E-commerce Payment

retail.sol

pragma solidity ^0.4.2;
contract retail {

     address public admin;
     uint public count=0;
    
    // a constructor to set the admin i.e the person who deploys the contract 
    function retail() {
       admin= msg.sender;
   }
   
   // A struct of a Item 
     struct  itemstruct {
        string itemname;
        address itemowner;
        uint itemprice;
        uint itemid;
        bool isSold;
    }
    
    mapping(uint => itemstruct) public itemStructs; // mapping the itemId with itemStruct
    uint[] public itemList;  //list of Items
    
    // A function to add a Item in the store
    function addItem(string _itemname,uint _itemprice)public returns (string){
        if(msg.sender!=admin) {throw;}
        count = count+1;
        itemStructs[count].itemname =_itemname;
        itemStructs[count].itemowner =msg.sender;
        itemStructs[count].itemprice =_itemprice;
        itemStructs[count].itemid =count;
        itemStructs[count].isSold =false;
        itemList.push(count);
        return ("successfully added item");
    }
    

     // A function to get a particular item by Id
      function getItem(uint itemId) public constant returns(string,address,uint,bool){
        return (itemStructs[itemId].itemname,itemStructs[itemId].itemowner,itemStructs[itemId].itemprice,itemStructs[itemId].isSold);
    }
    
    // A function to get the count of items in the list
    function getItemCount() public constant returns(uint itemCount){
        return itemList.length;
    }
    
    // A function to update items in the list
    function updateItem(uint itemId,string _itemname,uint _itemprice) public returns(string) {
    if(msg.sender!=admin) throw;    
    itemStructs[itemId].itemname    = _itemname;
    itemStructs[itemId].itemprice    = _itemprice;
    return ("updated successfully");
    }
    
    // A function to update the itemprice alone
    //this method will override updateItem
    function updateItem(uint itemId,uint _itemprice) public returns(string) {
    if(msg.sender!=admin) throw;    
    itemStructs[itemId].itemprice    = _itemprice;
    return ("updated successfully");
    }
    
    // A function to update the item name alone
    //this method will override updateItem
    function updateItem(uint itemId,string _itemname) public returns(string) {
    if(msg.sender!=admin) throw;    
    itemStructs[itemId].itemname    = _itemname;
    return ("updated successfully");
    }
  
    // a function to buy an Item 
    function buyItem(uint itemId) payable public returns (string) {
            if(itemStructs[itemId].isSold==true) throw; else {
            if(msg.value==itemStructs[itemId].itemprice) {    
            require(itemId >= 0 && itemId <= count);
            itemStructs[itemId].itemowner = msg.sender;
            itemStructs[itemId].isSold = true;
            return ("Item purchased"); }
            else { 
                 msg.sender.transfer(msg.value);
                 throw;
                }
         }     
    }
    
    // A function to check whether a product is sold 
    function isSold(uint itemId) public constant returns (bool){
        return itemStructs[itemId].isSold; 
    }
    
    // a function to get the item list
    function getItemList() public constant returns (uint[]){
        return itemList;
    }
    
    // A function to check the sender 
    function sender() public constant returns(address){
        return msg.sender;
    }
    
}