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pragma solidity ^0.4.17;
contract Auction {
// Data
//Structure to hold details of the item
struct Item {
uint itemId; // id of the item
uint[] itemTokens; //tokens bid in favor of the item
}
//Structure to hold the details of a persons
struct Person {
uint remainingTokens; // tokens remaining with bidder
uint personId; // it serves as tokenId as well
address addr;//address of the bidder
}
mapping(address => Person) tokenDetails; //address to person
Person [4] bidders;//Array containing 4 person objects
Item [3] public items;//Array containing 3 item objects
address[3] public winners;//Array for address of winners
address public beneficiary;//owner of the smart contract
uint bidderCount=0;//counter
//functions
function Auction() public payable{ //constructor
//Part 1 Task 1. Initialize beneficiary with address of smart contract’s owner
//Hint. In the constructor,"msg.sender" is the address of the owner.
// ** Start code here. 1 line approximately. **/
beneficiary = msg.sender;
//** End code here. **/
uint[] memory emptyArray;
items[0] = Item({itemId:0,itemTokens:emptyArray});
//Part 1 Task 2. Initialize two items with at index 1 and 2.
// ** Start code here. 2 lines approximately. **/
items[1] = Item({itemId:1,itemTokens:emptyArray});
items[2] = Item({itemId:2,itemTokens:emptyArray});
//** End code here**/
}
function register() public payable{
bidders[bidderCount].personId = bidderCount;
//Part 1 Task 3. Initialize the address of the bidder
/*Hint. Here the bidders[bidderCount].addr should be initialized with address of the registrant.*/
// ** Start code here. 1 line approximately. **/
bidders[bidderCount].addr = msg.sender;
//** End code here. **
bidders[bidderCount].remainingTokens = 5; // only 5 tokens
tokenDetails[msg.sender]=bidders[bidderCount];
bidderCount++;
}
function bid(uint _itemId, uint _count) public payable{
/*
Bids tokens to a particular item.
Arguments:
_itemId -- uint, id of the item
_count -- uint, count of tokens to bid for the item
*/
/*
Part 1 Task 4. Implement the three conditions below.
4.1 If the number of tokens remaining with the bidder is < count of tokens bidded, revert.
4.2 If there are no tokens remaining with the bidder, r evert.
4.3 If the id of the item for which bid is placed, is greater than 2, revert.
Hint: "tokenDetails[msg.sender].remainingTokens" gives the details of the number of tokens remaining with the bidder.
*/
// ** Start code here. 2 lines approximately. **/
if(tokenDetails[msg.sender].remainingTokens < _count ||
tokenDetails[msg.sender].remainingTokens <= 0 ||
_itemId > 2){
revert();
}
//** End code here. **
/*Part 1 Task 5. Decrement the remainingTokens by the number of tokens bid and store the value in balance variable.
Hint. "tokenDetails[msg.sender].remainingTokens" should be decremented by "_count". */
// ** Start code here. 1 line approximately. **
uint balance= (tokenDetails[msg.sender].remainingTokens - _count);
//** End code here. **
tokenDetails[msg.sender].remainingTokens=balance;
bidders[tokenDetails[msg.sender].personId].remainingTokens=balance;//updating the same balance in bidders map.
Item storage bidItem = items[_itemId];
for(uint i=0; i<_count;i++) {
bidItem.itemTokens.push(tokenDetails[msg.sender].personId);
}
}
// Part 2 Task 1. Create a modifier named "onlyOwner" to ensure that only owner is allowed to reveal winners
//Hint : Use require to validate if "msg.sender" is equal to the "beneficiary".
modifier onlyOwner {
// ** Start code here. 2 lines approximately. **
require(msg.sender == beneficiary);
_;
//** End code here. **
}
function revealWinners() public onlyOwner{
/*
Iterate over all the items present in the auction.
If at least on person has placed a bid, randomly select the winner */
for (uint id = 0; id < 3; id++) {
Item storage currentItem=items[id];
if(currentItem.itemTokens.length != 0){
// generate random# from block number
uint randomIndex = (block.number / currentItem.itemTokens.length)% currentItem.itemTokens.length;
// Obtain the winning tokenId
uint winnerId = currentItem.itemTokens[randomIndex];
/* Part 1 Task 6. Assign the winners.
Hint." bidders[winnerId] " will give you the person object with the winnerId.
you need to assign the address of the person obtained above to winners[id] */
// ** Start coding here *** 1 line approximately.
winners[id] = bidders[winnerId].addr;
//** end code here*
}
}
}
//Miscellaneous methods: Below methods are used to assist Grading. Please DONOT CHANGE THEM.
function getPersonDetails(uint id) public constant returns(uint,uint,address){
return (bidders[id].remainingTokens,bidders[id].personId,bidders[id].addr);
}
}
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