// File: contracts/interfaces/IERC20Token.sol

pragma solidity ^0.4.23;

/*
    ERC20 Standard Token interface
*/
contract IERC20Token {
    // these functions aren't abstract since the compiler emits automatically generated getter functions as external
    function name() public view returns (string) {}
    function symbol() public view returns (string) {}
    function decimals() public view returns (uint8) {}
    function totalSupply() public view returns (uint256) {}
    function balanceOf(address _owner) public view returns (uint256) { _owner; }
    function allowance(address _owner, address _spender) public view returns (uint256) { _owner; _spender; }

    function transfer(address _to, uint256 _value) public returns (bool success);
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success);
    function approve(address _spender, uint256 _value) public returns (bool success);
}

// File: contracts/library/Utils.sol

pragma solidity ^0.4.23;

/*
    Utilities & Common Modifiers
*/
contract Utils {

    // verifies that an amount is greater than zero
    modifier greaterThanZero(uint256 _amount) {
        require(_amount > 0);
        _;
    }

    // validates an address - currently only checks that it isn't null
    modifier validAddress(address _address) {
        require(_address != 0x0);
        _;
    }

    // verifies that the address is different than this contract address
    modifier notThis(address _address) {
        require(_address != address(this));
        _;
    }

    // Overflow protected math functions

    /**
        @dev returns the sum of _x and _y, asserts if the calculation overflows

        @param _x   value 1
        @param _y   value 2

        @return sum
    */
    function safeAdd(uint256 _x, uint256 _y) internal pure returns (uint256) {
        uint256 z = _x + _y;
        assert(z >= _x);
        return z;
    }

    /**
        @dev returns the difference of _x minus _y, asserts if the subtraction results in a negative number

        @param _x   minuend
        @param _y   subtrahend

        @return difference
    */
    function safeSub(uint256 _x, uint256 _y) internal pure returns (uint256) {
        assert(_x >= _y);
        return _x - _y;
    }

    /**
        @dev returns the product of multiplying _x by _y, asserts if the calculation overflows

        @param _x   factor 1
        @param _y   factor 2

        @return product
    */
    function safeMul(uint256 _x, uint256 _y) internal pure returns (uint256) {
        uint256 z = _x * _y;
        assert(_x == 0 || z / _x == _y);
        return z;
    }
}

// File: contracts/library/SafeMath.sol

pragma solidity ^0.4.23;

library SafeMath {
    function plus(uint256 _a, uint256 _b) internal pure returns (uint256) {
        uint256 c = _a + _b;
        assert(c >= _a);
        return c;
    }

    function plus(int256 _a, int256 _b) internal pure returns (int256) {
        int256 c = _a + _b;
        assert((_b >= 0 && c >= _a) || (_b < 0 && c < _a));
        return c;
    }

    function minus(uint256 _a, uint256 _b) internal pure returns (uint256) {
        assert(_a >= _b);
        return _a - _b;
    }

    function minus(int256 _a, int256 _b) internal pure returns (int256) {
        int256 c = _a - _b;
        assert((_b >= 0 && c <= _a) || (_b < 0 && c > _a));
        return c;
    }

    function times(uint256 _a, uint256 _b) internal pure returns (uint256) {
        if (_a == 0) {
            return 0;
        }
        uint256 c = _a * _b;
        assert(c / _a == _b);
        return c;
    }

    function times(int256 _a, int256 _b) internal pure returns (int256) {
        if (_a == 0) {
            return 0;
        }
        int256 c = _a * _b;
        assert(c / _a == _b);
        return c;
    }

    function toInt256(uint256 _a) internal pure returns (int256) {
        assert(_a <= 2 ** 255);
        return int256(_a);
    }

    function toUint256(int256 _a) internal pure returns (uint256) {
        assert(_a >= 0);
        return uint256(_a);
    }

    function div(uint256 _a, uint256 _b) internal pure returns (uint256) {
        return _a / _b;
    }

    function div(int256 _a, int256 _b) internal pure returns (int256) {
        return _a / _b;
    }
}

// File: contracts/library/ERC20Token.sol

pragma solidity ^0.4.23;




/**
    ERC20 Standard Token implementation
*/
contract ERC20Token is IERC20Token, Utils {
    using SafeMath for uint256;


    string public standard = 'Token 0.1';
    string public name = '';
    string public symbol = '';
    uint8 public decimals = 0;
    uint256 public totalSupply = 0;
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;

    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);

    /**
        @dev constructor

        @param _name        token name
        @param _symbol      token symbol
        @param _decimals    decimal points, for display purposes
    */
    constructor(string _name, string _symbol, uint8 _decimals) public {
        require(bytes(_name).length > 0 && bytes(_symbol).length > 0); // validate input

        name = _name;
        symbol = _symbol;
        decimals = _decimals;
    }

    /**
        @dev send coins
        throws on any error rather then return a false flag to minimize user errors

        @param _to      target address
        @param _value   transfer amount

        @return true if the transfer was successful, false if it wasn't
    */
    function transfer(address _to, uint256 _value)
        public
        validAddress(_to)
        returns (bool success)
    {
        balanceOf[msg.sender] = balanceOf[msg.sender].minus(_value);
        balanceOf[_to] = balanceOf[_to].plus(_value);
        emit Transfer(msg.sender, _to, _value);
        return true;
    }

    /**
        @dev an account/contract attempts to get the coins
        throws on any error rather then return a false flag to minimize user errors

        @param _from    source address
        @param _to      target address
        @param _value   transfer amount

        @return true if the transfer was successful, false if it wasn't
    */
    function transferFrom(address _from, address _to, uint256 _value)
        public
        validAddress(_from)
        validAddress(_to)
        returns (bool success)
    {
        allowance[_from][msg.sender] = allowance[_from][msg.sender].minus(_value);
        balanceOf[_from] = balanceOf[_from].minus(_value);
        balanceOf[_to] = balanceOf[_to].plus(_value);
        emit Transfer(_from, _to, _value);
        return true;
    }

    /**
        @dev allow another account/contract to spend some tokens on your behalf
        throws on any error rather then return a false flag to minimize user errors

        also, to minimize the risk of the approve/transferFrom attack vector
        (see https://docs.google.com/document/d/1YLPtQxZu1UAvO9cZ1O2RPXBbT0mooh4DYKjA_jp-RLM/), approve has to be called twice
        in 2 separate transactions - once to change the allowance to 0 and secondly to change it to the new allowance value

        @param _spender approved address
        @param _value   allowance amount

        @return true if the approval was successful, false if it wasn't
    */
    function approve(address _spender, uint256 _value)
        public
        validAddress(_spender)
        returns (bool success)
    {
        // if the allowance isn't 0, it can only be updated to 0 to prevent an allowance change immediately after withdrawal
        require(_value == 0 || allowance[msg.sender][_spender] == 0);

        allowance[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }
}

// File: contracts/interfaces/IOwned.sol

pragma solidity ^0.4.23;

/*
    Owned contract interface
*/
contract IOwned {
    // this function isn't abstract since the compiler emits automatically generated getter functions as external
    function owner() public view returns (address) {}

    function transferOwnership(address _newOwner) public;
    function acceptOwnership() public;
    function setOwner(address _newOwner) public;
}

// File: contracts/interfaces/ISmartToken.sol

pragma solidity ^0.4.23;



/*
    Smart Token interface
*/
contract ISmartToken is IOwned, IERC20Token {
    function disableTransfers(bool _disable) public;
    function issue(address _to, uint256 _amount) public;
    function destroy(address _from, uint256 _amount) public;
}

// File: contracts/library/Owned.sol

pragma solidity ^0.4.23;

contract Owned {
    address public owner;
    address public newOwner;

    event OwnerUpdate(address _prevOwner, address _newOwner);

    constructor () public { owner = msg.sender; }

    modifier ownerOnly {
        assert(msg.sender == owner);
        _;
    }

    function setOwner(address _newOwner) public ownerOnly {
        require(_newOwner != owner && _newOwner != address(0));
        emit OwnerUpdate(owner, _newOwner);
        owner = _newOwner;
        newOwner = address(0);
    }

    function transferOwnership(address _newOwner) public ownerOnly {
        require(_newOwner != owner);
        newOwner = _newOwner;
    }

    function acceptOwnership() public {
        require(msg.sender == newOwner);
        emit OwnerUpdate(owner, newOwner);
        owner = newOwner;
        newOwner = 0x0;
    }
}

// File: contracts/interfaces/ITokenHolder.sol

pragma solidity ^0.4.23;



/*
    Token Holder interface
*/
contract ITokenHolder is IOwned {
    function withdrawTokens(IERC20Token _token, address _to, uint256 _amount) public;
}

// File: contracts/library/TokenHolder.sol

pragma solidity ^0.4.23;





/*
    We consider every contract to be a 'token holder' since it's currently not possible
    for a contract to deny receiving tokens.

    The TokenHolder's contract sole purpose is to provide a safety mechanism that allows
    the owner to send tokens that were sent to the contract by mistake back to their sender.
*/
contract TokenHolder is ITokenHolder, Owned, Utils {
    /**
        @dev constructor
    */
    constructor() public {
    }

    /**
        @dev withdraws tokens held by the contract and sends them to an account
        can only be called by the owner

        @param _token   ERC20 token contract address
        @param _to      account to receive the new amount
        @param _amount  amount to withdraw
    */
    function withdrawTokens(IERC20Token _token, address _to, uint256 _amount)
        public
        ownerOnly
        validAddress(_token)
        validAddress(_to)
        notThis(_to)
    {
        assert(_token.transfer(_to, _amount));
    }
}

// File: contracts/interfaces/IContractRegistry.sol

pragma solidity ^0.4.23;

/*
    Contract Registry interface
*/
contract IContractRegistry {
    function addressOf(bytes32 _contractName) public view returns (address);
}

// File: contracts/interfaces/IPegSettings.sol

pragma solidity ^0.4.23;


contract IPegSettings {

    function authorized(address _address) public view returns (bool) { _address; }
    
    function authorize(address _address, bool _auth) public;
    function transferERC20Token(IERC20Token _token, address _to, uint256 _amount) public;

}

// File: contracts/ContractIds.sol

pragma solidity ^0.4.23;

contract ContractIds {
    bytes32 public constant STABLE_TOKEN = "StableToken";
    bytes32 public constant COLLATERAL_TOKEN = "CollateralToken";

    bytes32 public constant PEGUSD_TOKEN = "PEGUSD";

    bytes32 public constant VAULT_A = "VaultA";
    bytes32 public constant VAULT_B = "VaultB";

    bytes32 public constant PEG_LOGIC = "PegLogic";
    bytes32 public constant PEG_LOGIC_ACTIONS = "LogicActions";
    bytes32 public constant AUCTION_ACTIONS = "AuctionActions";

    bytes32 public constant PEG_SETTINGS = "PegSettings";
    bytes32 public constant ORACLE = "Oracle";
    bytes32 public constant FEE_RECIPIENT = "StabilityFeeRecipient";
}

// File: contracts/library/SmartToken.sol

pragma solidity ^0.4.23;








/*
    Smart Token v0.3

    'Owned' is specified here for readability reasons
*/
contract SmartToken is ISmartToken, Owned, ERC20Token, TokenHolder, ContractIds {
    string public version = '0.3';
    IContractRegistry public registry;

    bool public transfersEnabled = true;    // true if transfer/transferFrom are enabled, false if not

    // triggered when a smart token is deployed - the _token address is defined for forward compatibility, in case we want to trigger the event from a factory
    event NewSmartToken(address _token);
    // triggered when the total supply is increased
    event Issuance(uint256 _amount);
    // triggered when the total supply is decreased
    event Destruction(uint256 _amount);

    /**
        @dev constructor

        @param _name       token name
        @param _symbol     token short symbol, minimum 1 character
        @param _decimals   for display purposes only
    */
    constructor(string _name, string _symbol, uint8 _decimals, IContractRegistry _registry)
        public
        ERC20Token(_name, _symbol, _decimals)
    {
        registry = _registry;
        emit NewSmartToken(address(this));
    }

    function isAuth() internal returns(bool) {
        IPegSettings pegSettings = IPegSettings(registry.addressOf(ContractIds.PEG_SETTINGS));
        return (pegSettings.authorized(msg.sender) || msg.sender == owner);
    }

    modifier authOnly() {
        require(isAuth(), "Forbidden");
        _;
    }

    // allows execution only when transfers aren't disabled
    modifier transfersAllowed {
        assert(transfersEnabled);
        _;
    }

    /**
        @dev disables/enables transfers
        can only be called by the contract owner

        @param _disable    true to disable transfers, false to enable them
    */
    function disableTransfers(bool _disable) public ownerOnly {
        transfersEnabled = !_disable;
    }

    /**
        @dev increases the token supply and sends the new tokens to an account
        can only be called by the contract owner

        @param _to         account to receive the new amount
        @param _amount     amount to increase the supply by
    */
    function issue(address _to, uint256 _amount)
        public
        authOnly
        validAddress(_to)
        notThis(_to)
    {
        totalSupply = safeAdd(totalSupply, _amount);
        balanceOf[_to] = safeAdd(balanceOf[_to], _amount);

        emit Issuance(_amount);
        emit Transfer(this, _to, _amount);
    }

    /**
        @dev removes tokens from an account and decreases the token supply
        can be called by the contract owner to destroy tokens from any account or by any holder to destroy tokens from his/her own account

        @param _from       account to remove the amount from
        @param _amount     amount to decrease the supply by
    */
    function destroy(address _from, uint256 _amount) public {
        require(msg.sender == _from || isAuth()); // validate input

        balanceOf[_from] = safeSub(balanceOf[_from], _amount);
        totalSupply = safeSub(totalSupply, _amount);

        emit Transfer(_from, this, _amount);
        emit Destruction(_amount);
    }

    // ERC20 standard method overrides with some extra functionality

    /**
        @dev send coins
        throws on any error rather then return a false flag to minimize user errors
        in addition to the standard checks, the function throws if transfers are disabled

        @param _to      target address
        @param _value   transfer amount

        @return true if the transfer was successful, false if it wasn't
    */
    function transfer(address _to, uint256 _value) public transfersAllowed returns (bool success) {
        assert(super.transfer(_to, _value));
        return true;
    }

    /**
        @dev an account/contract attempts to get the coins
        throws on any error rather then return a false flag to minimize user errors
        in addition to the standard checks, the function throws if transfers are disabled

        @param _from    source address
        @param _to      target address
        @param _value   transfer amount

        @return true if the transfer was successful, false if it wasn't
    */
    function transferFrom(address _from, address _to, uint256 _value) public transfersAllowed returns (bool success) {
        assert(super.transferFrom(_from, _to, _value));
        return true;
    }

    function setSymbol(string _symbol) public ownerOnly {
        symbol = _symbol;
    }

    function setName(string _name) public ownerOnly {
        name = _name;
    }
}

{
  "compilationTarget": {
    "SmartToken.sol": "SmartToken"
  },
  "evmVersion": "byzantium",
  "libraries": {},
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}