/**
 *Submitted for verification at Etherscan.io on 2019-04-04
*/

pragma solidity ^0.4.24;

/**
 * @title SafeMath
 * @dev Math operations with safety checks that revert on error
 */
library SafeMath {

    /**
    * @dev Multiplies two numbers, reverts on 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-solidity/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b);

        return c;
    }

    /**
    * @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
    */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0); // Solidity only automatically asserts 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;
    }

    /**
    * @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
    */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        uint256 c = a - b;

        return c;
    }

    /**
    * @dev Adds two numbers, reverts on overflow.
    */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a);

        return c;
    }

    /**
    * @dev Divides two numbers and returns the remainder (unsigned integer modulo),
    * reverts when dividing by zero.
    */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0);
        return a % b;
    }
}


/**
 * @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 OwnershipRenounced(address indexed previousOwner);
    event OwnershipTransferred(
        address indexed previousOwner,
        address indexed newOwner
    );

    /**
    * @dev The Ownable constructor sets the original `owner` of the contract to the sender
    * account.
    */
    constructor() public {
        owner = msg.sender;
    }

    /**
    * @return the address of the owner.
    */
    function owner() public view returns(address) {
        return owner;
    }

    /**
    * @dev Throws if called by any account other than the owner.
    */
    modifier onlyOwner() {
        require(isOwner());
        _;
    }

    /**
    * @return true if `msg.sender` is the owner of the contract.
    */
    function isOwner() public view returns(bool) {
        return msg.sender == owner;
    }

    /**
    * @dev Allows the current owner to relinquish control of the contract.
    * @notice Renouncing to ownership will leave the contract without an owner.
    * It will not be possible to call the functions with the `onlyOwner`
    * modifier anymore.
    */
    function renounceOwnership() public onlyOwner {
        emit OwnershipRenounced(owner);
        owner = address(0);
    }

    /**
    * @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 {
        _transferOwnership(newOwner);
    }

    /**
    * @dev Transfers control of the contract to a newOwner.
    * @param newOwner The address to transfer ownership to.
    */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0));
        emit OwnershipTransferred(owner, newOwner);
        owner = newOwner;
    }
}


/**
 * @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(account != address(0));
        role.bearer[account] = true;
    }

    /**
    * @dev remove an account's access to this role
    */
    function remove(Role storage role, address account) internal {
        require(account != address(0));
        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));
        return role.bearer[account];
    }
}


contract MinterRole is Ownable {
    using Roles for Roles.Role;

    event MinterAdded(address indexed account);
    event MinterRemoved(address indexed account);

    Roles.Role private minters;

    constructor() public {
        _addMinter(msg.sender);
    }

    modifier onlyMinter() {
        require(isMinter(msg.sender));
        _;
    }

    function isMinter(address account) public view returns (bool) {
        return minters.has(account);
    }

    function addMinter(address account) public onlyOwner {
        _addMinter(account);
    }

    function renounceMinter() public {
        _removeMinter(msg.sender);
    }

    function _addMinter(address account) internal {
        minters.add(account);
        emit MinterAdded(account);
    }

    function _removeMinter(address account) internal {
        minters.remove(account);
        emit MinterRemoved(account);
    }
}


contract PauserRole is Ownable{
    using Roles for Roles.Role;

    event PauserAdded(address indexed account);
    event PauserRemoved(address indexed account);

    Roles.Role private pausers;

    constructor() public {
        _addPauser(msg.sender);
    }

    modifier onlyPauser() {
        require(isPauser(msg.sender));
        _;
    }

    function isPauser(address account) public view returns (bool) {
        return pausers.has(account);
    }

    function addPauser(address account) public onlyOwner {
        _addPauser(account);
    }

    function renouncePauser() public {
        _removePauser(msg.sender);
    }

    function _addPauser(address account) internal {
        pausers.add(account);
        emit PauserAdded(account);
    }

    function _removePauser(address account) internal {
        pausers.remove(account);
        emit PauserRemoved(account);
    }
}

/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
interface IERC20 {
  function totalSupply() external view returns (uint256);

  function balanceOf(address who) external view returns (uint256);

  function allowance(address owner, address spender)
    external view returns (uint256);

  function transfer(address to, uint256 value) external returns (bool);

  function approve(address spender, uint256 value)
    external returns (bool);

  function transferFrom(address from, address to, uint256 value)
    external returns (bool);

  event Transfer(
    address indexed from,
    address indexed to,
    uint256 value
  );

  event Approval(
    address indexed owner,
    address indexed spender,
    uint256 value
  );
}


/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
 * Originally based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 */
contract ERC20 is IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) public balances;

    mapping (address => mapping (address => uint256)) public allowed;

    uint256 public totalSupply;

    /**
    * @dev Total number of tokens in existence
    */
    function totalSupply() public view returns (uint256) {
        return totalSupply;
    }

    /**
    * @dev Gets the balance of the specified address.
    * @param owner The address to query the balance of.
    * @return An uint256 representing the amount owned by the passed address.
    */
    function balanceOf(address owner) public view returns (uint256) {
        return balances[owner];
    }

    /**
    * @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];
    }

    /**
    * @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(value <= balances[msg.sender]);
        require(to != address(0));

        balances[msg.sender] = balances[msg.sender].sub(value);
        balances[to] = balances[to].add(value);
        emit Transfer(msg.sender, 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) {
        require(spender != address(0));

        allowed[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
        return true;
    }

    /**
    * @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(value <= balances[from]);
        require(value <= allowed[from][msg.sender]);
        require(to != address(0));

        balances[from] = balances[from].sub(value);
        balances[to] = balances[to].add(value);
        allowed[from][msg.sender] = allowed[from][msg.sender].sub(value);
        emit Transfer(from, to, value);
        return true;
    }

    /**
    * @dev Increase the amount of tokens that an owner allowed to a 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
    * @param spender The address which will spend the funds.
    * @param addedValue The amount of tokens to increase the allowance by.
    */
    function increaseAllowance(
        address spender,
        uint256 addedValue
    )
        public
        returns (bool)
    {
        require(spender != address(0));

        allowed[msg.sender][spender] = (
        allowed[msg.sender][spender].add(addedValue));
        emit Approval(msg.sender, spender, allowed[msg.sender][spender]);
        return true;
    }

    /**
    * @dev Decrease the amount of tokens that an owner allowed to a spender.
    * approve should be called when allowed_[_spender] == 0. To decrement
    * allowed value is better to use this function to avoid 2 calls (and wait until
    * the first transaction is mined)
    * From MonolithDAO Token.sol
    * @param spender The address which will spend the funds.
    * @param subtractedValue The amount of tokens to decrease the allowance by.
    */
    function decreaseAllowance(
        address spender,
        uint256 subtractedValue
    )
        public
        returns (bool)
    {
        require(spender != address(0));

        allowed[msg.sender][spender] = (
        allowed[msg.sender][spender].sub(subtractedValue));
        emit Approval(msg.sender, spender, allowed[msg.sender][spender]);
        return true;
    }

    /**
    * @dev Internal function that mints an amount of the token and assigns it to
    * an account. This encapsulates the modification of balances such that the
    * proper events are emitted.
    * @param account The account that will receive the created tokens.
    * @param amount The amount that will be created.
    */
    function _mint(address account, uint256 amount) internal {
        require(account != 0);
        totalSupply = totalSupply.add(amount);
        balances[account] = balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
    * @dev Internal function that burns an amount of the token of a given
    * account.
    * @param account The account whose tokens will be burnt.
    * @param amount The amount that will be burnt.
    */
    function _burn(address account, uint256 amount) internal {
        require(account != 0);
        require(amount <= balances[account]);

        totalSupply = totalSupply.sub(amount);
        balances[account] = balances[account].sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
    * @dev Internal function that burns an amount of the token of a given
    * account, deducting from the sender's allowance for said account. Uses the
    * internal burn function.
    * @param account The account whose tokens will be burnt.
    * @param amount The amount that will be burnt.
    */
    function _burnFrom(address account, uint256 amount) internal {
        require(amount <= allowed[account][msg.sender]);

        // Should https://github.com/OpenZeppelin/zeppelin-solidity/issues/707 be accepted,
        // this function needs to emit an event with the updated approval.
        allowed[account][msg.sender] = allowed[account][msg.sender].sub(
        amount);
        _burn(account, amount);
    }
}


/**
 * @title Pausable
 * @dev Base contract which allows children to implement an emergency stop mechanism.
 */
contract Pausable is PauserRole {
    event Paused();
    event Unpaused();

    bool private _paused = false;

    /**
    * @return true if the contract is paused, false otherwise.
    */
    function paused() public view returns(bool) {
        return _paused;
    }

    /**
    * @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() public onlyPauser whenNotPaused {
        _paused = true;
        emit Paused();
    }

    /**
    * @dev called by the owner to unpause, returns to normal state
    */
    function unpause() public onlyPauser whenPaused {
        _paused = false;
        emit Unpaused();
    }
}



/**
 * @title Pausable token
 * @dev ERC20 modified with pausable transfers.
 **/
contract ERC20Pausable is ERC20, 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 increaseAllowance(
        address spender,
        uint addedValue
    )
        public
        whenNotPaused
        returns (bool success)
    {
        return super.increaseAllowance(spender, addedValue);
    }

    function decreaseAllowance(
        address spender,
        uint subtractedValue
    )
        public
        whenNotPaused
        returns (bool success)
    {
        return super.decreaseAllowance(spender, subtractedValue);
    }
}



/**
 * @title Burnable Token
 * @dev Token that can be irreversibly burned (destroyed).
 */
contract ERC20Burnable is ERC20 {

    /**
    * @dev Burns a specific amount of tokens.
    * @param value The amount of token to be burned.
    */
    function burn(uint256 value) public {
        _burn(msg.sender, value);
    }

    /**
    * @dev Burns a specific amount of tokens from the target address and decrements allowance
    * @param from address The address which you want to send tokens from
    * @param value uint256 The amount of token to be burned
    */
    function burnFrom(address from, uint256 value) public {
        _burnFrom(from, value);
    }

    /**
    * @dev Overrides ERC20._burn in order for burn and burnFrom to emit
    * an additional Burn event.
    */
    function _burn(address who, uint256 value) internal {
        super._burn(who, value);
    }
}


/**
 * @title ERC20Mintable
 * @dev ERC20 minting logic
 */
contract ERC20CappedMintable is ERC20, MinterRole {

    uint256 private _cap;

    constructor(uint256 cap)
        public
    {
        require(cap > 0,"Maximum supply has reached.");
        _cap = cap;
    }

    /**
    * @return the cap for the token minting.
    */
    function cap() public view returns(uint256) {
        return _cap;
    }

  /**
   * @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
    )
        public
        onlyMinter
        returns (bool)
    {   
        require(totalSupply.add(amount) <= _cap);
        _mint(to, amount);
        return true;
    }
}

/**
 * Define interface for releasing the token transfer after a successful crowdsale.
 */
contract ERC20Releasable is ERC20, Ownable {

    /* The finalizer contract that allows unlift the transfer limits on this token */
    address public releaseAgent;

    /** A crowdsale contract can release us to the wild if ICO success. If false we are are in transfer lock up period.*/
    bool public released = false;

    /** Map of agents that are allowed to transfer tokens regardless of the lock down period. These are crowdsale contracts and possible the team multisig itself. */
    mapping (address => bool) public transferAgents;

    /**
    * Limit token transfer until the crowdsale is over.
    *
    */
    modifier canTransfer(address _sender) {

        if(!released) {
            require(transferAgents[_sender]);
        }
        _;
    }

    /**
    * Set the contract that can call release and make the token transferable.
    *
    * Design choice. Allow reset the release agent to fix fat finger mistakes.
    */
    function setReleaseAgent(address addr) onlyOwner inReleaseState(false) public {

      // We don't do interface check here as we might want to a normal wallet address to act as a release agent
        releaseAgent = addr;
    }

    /**
    * Owner can allow a particular address (a crowdsale contract) to transfer tokens despite the lock up period.
    */
    function setTransferAgent(address addr, bool state) onlyOwner inReleaseState(false) public {
        transferAgents[addr] = state;
    }

    /**
    * One way function to release the tokens to the wild.
    *
    * Can be called only from the release agent that is the final ICO contract. It is only called if the crowdsale has been success (first milestone reached).
    */
    function releaseTokenTransfer() public onlyReleaseAgent {
        released = true;
    }

    /** The function can be called only before or after the tokens have been releasesd */
    modifier inReleaseState(bool releaseState) {
        require(releaseState == released);
        _;
    }

    /** The function can be called only by a whitelisted release agent. */
    modifier onlyReleaseAgent() {
        require(msg.sender == releaseAgent);
        _;
    }

    function transfer(
        address to,
        uint256 value
    )
        public
        canTransfer(msg.sender)
        returns (bool)
    {
        return super.transfer(to, value);
    }

    function transferFrom(
        address from,
        address to,
        uint256 value
    )
        public
        canTransfer(from)
        returns (bool)
    {
        return super.transferFrom(from, to, value);
    }



    function approve(
        address spender,
        uint256 value
    )
        public
        canTransfer(spender)
        returns (bool)
    {
        return super.approve(spender, value);
    }

    function increaseAllowance(
        address spender,
        uint addedValue
    )
        public
        canTransfer(spender)
        returns (bool success)
    {
        return super.increaseAllowance(spender, addedValue);
    }

    function decreaseAllowance(
        address spender,
        uint subtractedValue
    )
        public
        canTransfer(spender)
        returns (bool success)
    {
        return super.decreaseAllowance(spender, subtractedValue);
    }

}


contract BVTCoin is ERC20Burnable, ERC20CappedMintable, ERC20Pausable, ERC20Releasable {
    
    string public name;
    string public symbol;
    uint8 public decimals;

    /**
    * Construct the token.
    *
    * This token must be created through a team multisig wallet, so that it is owned by that wallet.
    *
    * @param _tokenName Token name
    * @param _tokenSymbol Token symbol - should be all caps
    * @param _initialSupply How many tokens we start with
    * @param _tokenDecimals Number of decimal places
    * @param _tokenCap Are new tokens created over the crowdsale or do we distribute only the initial supply? Note that when the token becomes transferable the minting always ends.
    */
    constructor (string _tokenName, string _tokenSymbol, uint _initialSupply, uint8 _tokenDecimals,uint256 _tokenCap)
        ERC20CappedMintable(_tokenCap)
        public
    {
        owner = msg.sender;
        name = _tokenName;
        symbol = _tokenSymbol;
        totalSupply = _initialSupply;
        decimals = _tokenDecimals;
        balances[owner] = totalSupply;
    }

    /**
    * When token is released to be transferable, enforce no new tokens can be created.
    */
    function releaseTokenTransfer() public onlyReleaseAgent {
        super.releaseTokenTransfer();
    }
}