EliteKnight

Ballot

pragma solidity ^0.4.4;

contract Ballot {
    struct Voter {
      uint weight; // weight is accumulated by delegation
      bool voted;  // if true, that person already voted
      address delegate; // person delegated to
      uint vote;   // index of the voted proposal
    }

    struct Proposal
    {
      bytes32 name;   // short name (up to 32 bytes)
      uint voteCount; // number of accumulated votes
    }

    address public chairperson;
    mapping(address => Voter) public voters;
    Proposal[] public proposals;

    function Ballot(bytes32[] proposalNames) {
      chairperson = msg.sender;
      voters[chairperson].weight = 1;

      for (uint i = 0; i < proposalNames.length; i++) {
        proposals.push(Proposal({
          name: proposalNames[i],
          voteCount: 0
        }));
      }
    }

    function giveRightToVote(address voter) {
      if (msg.sender != chairperson || voters[voter].voted) {
        throw;
      }
      voters[voter].weight = 1;
    }

    function delegate(address to) {
      Voter sender = voters[msg.sender];
      if (sender.voted)
        throw;

      while (
        voters[to].delegate != address(0) &&
        voters[to].delegate != msg.sender
      ) {
        to = voters[to].delegate;
      }

      if (to == msg.sender) {
        throw;
      }

      sender.voted = true;
      sender.delegate = to;
      Voter delegate = voters[to];
      if (delegate.voted) {
        proposals[delegate.vote].voteCount += sender.weight;
      } else {
        delegate.weight += sender.weight;
      }
    }

    function vote(uint proposal) {
      Voter sender = voters[msg.sender];
      if (sender.voted)
          throw;
      sender.voted = true;
      sender.vote = proposal;

      proposals[proposal].voteCount += sender.weight;
    }

    function winningProposal() constant
            returns (uint winningProposal)
    {
      uint winningVoteCount = 0;
      for (uint p = 0; p < proposals.length; p++) {
        if (proposals[p].voteCount > winningVoteCount) {
          winningVoteCount = proposals[p].voteCount;
          winningProposal = p;
        }
      }
    }

    function winnerName() constant
            returns (bytes32 winnerName)
    {
      winnerName = proposals[winningProposal()].name;
    }
}