pragma solidity ^0.4.24;
import "./StandardToken.sol";
import "./Proxy.sol";

contract OutcomeTokenData {

    /*
     *  Events
     */
    event Issuance(address indexed owner, uint amount);
    event Revocation(address indexed owner, uint amount);

    /*
     *  Storage
     */
    address public eventContract;
    /*
     *  Modifiers
     */
    modifier isEventContract () {
        // Only event contract is allowed to proceed
        require(msg.sender == eventContract, "contract not event Contract");
        _;
    }
}


/// @title Outcome token contract - Issuing and revoking outcome tokens
/// @author Stefan George - <stefan@gnosis.pm>
contract OutcomeToken is StandardToken, OutcomeTokenData {
    using Math for *;


     /// @dev Constructor sets events contract address
    constructor(string _symbol, string _name)
        public
    {
        name = _name;
        symbol = _symbol;
        eventContract = msg.sender;
    }

    /*
     *  Public functions
     */
    /// @dev Events contract issues new tokens for address. Returns success
    /// @param _for Address of receiver
    /// @param outcomeTokenCount Number of tokens to issue
    function issue(address _for, uint outcomeTokenCount)
        public
        isEventContract()
    {
        balances[_for] = balances[_for].add(outcomeTokenCount);
        totalTokens = totalTokens.add(outcomeTokenCount);
        emit Issuance(_for, outcomeTokenCount);
    }

    /// @dev Events contract revokes tokens for address. Returns success
    /// @param _for Address of token holder
    /// @param outcomeTokenCount Number of tokens to revoke
    function revoke(address _for, uint outcomeTokenCount)
        public
        isEventContract()
    {
        balances[_for] = balances[_for].sub(outcomeTokenCount);
        totalTokens = totalTokens.sub(outcomeTokenCount);
        emit Revocation(_for, outcomeTokenCount);
    }
}