add: 增加优惠券分摊计算策略

src/Strategy/ShareWorker.php

+<?php
+
+namespace Api\PhpUtils\Strategy;
+
+class ShareWorker {
+
+    /**
+     * @param $items = ['sku_1'=>100, 'sku_2'=>85]
+     * @param $tip = 100
+     * @throws \ErrorException
+     * 根据商品价格等比做优惠金额的分摊, 做四舍五入。
+     */
+    public static function coupon($items, $total_tip) {
+
+        if(!is_array($items) || $total_tip <= 0) {
+            throw new \ErrorException('输入分摊条件失败，请确认', '3001');
+        }
+        $total = 0;
+        foreach ($items as $k=>$price) {
+            if(!is_int($price) || $price < 0) {
+                throw new \ErrorException('存在金额非法，请核对金额', '3002');
+            }
+            $total += $price;
+        }
+
+        $ret = [];
+
+        $cleared = $cleared_tip = 0;
+        foreach ($items as $k=>$price) {
+            $left = $total - $cleared;
+            $ret[$k] = intval(round($price/$left * ($total_tip - $cleared_tip)));
+
+            $cleared_tip += $ret[$k];
+            $cleared += $price;
+        }
+
+        return $ret;
+    }
+
+    /**
+     * @param $mutiArr = [
+                            ['goods'=>['a1'=>600, 'a2'=>100, 'a3'=>1300], 'tip'=>100],
+                            ['goods'=>['a1'=>600, 'a2'=>600, 'a3'=>600], 'tip'=>4],
+                        ];
+     * @return array = [
+                            ['a1' => 30, 'a2' => 5, 'a3' => 65],
+                            ['a1' => 1, 'a2' => 2, 'a3' => 1]
+                        ];
+     * @throws \ErrorException
+     * 批量计算奖励，
+     */
+    public static function batchCoupon($mutiArr) {
+
+        $ret = [];
+        foreach ($mutiArr as $k=>$item) {
+            $ret[$k] = self::coupon($item['goods'], $item['tip']);
+        }
+        return $ret;
+    }
+}
+
+