contract PLCRVoting {

    // ============
    // EVENTS:
    // ============

    event _VoteCommitted(uint indexed pollID, uint numTokens, address indexed voter);
    event _VoteRevealed(uint indexed pollID, uint numTokens, uint votesFor, uint votesAgainst, uint indexed choice, address indexed voter);
    event _PollCreated(uint voteQuorum, uint commitEndDate, uint revealEndDate, uint indexed pollID, address indexed creator);
    event _VotingRightsGranted(uint numTokens, address indexed voter);
    event _VotingRightsWithdrawn(uint numTokens, address indexed voter);
    event _TokensRescued(uint indexed pollID, address indexed voter);

    // ============
    // DATA STRUCTURES:
    // ============

    using AttributeStore for AttributeStore.Data;
    using DLL for DLL.Data;
    using SafeMath for uint;

    struct Poll {
        uint commitEndDate;     /// expiration date of commit period for poll
        uint revealEndDate;     /// expiration date of reveal period for poll
        uint voteQuorum;	    /// number of votes required for a proposal to pass
        uint votesFor;		    /// tally of votes supporting proposal
        uint votesAgainst;      /// tally of votes countering proposal
        mapping(address => bool) didCommit;  /// indicates whether an address committed a vote for this poll
        mapping(address => bool) didReveal;   /// indicates whether an address revealed a vote for this poll
    }

    // ============
    // STATE VARIABLES:
    // ============

    uint constant public INITIAL_POLL_NONCE = 0;
    uint public pollNonce;

    mapping(uint => Poll) public pollMap; // maps pollID to Poll struct
    mapping(address => uint) public voteTokenBalance; // maps user's address to voteToken balance

    mapping(address => DLL.Data) dllMap;
    AttributeStore.Data store;

    EIP20Interface public token;

    // ============
    // CONSTRUCTOR:
    // ============

    /**
    @dev Initializes voteQuorum, commitDuration, revealDuration, and pollNonce in addition to token contract and trusted mapping
    @param _tokenAddr The address where the ERC20 token contract is deployed
    */
    function PLCRVoting(address _tokenAddr) public {
        token = EIP20Interface(_tokenAddr);
        pollNonce = INITIAL_POLL_NONCE;
    }

    // ================
    // TOKEN INTERFACE:
    // ================

    /**
    @notice Loads _numTokens ERC20 tokens into the voting contract for one-to-one voting rights
    @dev Assumes that msg.sender has approved voting contract to spend on their behalf
    @param _numTokens The number of votingTokens desired in exchange for ERC20 tokens
    */
    function requestVotingRights(uint _numTokens) external {
        require(token.balanceOf(msg.sender) >= _numTokens);
        voteTokenBalance[msg.sender] += _numTokens;
        require(token.transferFrom(msg.sender, this, _numTokens));
        _VotingRightsGranted(_numTokens, msg.sender);
    }

    /**
    @notice Withdraw _numTokens ERC20 tokens from the voting contract, revoking these voting rights
    @param _numTokens The number of ERC20 tokens desired in exchange for voting rights
    */
    function withdrawVotingRights(uint _numTokens) external {
        uint availableTokens = voteTokenBalance[msg.sender].sub(getLockedTokens(msg.sender));
        require(availableTokens >= _numTokens);
        voteTokenBalance[msg.sender] -= _numTokens;
        require(token.transfer(msg.sender, _numTokens));
        _VotingRightsWithdrawn(_numTokens, msg.sender);
    }

    /**
    @dev Unlocks tokens locked in unrevealed vote where poll has ended
    @param _pollID Integer identifier associated with the target poll
    */
    function rescueTokens(uint _pollID) external {
        require(isExpired(pollMap[_pollID].revealEndDate));
        require(dllMap[msg.sender].contains(_pollID));

        dllMap[msg.sender].remove(_pollID);
        _TokensRescued(_pollID, msg.sender);
    }

    // =================
    // VOTING INTERFACE:
    // =================

    /**
    @notice Commits vote using hash of choice and secret salt to conceal vote until reveal
    @param _pollID Integer identifier associated with target poll
    @param _secretHash Commit keccak256 hash of voter's choice and salt (tightly packed in this order)
    @param _numTokens The number of tokens to be committed towards the target poll
    @param _prevPollID The ID of the poll that the user has voted the maximum number of tokens in which is still less than or equal to numTokens
    */
    function commitVote(uint _pollID, bytes32 _secretHash, uint _numTokens, uint _prevPollID) external {
        require(commitPeriodActive(_pollID));
        require(voteTokenBalance[msg.sender] >= _numTokens); // prevent user from overspending
        require(_pollID != 0);                // prevent user from committing to zero node placeholder

        // Check if _prevPollID exists in the user's DLL or if _prevPollID is 0
        require(_prevPollID == 0 || dllMap[msg.sender].contains(_prevPollID));

        uint nextPollID = dllMap[msg.sender].getNext(_prevPollID);

        // if nextPollID is equal to _pollID, _pollID is being updated,
        nextPollID = (nextPollID == _pollID) ? dllMap[msg.sender].getNext(_pollID) : nextPollID;

        require(validPosition(_prevPollID, nextPollID, msg.sender, _numTokens));
        dllMap[msg.sender].insert(_prevPollID, _pollID, nextPollID);

        bytes32 UUID = attrUUID(msg.sender, _pollID);

        store.setAttribute(UUID, "numTokens", _numTokens);
        store.setAttribute(UUID, "commitHash", uint(_secretHash));

        pollMap[_pollID].didCommit[msg.sender] = true;
        _VoteCommitted(_pollID, _numTokens, msg.sender);
    }

    /**
    @dev Compares previous and next poll's committed tokens for sorting purposes
    @param _prevID Integer identifier associated with previous poll in sorted order
    @param _nextID Integer identifier associated with next poll in sorted order
    @param _voter Address of user to check DLL position for
    @param _numTokens The number of tokens to be committed towards the poll (used for sorting)
    @return valid Boolean indication of if the specified position maintains the sort
    */
    function validPosition(uint _prevID, uint _nextID, address _voter, uint _numTokens) public constant returns (bool valid) {
        bool prevValid = (_numTokens >= getNumTokens(_voter, _prevID));
        // if next is zero node, _numTokens does not need to be greater
        bool nextValid = (_numTokens <= getNumTokens(_voter, _nextID) || _nextID == 0);
        return prevValid && nextValid;
    }

    /**
    @notice Reveals vote with choice and secret salt used in generating commitHash to attribute committed tokens
    @param _pollID Integer identifier associated with target poll
    @param _voteOption Vote choice used to generate commitHash for associated poll
    @param _salt Secret number used to generate commitHash for associated poll
    */
    function revealVote(uint _pollID, uint _voteOption, uint _salt) external {
        // Make sure the reveal period is active
        require(revealPeriodActive(_pollID));
        require(pollMap[_pollID].didCommit[msg.sender]);                         // make sure user has committed a vote for this poll
        require(!pollMap[_pollID].didReveal[msg.sender]);                        // prevent user from revealing multiple times
        require(keccak256(_voteOption, _salt) == getCommitHash(msg.sender, _pollID)); // compare resultant hash from inputs to original commitHash

        uint numTokens = getNumTokens(msg.sender, _pollID);

        if (_voteOption == 1) {// apply numTokens to appropriate poll choice
            pollMap[_pollID].votesFor += numTokens;
        } else {
            pollMap[_pollID].votesAgainst += numTokens;
        }

        dllMap[msg.sender].remove(_pollID); // remove the node referring to this vote upon reveal
        pollMap[_pollID].didReveal[msg.sender] = true;

        _VoteRevealed(_pollID, numTokens, pollMap[_pollID].votesFor, pollMap[_pollID].votesAgainst, _voteOption, msg.sender);
    }

    /**
    @param _pollID Integer identifier associated with target poll
    @param _salt Arbitrarily chosen integer used to generate secretHash
    @return correctVotes Number of tokens voted for winning option
    */
    function getNumPassingTokens(address _voter, uint _pollID, uint _salt) public constant returns (uint correctVotes) {
        require(pollEnded(_pollID));
        require(pollMap[_pollID].didReveal[_voter]);

        uint winningChoice = isPassed(_pollID) ? 1 : 0;
        bytes32 winnerHash = keccak256(winningChoice, _salt);
        bytes32 commitHash = getCommitHash(_voter, _pollID);

        require(winnerHash == commitHash);

        return getNumTokens(_voter, _pollID);
    }

    // ==================
    // POLLING INTERFACE:
    // ==================

    /**
    @dev Initiates a poll with canonical configured parameters at pollID emitted by PollCreated event
    @param _voteQuorum Type of majority (out of 100) that is necessary for poll to be successful
    @param _commitDuration Length of desired commit period in seconds
    @param _revealDuration Length of desired reveal period in seconds
    */
    function startPoll(uint _voteQuorum, uint _commitDuration, uint _revealDuration) public returns (uint pollID) {
        pollNonce = pollNonce + 1;

        uint commitEndDate = block.timestamp.add(_commitDuration);
        uint revealEndDate = commitEndDate.add(_revealDuration);

        pollMap[pollNonce] = Poll({
            voteQuorum: _voteQuorum,
            commitEndDate: commitEndDate,
            revealEndDate: revealEndDate,
            votesFor: 0,
            votesAgainst: 0
        });

        _PollCreated(_voteQuorum, commitEndDate, revealEndDate, pollNonce, msg.sender);
        return pollNonce;
    }

    /**
    @notice Determines if proposal has passed
    @dev Check if votesFor out of totalVotes exceeds votesQuorum (requires pollEnded)
    @param _pollID Integer identifier associated with target poll
    */
    function isPassed(uint _pollID) constant public returns (bool passed) {
        require(pollEnded(_pollID));

        Poll memory poll = pollMap[_pollID];
        return (100 * poll.votesFor) > (poll.voteQuorum * (poll.votesFor + poll.votesAgainst));
    }

    // ----------------
    // POLLING HELPERS:
    // ----------------

    /**
    @dev Gets the total winning votes for reward distribution purposes
    @param _pollID Integer identifier associated with target poll
    @return Total number of votes committed to the winning option for specified poll
    */
    function getTotalNumberOfTokensForWinningOption(uint _pollID) constant public returns (uint numTokens) {
        require(pollEnded(_pollID));

        if (isPassed(_pollID))
            return pollMap[_pollID].votesFor;
        else
            return pollMap[_pollID].votesAgainst;
    }

    /**
    @notice Determines if poll is over
    @dev Checks isExpired for specified poll's revealEndDate
    @return Boolean indication of whether polling period is over
    */
    function pollEnded(uint _pollID) constant public returns (bool ended) {
        require(pollExists(_pollID));

        return isExpired(pollMap[_pollID].revealEndDate);
    }

    /**
    @notice Checks if the commit period is still active for the specified poll
    @dev Checks isExpired for the specified poll's commitEndDate
    @param _pollID Integer identifier associated with target poll
    @return Boolean indication of isCommitPeriodActive for target poll
    */
    function commitPeriodActive(uint _pollID) constant public returns (bool active) {
        require(pollExists(_pollID));

        return !isExpired(pollMap[_pollID].commitEndDate);
    }

    /**
    @notice Checks if the reveal period is still active for the specified poll
    @dev Checks isExpired for the specified poll's revealEndDate
    @param _pollID Integer identifier associated with target poll
    */
    function revealPeriodActive(uint _pollID) constant public returns (bool active) {
        require(pollExists(_pollID));

        return !isExpired(pollMap[_pollID].revealEndDate) && !commitPeriodActive(_pollID);
    }

    /**
    @dev Checks if user has committed for specified poll
    @param _voter Address of user to check against
    @param _pollID Integer identifier associated with target poll
    @return Boolean indication of whether user has committed
    */
    function didCommit(address _voter, uint _pollID) constant public returns (bool committed) {
        require(pollExists(_pollID));

        return pollMap[_pollID].didCommit[_voter];
    }

    /**
    @dev Checks if user has revealed for specified poll
    @param _voter Address of user to check against
    @param _pollID Integer identifier associated with target poll
    @return Boolean indication of whether user has revealed
    */
    function didReveal(address _voter, uint _pollID) constant public returns (bool revealed) {
        require(pollExists(_pollID));

        return pollMap[_pollID].didReveal[_voter];
    }

    /**
    @dev Checks if a poll exists
    @param _pollID The pollID whose existance is to be evaluated.
    @return Boolean Indicates whether a poll exists for the provided pollID
    */
    function pollExists(uint _pollID) constant public returns (bool exists) {
        return (_pollID != 0 && _pollID <= pollNonce);
    }

    // ---------------------------
    // DOUBLE-LINKED-LIST HELPERS:
    // ---------------------------

    /**
    @dev Gets the bytes32 commitHash property of target poll
    @param _voter Address of user to check against
    @param _pollID Integer identifier associated with target poll
    @return Bytes32 hash property attached to target poll
    */
    function getCommitHash(address _voter, uint _pollID) constant public returns (bytes32 commitHash) {
        return bytes32(store.getAttribute(attrUUID(_voter, _pollID), "commitHash"));
    }

    /**
    @dev Wrapper for getAttribute with attrName="numTokens"
    @param _voter Address of user to check against
    @param _pollID Integer identifier associated with target poll
    @return Number of tokens committed to poll in sorted poll-linked-list
    */
    function getNumTokens(address _voter, uint _pollID) constant public returns (uint numTokens) {
        return store.getAttribute(attrUUID(_voter, _pollID), "numTokens");
    }

    /**
    @dev Gets top element of sorted poll-linked-list
    @param _voter Address of user to check against
    @return Integer identifier to poll with maximum number of tokens committed to it
    */
    function getLastNode(address _voter) constant public returns (uint pollID) {
        return dllMap[_voter].getPrev(0);
    }

    /**
    @dev Gets the numTokens property of getLastNode
    @param _voter Address of user to check against
    @return Maximum number of tokens committed in poll specified
    */
    function getLockedTokens(address _voter) constant public returns (uint numTokens) {
        return getNumTokens(_voter, getLastNode(_voter));
    }

    /*
    @dev Takes the last node in the user's DLL and iterates backwards through the list searching
    for a node with a value less than or equal to the provided _numTokens value. When such a node
    is found, if the provided _pollID matches the found nodeID, this operation is an in-place
    update. In that case, return the previous node of the node being updated. Otherwise return the
    first node that was found with a value less than or equal to the provided _numTokens.
    @param _voter The voter whose DLL will be searched
    @param _numTokens The value for the numTokens attribute in the node to be inserted
    @return the node which the propoded node should be inserted after
    */
    function getInsertPointForNumTokens(address _voter, uint _numTokens, uint _pollID)
    constant public returns (uint prevNode) {
      // Get the last node in the list and the number of tokens in that node
      uint nodeID = getLastNode(_voter);
      uint tokensInNode = getNumTokens(_voter, nodeID);

      // Iterate backwards through the list until reaching the root node
      while(nodeID != 0) {
        // Get the number of tokens in the current node
        tokensInNode = getNumTokens(_voter, nodeID);
        if(tokensInNode <= _numTokens) { // We found the insert point!
          if(nodeID == _pollID) {
            // This is an in-place update. Return the prev node of the node being updated
            nodeID = dllMap[_voter].getPrev(nodeID);
          }
          // Return the insert point
          return nodeID; 
        }
        // We did not find the insert point. Continue iterating backwards through the list
        nodeID = dllMap[_voter].getPrev(nodeID);
      }

      // The list is empty, or a smaller value than anything else in the list is being inserted
      return nodeID;
    }

    // ----------------
    // GENERAL HELPERS:
    // ----------------

    /**
    @dev Checks if an expiration date has been reached
    @param _terminationDate Integer timestamp of date to compare current timestamp with
    @return expired Boolean indication of whether the terminationDate has passed
    */
    function isExpired(uint _terminationDate) constant public returns (bool expired) {
        return (block.timestamp > _terminationDate);
    }

    /**
    @dev Generates an identifier which associates a user and a poll together
    @param _pollID Integer identifier associated with target poll
    @return UUID Hash which is deterministic from _user and _pollID
    */
    function attrUUID(address _user, uint _pollID) public pure returns (bytes32 UUID) {
        return keccak256(_user, _pollID);
    }
}
/**
 @title Partial-Lock-Commit-Reveal Voting scheme with ERC20 tokens
 @author Team: Aspyn Palatnick, Cem Ozer, Yorke Rhodes
 */
function getCommitHash(address _voter, uint _pollID) constant public returns (bytes32 commitHash) {
    return bytes32(store.getAttribute(attrUUID(_voter, _pollID), "commitHash"));
}

/**
 @dev Gets the bytes32 commitHash property of target poll
 @param _voter Address of user to check against
 @param _pollID Integer identifier associated with target poll
 @return Bytes32 hash property attached to target poll
 */