriveContext:
        return cls(
            feed_group=feed_group,
            is_main_feed=main_feed_g > 0,
        )

    @classmethod
    def infer_from_cells(cls, cells: dict[str, float], feed_group: FeedGroup = "unknown") -> DeriveContext:
        main_feed = cells.get("E", 0.0)
        return cls.from_cells(main_feed_g=main_feed, feed_group=feed_group)


def default_om_digestibility_pct(ctx: DeriveContext | None) -> float:
    """Дефолт переваримости ОВ (%) при отсутствии ВРХ Орг Вещ."""
    if ctx is None:
        return DEFAULT_OMD_CONCENTRATE_PCT
    if ctx.is_main_feed or ctx.feed_group == "rough":
        return DEFAULT_OMD_ROUGH_PCT
    if ctx.feed_group == "succulent":
        return DEFAULT_OMD_SUCCULENT_PCT
    return DEFAULT_OMD_CONCENTRATE_PCT


def default_digestibility_coefficients() -> dict[str, float]:
    return {
        "cp": DEFAULT_CP_DIGEST_PCT,
        "fat": DEFAULT_FAT_DIGEST_PCT,
        "fiber": DEFAULT_FIBER_DIGEST_PCT,
        "nfe": DEFAULT_NFE_DIGEST_PCT,
        "insoluble_protein": DEFAULT_INSOLUBLE_PROTEIN_PCT,
        "protein_fraction": DEFAULT_PROTEIN_FRACTION_PCT,
    }