<?php

class RedPacket
{
    /**
     * @param float $rmb 红包总金额
     * @param int $num 红包合适
     * @param int $kind int 0 随机 1平均
     * @param int $max  最大红包金额
     * @return array|bool
     */
    public static function create($rmb, $num, $kind = 0, $max = 0)
    {
        if ($num < 2) $kind = 1;
        $min = 0.01;//最小金额
        $packets = [];
        switch ($kind) {
            case 1://固定金额红包
                $money = sprintf("%.2f", $rmb / $num);
                for ($i = 1; $i <= $num; $i++) {
                    $packets[] = $money;
                }
                return $packets;
            default://随机红包
                if ($min * $num > $rmb) {
                    return false;
                }
                if ($num * $max < $rmb || $max + $num * $min > $rmb) {//验证最大红包金额是否正确
                    $max = $rmb / 3;
                }

                while ($num >= 1) {
                    $num--;
                    $kMin = max($min, $rmb - $num * $max);
                    $kMax = min($max, $rmb - $num * $min);
                    $kAvg = $rmb / ($num + 1);
                    //获取最大值和最小值的距离之间的最小值
                    $kDis = min($kAvg - $kMin, $kMax - $kAvg);
                    //获取0到1之间的随机数与距离最小值相乘得出浮动区间，这使得浮动区间不会超出范围
                    $r = ((float)(rand(1, 10000) / 10000) - 0.5) * $kDis * 2;
                    $k = sprintf("%.2f", $kAvg + $r);
                    $rmb -= $k;
                    $packets[] = $k;
                }

                shuffle($packets);
                return $packets;
        }
    }
}