from __future__ import annotations

from typing import Any

from app.modules.zootech.lab.calc.nutrients import rnb


def apply_content_derived(
    content_by_key: dict[str, float | None],
    defn: dict[str, Any],
    *,
    total_kg: float = 0,
    heads_per_trip: int = 1,
    profile_mass_kg: float | None = None,
    compound_mode: bool = False,
) -> float | None:
    derived = defn.get("derived")
    if derived == "alias":
        return content_by_key.get(defn.get("alias_of"))
    if derived == "pct_of_dm":
        src = content_by_key.get(defn.get("from_key"))
        dm = content_by_key.get("dry_matter")
        if src is None or not dm or dm <= 0:
            return None
        return src / dm * 100.0
    if derived == "g_per_kg_dm":
        src = content_by_key.get(defn.get("from_key"))
        dm = content_by_key.get("dry_matter")
        if src is None or not dm or dm <= 0:
            return None
        if compound_mode:
            return src
        return src / (dm / 1000.0)
    if derived == "nel_per_kg_dm":
        dm = content_by_key.get("dry_matter")
        nel = content_by_key.get("nel")
        if not dm or dm <= 0 or nel is None:
            return None
        if compound_mode:
            return nel
        return nel / (dm / 1000.0)
    if derived == "ratio":
        num = content_by_key.get(defn.get("ratio_num"))
        den = content_by_key.get(defn.get("ratio_den"))
        if num is None or den is None or den == 0:
            return None
        return num / den
    if derived == "dm_pct_bw":
        dm = content_by_key.get("dry_matter")
        if dm is None or not profile_mass_kg or profile_mass_kg <= 0:
            return None
        return (dm / 1000.0 / profile_mass_kg) * 100.0
    if derived == "ration_pct_bw":
        if not profile_mass_kg or profile_mass_kg <= 0 or total_kg <= 0:
            return None
        heads = max(int(heads_per_trip or 1), 1)
        kg_per_head = total_kg / heads
        return (kg_per_head / profile_mass_kg) * 100.0
    if derived in ("rnb", "bra_rnb"):
        return rnb(
            content_by_key.get("crude_protein"),
            content_by_key.get("usp"),
        )
    return None