pragma solidity ^0.4.24;

import "zos-lib/contracts/Initializable.sol";
import "../access/roles/PauserRole.sol";


/**
 * @title Pausable
 * @dev Base contract which allows children to implement an emergency stop mechanism.
 */
contract Pausable is Initializable, PauserRole {
    event Paused();
    event Unpaused();

    bool private _paused = false;

    function initialize(address sender) public initializer {
        PauserRole.initialize(sender);
    }

    /**
     * @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();
    }

    uint256[50] private ______gap;
}