pragma solidity ^0.4.0;



/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }
        uint256 c = a * b;
        assert(c / a == b);
        return c;
    }

    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 c;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        assert(b <= a);
        return a - b;
    }

    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        assert(c >= a);
        return c;
    }
}



/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
contract Ownable {
    address public owner;


    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);


    /**
     * @dev The Ownable constructor sets the original `owner` of the contract to the sender
     * account.
     */
    function Ownable() 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 transfer control of the contract to a newOwner.
     * @param newOwner The address to transfer ownership to.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        require(newOwner != address(0));
        OwnershipTransferred(owner, newOwner);
        owner = newOwner;
    }

}



/**
 * @title ERC20Basic
 * @dev Simpler version of ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/179
 */
contract ERC20Basic {
    uint256 public totalSupply;
    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);
}


/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
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);
}


/**
 * @title Pausable
 * @dev Base contract which allows children to implement an emergency stop mechanism.
 */
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;
        Pause();
    }

    /**
     * @dev called by the owner to unpause, returns to normal state
     */
    function unpause() onlyOwner whenPaused public {
        paused = false;
        Unpause();
    }
}


/**
 * @title Basic token
 * @dev Basic version of StandardToken, with no allowances.
 */
contract BasicToken is ERC20Basic {
    using SafeMath for uint256;

    mapping(address => uint256) balances;

    /**
    * @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]);

        // SafeMath.sub will throw if there is not enough balance.
        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        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 balance) {
        return balances[_owner];
    }

}


/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure.
 * To use this library you can add a `using SafeERC20 for ERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    function safeTransfer(ERC20Basic token, address to, uint256 value) internal {
        assert(token.transfer(to, value));
    }

    function safeTransferFrom(ERC20 token, address from, address to, uint256 value) internal {
        assert(token.transferFrom(from, to, value));
    }

    function safeApprove(ERC20 token, address spender, uint256 value) internal {
        assert(token.approve(spender, value));
    }
}



/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * @dev https://github.com/ethereum/EIPs/issues/20
 * @dev Based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 */
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);
        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;
        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];
    }

    /**
     * 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
     */
    function increaseApproval(address _spender, uint _addedValue) public returns (bool) {
        allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
        Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }

    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);
        }
        Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }

}


/**
 * @title Burnable Token
 * @dev Token that can be irreversibly burned (destroyed).
 */
contract BurnableToken is StandardToken {

    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 {
        require(_value > 0);
        require(_value <= balances[msg.sender]);
        // 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

        address burner = msg.sender;
        balances[burner] = balances[burner].sub(_value);
        totalSupply = totalSupply.sub(_value);
        Burn(burner, _value);
    }
}



/**
 * @title Mintable token
 * @dev Simple ERC20 Token example, with mintable token creation
 * @dev Issue: * https://github.com/OpenZeppelin/zeppelin-solidity/issues/120
 * Based on code by TokenMarketNet: https://github.com/TokenMarketNet/ico/blob/master/contracts/MintableToken.sol
 */

contract MintableToken is StandardToken, Ownable {
    event Mint(address indexed to, uint256 amount);
    event MintFinished();

    bool public mintingFinished = false;


    modifier canMint() {
        require(!mintingFinished);
        _;
    }

    /**
     * @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) onlyOwner canMint public returns (bool) {
        totalSupply = totalSupply.add(_amount);
        balances[_to] = balances[_to].add(_amount);
        Mint(_to, _amount);
        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;
        MintFinished();
        return true;
    }
}



/**
 * @title TokenTimelock
 * @dev TokenTimelock is a token holder contract that will allow a
 * beneficiary to extract the tokens after a given release time
 */
contract TokenTimelock {
    using SafeERC20 for ERC20Basic;

    // ERC20 basic token contract being held
    ERC20Basic public token;

    // beneficiary of tokens after they are released
    address public beneficiary;

    // timestamp when token release is enabled
    uint64 public releaseTime;

    function TokenTimelock(ERC20Basic _token, address _beneficiary, uint64 _releaseTime) public {
        require(_releaseTime > now);
        token = _token;
        beneficiary = _beneficiary;
        releaseTime = _releaseTime;
    }

    /**
     * @notice Transfers tokens held by timelock to beneficiary.
     */
    function release() public {
        require(now >= releaseTime);

        uint256 amount = token.balanceOf(this);
        require(amount > 0);

        token.safeTransfer(beneficiary, amount);
    }
}


contract usingConsts {
    uint constant TOKEN_DECIMALS = 18;
    uint8 constant TOKEN_DECIMALS_UINT8 = 18;
    uint constant TOKEN_DECIMAL_MULTIPLIER = 10 ** TOKEN_DECIMALS;

    string constant TOKEN_NAME = "Cronos";
    string constant TOKEN_SYMBOL = "CRS";
    bool constant PAUSED = true;
    address constant TARGET_USER = 0x216C619CB44BeEe746DC781740C215Bce23fA892;
    uint constant START_TIME = 1518697500;
    bool constant CONTINUE_MINTING = false;
}


contract FreezableToken is StandardToken {
    mapping (address => uint64) internal roots;

    mapping (bytes32 => uint64) internal chains;

    event Freezed(address indexed to, uint64 release, uint amount);
    event Released(address indexed owner, uint amount);

    /**
     * @dev gets summary information about all freeze tokens for the specified address.
     * @param _addr Address of freeze tokens owner.
     */
    function getFreezingSummaryOf(address _addr) public constant returns (uint tokenAmount, uint freezingCount) {
        uint count;
        uint total;
        uint64 release = roots[_addr];
        while (release != 0) {
            count ++;
            total += balanceOf(address(keccak256(toKey(_addr, release))));
            release = chains[toKey(_addr, release)];
        }

        return (total, count);
    }

    /**
     * @dev gets freezing end date and freezing balance for the freezing portion specified by index.
     * @param _addr Address of freeze tokens owner.
     * @param _index Freezing portion index. It ordered by release date descending.
     */
    function getFreezing(address _addr, uint _index) public constant returns (uint64 _release, uint _balance) {
        uint64 release = roots[_addr];
        for (uint i = 0; i < _index; i ++) {
            release = chains[toKey(_addr, release)];
        }
        return (release, balanceOf(address(keccak256(toKey(_addr, release)))));
    }

    /**
     * @dev freeze your tokens to the specified address.
     *      Be careful, gas usage is not deterministic,
     *      and depends on how many freezes _to address already has.
     * @param _to Address to which token will be freeze.
     * @param _amount Amount of token to freeze.
     * @param _until Release date, must be in future.
     */
    function freezeTo(address _to, uint _amount, uint64 _until) public {
        bytes32 currentKey = toKey(_to, _until);
        transfer(address(keccak256(currentKey)), _amount);

        freeze(_to, _until);
        Freezed(_to, _until, _amount);
    }

    /**
     * @dev release first available freezing tokens.
     */
    function releaseOnce() public {
        uint64 head = roots[msg.sender];
        require(head != 0);
        require(uint64(block.timestamp) > head);
        bytes32 currentKey = toKey(msg.sender, head);

        uint64 next = chains[currentKey];

        address currentAddress = address(keccak256(currentKey));
        uint amount = balances[currentAddress];
        delete balances[currentAddress];

        balances[msg.sender] += amount;

        if (next == 0) {
            delete roots[msg.sender];
        }
        else {
            roots[msg.sender] = next;
        }
        Released(msg.sender, amount);
    }

    /**
     * @dev release all available for release freezing tokens. Gas usage is not deterministic!
     * @return how many tokens was released
     */
    function releaseAll() public returns (uint tokens) {
        uint release;
        uint balance;
        (release, balance) = getFreezing(msg.sender, 0);
        while (release != 0 && block.timestamp > release) {
            releaseOnce();
            tokens += balance;
            (release, balance) = getFreezing(msg.sender, 0);
        }
    }

    function toKey(address _addr, uint _release) internal constant returns (bytes32 result) {
        // WISH masc to increase entropy
        result = 0x5749534800000000000000000000000000000000000000000000000000000000;
        assembly {
            result := or(result, mul(_addr, 0x10000000000000000))
            result := or(result, _release)
        }
    }

    function freeze(address _to, uint64 _until) internal {
        require(_until > block.timestamp);
        uint64 head = roots[_to];

        if (head == 0) {
            roots[_to] = _until;
            return;
        }

        bytes32 headKey = toKey(_to, head);
        uint parent;
        bytes32 parentKey;

        while (head != 0 && _until > head) {
            parent = head;
            parentKey = headKey;

            head = chains[headKey];
            headKey = toKey(_to, head);
        }

        if (_until == head) {
            return;
        }

        if (head != 0) {
            chains[toKey(_to, _until)] = head;
        }

        if (parent == 0) {
            roots[_to] = _until;
        }
        else {
            chains[parentKey] = _until;
        }
    }
}




contract FreezableMintableToken is FreezableToken, MintableToken {
    /**
     * @dev Mint the specified amount of token to the specified address and freeze it until the specified date.
     *      Be careful, gas usage is not deterministic,
     *      and depends on how many freezes _to address already has.
     * @param _to Address to which token will be freeze.
     * @param _amount Amount of token to mint and freeze.
     * @param _until Release date, must be in future.
     */
    function mintAndFreeze(address _to, uint _amount, uint64 _until) public onlyOwner {
        bytes32 currentKey = toKey(_to, _until);
        mint(address(keccak256(currentKey)), _amount);

        freeze(_to, _until);
        Freezed(_to, _until, _amount);
    }
}



contract MainToken is usingConsts, FreezableMintableToken, BurnableToken, Pausable {
    function MainToken() {
        if (PAUSED) {
            pause();
        }
    }

    function name() constant public returns (string _name) {
        return TOKEN_NAME;
    }

    function symbol() constant public returns (string _symbol) {
        return TOKEN_SYMBOL;
    }

    function decimals() constant public returns (uint8 _decimals) {
        return TOKEN_DECIMALS_UINT8;
    }

    function transferFrom(address _from, address _to, uint256 _value) returns (bool _success) {
        require(!paused);
        return super.transferFrom(_from, _to, _value);
    }

    function transfer(address _to, uint256 _value) returns (bool _success) {
        require(!paused);
        return super.transfer(_to, _value);
    }
}