pragma solidity ^0.4.18;

/**
 * @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;
    }
}

contract token {
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool);
    function setStartTime(uint _startTime) external;
}

/**
 * @title BitDegree Crowdsale
 */
contract BitDegreeCrowdsale {
    using SafeMath for uint256;

    // Investor contributions
    mapping(address => uint256) balances;

    // The token being sold
    token public reward;

    // Owner of the token
    address public owner;

    // Start and end timestamps
    uint public startTime;
    uint public endTime;

    // Address where funds are collected
    address public wallet;

    // Amount of tokens that were sold
    uint256 public tokensSold;

    // Soft cap in BDG tokens
    uint256 constant public softCap = 6250000 * (10**18);

    // Hard cap in BDG tokens
    uint256 constant public hardCap = 336600000 * (10**18);

    // Switched to true once token contract is notified of when to enable token transfers
    bool private isStartTimeSet = false;

    /**
     * @dev Event for token purchase logging
     * @param purchaser Address that paid for the tokens
     * @param beneficiary Address that got the tokens
     * @param value The amount that was paid (in wei)
     * @param amount The amount of tokens that were bought
     */
    event TokenPurchase(address indexed purchaser, address indexed beneficiary, uint256 value, uint256 amount);

    /**
     * @dev Event for refund logging
     * @param receiver The address that received the refund
     * @param amount The amount that is being refunded (in wei)
     */
    event Refund(address indexed receiver, uint256 amount);

    /**
     * @param _startTime Unix timestamp for the start of the token sale
     * @param _endTime Unix timestamp for the end of the token sale
     * @param _wallet Ethereum address to which the invested funds are forwarded
     * @param _token Address of the token that will be rewarded for the investors
     * @param _owner Address of the owner of the smart contract who can execute restricted functions
     */
    function BitDegreeCrowdsale(uint256 _startTime, uint256 _endTime, address _wallet, address _token, address _owner)  public {
        require(_startTime >= now);
        require(_endTime >= _startTime);
        require(_wallet != address(0));
        require(_token != address(0));
        require(_owner != address(0));

        startTime = _startTime;
        endTime = _endTime;
        wallet = _wallet;
        owner = _owner;
        reward = token(_token);
    }

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

    /**
     * @dev Fallback function that can be used to buy tokens. Or in case of the owner, return ether to allow refunds.
     */
    function () external payable {
        if(msg.sender == wallet) {
            require(hasEnded() && tokensSold < softCap);
        } else {
            buyTokens(msg.sender);
        }
    }

    /**
     * @dev Function for buying tokens
     * @param beneficiary The address that should receive bought tokens
     */
    function buyTokens(address beneficiary) public payable {
        require(beneficiary != address(0));
        require(validPurchase());

        uint256 weiAmount = msg.value;
        uint256 returnToSender = 0;

        // Retrieve the current token rate
        uint256 rate = getRate();

        // Calculate token amount to be transferred
        uint256 tokens = weiAmount.mul(rate);

        // Distribute only the remaining tokens if final contribution exceeds hard cap
        if(tokensSold.add(tokens) > hardCap) {
            tokens = hardCap.sub(tokensSold);
            weiAmount = tokens.div(rate);
            returnToSender = msg.value.sub(weiAmount);
        }

        // update state
        tokensSold = tokensSold.add(tokens);

        // update balance
        balances[beneficiary] = balances[beneficiary].add(weiAmount);

        assert(reward.transferFrom(owner, beneficiary, tokens));
        TokenPurchase(msg.sender, beneficiary, weiAmount, tokens);

        // Forward funds
        wallet.transfer(weiAmount);

        // Allow transfers 2 weeks after hard cap is reached
        if(tokensSold == hardCap) {
            reward.setStartTime(now + 2 weeks);
        }

        // Notify token contract about sale end time
        if(!isStartTimeSet) {
            isStartTimeSet = true;
            reward.setStartTime(endTime + 2 weeks);
        }

        // Return funds that are over hard cap
        if(returnToSender > 0) {
            msg.sender.transfer(returnToSender);
        }
    }

    /**
     * @dev Internal function that is used to determine the current rate for token / ETH conversion
     * @return The current token rate
     */
    function getRate() internal constant returns (uint256) {
        if(now < (startTime + 1 weeks)) {
            return 11500;
        }

        if(now < (startTime + 2 weeks)) {
            return 11000;
        }

        if(now < (startTime + 3 weeks)) {
            return 10500;
        }

        return 10000;
    }

    /**
     * @dev Internal function that is used to check if the incoming purchase should be accepted.
     * @return True if the transaction can buy tokens
     */
    function validPurchase() internal constant returns (bool) {
        bool withinPeriod = now >= startTime && now <= endTime;
        bool nonZeroPurchase = msg.value != 0;
        bool hardCapNotReached = tokensSold < hardCap;
        return withinPeriod && nonZeroPurchase && hardCapNotReached;
    }

    /**
     * @return True if crowdsale event has ended
     */
    function hasEnded() public constant returns (bool) {
        return now > endTime || tokensSold >= hardCap;
    }

    /**
     * @dev Returns ether to token holders in case soft cap is not reached.
     */
    function claimRefund() external {
        require(hasEnded());
        require(tokensSold < softCap);

        uint256 amount = balances[msg.sender];

        if(address(this).balance >= amount) {
            balances[msg.sender] = 0;
            if (amount > 0) {
                msg.sender.transfer(amount);
                Refund(msg.sender, amount);
            }
        }
    }

    /**
    * @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) external constant returns (uint256 balance) {
        return balances[_owner];
    }

}

pragma solidity ^0.4.18;

/**
 * @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 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 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 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 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 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 Pausable token
 *
 * @dev StandardToken modified with pausable transfers.
 **/
contract PausableToken is StandardToken, Pausable {

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

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

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

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

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


contract BitDegreeToken is PausableToken {
    string public constant name = "BitDegree Token";
    string public constant symbol = "BDG";
    uint8 public constant decimals = 18;

    uint256 private constant TOKEN_UNIT = 10 ** uint256(decimals);

    uint256 public constant totalSupply = 660000000 * TOKEN_UNIT;
    uint256 public constant publicAmount = 336600000 * TOKEN_UNIT; // Tokens for public

    uint public startTime;
    address public crowdsaleAddress;

    struct TokenLock { uint256 amount; uint duration; bool withdrawn; }

    TokenLock public foundationLock = TokenLock({
        amount: 66000000 * TOKEN_UNIT,
        duration: 360 days,
        withdrawn: false
    });

    TokenLock public teamLock = TokenLock({
        amount: 66000000 * TOKEN_UNIT,
        duration: 720 days,
        withdrawn: false
    });

    TokenLock public advisorLock = TokenLock({
        amount: 13200000 * TOKEN_UNIT,
        duration: 160 days,
        withdrawn: false
    });

    function BitDegreeToken() public {
        startTime = now + 70 days;

        balances[owner] = totalSupply;
        Transfer(address(0), owner, balances[owner]);

        lockTokens(foundationLock);
        lockTokens(teamLock);
        lockTokens(advisorLock);
    }

    function setCrowdsaleAddress(address _crowdsaleAddress) external onlyOwner {
        crowdsaleAddress = _crowdsaleAddress;
        assert(approve(crowdsaleAddress, publicAmount));
    }

    function withdrawLocked() external onlyOwner {
        if(unlockTokens(foundationLock)) foundationLock.withdrawn = true;
        if(unlockTokens(teamLock)) teamLock.withdrawn = true;
        if(unlockTokens(advisorLock)) advisorLock.withdrawn = true;
    }

    function lockTokens(TokenLock lock) internal {
        balances[owner] = balances[owner].sub(lock.amount);
        balances[address(0)] = balances[address(0)].add(lock.amount);
        Transfer(owner, address(0), lock.amount);
    }

    function unlockTokens(TokenLock lock) internal returns (bool) {
        uint lockReleaseTime = startTime + lock.duration;

        if(lockReleaseTime < now && lock.withdrawn == false) {
            balances[owner] = balances[owner].add(lock.amount);
            balances[address(0)] = balances[address(0)].sub(lock.amount);
            Transfer(address(0), owner, lock.amount);
            return true;
        }

        return false;
    }

    function setStartTime(uint _startTime) external {
        require(msg.sender == crowdsaleAddress);
        if(_startTime < startTime) {
            startTime = _startTime;
        }
    }

    function transfer(address _to, uint _value) public returns (bool) {
        // Only possible after ICO ends
        require(now >= startTime);

        return super.transfer(_to, _value);
    }

    function transferFrom(address _from, address _to, uint _value) public returns (bool) {
        // Only owner's tokens can be transferred before ICO ends
        if (now < startTime)
            require(_from == owner);

        return super.transferFrom(_from, _to, _value);
    }

    function transferOwnership(address newOwner) public onlyOwner {
        require(now >= startTime);
        super.transferOwnership(newOwner);
    }
}