147 lines
3.9 KiB
PHP
147 lines
3.9 KiB
PHP
<?php
|
||
|
||
namespace app\api\service\bargain;
|
||
|
||
class Amount
|
||
{
|
||
/**
|
||
* 砍价金额
|
||
*
|
||
* @var float
|
||
*/
|
||
protected $amount;
|
||
|
||
/**
|
||
* 砍价人数
|
||
*
|
||
* @var int
|
||
*/
|
||
protected $num;
|
||
|
||
/**
|
||
* 砍价的最小金额
|
||
*
|
||
* @var float
|
||
*/
|
||
protected $coupon_min;
|
||
|
||
/**
|
||
* 砍价分配结果
|
||
*
|
||
* @var array
|
||
*/
|
||
protected $items = [];
|
||
|
||
/**
|
||
* 初始化
|
||
* @param float $amount 砍价金额（单位：元）最多保留2位小数
|
||
* @param int $num 砍价个数
|
||
* @param float $coupon_min 每个至少领取的砍价金额
|
||
*/
|
||
public function __construct($amount, $num = 1, $coupon_min = 0.01)
|
||
{
|
||
$this->amount = $amount;
|
||
$this->num = $num;
|
||
$this->coupon_min = $coupon_min;
|
||
}
|
||
|
||
/**
|
||
* 处理返回
|
||
* @return array
|
||
* @throws \Exception
|
||
*/
|
||
public function handle()
|
||
{
|
||
// A. 验证
|
||
if ($this->amount < $validAmount = $this->coupon_min * $this->num) {
|
||
throw new \Exception('砍价总金额必须≥' . $validAmount . '元');
|
||
}
|
||
// B. 分配砍价
|
||
$this->apportion();
|
||
return [
|
||
'items' => $this->items,
|
||
];
|
||
}
|
||
|
||
/**
|
||
* 分配砍价
|
||
*/
|
||
protected function apportion()
|
||
{
|
||
$num = $this->num; // 剩余可分配的砍价个数
|
||
$amount = $this->amount; //剩余可领取的砍价金额
|
||
while ($num >= 1) {
|
||
// 剩余一个的时候，直接取剩余砍价
|
||
if ($num == 1) {
|
||
$coupon_amount = $this->decimal_number($amount);
|
||
} else {
|
||
$avg_amount = $this->decimal_number($amount / $num); // 剩余的砍价的平均金额
|
||
$coupon_amount = $this->decimal_number(
|
||
$this->calcCouponAmount($avg_amount, $amount, $num)
|
||
);
|
||
}
|
||
$this->items[] = $coupon_amount; // 追加分配
|
||
$amount -= $coupon_amount;
|
||
--$num;
|
||
}
|
||
shuffle($this->items); // 随机打乱
|
||
}
|
||
|
||
/**
|
||
* 计算分配的砍价金额
|
||
* @param float $avg_amount 每次计算的平均金额
|
||
* @param float $amount 剩余可领取金额
|
||
* @param int $num 剩余可领取的砍价个数
|
||
*
|
||
* @return float
|
||
*/
|
||
protected function calcCouponAmount($avg_amount, $amount, $num)
|
||
{
|
||
// 如果平均金额小于等于最低金额，则直接返回最低金额
|
||
if ($avg_amount <= $this->coupon_min) {
|
||
return $this->coupon_min;
|
||
}
|
||
// 浮动计算
|
||
$coupon_amount = $this->decimal_number($avg_amount * (1 + $this->apportionRandRatio()));
|
||
// 如果低于最低金额或超过可领取的最大金额，则重新获取
|
||
if ($coupon_amount < $this->coupon_min
|
||
|| $coupon_amount > $this->calcCouponAmountMax($amount, $num)
|
||
) {
|
||
return $this->calcCouponAmount($avg_amount, $amount, $num);
|
||
}
|
||
return $coupon_amount;
|
||
}
|
||
|
||
/**
|
||
* 计算分配的砍价金额-可领取的最大金额
|
||
* @param $amount
|
||
* @param $num
|
||
* @return float|int
|
||
*/
|
||
protected function calcCouponAmountMax($amount, $num)
|
||
{
|
||
return $this->coupon_min + $amount - $num * $this->coupon_min;
|
||
}
|
||
|
||
/**
|
||
* 砍价金额浮动比例
|
||
*/
|
||
protected function apportionRandRatio()
|
||
{
|
||
// 60%机率获取剩余平均值的大幅度砍价（可能正数、可能负数）
|
||
if (rand(1, 100) <= 60) {
|
||
return rand(-70, 70) / 100; // 上下幅度70%
|
||
}
|
||
return rand(-30, 30) / 100; // 其他情况，上下浮动30%；
|
||
}
|
||
|
||
/**
|
||
* 格式化金额，保留2位
|
||
* @param float $amount
|
||
* @return float
|
||
*/
|
||
protected function decimal_number($amount)
|
||
{
|
||
return sprintf('%01.2f', round($amount, 2));
|
||
}
|
||
} |