package com.example.pdaplccontrol;

import java.math.BigDecimal;

final class WeightInputParser {

    private static final BigDecimal GRAMS_PER_KG = new BigDecimal("1000");

    private WeightInputParser() {
    }

    static short kgToGrams(String input) {
        if (input == null || input.trim().isEmpty()) {
            throw new IllegalArgumentException("请输入重量");
        }

        BigDecimal kg;
        try {
            kg = new BigDecimal(input.trim());
        } catch (NumberFormatException e) {
            throw new IllegalArgumentException("重量格式不正确");
        }

        BigDecimal grams = kg.movePointRight(3).stripTrailingZeros();
        if (kg.compareTo(BigDecimal.ZERO) < 0
                || grams.compareTo(BigDecimal.valueOf(PlcConfig.MAX_WEIGHT_GRAMS)) > 0) {
            throw new IllegalArgumentException("重量范围为 0-30kg");
        }

        try {
            return grams.shortValueExact();
        } catch (ArithmeticException e) {
            throw new IllegalArgumentException("重量最多精确到 0.001kg");
        }
    }
}