package com.ruoyi.http.util;

import com.alibaba.fastjson2.JSONArray;

import java.math.BigDecimal;
import java.math.RoundingMode;

/**
 * 电量读数与倍率计算
 */
public final class StatisticEleReadingUtil {

    public static final int CONSUMPTION_SCALE = 4;

    private StatisticEleReadingUtil() {
    }

    public static BigDecimal firstReading(JSONArray arr) {
        if (arr == null || arr.isEmpty()) {
            return null;
        }
        return arr.getBigDecimal(0);
    }

    public static BigDecimal calcConsumption(BigDecimal prev, BigDecimal curr, Integer ratio) {
        if (prev == null || curr == null) {
            return null;
        }
        BigDecimal diff = curr.subtract(prev);
        return applyRatio(diff, ratio);
    }

    public static BigDecimal calcConsumptionFromRaw(BigDecimal raw, Integer ratio) {
        if (raw == null) {
            return null;
        }
        return applyRatio(raw, ratio);
    }

    public static BigDecimal applyRatio(BigDecimal value, Integer ratio) {
        if (value == null) {
            return null;
        }
        int r = ratio == null || ratio <= 0 ? 1 : ratio;
        return value.multiply(BigDecimal.valueOf(r)).setScale(CONSUMPTION_SCALE, RoundingMode.HALF_UP);
    }

    public static String formatReadingArray(JSONArray arr) {
        if (arr == null || arr.isEmpty()) {
            return "";
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < arr.size(); i++) {
            if (i > 0) {
                sb.append("/");
            }
            sb.append(arr.getDouble(i));
        }
        return sb.toString();
    }

    public static BigDecimal parseFirstReading(String reading) {
        if (reading == null || reading.isBlank()) {
            return null;
        }
        int idx = reading.indexOf('/');
        String first = idx > 0 ? reading.substring(0, idx) : reading;
        try {
            return new BigDecimal(first.trim());
        } catch (NumberFormatException e) {
            return null;
        }
    }
}