pragma solidity ^0.4.24;
// produced by the Solididy File Flattener (c) David Appleton 2018
// contact : [email protected]
// released under Apache 2.0 licence
contract Ownable {
  address public owner;


  event OwnershipRenounced(address indexed previousOwner);
  event OwnershipTransferred(
    address indexed previousOwner,
    address indexed newOwner
  );


  /**
   * @dev The Ownable constructor sets the original `owner` of the contract to the sender
   * account.
   */
  constructor() public {
    owner = msg.sender;
  }

  /**
   * @dev Throws if called by any account other than the owner.
   */
  modifier onlyOwner() {
    require(msg.sender == owner);
    _;
  }

  /**
   * @dev Allows the current owner to relinquish control of the contract.
   */
  function renounceOwnership() public onlyOwner {
    emit OwnershipRenounced(owner);
    owner = address(0);
  }

  /**
   * @dev Allows the current owner to transfer control of the contract to a newOwner.
   * @param _newOwner The address to transfer ownership to.
   */
  function transferOwnership(address _newOwner) public onlyOwner {
    _transferOwnership(_newOwner);
  }

  /**
   * @dev Transfers control of the contract to a newOwner.
   * @param _newOwner The address to transfer ownership to.
   */
  function _transferOwnership(address _newOwner) internal {
    require(_newOwner != address(0));
    emit OwnershipTransferred(owner, _newOwner);
    owner = _newOwner;
  }
}

contract ERC20 {
    function transfer(address _to, uint256 _value) external returns (bool);
    function transferFrom(address _from, address _to, uint256 _value) external returns (bool);
}


contract V00_Marketplace is Ownable {

    /**
    * @notice All events have the same indexed signature offsets for easy filtering
    */
    event MarketplaceData  (address indexed party, bytes32 ipfsHash);
    event AffiliateAdded   (address indexed party, bytes32 ipfsHash);
    event AffiliateRemoved (address indexed party, bytes32 ipfsHash);
    event ListingCreated   (address indexed party, uint indexed listingID, bytes32 ipfsHash);
    event ListingUpdated   (address indexed party, uint indexed listingID, bytes32 ipfsHash);
    event ListingWithdrawn (address indexed party, uint indexed listingID, bytes32 ipfsHash);
    event ListingArbitrated(address indexed party, uint indexed listingID, bytes32 ipfsHash);
    event ListingData      (address indexed party, uint indexed listingID, bytes32 ipfsHash);
    event OfferCreated     (address indexed party, uint indexed listingID, uint indexed offerID, bytes32 ipfsHash);
    event OfferAccepted    (address indexed party, uint indexed listingID, uint indexed offerID, bytes32 ipfsHash);
    event OfferFinalized   (address indexed party, uint indexed listingID, uint indexed offerID, bytes32 ipfsHash);
    event OfferWithdrawn   (address indexed party, uint indexed listingID, uint indexed offerID, bytes32 ipfsHash);
    event OfferFundsAdded  (address indexed party, uint indexed listingID, uint indexed offerID, bytes32 ipfsHash);
    event OfferDisputed    (address indexed party, uint indexed listingID, uint indexed offerID, bytes32 ipfsHash);
    event OfferRuling      (address indexed party, uint indexed listingID, uint indexed offerID, bytes32 ipfsHash, uint ruling);
    event OfferData        (address indexed party, uint indexed listingID, uint indexed offerID, bytes32 ipfsHash);

    struct Listing {
        address seller;     // Seller wallet / identity contract / other contract
        uint deposit;       // Deposit in Origin Token
        address depositManager; // Address that decides token distribution
    }

    struct Offer {
        uint value;         // Amount in Eth or ERC20 buyer is offering
        uint commission;    // Amount of commission earned if offer is finalized
        uint refund;        // Amount to refund buyer upon finalization
        ERC20 currency;     // Currency of listing
        address buyer;      // Buyer wallet / identity contract / other contract
        address affiliate;  // Address to send any commission
        address arbitrator; // Address that settles disputes
        uint finalizes;     // Timestamp offer finalizes
        uint8 status;       // 0: Undefined, 1: Created, 2: Accepted, 3: Disputed
    }

    Listing[] public listings;
    mapping(uint => Offer[]) public offers; // listingID => Offers
    mapping(address => bool) public allowedAffiliates;

    ERC20 public tokenAddr; // Origin Token address

    constructor(address _tokenAddr) public {
        owner = msg.sender;
        setTokenAddr(_tokenAddr); // Origin Token contract
        allowedAffiliates[0x0] = true; // Allow null affiliate by default
    }

    // @dev Return the total number of listings
    function totalListings() public view returns (uint) {
        return listings.length;
    }

    // @dev Return the total number of offers
    function totalOffers(uint listingID) public view returns (uint) {
        return offers[listingID].length;
    }

    // @dev Seller creates listing
    function createListing(bytes32 _ipfsHash, uint _deposit, address _depositManager)
        public
    {
        _createListing(msg.sender, _ipfsHash, _deposit, _depositManager);
    }

    // @dev Can only be called by token
    function createListingWithSender(
        address _seller,
        bytes32 _ipfsHash,
        uint _deposit,
        address _depositManager
    )
        public returns (bool)
    {
        require(msg.sender == address(tokenAddr), "Token must call");
        _createListing(_seller, _ipfsHash, _deposit, _depositManager);
        return true;
    }

    // Private
    function _createListing(
        address _seller,
        bytes32 _ipfsHash,  // IPFS JSON with details, pricing, availability
        uint _deposit,      // Deposit in Origin Token
        address _depositManager // Address of listing depositManager
    )
        private
    {
        /* require(_deposit > 0); // Listings must deposit some amount of Origin Token */
        require(_depositManager != 0x0, "Must specify depositManager");

        listings.push(Listing({
            seller: _seller,
            deposit: _deposit,
            depositManager: _depositManager
        }));

        if (_deposit > 0) {
            tokenAddr.transferFrom(_seller, this, _deposit); // Transfer Origin Token
        }
        emit ListingCreated(_seller, listings.length - 1, _ipfsHash);
    }

    // @dev Seller updates listing
    function updateListing(
        uint listingID,
        bytes32 _ipfsHash,
        uint _additionalDeposit
    ) public {
        _updateListing(msg.sender, listingID, _ipfsHash, _additionalDeposit);
    }

    function updateListingWithSender(
        address _seller,
        uint listingID,
        bytes32 _ipfsHash,
        uint _additionalDeposit
    )
        public returns (bool)
    {
        require(msg.sender == address(tokenAddr), "Token must call");
        _updateListing(_seller, listingID, _ipfsHash, _additionalDeposit);
        return true;
    }

    function _updateListing(
        address _seller,
        uint listingID,
        bytes32 _ipfsHash,      // Updated IPFS hash
        uint _additionalDeposit // Additional deposit to add
    ) private {
        Listing storage listing = listings[listingID];
        require(listing.seller == _seller, "Seller must call");

        if (_additionalDeposit > 0) {
            tokenAddr.transferFrom(_seller, this, _additionalDeposit);
            listing.deposit += _additionalDeposit;
        }

        emit ListingUpdated(listing.seller, listingID, _ipfsHash);
    }

    // @dev Listing depositManager withdraws listing. IPFS hash contains reason for withdrawl.
    function withdrawListing(uint listingID, address _target, bytes32 _ipfsHash) public {
        Listing storage listing = listings[listingID];
        require(msg.sender == listing.depositManager, "Must be depositManager");
        require(_target != 0x0, "No target");
        tokenAddr.transfer(_target, listing.deposit); // Send deposit to target
        emit ListingWithdrawn(_target, listingID, _ipfsHash);
    }

    // @dev Buyer makes offer.
    function makeOffer(
        uint listingID,
        bytes32 _ipfsHash,   // IPFS hash containing offer data
        uint _finalizes,     // Timestamp an accepted offer will finalize
        address _affiliate,  // Address to send any required commission to
        uint256 _commission, // Amount of commission to send in Origin Token if offer finalizes
        uint _value,         // Offer amount in ERC20 or Eth
        ERC20 _currency,     // ERC20 token address or 0x0 for Eth
        address _arbitrator  // Escrow arbitrator
    )
        public
        payable
    {
        bool affiliateWhitelistDisabled = allowedAffiliates[address(this)];
        require(
            affiliateWhitelistDisabled || allowedAffiliates[_affiliate],
            "Affiliate not allowed"
        );

        if (_affiliate == 0x0) {
            // Avoid commission tokens being trapped in marketplace contract.
            require(_commission == 0, "commission requires affiliate");
        }

        offers[listingID].push(Offer({
            status: 1,
            buyer: msg.sender,
            finalizes: _finalizes,
            affiliate: _affiliate,
            commission: _commission,
            currency: _currency,
            value: _value,
            arbitrator: _arbitrator,
            refund: 0
        }));

        if (address(_currency) == 0x0) { // Listing is in ETH
            require(msg.value == _value, "ETH value doesn't match offer");
        } else { // Listing is in ERC20
            require(msg.value == 0, "ETH would be lost");
            require(
                _currency.transferFrom(msg.sender, this, _value),
                "transferFrom failed"
            );
        }

        emit OfferCreated(msg.sender, listingID, offers[listingID].length-1, _ipfsHash);
    }

    // @dev Make new offer after withdrawl
    function makeOffer(
        uint listingID,
        bytes32 _ipfsHash,
        uint _finalizes,
        address _affiliate,
        uint256 _commission,
        uint _value,
        ERC20 _currency,
        address _arbitrator,
        uint _withdrawOfferID
    )
        public
        payable
    {
        withdrawOffer(listingID, _withdrawOfferID, _ipfsHash);
        makeOffer(listingID, _ipfsHash, _finalizes, _affiliate, _commission, _value, _currency, _arbitrator);
    }

    // @dev Seller accepts offer
    function acceptOffer(uint listingID, uint offerID, bytes32 _ipfsHash) public {
        Listing storage listing = listings[listingID];
        Offer storage offer = offers[listingID][offerID];
        require(msg.sender == listing.seller, "Seller must accept");
        require(offer.status == 1, "status != created");
        require(
            listing.deposit >= offer.commission,
            "deposit must cover commission"
        );
        if (offer.finalizes < 1000000000) { // Relative finalization window
            offer.finalizes = now + offer.finalizes;
        }
        listing.deposit -= offer.commission; // Accepting an offer puts Origin Token into escrow
        offer.status = 2; // Set offer to 'Accepted'
        emit OfferAccepted(msg.sender, listingID, offerID, _ipfsHash);
    }

    // @dev Buyer withdraws offer. IPFS hash contains reason for withdrawl.
    function withdrawOffer(uint listingID, uint offerID, bytes32 _ipfsHash) public {
        Listing storage listing = listings[listingID];
        Offer storage offer = offers[listingID][offerID];
        require(
            msg.sender == offer.buyer || msg.sender == listing.seller,
            "Restricted to buyer or seller"
        );
        require(offer.status == 1, "status != created");
        refundBuyer(listingID, offerID);
        emit OfferWithdrawn(msg.sender, listingID, offerID, _ipfsHash);
        delete offers[listingID][offerID];
    }

    // @dev Buyer adds extra funds to an accepted offer.
    function addFunds(uint listingID, uint offerID, bytes32 _ipfsHash, uint _value) public payable {
        Offer storage offer = offers[listingID][offerID];
        require(msg.sender == offer.buyer, "Buyer must call");
        require(offer.status == 2, "status != accepted");
        if (address(offer.currency) == 0x0) { // Listing is in ETH
            require(
                msg.value == _value,
                "sent != offered value"
            );
        } else { // Listing is in ERC20
            require(msg.value == 0, "ETH must not be sent");
            require(
                offer.currency.transferFrom(msg.sender, this, _value),
                "transferFrom failed"
            );
        }
        offer.value += _value;
        emit OfferFundsAdded(msg.sender, listingID, offerID, _ipfsHash);
    }

    // @dev Buyer must finalize transaction to receive commission
    function finalize(uint listingID, uint offerID, bytes32 _ipfsHash) public {
        Listing storage listing = listings[listingID];
        Offer storage offer = offers[listingID][offerID];
        if (now <= offer.finalizes) { // Only buyer can finalize before finalization window
            require(
                msg.sender == offer.buyer,
                "Only buyer can finalize"
            );
        } else { // Allow both seller and buyer to finalize if finalization window has passed
            require(
                msg.sender == offer.buyer || msg.sender == listing.seller,
                "Seller or buyer must finalize"
            );
        }
        require(offer.status == 2, "status != accepted");
        paySeller(listingID, offerID); // Pay seller
        if (msg.sender == offer.buyer) { // Only pay commission if buyer is finalizing
            payCommission(listingID, offerID);
        }
        emit OfferFinalized(msg.sender, listingID, offerID, _ipfsHash);
        delete offers[listingID][offerID];
    }

    // @dev Buyer or seller can dispute transaction during finalization window
    function dispute(uint listingID, uint offerID, bytes32 _ipfsHash) public {
        Listing storage listing = listings[listingID];
        Offer storage offer = offers[listingID][offerID];
        require(
            msg.sender == offer.buyer || msg.sender == listing.seller,
            "Must be seller or buyer"
        );
        require(offer.status == 2, "status != accepted");
        require(now <= offer.finalizes, "Already finalized");
        offer.status = 3; // Set status to "Disputed"
        emit OfferDisputed(msg.sender, listingID, offerID, _ipfsHash);
    }

    // @dev Called by arbitrator
    function executeRuling(
        uint listingID,
        uint offerID,
        bytes32 _ipfsHash,
        uint _ruling, // 0: Seller, 1: Buyer, 2: Com + Seller, 3: Com + Buyer
        uint _refund
    ) public {
        Offer storage offer = offers[listingID][offerID];
        require(msg.sender == offer.arbitrator, "Must be arbitrator");
        require(offer.status == 3, "status != disputed");
        require(_refund <= offer.value, "refund too high");
        offer.refund = _refund;
        if (_ruling & 1 == 1) {
            refundBuyer(listingID, offerID);
        } else  {
            paySeller(listingID, offerID);
        }
        if (_ruling & 2 == 2) {
            payCommission(listingID, offerID);
        } else  { // Refund commission to seller
            listings[listingID].deposit += offer.commission;
        }
        emit OfferRuling(offer.arbitrator, listingID, offerID, _ipfsHash, _ruling);
        delete offers[listingID][offerID];
    }

    // @dev Sets the amount that a seller wants to refund to a buyer.
    function updateRefund(uint listingID, uint offerID, uint _refund, bytes32 _ipfsHash) public {
        Offer storage offer = offers[listingID][offerID];
        Listing storage listing = listings[listingID];
        require(msg.sender == listing.seller, "Seller must call");
        require(offer.status == 2, "status != accepted");
        require(_refund <= offer.value, "Excessive refund");
        offer.refund = _refund;
        emit OfferData(msg.sender, listingID, offerID, _ipfsHash);
    }

    // @dev Refunds buyer in ETH or ERC20 - used by 1) executeRuling() and 2) to allow a seller to refund a purchase
    function refundBuyer(uint listingID, uint offerID) private {
        Offer storage offer = offers[listingID][offerID];
        if (address(offer.currency) == 0x0) {
            require(offer.buyer.send(offer.value), "ETH refund failed");
        } else {
            require(
                offer.currency.transfer(offer.buyer, offer.value),
                "Refund failed"
            );
        }
    }

    // @dev Pay seller in ETH or ERC20
    function paySeller(uint listingID, uint offerID) private {
        Listing storage listing = listings[listingID];
        Offer storage offer = offers[listingID][offerID];
        uint value = offer.value - offer.refund;

        if (address(offer.currency) == 0x0) {
            require(offer.buyer.send(offer.refund), "ETH refund failed");
            require(listing.seller.send(value), "ETH send failed");
        } else {
            require(
                offer.currency.transfer(offer.buyer, offer.refund),
                "Refund failed"
            );
            require(
                offer.currency.transfer(listing.seller, value),
                "Transfer failed"
            );
        }
    }

    // @dev Pay commission to affiliate
    function payCommission(uint listingID, uint offerID) private {
        Offer storage offer = offers[listingID][offerID];
        if (offer.affiliate != 0x0) {
            require(
                tokenAddr.transfer(offer.affiliate, offer.commission),
                "Commission transfer failed"
            );
        }
    }

    // @dev Associate ipfs data with the marketplace
    function addData(bytes32 ipfsHash) public {
        emit MarketplaceData(msg.sender, ipfsHash);
    }

    // @dev Associate ipfs data with a listing
    function addData(uint listingID, bytes32 ipfsHash) public {
        emit ListingData(msg.sender, listingID, ipfsHash);
    }

    // @dev Associate ipfs data with an offer
    function addData(uint listingID, uint offerID, bytes32 ipfsHash) public {
        emit OfferData(msg.sender, listingID, offerID, ipfsHash);
    }

    // @dev Allow listing depositManager to send deposit
    function sendDeposit(uint listingID, address target, uint value, bytes32 ipfsHash) public {
        Listing storage listing = listings[listingID];
        require(listing.depositManager == msg.sender, "depositManager must call");
        require(listing.deposit >= value, "Value too high");
        listing.deposit -= value;
        require(tokenAddr.transfer(target, value), "Transfer failed");
        emit ListingArbitrated(target, listingID, ipfsHash);
    }

    // @dev Set the address of the Origin token contract
    function setTokenAddr(address _tokenAddr) public onlyOwner {
        tokenAddr = ERC20(_tokenAddr);
    }

    // @dev Add affiliate to whitelist. Set to address(this) to disable.
    function addAffiliate(address _affiliate, bytes32 ipfsHash) public onlyOwner {
        allowedAffiliates[_affiliate] = true;
        emit AffiliateAdded(_affiliate, ipfsHash);
    }

    // @dev Remove affiliate from whitelist.
    function removeAffiliate(address _affiliate, bytes32 ipfsHash) public onlyOwner {
        delete allowedAffiliates[_affiliate];
        emit AffiliateRemoved(_affiliate, ipfsHash);
    }
}

pragma solidity ^0.4.24;
// produced by the Solididy File Flattener (c) David Appleton 2018
// contact : [email protected]
// released under Apache 2.0 licence
contract ERC20Basic {
  function totalSupply() public view returns (uint256);
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
}

contract Ownable {
  address public owner;


  event OwnershipRenounced(address indexed previousOwner);
  event OwnershipTransferred(
    address indexed previousOwner,
    address indexed newOwner
  );


  /**
   * @dev The Ownable constructor sets the original `owner` of the contract to the sender
   * account.
   */
  constructor() public {
    owner = msg.sender;
  }

  /**
   * @dev Throws if called by any account other than the owner.
   */
  modifier onlyOwner() {
    require(msg.sender == owner);
    _;
  }

  /**
   * @dev Allows the current owner to relinquish control of the contract.
   */
  function renounceOwnership() public onlyOwner {
    emit OwnershipRenounced(owner);
    owner = address(0);
  }

  /**
   * @dev Allows the current owner to transfer control of the contract to a newOwner.
   * @param _newOwner The address to transfer ownership to.
   */
  function transferOwnership(address _newOwner) public onlyOwner {
    _transferOwnership(_newOwner);
  }

  /**
   * @dev Transfers control of the contract to a newOwner.
   * @param _newOwner The address to transfer ownership to.
   */
  function _transferOwnership(address _newOwner) internal {
    require(_newOwner != address(0));
    emit OwnershipTransferred(owner, _newOwner);
    owner = _newOwner;
  }
}

library SafeMath {

  /**
  * @dev Multiplies two numbers, throws on overflow.
  */
  function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
    // Gas optimization: this is cheaper than asserting 'a' not being zero, but the
    // benefit is lost if 'b' is also tested.
    // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
    if (a == 0) {
      return 0;
    }

    c = a * b;
    assert(c / a == b);
    return c;
  }

  /**
  * @dev Integer division of two numbers, truncating the quotient.
  */
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    // uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return a / b;
  }

  /**
  * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  /**
  * @dev Adds two numbers, throws on overflow.
  */
  function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
    c = a + b;
    assert(c >= a);
    return c;
  }
}

contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender)
    public view returns (uint256);

  function transferFrom(address from, address to, uint256 value)
    public returns (bool);

  function approve(address spender, uint256 value) public returns (bool);
  event Approval(
    address indexed owner,
    address indexed spender,
    uint256 value
  );
}

contract Pausable is Ownable {
  event Pause();
  event Unpause();

  bool public paused = false;


  /**
   * @dev Modifier to make a function callable only when the contract is not paused.
   */
  modifier whenNotPaused() {
    require(!paused);
    _;
  }

  /**
   * @dev Modifier to make a function callable only when the contract is paused.
   */
  modifier whenPaused() {
    require(paused);
    _;
  }

  /**
   * @dev called by the owner to pause, triggers stopped state
   */
  function pause() onlyOwner whenNotPaused public {
    paused = true;
    emit Pause();
  }

  /**
   * @dev called by the owner to unpause, returns to normal state
   */
  function unpause() onlyOwner whenPaused public {
    paused = false;
    emit Unpause();
  }
}

contract DetailedERC20 is ERC20 {
  string public name;
  string public symbol;
  uint8 public decimals;

  constructor(string _name, string _symbol, uint8 _decimals) public {
    name = _name;
    symbol = _symbol;
    decimals = _decimals;
  }
}

contract BasicToken is ERC20Basic {
  using SafeMath for uint256;

  mapping(address => uint256) balances;

  uint256 totalSupply_;

  /**
  * @dev total number of tokens in existence
  */
  function totalSupply() public view returns (uint256) {
    return totalSupply_;
  }

  /**
  * @dev transfer token for a specified address
  * @param _to The address to transfer to.
  * @param _value The amount to be transferred.
  */
  function transfer(address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));
    require(_value <= balances[msg.sender]);

    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    emit Transfer(msg.sender, _to, _value);
    return true;
  }

  /**
  * @dev Gets the balance of the specified address.
  * @param _owner The address to query the the balance of.
  * @return An uint256 representing the amount owned by the passed address.
  */
  function balanceOf(address _owner) public view returns (uint256) {
    return balances[_owner];
  }

}

contract BurnableToken is BasicToken {

  event Burn(address indexed burner, uint256 value);

  /**
   * @dev Burns a specific amount of tokens.
   * @param _value The amount of token to be burned.
   */
  function burn(uint256 _value) public {
    _burn(msg.sender, _value);
  }

  function _burn(address _who, uint256 _value) internal {
    require(_value <= balances[_who]);
    // no need to require value <= totalSupply, since that would imply the
    // sender's balance is greater than the totalSupply, which *should* be an assertion failure

    balances[_who] = balances[_who].sub(_value);
    totalSupply_ = totalSupply_.sub(_value);
    emit Burn(_who, _value);
    emit Transfer(_who, address(0), _value);
  }
}

contract StandardToken is ERC20, BasicToken {

  mapping (address => mapping (address => uint256)) internal allowed;


  /**
   * @dev Transfer tokens from one address to another
   * @param _from address The address which you want to send tokens from
   * @param _to address The address which you want to transfer to
   * @param _value uint256 the amount of tokens to be transferred
   */
  function transferFrom(
    address _from,
    address _to,
    uint256 _value
  )
    public
    returns (bool)
  {
    require(_to != address(0));
    require(_value <= balances[_from]);
    require(_value <= allowed[_from][msg.sender]);

    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
    emit Transfer(_from, _to, _value);
    return true;
  }

  /**
   * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
   *
   * Beware that changing an allowance with this method brings the risk that someone may use both the old
   * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
   * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
   * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
   * @param _spender The address which will spend the funds.
   * @param _value The amount of tokens to be spent.
   */
  function approve(address _spender, uint256 _value) public returns (bool) {
    allowed[msg.sender][_spender] = _value;
    emit Approval(msg.sender, _spender, _value);
    return true;
  }

  /**
   * @dev Function to check the amount of tokens that an owner allowed to a spender.
   * @param _owner address The address which owns the funds.
   * @param _spender address The address which will spend the funds.
   * @return A uint256 specifying the amount of tokens still available for the spender.
   */
  function allowance(
    address _owner,
    address _spender
   )
    public
    view
    returns (uint256)
  {
    return allowed[_owner][_spender];
  }

  /**
   * @dev Increase the amount of tokens that an owner allowed to a spender.
   *
   * approve should be called when allowed[_spender] == 0. To increment
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param _spender The address which will spend the funds.
   * @param _addedValue The amount of tokens to increase the allowance by.
   */
  function increaseApproval(
    address _spender,
    uint _addedValue
  )
    public
    returns (bool)
  {
    allowed[msg.sender][_spender] = (
      allowed[msg.sender][_spender].add(_addedValue));
    emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

  /**
   * @dev Decrease the amount of tokens that an owner allowed to a spender.
   *
   * approve should be called when allowed[_spender] == 0. To decrement
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param _spender The address which will spend the funds.
   * @param _subtractedValue The amount of tokens to decrease the allowance by.
   */
  function decreaseApproval(
    address _spender,
    uint _subtractedValue
  )
    public
    returns (bool)
  {
    uint oldValue = allowed[msg.sender][_spender];
    if (_subtractedValue > oldValue) {
      allowed[msg.sender][_spender] = 0;
    } else {
      allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
    }
    emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

}

contract PausableToken is StandardToken, Pausable {

  function transfer(
    address _to,
    uint256 _value
  )
    public
    whenNotPaused
    returns (bool)
  {
    return super.transfer(_to, _value);
  }

  function transferFrom(
    address _from,
    address _to,
    uint256 _value
  )
    public
    whenNotPaused
    returns (bool)
  {
    return super.transferFrom(_from, _to, _value);
  }

  function approve(
    address _spender,
    uint256 _value
  )
    public
    whenNotPaused
    returns (bool)
  {
    return super.approve(_spender, _value);
  }

  function increaseApproval(
    address _spender,
    uint _addedValue
  )
    public
    whenNotPaused
    returns (bool success)
  {
    return super.increaseApproval(_spender, _addedValue);
  }

  function decreaseApproval(
    address _spender,
    uint _subtractedValue
  )
    public
    whenNotPaused
    returns (bool success)
  {
    return super.decreaseApproval(_spender, _subtractedValue);
  }
}

contract MintableToken is StandardToken, Ownable {
  event Mint(address indexed to, uint256 amount);
  event MintFinished();

  bool public mintingFinished = false;


  modifier canMint() {
    require(!mintingFinished);
    _;
  }

  modifier hasMintPermission() {
    require(msg.sender == owner);
    _;
  }

  /**
   * @dev Function to mint tokens
   * @param _to The address that will receive the minted tokens.
   * @param _amount The amount of tokens to mint.
   * @return A boolean that indicates if the operation was successful.
   */
  function mint(
    address _to,
    uint256 _amount
  )
    hasMintPermission
    canMint
    public
    returns (bool)
  {
    totalSupply_ = totalSupply_.add(_amount);
    balances[_to] = balances[_to].add(_amount);
    emit Mint(_to, _amount);
    emit Transfer(address(0), _to, _amount);
    return true;
  }

  /**
   * @dev Function to stop minting new tokens.
   * @return True if the operation was successful.
   */
  function finishMinting() onlyOwner canMint public returns (bool) {
    mintingFinished = true;
    emit MintFinished();
    return true;
  }
}

contract WhitelistedPausableToken is PausableToken {
    // UNIX timestamp (in seconds) after which this whitelist no longer applies
    uint256 public whitelistExpiration;
    // While the whitelist is active, either the sender or recipient must be
    // in allowedTransactors.
    mapping (address => bool) public allowedTransactors;

    event SetWhitelistExpiration(uint256 expiration);
    event AllowedTransactorAdded(address sender);
    event AllowedTransactorRemoved(address sender);

    //
    // Functions for maintaining whitelist
    //

    modifier allowedTransfer(address _from, address _to) {
        require(
            // solium-disable-next-line operator-whitespace
            !whitelistActive() ||
            allowedTransactors[_from] ||
            allowedTransactors[_to],
            "neither sender nor recipient are allowed"
        );
        _;
    }

    function whitelistActive() public view returns (bool) {
        return block.timestamp < whitelistExpiration;
    }

    function addAllowedTransactor(address _transactor) public onlyOwner {
        emit AllowedTransactorAdded(_transactor);
        allowedTransactors[_transactor] = true;
    }

    function removeAllowedTransactor(address _transactor) public onlyOwner {
        emit AllowedTransactorRemoved(_transactor);
        delete allowedTransactors[_transactor];
    }

    /**
    * @dev Set the whitelist expiration, after which the whitelist no longer
    * applies.
    */
    function setWhitelistExpiration(uint256 _expiration) public onlyOwner {
        // allow only if whitelist expiration hasn't yet been set, or if the
        // whitelist expiration hasn't passed yet
        require(
            whitelistExpiration == 0 || whitelistActive(),
            "an expired whitelist cannot be extended"
        );
        // prevent possible mistakes in calling this function
        require(
            _expiration >= block.timestamp + 1 days,
            "whitelist expiration not far enough into the future"
        );
        emit SetWhitelistExpiration(_expiration);
        whitelistExpiration = _expiration;
    }

    //
    // ERC20 transfer functions that have been overridden to enforce the
    // whitelist.
    //

    function transfer(
        address _to,
        uint256 _value
    )
        public
        allowedTransfer(msg.sender, _to)
        returns (bool)
    {
        return super.transfer(_to, _value);
    }

    function transferFrom(
        address _from,
        address _to,
        uint256 _value
    )
    public
        allowedTransfer(_from, _to)
    returns (bool)
    {
        return super.transferFrom(_from, _to, _value);
    }
}

contract OriginToken is BurnableToken, MintableToken, WhitelistedPausableToken, DetailedERC20 {
    event AddCallSpenderWhitelist(address enabler, address spender);
    event RemoveCallSpenderWhitelist(address disabler, address spender);

    mapping (address => bool) public callSpenderWhitelist;

    // @dev Constructor that gives msg.sender all initial tokens.
    constructor(uint256 _initialSupply) DetailedERC20("OriginToken", "OGN", 18) public {
        owner = msg.sender;
        mint(owner, _initialSupply);
    }

    //
    // Burn methods
    //

    // @dev Burns tokens belonging to the sender
    // @param _value Amount of token to be burned
    function burn(uint256 _value) public onlyOwner {
        // TODO: add a function & modifier to enable for all accounts without doing
        // a contract migration?
        super.burn(_value);
    }

    // @dev Burns tokens belonging to the specified address
    // @param _who The account whose tokens we're burning
    // @param _value Amount of token to be burned
    function burn(address _who, uint256 _value) public onlyOwner {
        _burn(_who, _value);
    }

    //
    // approveAndCall methods
    //

    // @dev Add spender to whitelist of spenders for approveAndCall
    // @param _spender Address to add
    function addCallSpenderWhitelist(address _spender) public onlyOwner {
        callSpenderWhitelist[_spender] = true;
        emit AddCallSpenderWhitelist(msg.sender, _spender);
    }

    // @dev Remove spender from whitelist of spenders for approveAndCall
    // @param _spender Address to remove
    function removeCallSpenderWhitelist(address _spender) public onlyOwner {
        delete callSpenderWhitelist[_spender];
        emit RemoveCallSpenderWhitelist(msg.sender, _spender);
    }

    // @dev Approve transfer of tokens and make a contract call in a single
    // @dev transaction. This allows a DApp to avoid requiring two MetaMask
    // @dev approvals for a single logical action, such as creating a listing,
    // @dev which requires the seller to approve a token transfer and the
    // @dev marketplace contract to transfer tokens from the seller.
    //
    // @dev This is based on the ERC827 function approveAndCall and avoids
    // @dev security issues by only working with a whitelisted set of _spender
    // @dev addresses. The other difference is that the combination of this
    // @dev function ensures that the proxied function call receives the
    // @dev msg.sender for this function as its first parameter.
    //
    // @param _spender The address that will spend the funds.
    // @param _value The amount of tokens to be spent.
    // @param _selector Function selector for function to be called.
    // @param _callParams Packed, encoded parameters, omitting the first parameter which is always msg.sender
    function approveAndCallWithSender(
        address _spender,
        uint256 _value,
        bytes4 _selector,
        bytes _callParams
    )
        public
        payable
        returns (bool)
    {
        require(_spender != address(this), "token contract can't be approved");
        require(callSpenderWhitelist[_spender], "spender not in whitelist");

        require(super.approve(_spender, _value), "approve failed");

        bytes memory callData = abi.encodePacked(_selector, uint256(msg.sender), _callParams);
        // solium-disable-next-line security/no-call-value
        require(_spender.call.value(msg.value)(callData), "proxied call failed");
        return true;
    }
}