"""Unitati de masa, normalizare si conversii.

Etichetele de produs finit sunt exprimate de obicei in grame, iar cantarul
poate raporta kilograme. Toate cantaririle sunt convertite in unitatea retetei
inainte de a fi salvate.
"""
from __future__ import annotations

from typing import Optional

# Unitati acceptate, in ordinea afisata in interfata.
UNITS: tuple[str, ...] = ("g", "kg", "mg", "t", "lb", "oz")

GRAMS_PER: dict[str, float] = {
    "g": 1.0,
    "kg": 1000.0,
    "mg": 0.001,
    "t": 1_000_000.0,
    "lb": 453.59237,
    "oz": 28.349523125,
}

ALIASES: dict[str, str] = {
    "gr": "g", "gram": "g", "grame": "g", "grams": "g",
    "kg": "kg", "kgs": "kg", "kilogram": "kg", "kilograme": "kg",
    "mg": "mg", "miligram": "mg", "miligrame": "mg",
    "t": "t", "tona": "t", "ton": "t", "to": "t",
    "lb": "lb", "lbs": "lb", "pound": "lb",
    "oz": "oz", "ounce": "oz",
}


def normalize_unit(value: object, default: str = "g") -> str:
    text = str(value or "").strip().lower()
    if not text:
        return default
    return ALIASES.get(text, text if text in GRAMS_PER else default)


def convert(value: float, from_unit: str, to_unit: str) -> Optional[float]:
    """Converteste intre unitati de masa; None daca una nu este unitate de masa."""
    source = GRAMS_PER.get(from_unit)
    target = GRAMS_PER.get(to_unit)
    if source is None or target is None:
        return None
    return value * source / target


def format_weight(value: object, decimals: int = 3) -> str:
    """Formatare pentru etichete: fara zerouri finale inutile."""
    try:
        number = float(value)  # type: ignore[arg-type]
    except (TypeError, ValueError):
        return str(value)
    text = f"{number:.{int(decimals)}f}"
    if "." in text:
        text = text.rstrip("0").rstrip(".")
    return text or "0"