PizzaStore.sol

pragma solidity ^0.4.24;


contract PizzaStore {
    uint constant SLICE_PRICE_IN_ETH = 1e17;
    uint constant SLICE_PRICE_IN_TOKEN = 1e19;
    
    ERC20Interface constant PIZZA_TOKEN = ERC20Interface(0xdd974D5C2e2928deA5F71b9825b8b646686BD200);
    
    event ProofOfPayment(address _beneficiary, address _token, uint _amount, bytes32 _data);
    
    function buyPizzaWithEther(uint _slices, address _beneficiary, string _homeAddress) public payable {
        require(msg.value == _slices * SLICE_PRICE_IN_ETH);

        bytes32 data = keccak256(abi.encodePacked(_slices,_homeAddress));
        
        emit ProofOfPayment(_beneficiary,0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE,msg.value,data);
    }
    
    function buyPizzaWithToken(uint _slices, address _beneficiary, string _homeAddress) public {
        require(PIZZA_TOKEN.transferFrom(msg.sender,this,_slices * SLICE_PRICE_IN_TOKEN));

        bytes32 data = keccak256(abi.encodePacked(_slices,_homeAddress));
        
        emit ProofOfPayment(_beneficiary,PIZZA_TOKEN,_slices * SLICE_PRICE_IN_TOKEN,data);
    }    
}



contract ERC20Interface {
     function totalSupply() public view returns (uint);
     function balanceOf(address tokenOwner) public view returns (uint balance);
     function allowance(address tokenOwner, address spender) public view returns (uint remaining);
     function transfer(address to, uint tokens) public returns (bool success);
     function approve(address spender, uint tokens) public returns (bool success);
     function transferFrom(address from, address to, uint tokens) public returns (bool success);
 
     event Transfer(address indexed from, address indexed to, uint tokens);
     event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
}