/**
 * Source Code first verified at https://etherscan.io on Monday, April 15, 2019
 (UTC) */

// File: @gnosis.pm/util-contracts/contracts/Math.sol

pragma solidity ^0.5.2;

/// @title Math library - Allows calculation of logarithmic and exponential functions
/// @author Alan Lu - <<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="553439343b7b392015323b3a263c267b2538">[email protected]</a>>
/// @author Stefan George - <<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="0172756467606f41666f6e7268722f716c">[email protected]</a>>
library GnosisMath {
    /*
     *  Constants
     */
    // This is equal to 1 in our calculations
    uint public constant ONE = 0x10000000000000000;
    uint public constant LN2 = 0xb17217f7d1cf79ac;
    uint public constant LOG2_E = 0x171547652b82fe177;

    /*
     *  Public functions
     */
    /// @dev Returns natural exponential function value of given x
    /// @param x x
    /// @return e**x
    function exp(int x) public pure returns (uint) {
        // revert if x is > MAX_POWER, where
        // MAX_POWER = int(mp.floor(mp.log(mpf(2**256 - 1) / ONE) * ONE))
        require(x <= 2454971259878909886679);
        // return 0 if exp(x) is tiny, using
        // MIN_POWER = int(mp.floor(mp.log(mpf(1) / ONE) * ONE))
        if (x < -818323753292969962227) return 0;
        // Transform so that e^x -> 2^x
        x = x * int(ONE) / int(LN2);
        // 2^x = 2^whole(x) * 2^frac(x)
        //       ^^^^^^^^^^ is a bit shift
        // so Taylor expand on z = frac(x)
        int shift;
        uint z;
        if (x >= 0) {
            shift = x / int(ONE);
            z = uint(x % int(ONE));
        } else {
            shift = x / int(ONE) - 1;
            z = ONE - uint(-x % int(ONE));
        }
        // 2^x = 1 + (ln 2) x + (ln 2)^2/2! x^2 + ...
        //
        // Can generate the z coefficients using mpmath and the following lines
        // >>> from mpmath import mp
        // >>> mp.dps = 100
        // >>> ONE =  0x10000000000000000
        // >>> print('\n'.join(hex(int(mp.log(2)**i / mp.factorial(i) * ONE)) for i in range(1, 7)))
        // 0xb17217f7d1cf79ab
        // 0x3d7f7bff058b1d50
        // 0xe35846b82505fc5
        // 0x276556df749cee5
        // 0x5761ff9e299cc4
        // 0xa184897c363c3
        uint zpow = z;
        uint result = ONE;
        result += 0xb17217f7d1cf79ab * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0x3d7f7bff058b1d50 * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0xe35846b82505fc5 * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0x276556df749cee5 * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0x5761ff9e299cc4 * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0xa184897c363c3 * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0xffe5fe2c4586 * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0x162c0223a5c8 * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0x1b5253d395e * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0x1e4cf5158b * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0x1e8cac735 * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0x1c3bd650 * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0x1816193 * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0x131496 * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0xe1b7 * zpow / ONE;
        zpow = zpow * z / ONE;
        result += 0x9c7 * zpow / ONE;
        if (shift >= 0) {
            if (result >> (256 - shift) > 0) return (2 ** 256 - 1);
            return result << shift;
        } else return result >> (-shift);
    }

    /// @dev Returns natural logarithm value of given x
    /// @param x x
    /// @return ln(x)
    function ln(uint x) public pure returns (int) {
        require(x > 0);
        // binary search for floor(log2(x))
        int ilog2 = floorLog2(x);
        int z;
        if (ilog2 < 0) z = int(x << uint(-ilog2));
        else z = int(x >> uint(ilog2));
        // z = x * 2^-⌊log₂x⌋
        // so 1 <= z < 2
        // and ln z = ln x - ⌊log₂x⌋/log₂e
        // so just compute ln z using artanh series
        // and calculate ln x from that
        int term = (z - int(ONE)) * int(ONE) / (z + int(ONE));
        int halflnz = term;
        int termpow = term * term / int(ONE) * term / int(ONE);
        halflnz += termpow / 3;
        termpow = termpow * term / int(ONE) * term / int(ONE);
        halflnz += termpow / 5;
        termpow = termpow * term / int(ONE) * term / int(ONE);
        halflnz += termpow / 7;
        termpow = termpow * term / int(ONE) * term / int(ONE);
        halflnz += termpow / 9;
        termpow = termpow * term / int(ONE) * term / int(ONE);
        halflnz += termpow / 11;
        termpow = termpow * term / int(ONE) * term / int(ONE);
        halflnz += termpow / 13;
        termpow = termpow * term / int(ONE) * term / int(ONE);
        halflnz += termpow / 15;
        termpow = termpow * term / int(ONE) * term / int(ONE);
        halflnz += termpow / 17;
        termpow = termpow * term / int(ONE) * term / int(ONE);
        halflnz += termpow / 19;
        termpow = termpow * term / int(ONE) * term / int(ONE);
        halflnz += termpow / 21;
        termpow = termpow * term / int(ONE) * term / int(ONE);
        halflnz += termpow / 23;
        termpow = termpow * term / int(ONE) * term / int(ONE);
        halflnz += termpow / 25;
        return (ilog2 * int(ONE)) * int(ONE) / int(LOG2_E) + 2 * halflnz;
    }

    /// @dev Returns base 2 logarithm value of given x
    /// @param x x
    /// @return logarithmic value
    function floorLog2(uint x) public pure returns (int lo) {
        lo = -64;
        int hi = 193;
        // I use a shift here instead of / 2 because it floors instead of rounding towards 0
        int mid = (hi + lo) >> 1;
        while ((lo + 1) < hi) {
            if (mid < 0 && x << uint(-mid) < ONE || mid >= 0 && x >> uint(mid) < ONE) hi = mid;
            else lo = mid;
            mid = (hi + lo) >> 1;
        }
    }

    /// @dev Returns maximum of an array
    /// @param nums Numbers to look through
    /// @return Maximum number
    function max(int[] memory nums) public pure returns (int maxNum) {
        require(nums.length > 0);
        maxNum = -2 ** 255;
        for (uint i = 0; i < nums.length; i++) if (nums[i] > maxNum) maxNum = nums[i];
    }

    /// @dev Returns whether an add operation causes an overflow
    /// @param a First addend
    /// @param b Second addend
    /// @return Did no overflow occur?
    function safeToAdd(uint a, uint b) internal pure returns (bool) {
        return a + b >= a;
    }

    /// @dev Returns whether a subtraction operation causes an underflow
    /// @param a Minuend
    /// @param b Subtrahend
    /// @return Did no underflow occur?
    function safeToSub(uint a, uint b) internal pure returns (bool) {
        return a >= b;
    }

    /// @dev Returns whether a multiply operation causes an overflow
    /// @param a First factor
    /// @param b Second factor
    /// @return Did no overflow occur?
    function safeToMul(uint a, uint b) internal pure returns (bool) {
        return b == 0 || a * b / b == a;
    }

    /// @dev Returns sum if no overflow occurred
    /// @param a First addend
    /// @param b Second addend
    /// @return Sum
    function add(uint a, uint b) internal pure returns (uint) {
        require(safeToAdd(a, b));
        return a + b;
    }

    /// @dev Returns difference if no overflow occurred
    /// @param a Minuend
    /// @param b Subtrahend
    /// @return Difference
    function sub(uint a, uint b) internal pure returns (uint) {
        require(safeToSub(a, b));
        return a - b;
    }

    /// @dev Returns product if no overflow occurred
    /// @param a First factor
    /// @param b Second factor
    /// @return Product
    function mul(uint a, uint b) internal pure returns (uint) {
        require(safeToMul(a, b));
        return a * b;
    }

    /// @dev Returns whether an add operation causes an overflow
    /// @param a First addend
    /// @param b Second addend
    /// @return Did no overflow occur?
    function safeToAdd(int a, int b) internal pure returns (bool) {
        return (b >= 0 && a + b >= a) || (b < 0 && a + b < a);
    }

    /// @dev Returns whether a subtraction operation causes an underflow
    /// @param a Minuend
    /// @param b Subtrahend
    /// @return Did no underflow occur?
    function safeToSub(int a, int b) internal pure returns (bool) {
        return (b >= 0 && a - b <= a) || (b < 0 && a - b > a);
    }

    /// @dev Returns whether a multiply operation causes an overflow
    /// @param a First factor
    /// @param b Second factor
    /// @return Did no overflow occur?
    function safeToMul(int a, int b) internal pure returns (bool) {
        return (b == 0) || (a * b / b == a);
    }

    /// @dev Returns sum if no overflow occurred
    /// @param a First addend
    /// @param b Second addend
    /// @return Sum
    function add(int a, int b) internal pure returns (int) {
        require(safeToAdd(a, b));
        return a + b;
    }

    /// @dev Returns difference if no overflow occurred
    /// @param a Minuend
    /// @param b Subtrahend
    /// @return Difference
    function sub(int a, int b) internal pure returns (int) {
        require(safeToSub(a, b));
        return a - b;
    }

    /// @dev Returns product if no overflow occurred
    /// @param a First factor
    /// @param b Second factor
    /// @return Product
    function mul(int a, int b) internal pure returns (int) {
        require(safeToMul(a, b));
        return a * b;
    }
}

// File: @gnosis.pm/util-contracts/contracts/Token.sol

/// Implements ERC 20 Token standard: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20-token-standard.md
pragma solidity ^0.5.2;

/// @title Abstract token contract - Functions to be implemented by token contracts
contract Token {
    /*
     *  Events
     */
    event Transfer(address indexed from, address indexed to, uint value);
    event Approval(address indexed owner, address indexed spender, uint value);

    /*
     *  Public functions
     */
    function transfer(address to, uint value) public returns (bool);
    function transferFrom(address from, address to, uint value) public returns (bool);
    function approve(address spender, uint value) public returns (bool);
    function balanceOf(address owner) public view returns (uint);
    function allowance(address owner, address spender) public view returns (uint);
    function totalSupply() public view returns (uint);
}

// File: @gnosis.pm/util-contracts/contracts/Proxy.sol

pragma solidity ^0.5.2;

/// @title Proxied - indicates that a contract will be proxied. Also defines storage requirements for Proxy.
/// @author Alan Lu - <<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="b2d3ded3dcf2d5dcddc1dbc19cc2df">[email protected]</a>>
contract Proxied {
    address public masterCopy;
}

/// @title Proxy - Generic proxy contract allows to execute all transactions applying the code of a master contract.
/// @author Stefan George - <<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="196a6d7c7f7877597e77766a706a376974">[email protected]</a>>
contract Proxy is Proxied {
    /// @dev Constructor function sets address of master copy contract.
    /// @param _masterCopy Master copy address.
    constructor(address _masterCopy) public {
        require(_masterCopy != address(0), "The master copy is required");
        masterCopy = _masterCopy;
    }

    /// @dev Fallback function forwards all transactions and returns all received return data.
    function() external payable {
        address _masterCopy = masterCopy;
        assembly {
            calldatacopy(0, 0, calldatasize)
            let success := delegatecall(not(0), _masterCopy, 0, calldatasize, 0, 0)
            returndatacopy(0, 0, returndatasize)
            switch success
                case 0 {
                    revert(0, returndatasize)
                }
                default {
                    return(0, returndatasize)
                }
        }
    }
}

// File: @gnosis.pm/util-contracts/contracts/GnosisStandardToken.sol

pragma solidity ^0.5.2;




/**
 * Deprecated: Use Open Zeppeling one instead
 */
contract StandardTokenData {
    /*
     *  Storage
     */
    mapping(address => uint) balances;
    mapping(address => mapping(address => uint)) allowances;
    uint totalTokens;
}

/**
 * Deprecated: Use Open Zeppeling one instead
 */
/// @title Standard token contract with overflow protection
contract GnosisStandardToken is Token, StandardTokenData {
    using GnosisMath for *;

    /*
     *  Public functions
     */
    /// @dev Transfers sender's tokens to a given address. Returns success
    /// @param to Address of token receiver
    /// @param value Number of tokens to transfer
    /// @return Was transfer successful?
    function transfer(address to, uint value) public returns (bool) {
        if (!balances[msg.sender].safeToSub(value) || !balances[to].safeToAdd(value)) {
            return false;
        }

        balances[msg.sender] -= value;
        balances[to] += value;
        emit Transfer(msg.sender, to, value);
        return true;
    }

    /// @dev Allows allowed third party to transfer tokens from one address to another. Returns success
    /// @param from Address from where tokens are withdrawn
    /// @param to Address to where tokens are sent
    /// @param value Number of tokens to transfer
    /// @return Was transfer successful?
    function transferFrom(address from, address to, uint value) public returns (bool) {
        if (!balances[from].safeToSub(value) || !allowances[from][msg.sender].safeToSub(
            value
        ) || !balances[to].safeToAdd(value)) {
            return false;
        }
        balances[from] -= value;
        allowances[from][msg.sender] -= value;
        balances[to] += value;
        emit Transfer(from, to, value);
        return true;
    }

    /// @dev Sets approved amount of tokens for spender. Returns success
    /// @param spender Address of allowed account
    /// @param value Number of approved tokens
    /// @return Was approval successful?
    function approve(address spender, uint value) public returns (bool) {
        allowances[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
        return true;
    }

    /// @dev Returns number of allowed tokens for given address
    /// @param owner Address of token owner
    /// @param spender Address of token spender
    /// @return Remaining allowance for spender
    function allowance(address owner, address spender) public view returns (uint) {
        return allowances[owner][spender];
    }

    /// @dev Returns number of tokens owned by given address
    /// @param owner Address of token owner
    /// @return Balance of owner
    function balanceOf(address owner) public view returns (uint) {
        return balances[owner];
    }

    /// @dev Returns total supply of tokens
    /// @return Total supply
    function totalSupply() public view returns (uint) {
        return totalTokens;
    }
}

// File: contracts/TokenOWL.sol

pragma solidity ^0.5.2;




contract TokenOWL is Proxied, GnosisStandardToken {
    using GnosisMath for *;

    string public constant name = "OWL Token";
    string public constant symbol = "OWL";
    uint8 public constant decimals = 18;

    struct masterCopyCountdownType {
        address masterCopy;
        uint timeWhenAvailable;
    }

    masterCopyCountdownType masterCopyCountdown;

    address public creator;
    address public minter;

    event Minted(address indexed to, uint256 amount);
    event Burnt(address indexed from, address indexed user, uint256 amount);

    modifier onlyCreator() {
        // R1
        require(msg.sender == creator, "Only the creator can perform the transaction");
        _;
    }
    /// @dev trickers the update process via the proxyMaster for a new address _masterCopy
    /// updating is only possible after 30 days
    function startMasterCopyCountdown(address _masterCopy) public onlyCreator {
        require(address(_masterCopy) != address(0), "The master copy must be a valid address");

        // Update masterCopyCountdown
        masterCopyCountdown.masterCopy = _masterCopy;
        masterCopyCountdown.timeWhenAvailable = now + 30 days;
    }

    /// @dev executes the update process via the proxyMaster for a new address _masterCopy
    function updateMasterCopy() public onlyCreator {
        require(address(masterCopyCountdown.masterCopy) != address(0), "The master copy must be a valid address");
        require(
            block.timestamp >= masterCopyCountdown.timeWhenAvailable,
            "It's not possible to update the master copy during the waiting period"
        );

        // Update masterCopy
        masterCopy = masterCopyCountdown.masterCopy;
    }

    function getMasterCopy() public view returns (address) {
        return masterCopy;
    }

    /// @dev Set minter. Only the creator of this contract can call this.
    /// @param newMinter The new address authorized to mint this token
    function setMinter(address newMinter) public onlyCreator {
        minter = newMinter;
    }

    /// @dev change owner/creator of the contract. Only the creator/owner of this contract can call this.
    /// @param newOwner The new address, which should become the owner
    function setNewOwner(address newOwner) public onlyCreator {
        creator = newOwner;
    }

    /// @dev Mints OWL.
    /// @param to Address to which the minted token will be given
    /// @param amount Amount of OWL to be minted
    function mintOWL(address to, uint amount) public {
        require(minter != address(0), "The minter must be initialized");
        require(msg.sender == minter, "Only the minter can mint OWL");
        balances[to] = balances[to].add(amount);
        totalTokens = totalTokens.add(amount);
        emit Minted(to, amount);
        emit Transfer(address(0), to, amount);
    }

    /// @dev Burns OWL.
    /// @param user Address of OWL owner
    /// @param amount Amount of OWL to be burnt
    function burnOWL(address user, uint amount) public {
        allowances[user][msg.sender] = allowances[user][msg.sender].sub(amount);
        balances[user] = balances[user].sub(amount);
        totalTokens = totalTokens.sub(amount);
        emit Burnt(msg.sender, user, amount);
        emit Transfer(user, address(0), amount);
    }

    function getMasterCopyCountdown() public view returns (address, uint) {
        return (masterCopyCountdown.masterCopy, masterCopyCountdown.timeWhenAvailable);
    }
}