<?php

namespace Home\Tool;

abstract class ACarTool{

    //向购物车添加一个商品

    abstract public function add($goods_id,$goods_name,$shop_price);

    //向购物车减少一个商品的数量，如果为0则删除

    abstract public function decr($goods_id);

    //从购物车删除某商品

    abstract public function del($goods_id);

    //列出购物车的所有东西

    abstract public function items();

    //返回购物车中有几种商品

    abstract public function calcType();

    //返回购物车中商品的个数

    abstract public function calcCnt();

    //返回购物车商品的总价格

    abstract public function calcMoney();

    //清空购物车

    abstract public function clear();

}

class AddTool extends ACarTool{

    //声明一个属性

    public $item = array();

    //单例模式

    public static $ins = null;

    public static function getIns(){

        if(self::$ins == null){

            self::$ins = new self();

        }

        return self::$ins;

    }

    final protected function __construct(){

        //session('?kache')检测是否存在session

        $this->item = session('?kache') ? session('kache') : array();

    }

    //向购物车添加一个商品

    public function add($goods_id,$goods_name,$shop_price){

        if($this->item[$goods_id]){

            $this->item[$goods_id]['num'] += 1;

        }else{

            $goods['goods_name'] = $goods_name;

        $goods['shop_price'] = $shop_price;

        $goods['num'] = 1;

        $this->item[$goods_id] = $goods;

        }

    }

    //减少购物车一个商品的数量，如果到0则删除此商品

    public function decr($goods_id){

        if($this->item[$goods_id]){

            $this->item[$goods_id]['num'] -= 1;

        }

        if($this->item[$goods_id]['num'] <=0){

            $this->del($goods_id);

        }

    }

    //从购物车删除某商品

    public function del($goods_id){

        unset($this->item[$goods_id]);

    }

    //列出购物车所有的商品

    public function items(){

        return $this->item;

    }

    //返回购物车有几种物品

    public function calcType(){

        return count($this->item);

    }

    //返回购物车商品的个数

    public function calcCnt(){

        $n = 0;

        foreach ($this->item as $k => $v) {

            $n +=$v['num'];

        }

        return $n;

    }

    //返回购物车的总价格

    public function calcMoney(){

        $n = 0;

        foreach ($this->item as $k => $v) {

            $n += $v['num'] * $v['shop_price'];

        }

        return $n;

    }

    //清空购物车

    public function clear(){

         $this->item = array();

    }

    public function __destruct(){

        session('kache',$this->item);

    }

}