pragma solidity 0.5.14;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

/**
 * @title Roles
 * @dev Library for managing addresses assigned to a Role.
 */
library Roles {
    struct Role {
        mapping (address => bool) bearer;
    }

    /**
     * @dev Give an account access to this role.
     */
    function add(Role storage role, address account) internal {
        require(!has(role, account), "Roles: account already has role");
        role.bearer[account] = true;
    }

    /**
     * @dev Remove an account's access to this role.
     */
    function remove(Role storage role, address account) internal {
        require(has(role, account), "Roles: account does not have role");
        role.bearer[account] = false;
    }

    /**
     * @dev Check if an account has this role.
     * @return bool
     */
    function has(Role storage role, address account) internal view returns (bool) {
        require(account != address(0), "Roles: account is the zero address");
        return role.bearer[account];
    }
}

contract LexDAORole is Context {
    using Roles for Roles.Role;

    event LexDAOAdded(address indexed account);
    event LexDAORemoved(address indexed account);

    Roles.Role private _lexDAOs;

    modifier onlyLexDAO() {
        require(isLexDAO(_msgSender()), "LexDAORole: caller does not have the LexDAO role");
        _;
    }
    
    function isLexDAO(address account) public view returns (bool) {
        return _lexDAOs.has(account);
    }

    function addLexDAO(address account) public onlyLexDAO {
        _addLexDAO(account);
    }

    function renounceLexDAO() public {
        _removeLexDAO(_msgSender());
    }

    function _addLexDAO(address account) internal {
        _lexDAOs.add(account);
        emit LexDAOAdded(account);
    }

    function _removeLexDAO(address account) internal {
        _lexDAOs.remove(account);
        emit LexDAORemoved(account);
    }
}

contract MinterRole is Context {
    using Roles for Roles.Role;

    event MinterAdded(address indexed account);
    event MinterRemoved(address indexed account);

    Roles.Role private _minters;

    modifier onlyMinter() {
        require(isMinter(_msgSender()), "MinterRole: caller does not have the Minter role");
        _;
    }

    function isMinter(address account) public view returns (bool) {
        return _minters.has(account);
    }

    function addMinter(address account) public onlyMinter {
        _addMinter(account);
    }

    function renounceMinter() public {
        _removeMinter(_msgSender());
    }

    function _addMinter(address account) internal {
        _minters.add(account);
        emit MinterAdded(account);
    }

    function _removeMinter(address account) internal {
        _minters.remove(account);
        emit MinterRemoved(account);
    }
}

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return _msgSender() == _owner;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

/**
Restrictions start off as enabled.
Once they are disabled, they cannot be re-enabled.
Only the owner may disable restrictions.
 */
contract Restrictable is Ownable {
    // State variable to track whether restrictions are enabled.  Defaults to true.
    bool private _restrictionsEnabled = true;

    // Event emitted when flag is disabled
    event RestrictionsDisabled(address indexed owner);

    /**
    View function to determine if restrictions are enabled
     */
    function isRestrictionEnabled() public view returns (bool) {
        return _restrictionsEnabled;
    }

    /**
    Function to update the enabled flag on restrictions to disabled.  Only the owner should be able to call.
    This is a permanent change that cannot be undone
     */
    function disableRestrictions() public onlyOwner {
        require(_restrictionsEnabled, "Restrictions are already disabled.");
        
        // Set the flag
        _restrictionsEnabled = false;

        // Trigger the event
        emit RestrictionsDisabled(msg.sender);
    }
}

/**
This contract allows a list of administrators to be tracked.  This list can then be enforced
on functions with administrative permissions.  Only the owner of the contract should be allowed
to modify the administrator list.
 */
contract Administratable is Ownable {
    // The mapping to track administrator accounts - true is reserved for admin addresses.
    mapping (address => bool) public administrators;

    // Events to allow tracking add/remove.
    event AdminAdded(address indexed addedAdmin, address indexed addedBy);
    event AdminRemoved(address indexed removedAdmin, address indexed removedBy);

    /**
    Function modifier to enforce administrative permissions.
     */
    modifier onlyAdministrator() {
        require(isAdministrator(msg.sender), "Calling account is not an administrator.");
        _;
    }

    /**
    Determine if the message sender is in the administrators list.
     */
    function isAdministrator(address addressToTest) public view returns (bool) {
        return administrators[addressToTest];
    }

    /**
    Add an admin to the list.  This should only be callable by the owner of the contract.
     */
    function addAdmin(address adminToAdd) public onlyOwner {
        // Verify the account is not already an admin
        require(administrators[adminToAdd] == false, "Account to be added to admin list is already an admin");

        // Set the address mapping to true to indicate it is an administrator account.
        administrators[adminToAdd] = true;

        // Emit the event for any watchers.
        emit AdminAdded(adminToAdd, msg.sender);
    }

    /**
    Remove an admin from the list.  This should only be callable by the owner of the contract.
     */
    function removeAdmin(address adminToRemove) public onlyOwner {
        // Verify the account is an admin
        require(administrators[adminToRemove] == true, "Account to be removed from admin list is not already an admin");

        // Set the address mapping to false to indicate it is NOT an administrator account.  
        administrators[adminToRemove] = false;

        // Emit the event for any watchers.
        emit AdminRemoved(adminToRemove, msg.sender);
    }
}

/**
Keeps track of whitelists and can check if sender and reciever are configured to allow a transfer.
Only administrators can update the whitelists.
Any address can only be a member of one whitelist at a time.
 */
contract Whitelistable is Administratable {
    /**
    Sets an address's whitelist ID.  Only administrators should be allowed to update this.
    If an address is on an existing whitelist, it will just get updated to the new value (removed from previous).
     */
    function addToWhitelist(address[] memory addressToAdd, uint8 whitelist) public onlyAdministrator {
        for (uint256 i = 0; i < addressToAdd.length; i++) {
        // Verify the whitelist is valid
        require(whitelist != NO_WHITELIST, "Invalid whitelist ID supplied");

        // Save off the previous whitelist
        uint8 previousWhitelist = addressWhitelists[addressToAdd[i]];

        // Set the address's whitelist ID
        addressWhitelists[addressToAdd[i]] = whitelist;        

        // If the previous whitelist existed then we want to indicate it has been removed
        if(previousWhitelist != NO_WHITELIST) {
            // Emit the event for tracking
            emit AddressRemovedFromWhitelist(addressToAdd[i], previousWhitelist, msg.sender);
        }

        // Emit the event for new whitelist
        emit AddressAddedToWhitelist(addressToAdd[i], whitelist, msg.sender);
        }
    }

    /**
    Clears out an address's whitelist ID.  Only administrators should be allowed to update this.
     */
    function removeFromWhitelist(address[] memory addressToRemove) public onlyAdministrator {
        for (uint256 i = 0; i < addressToRemove.length; i++) {
        // Save off the previous whitelist
        uint8 previousWhitelist = addressWhitelists[addressToRemove[i]];

        // Zero out the previous whitelist
        addressWhitelists[addressToRemove[i]] = NO_WHITELIST;

        // Emit the event for tracking
        emit AddressRemovedFromWhitelist(addressToRemove[i], previousWhitelist, msg.sender);
        }
    }
        
    // Zero is reserved for indicating it is not on a whitelist
    uint8 constant NO_WHITELIST = 0;

    // The mapping to keep track of which whitelist any address belongs to.
    // 0 is reserved for no whitelist and is the default for all addresses.
    mapping (address => uint8) public addressWhitelists;

    // The mapping to keep track of each whitelist's outbound whitelist flags.
    // Boolean flag indicates whether outbound transfers are enabled.
    mapping(uint8 => mapping (uint8 => bool)) public outboundWhitelistsEnabled;

    // Events to allow tracking add/remove.
    event AddressAddedToWhitelist(address indexed addedAddress, uint8 indexed whitelist, address indexed addedBy);
    event AddressRemovedFromWhitelist(address indexed removedAddress, uint8 indexed whitelist, address indexed removedBy);
    event OutboundWhitelistUpdated(address indexed updatedBy, uint8 indexed sourceWhitelist, uint8 indexed destinationWhitelist, bool from, bool to);

    /**
    Sets the flag to indicate whether source whitelist is allowed to send to destination whitelist.
    Only administrators should be allowed to update this.
     */
    function updateOutboundWhitelistEnabled(uint8 sourceWhitelist, uint8 destinationWhitelist, bool newEnabledValue) public onlyAdministrator {
        // Get the old enabled flag
        bool oldEnabledValue = outboundWhitelistsEnabled[sourceWhitelist][destinationWhitelist];

        // Update to the new value
        outboundWhitelistsEnabled[sourceWhitelist][destinationWhitelist] = newEnabledValue;

        // Emit event for tracking
        emit OutboundWhitelistUpdated(msg.sender, sourceWhitelist, destinationWhitelist, oldEnabledValue, newEnabledValue);
    }

    /**
    Determine if the sender is allowed to send to the receiver.
    The source whitelist must be enabled to send to the whitelist where the receiver exists.
     */
    function checkWhitelistAllowed(address sender, address receiver) public view returns (bool) {
        // First get each address whitelist
        uint8 senderWhiteList = addressWhitelists[sender];
        uint8 receiverWhiteList = addressWhitelists[receiver];

        // If either address is not on a whitelist then the check should fail
        if(senderWhiteList == NO_WHITELIST || receiverWhiteList == NO_WHITELIST){
            return false;
        }

        // Determine if the sending whitelist is allowed to send to the destination whitelist        
        return outboundWhitelistsEnabled[senderWhiteList][receiverWhiteList];
    }
}

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

/**
 * @title SafeMathUint
 * @dev Math operations with safety checks that revert on error
 */
library SafeMathUint {
  function toInt256Safe(uint256 a) internal pure returns (int256) {
    int256 b = int256(a);
    require(b >= 0);
    return b;
  }
}

/**
 * @title SafeMathInt
 * @dev Math operations with safety checks that revert on error
 * @dev SafeMath adapted for int256
 * Based on code of https://github.com/RequestNetwork/requestNetwork/blob/master/packages/requestNetworkSmartContracts/contracts/base/math/SafeMathInt.sol
 */
library SafeMathInt {
  function mul(int256 a, int256 b) internal pure returns (int256) {
    // Prevent overflow when multiplying INT256_MIN with -1
    // https://github.com/RequestNetwork/requestNetwork/issues/43
    require(!(a == - 2**255 && b == -1) && !(b == - 2**255 && a == -1));

    int256 c = a * b;
    require((b == 0) || (c / b == a));
    return c;
  }

  function div(int256 a, int256 b) internal pure returns (int256) {
    // Prevent overflow when dividing INT256_MIN by -1
    // https://github.com/RequestNetwork/requestNetwork/issues/43
    require(!(a == - 2**255 && b == -1) && (b > 0));

    return a / b;
  }

  function sub(int256 a, int256 b) internal pure returns (int256) {
    require((b >= 0 && a - b <= a) || (b < 0 && a - b > a));

    return a - b;
  }

  function add(int256 a, int256 b) internal pure returns (int256) {
    int256 c = a + b;
    require((b >= 0 && c >= a) || (b < 0 && c < a));
    return c;
  }

  function toUint256Safe(int256 a) internal pure returns (uint256) {
    require(a >= 0);
    return uint256(a);
  }
}

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: 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
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20Mintable}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20};
     *
     * Requirements:
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for `sender`'s tokens of at least
     * `amount`.
     */
    function transferFrom(address sender, address recipient, uint256 amount) public returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: mint to the zero address");

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: burn from the zero address");

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner`s tokens.
     *
     * This is internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`.`amount` is then deducted
     * from the caller's allowance.
     *
     * See {_burn} and {_approve}.
     */
    function _burnFrom(address account, uint256 amount) internal {
        _burn(account, amount);
        _approve(account, _msgSender(), _allowances[account][_msgSender()].sub(amount, "ERC20: burn amount exceeds allowance"));
    }
}

/**
 * @dev Optional functions from the ERC20 standard.
 */
contract ERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for `name`, `symbol`, and `decimals`. All three of
     * these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name, string memory symbol, uint8 decimals) public {
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei.
     *
     * > Note that this information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * `IERC20.balanceOf` and `IERC20.transfer`.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }
}

/**
 * @dev Extension of `ERC20` that adds a set of accounts with the `MinterRole`,
 * which have permission to mint (create) new tokens as they see fit.
 *
 * At construction, the deployer of the contract is the only minter.
 */
contract ERC20Mintable is MinterRole, ERC20 {
    /**
     * @dev See `ERC20._mint`.
     *
     * Requirements:
     *
     * - the caller must have the `MinterRole`.
     */
    function mint(address account, uint256 amount) public onlyMinter returns (bool) {
        _mint(account, amount);
        return true;
    }
}

contract ERC1404 is IERC20 {
    /// @notice Detects if a transfer will be reverted and if so returns an appropriate reference code
    /// @param from Sending address
    /// @param to Receiving address
    /// @param value Amount of tokens being transferred
    /// @return Code by which to reference message for rejection reasoning
    /// @dev Overwrite with your custom transfer restriction logic
    function detectTransferRestriction (address from, address to, uint256 value) public view returns (uint8);

    /// @notice Returns a human-readable message for a given restriction code
    /// @param restrictionCode Identifier for looking up a message
    /// @return Text showing the restriction's reasoning
    /// @dev Overwrite with your custom message and restrictionCode handling
    function messageForTransferRestriction (uint8 restrictionCode) public view returns (string memory);
}

interface IFundsDistributionToken {
	/**
	 * @dev Returns the total amount of funds a given address is able to withdraw currently.
	 * @param owner Address of FundsDistributionToken holder
	 * @return A uint256 representing the available funds for a given account
	 */
	function withdrawableFundsOf(address owner) external view returns (uint256);

	/**
	 * @dev Withdraws all available funds for a FundsDistributionToken holder.
	 */
	function withdrawFunds() external;

	/**
	 * @dev This event emits when new funds are distributed
	 * @param by the address of the sender who distributed funds
	 * @param fundsDistributed the amount of funds received for distribution
	 */
	event FundsDistributed(address indexed by, uint256 fundsDistributed);

	/**
	 * @dev This event emits when distributed funds are withdrawn by a token holder.
	 * @param by the address of the receiver of funds
	 * @param fundsWithdrawn the amount of funds that were withdrawn
	 */
	event FundsWithdrawn(address indexed by, uint256 fundsWithdrawn);
}

/** 
 * @title FundsDistributionToken
 * @author Johannes Escherich
 * @author Roger-Wu
 * @author Johannes Pfeffer
 * @author Tom Lam
 * @dev A mintable token that can represent claims on cash flow of arbitrary assets such as dividends, loan repayments, 
 * fee or revenue shares among large numbers of token holders. Anyone can deposit funds, token holders can withdraw 
 * their claims.
 * FundsDistributionToken (FDT) implements the accounting logic. FDT-Extension contracts implement methods for depositing and 
 * withdrawing funds in Ether or according to a token standard such as ERC20, ERC223, ERC777.
 */
contract FundsDistributionToken is ERC20Mintable, IFundsDistributionToken {
	using SafeMath for uint256;
	using SafeMathUint for uint256;
	using SafeMathInt for int256;

	// optimize, see https://github.com/ethereum/EIPs/issues/1726#issuecomment-472352728
	uint256 constant internal pointsMultiplier = 2**128;
	uint256 internal pointsPerShare;

	mapping(address => int256) internal pointsCorrection;
	mapping(address => uint256) internal withdrawnFunds;

	/** 
	 * prev. distributeDividends
	 * @notice Distributes funds to token holders.
	 * @dev It reverts if the total supply of tokens is 0.
	 * It emits the `FundsDistributed` event if the amount of received ether is greater than 0.
	 * About undistributed funds:
	 *   In each distribution, there is a small amount of funds which does not get distributed,
	 *     which is `(msg.value * pointsMultiplier) % totalSupply()`.
	 *   With a well-chosen `pointsMultiplier`, the amount funds that are not getting distributed
	 *     in a distribution can be less than 1 (base unit).
	 *   We can actually keep track of the undistributed ether in a distribution
	 *     and try to distribute it in the next distribution ....... todo implement  
	 */
	function _distributeFunds(uint256 value) internal {
		require(totalSupply() > 0, "FundsDistributionToken._distributeFunds: SUPPLY_IS_ZERO");

		if (value > 0) {
			pointsPerShare = pointsPerShare.add(
				value.mul(pointsMultiplier) / totalSupply()
			);
			emit FundsDistributed(msg.sender, value);
		}
	}

	/**
	 * prev. withdrawDividend
	 * @notice Prepares funds withdrawal
	 * @dev It emits a `FundsWithdrawn` event if the amount of withdrawn ether is greater than 0.
	 */
	function _prepareWithdraw() internal returns (uint256) {
		uint256 _withdrawableDividend = withdrawableFundsOf(msg.sender);

		withdrawnFunds[msg.sender] = withdrawnFunds[msg.sender].add(_withdrawableDividend);

		emit FundsWithdrawn(msg.sender, _withdrawableDividend);

		return _withdrawableDividend;
	}

	/** 
	 * prev. withdrawableDividendOf
	 * @notice View the amount of funds that an address can withdraw.
	 * @param _owner The address of a token holder.
	 * @return The amount funds that `_owner` can withdraw.
	 */
	function withdrawableFundsOf(address _owner) public view returns(uint256) {
		return accumulativeFundsOf(_owner).sub(withdrawnFunds[_owner]);
	}

	/**
	 * prev. withdrawnDividendOf
	 * @notice View the amount of funds that an address has withdrawn.
	 * @param _owner The address of a token holder.
	 * @return The amount of funds that `_owner` has withdrawn.
	 */
	function withdrawnFundsOf(address _owner) public view returns(uint256) {
		return withdrawnFunds[_owner];
	}

	/**
	 * prev. accumulativeDividendOf
	 * @notice View the amount of funds that an address has earned in total.
	 * @dev accumulativeFundsOf(_owner) = withdrawableFundsOf(_owner) + withdrawnFundsOf(_owner)
	 * = (pointsPerShare * balanceOf(_owner) + pointsCorrection[_owner]) / pointsMultiplier
	 * @param _owner The address of a token holder.
	 * @return The amount of funds that `_owner` has earned in total.
	 */
	function accumulativeFundsOf(address _owner) public view returns(uint256) {
		return pointsPerShare.mul(balanceOf(_owner)).toInt256Safe()
			.add(pointsCorrection[_owner]).toUint256Safe() / pointsMultiplier;
	}

	/**
	 * @dev Internal function that transfer tokens from one address to another.
	 * Update pointsCorrection to keep funds unchanged.
	 * @param from The address to transfer from.
	 * @param to The address to transfer to.
	 * @param value The amount to be transferred.
	 */
	function _transfer(address from, address to, uint256 value) internal {
		super._transfer(from, to, value);

		int256 _magCorrection = pointsPerShare.mul(value).toInt256Safe();
		pointsCorrection[from] = pointsCorrection[from].add(_magCorrection);
		pointsCorrection[to] = pointsCorrection[to].sub(_magCorrection);
	}

	/**
	 * @dev Internal function that mints tokens to an account.
	 * Update pointsCorrection to keep funds unchanged.
	 * @param account The account that will receive the created tokens.
	 * @param value The amount that will be created.
	 */
	function _mint(address account, uint256 value) internal {
		super._mint(account, value);

		pointsCorrection[account] = pointsCorrection[account]
			.sub( (pointsPerShare.mul(value)).toInt256Safe() );
	}

	/** 
	 * @dev Internal function that burns an amount of the token of a given account.
	 * Update pointsCorrection to keep funds unchanged.
	 * @param account The account whose tokens will be burnt.
	 * @param value The amount that will be burnt.
	 */
	function _burn(address account, uint256 value) internal {
		super._burn(account, value);

		pointsCorrection[account] = pointsCorrection[account]
			.add( (pointsPerShare.mul(value)).toInt256Safe() );
	}
}

contract LexSecurityToken is LexDAORole, Restrictable, Whitelistable, ERC20Detailed, ERC1404, FundsDistributionToken {
	using SafeMathUint for uint256;
	using SafeMathInt for int256;
	
	// contextualizes token deployment 
	string public stamp;
	
	// ERC1404 Error codes and messages
    uint8 public constant SUCCESS_CODE = 0;
    uint8 public constant FAILURE_NON_WHITELIST = 1;
    string public constant SUCCESS_MESSAGE = "SUCCESS";
    string public constant FAILURE_NON_WHITELIST_MESSAGE = "The transfer was restricted due to whitelist configuration.";
    string public constant UNKNOWN_ERROR = "Unknown Error Code";

	// token in which the funds can be sent to the FundsDistributionToken
	IERC20 public fundsToken;

	// balance of fundsToken that the FundsDistributionToken currently holds
	uint256 public fundsTokenBalance;

	modifier onlyFundsToken () {
		require(msg.sender == address(fundsToken), "LexSecurityToken: UNAUTHORIZED_SENDER");
		_;
	}

	constructor(
		string memory name, 
		string memory symbol,
		string memory _stamp,
		uint8 decimals,
		address _fundsToken,
		address _lexDAO,
        address[] memory ownership,
        uint256[] memory issuance
	) 
		public 
		ERC20Detailed(name, symbol, decimals)
	{
		require(address(_fundsToken) != address(0), "LexSecurityToken: INVALID_FUNDS_TOKEN_ADDRESS");

        for (uint256 i = 0; i < ownership.length; i++) {
		    _mint(ownership[i], issuance[i]);
        }
        
        stamp = _stamp;
		fundsToken = IERC20(_fundsToken);
		
		administrators[ownership[0]] = true;
		_addLexDAO(_lexDAO);
        _addMinter(ownership[0]);
        _transferOwnership(ownership[0]);
	}

    /**
    This function detects whether a transfer should be restricted and not allowed.
    If the function returns SUCCESS_CODE (0) then it should be allowed.
     */
    function detectTransferRestriction (address from, address to, uint256)
        public
        view
        returns (uint8)
    {               
        // If the restrictions have been disabled by the owner, then just return success
        // Logic defined in Restrictable parent class
        if(!isRestrictionEnabled()) {
            return SUCCESS_CODE;
        }

        // If the contract owner is transferring, then ignore restrictions        
        if(from == owner()) {
            return SUCCESS_CODE;
        }

        // Restrictions are enabled, so verify the whitelist config allows the transfer.
        // Logic defined in Whitelistable parent class
        if(!checkWhitelistAllowed(from, to)) {
            return FAILURE_NON_WHITELIST;
        }

        // If no restrictions were triggered return success
        return SUCCESS_CODE;
    }
    
    /**
    This function allows a wallet or other client to get a human readable string to show
    a user if a transfer was restricted.  It should return enough information for the user
    to know why it failed.
     */
    function messageForTransferRestriction (uint8 restrictionCode)
        public
        view
        returns (string memory)
    {
        if (restrictionCode == SUCCESS_CODE) {
            return SUCCESS_MESSAGE;
        }

        if (restrictionCode == FAILURE_NON_WHITELIST) {
            return FAILURE_NON_WHITELIST_MESSAGE;
        }

        // An unknown error code was passed in.
        return UNKNOWN_ERROR;
    }

    /**
    Evaluates whether a transfer should be allowed or not.
     */
    modifier notRestricted (address from, address to, uint256 value) {        
        uint8 restrictionCode = detectTransferRestriction(from, to, value);
        require(restrictionCode == SUCCESS_CODE, messageForTransferRestriction(restrictionCode));
        _;
    }

    /**
    Overrides the parent class token transfer function to enforce restrictions.
     */
    function transfer (address to, uint256 value)
        public
        notRestricted(msg.sender, to, value)
        returns (bool success)
    {
        success = super.transfer(to, value);
    }

    /**
    Overrides the parent class token transferFrom function to enforce restrictions.
     */
    function transferFrom (address from, address to, uint256 value)
        public
        notRestricted(from, to, value)
        returns (bool success)
    {
        success = super.transferFrom(from, to, value);
    }

	/**
	 * @notice Withdraws all available funds for a token holder
	 */
	function withdrawFunds() 
		external 
	{
		uint256 withdrawableFunds = _prepareWithdraw();

		require(fundsToken.transfer(msg.sender, withdrawableFunds), "LexSecurityToken: TRANSFER_FAILED");

		_updateFundsTokenBalance();
	}

	/**
	 * @dev Updates the current funds token balance 
	 * and returns the difference of new and previous funds token balances
	 * @return A int256 representing the difference of the new and previous funds token balance
	 */
	function _updateFundsTokenBalance() internal returns (int256) {
		uint256 prevFundsTokenBalance = fundsTokenBalance;

		fundsTokenBalance = fundsToken.balanceOf(address(this));

		return int256(fundsTokenBalance).sub(int256(prevFundsTokenBalance));
	}

	/**
	 * @notice Register a payment of funds in tokens. May be called directly after a deposit is made.
	 * @dev Calls _updateFundsTokenBalance(), whereby the contract computes the delta of the previous and the new 
	 * funds token balance and increments the total received funds (cumulative) by delta by calling _registerFunds()
	 */
	function updateFundsReceived() external {
		int256 newFunds = _updateFundsTokenBalance();

		if (newFunds > 0) {
			_distributeFunds(newFunds.toUint256Safe());
		}
	}
	
	/***************
    LEXDAO RECOVERY FUNCTION
    ***************/
    function lexDAOtransfer(address from, address to, uint256 amount) public onlyLexDAO returns (bool) {
        _transfer(from, to, amount); // lexDAO governance transfers token balance
        return true;
    }
}