import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'dart:convert';
import '../model/cartInfo.dart';class CartProvide with ChangeNotifier{String cartString="[]";//声明一个变量 做持久化的存储List<CartInfoModel> cartList=[];double allPrice = 0;//总价格int allGoodsCount = 0;//商品总数bool isAllCheck=true;//全选 默认true//声明一个异步的方法,购物车操作放在前台不在请求后台的数据save(goodsId,goodsName,count,price,images) async {SharedPreferences prefs = await SharedPreferences.getInstance();cartString= prefs.getString('cartInfo');//先从持久化中获取var temp = cartString==null?[]:json.decode(cartString.toString());//声明list 强制类型是MapList<Map> tempList=(temp as List).cast();//把temp转成listbool isHave=false;//是否已经存在了这条记录int ival=0;//foreach循环的索引//循环判断列表是否存在该goodsId的商品，如果有就数量+1
    tempList.forEach((item){if(item['goodsId']==goodsId){tempList[ival]['count']=item['count']+1;cartList[ival].count++;isHave=true;}ival++;});//没有不存在这个商品，就把商品的json数据加入的tempList中if(!isHave){Map<String,dynamic> newGoods={'goodsId':goodsId,//传入进来的值'goodsName':goodsName,'count':count,'price':price,'images':images,'isCheck':true};tempList.add(newGoods);cartList.add(CartInfoModel.fromJson(newGoods));}cartString=json.encode(tempList).toString();//json数据转字符串// print('字符串》》》》》》》》》》》${cartString}');// print('字符串》》》》》》》》》》》${cartList}');
prefs.setString('cartInfo', cartString);notifyListeners();}remove() async{SharedPreferences prefs=await SharedPreferences.getInstance();prefs.remove('cartInfo');cartList=[];print('清空完成----------------------');notifyListeners();}getCartInfo() async{SharedPreferences prefs=await SharedPreferences.getInstance();cartString=prefs.getString('cartInfo');//持久化中获得字符串print('购物车持久化的数据================>'+cartString);cartList=[];//把最终的结果先设置为空listif(cartString==null){cartList=[];//如果持久化内没有数据 那么就还是空的list}else{//声明临时的变量List<Map> tempList=(json.decode(cartString.toString()) as List).cast();allPrice=0;//价格先初始化为0allGoodsCount=0;//数量先初始化为0isAllCheck=true;//循环之前初始化一下
      tempList.forEach((item){if(item['isCheck']){allPrice+=(item['count']*item['price']);allGoodsCount +=item['count'];}else{isAllCheck=false;}cartList.add(CartInfoModel.fromJson(item));//json转成对象，加入到cartList中
      });}notifyListeners();//通知
  }//删除单个购物车商品deleteOneGoods(String goodsId) async{SharedPreferences prefs=await SharedPreferences.getInstance();cartString=prefs.getString('cartInfo');List<Map> tempList=(json.decode(cartString.toString()) as List).cast();int tempIndex=0;//定义循环的索引int deleteIndex=0;//要删除的索引
    tempList.forEach((item){if(item['goodsId']==goodsId){deleteIndex=tempIndex;}tempIndex++;});tempList.removeAt(deleteIndex);//删除//删除后转换成string进行持久化cartString=json.encode(tempList).toString();//list转字符串prefs.setString('cartInfo', cartString);await getCartInfo();//重新获取下列表数据，因为getCartInfo方法里面有通知，这里就不再调用了
  }changeCheckState(CartInfoModel cartItem) async{SharedPreferences prefs=await SharedPreferences.getInstance();cartString=prefs.getString('cartInfo');List<Map> tempList=(json.decode(cartString.toString()) as List).cast();int tempIndx=0;//历史索引int changeIndex=0;//改变的索引
    tempList.forEach((item){if(item['goodsId']==cartItem.goodsId){changeIndex=tempIndx;}tempIndx++;});tempList[changeIndex]=cartItem.toJson();//toJson就变成了Map值cartString=json.encode(tempList).toString();prefs.setString('cartInfo', cartString);await getCartInfo();//再次重新获取购物车的数据
  }//点击全选按钮操作changeAllCheckBtnState(bool isCheck) async{SharedPreferences prefs=await SharedPreferences.getInstance();cartString=prefs.getString('cartInfo');List<Map> tempList=(json.decode(cartString.toString()) as List).cast();List<Map> newList=[];//这里必须初始化为[]声明为一个空的值for(var item in tempList){//dart在循环的时候是不允许改变老的值的var newItem=item;//把老的item赋值给新的itemnewItem['isCheck']=isCheck;newList.add(newItem);}cartString=json.encode(newList).toString();prefs.setString('cartInfo', cartString);await getCartInfo();//最后中心获取一下购物车的列表数据
  }}

import 'package:flutter/material.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';
import 'package:provide/provide.dart';
import '../../provide/cart.dart';class CartBottom extends StatelessWidget {@overrideWidget build(BuildContext context) {return Container(padding: EdgeInsets.all(5.0),color: Colors.white,child: Provide<CartProvide>(builder: (context,child,val){return Row(children: <Widget>[_selectAllBtn(context),_allPriceArea(context),_goButton(context)],);}));}//全选
  Widget _selectAllBtn(context){bool isAllCheck=Provide.value<CartProvide>(context).isAllCheck;return Container(child: Row(children: <Widget>[Checkbox(value: isAllCheck,activeColor: Colors.pink,//激活的颜色onChanged: (bool val){Provide.value<CartProvide>(context).changeAllCheckBtnState(val);},//事件
          ),Text('全选')],),);}//合计
  Widget _allPriceArea(context){double allPrice = Provide.value<CartProvide>(context).allPrice;return Container(width: ScreenUtil().setWidth(430),child: Column(children: <Widget>[Row(children: <Widget>[Container(alignment: Alignment.centerRight,width: ScreenUtil().setWidth(280),child: Text('合计：',style:TextStyle(fontSize:ScreenUtil().setSp(36))),),//红色的价格
              Container(alignment: Alignment.centerLeft,width: ScreenUtil().setWidth(150),child: Text('${allPrice}',style: TextStyle(fontSize: ScreenUtil().setSp(36),color: Colors.red)),)],),//第二行
          Container(width: ScreenUtil().setWidth(430),//和第一行一样宽
            alignment: Alignment.centerRight,child: Text('满10元免配送费,预购免配送费',style: TextStyle(color: Colors.black38,fontSize: ScreenUtil().setSp(22)),),)],),);}//结算 用 inkWell
  Widget _goButton(context){int allGoodsCount= Provide.value<CartProvide>(context).allGoodsCount;return Container(width: ScreenUtil().setWidth(160),padding: EdgeInsets.only(left:10.0),child: InkWell(onTap: (){},child: Container(padding: EdgeInsets.all(10.0),alignment: Alignment.center,//居中对齐
          decoration: BoxDecoration(color: Colors.red,borderRadius: BorderRadius.circular(3.0)//圆角
          ),child: Text('结算(${allGoodsCount})',style: TextStyle(color: Colors.white),),),),);}
}