pragma solidity ^0.4.24;

// File: openzeppelin-solidity/contracts/math/SafeMath.sol

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, throws on overflow.
  */
  function mul(uint256 _a, uint256 _b) internal pure returns (uint256 c) {
    // Gas optimization: this is cheaper than asserting '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;
    }

    c = _a * _b;
    assert(c / _a == _b);
    return c;
  }

  /**
  * @dev Integer division of two numbers, truncating the quotient.
  */
  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 _a / _b;
  }

  /**
  * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 _a, uint256 _b) internal pure returns (uint256) {
    assert(_b <= _a);
    return _a - _b;
  }

  /**
  * @dev Adds two numbers, throws on overflow.
  */
  function add(uint256 _a, uint256 _b) internal pure returns (uint256 c) {
    c = _a + _b;
    assert(c >= _a);
    return c;
  }
}

// File: openzeppelin-solidity/contracts/ownership/Ownable.sol

/**
 * @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;
  }

  /**
   * @dev Throws if called by any account other than the owner.
   */
  modifier onlyOwner() {
    require(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;
  }
}

// File: openzeppelin-solidity/contracts/access/rbac/Roles.sol

/**
 * @title Roles
 * @author Francisco Giordano (@frangio)
 * @dev Library for managing addresses assigned to a Role.
 * See RBAC.sol for example usage.
 */
library Roles {
  struct Role {
    mapping (address => bool) bearer;
  }

  /**
   * @dev give an address access to this role
   */
  function add(Role storage _role, address _addr)
    internal
  {
    _role.bearer[_addr] = true;
  }

  /**
   * @dev remove an address' access to this role
   */
  function remove(Role storage _role, address _addr)
    internal
  {
    _role.bearer[_addr] = false;
  }

  /**
   * @dev check if an address has this role
   * // reverts
   */
  function check(Role storage _role, address _addr)
    internal
    view
  {
    require(has(_role, _addr));
  }

  /**
   * @dev check if an address has this role
   * @return bool
   */
  function has(Role storage _role, address _addr)
    internal
    view
    returns (bool)
  {
    return _role.bearer[_addr];
  }
}

// File: openzeppelin-solidity/contracts/access/rbac/RBAC.sol

/**
 * @title RBAC (Role-Based Access Control)
 * @author Matt Condon (@Shrugs)
 * @dev Stores and provides setters and getters for roles and addresses.
 * Supports unlimited numbers of roles and addresses.
 * See //contracts/mocks/RBACMock.sol for an example of usage.
 * This RBAC method uses strings to key roles. It may be beneficial
 * for you to write your own implementation of this interface using Enums or similar.
 */
contract RBAC {
  using Roles for Roles.Role;

  mapping (string => Roles.Role) private roles;

  event RoleAdded(address indexed operator, string role);
  event RoleRemoved(address indexed operator, string role);

  /**
   * @dev reverts if addr does not have role
   * @param _operator address
   * @param _role the name of the role
   * // reverts
   */
  function checkRole(address _operator, string _role)
    public
    view
  {
    roles[_role].check(_operator);
  }

  /**
   * @dev determine if addr has role
   * @param _operator address
   * @param _role the name of the role
   * @return bool
   */
  function hasRole(address _operator, string _role)
    public
    view
    returns (bool)
  {
    return roles[_role].has(_operator);
  }

  /**
   * @dev add a role to an address
   * @param _operator address
   * @param _role the name of the role
   */
  function addRole(address _operator, string _role)
    internal
  {
    roles[_role].add(_operator);
    emit RoleAdded(_operator, _role);
  }

  /**
   * @dev remove a role from an address
   * @param _operator address
   * @param _role the name of the role
   */
  function removeRole(address _operator, string _role)
    internal
  {
    roles[_role].remove(_operator);
    emit RoleRemoved(_operator, _role);
  }

  /**
   * @dev modifier to scope access to a single role (uses msg.sender as addr)
   * @param _role the name of the role
   * // reverts
   */
  modifier onlyRole(string _role)
  {
    checkRole(msg.sender, _role);
    _;
  }

  /**
   * @dev modifier to scope access to a set of roles (uses msg.sender as addr)
   * @param _roles the names of the roles to scope access to
   * // reverts
   *
   * @TODO - when solidity supports dynamic arrays as arguments to modifiers, provide this
   *  see: https://github.com/ethereum/solidity/issues/2467
   */
  // modifier onlyRoles(string[] _roles) {
  //     bool hasAnyRole = false;
  //     for (uint8 i = 0; i < _roles.length; i++) {
  //         if (hasRole(msg.sender, _roles[i])) {
  //             hasAnyRole = true;
  //             break;
  //         }
  //     }

  //     require(hasAnyRole);

  //     _;
  // }
}

// File: openzeppelin-solidity/contracts/ownership/Superuser.sol

/**
 * @title Superuser
 * @dev The Superuser contract defines a single superuser who can transfer the ownership
 * of a contract to a new address, even if he is not the owner.
 * A superuser can transfer his role to a new address.
 */
contract Superuser is Ownable, RBAC {
  string public constant ROLE_SUPERUSER = "superuser";

  constructor () public {
    addRole(msg.sender, ROLE_SUPERUSER);
  }

  /**
   * @dev Throws if called by any account that's not a superuser.
   */
  modifier onlySuperuser() {
    checkRole(msg.sender, ROLE_SUPERUSER);
    _;
  }

  modifier onlyOwnerOrSuperuser() {
    require(msg.sender == owner || isSuperuser(msg.sender));
    _;
  }

  /**
   * @dev getter to determine if address has superuser role
   */
  function isSuperuser(address _addr)
    public
    view
    returns (bool)
  {
    return hasRole(_addr, ROLE_SUPERUSER);
  }

  /**
   * @dev Allows the current superuser to transfer his role to a newSuperuser.
   * @param _newSuperuser The address to transfer ownership to.
   */
  function transferSuperuser(address _newSuperuser) public onlySuperuser {
    require(_newSuperuser != address(0));
    removeRole(msg.sender, ROLE_SUPERUSER);
    addRole(_newSuperuser, ROLE_SUPERUSER);
  }

  /**
   * @dev Allows the current superuser or owner to transfer control of the contract to a newOwner.
   * @param _newOwner The address to transfer ownership to.
   */
  function transferOwnership(address _newOwner) public onlyOwnerOrSuperuser {
    _transferOwnership(_newOwner);
  }
}

// File: openzeppelin-solidity/contracts/token/ERC20/ERC20Basic.sol

/**
 * @title ERC20Basic
 * @dev Simpler version of ERC20 interface
 * See https://github.com/ethereum/EIPs/issues/179
 */
contract ERC20Basic {
  function totalSupply() public view returns (uint256);
  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);
}

// File: openzeppelin-solidity/contracts/token/ERC20/BasicToken.sol

/**
 * @title Basic token
 * @dev Basic version of StandardToken, with no allowances.
 */
contract BasicToken is ERC20Basic {
  using SafeMath for uint256;

  mapping(address => uint256) internal balances;

  uint256 internal totalSupply_;

  /**
  * @dev Total number of tokens in existence
  */
  function totalSupply() public view returns (uint256) {
    return totalSupply_;
  }

  /**
  * @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 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) {
    return balances[_owner];
  }

}

// File: openzeppelin-solidity/contracts/token/ERC20/ERC20.sol

/**
 * @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
  );
}

// File: openzeppelin-solidity/contracts/token/ERC20/StandardToken.sol

/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * https://github.com/ethereum/EIPs/issues/20
 * 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(_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 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;
    emit 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];
  }

  /**
   * @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 increaseApproval(
    address _spender,
    uint256 _addedValue
  )
    public
    returns (bool)
  {
    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 decreaseApproval(
    address _spender,
    uint256 _subtractedValue
  )
    public
    returns (bool)
  {
    uint256 oldValue = allowed[msg.sender][_spender];
    if (_subtractedValue >= oldValue) {
      allowed[msg.sender][_spender] = 0;
    } else {
      allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
    }
    emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

}

// File: openzeppelin-solidity/contracts/token/ERC20/MintableToken.sol

/**
 * @title Mintable token
 * @dev Simple ERC20 Token example, with mintable token creation
 * 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);
    _;
  }

  modifier hasMintPermission() {
    require(msg.sender == owner);
    _;
  }

  /**
   * @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
    hasMintPermission
    canMint
    returns (bool)
  {
    totalSupply_ = totalSupply_.add(_amount);
    balances[_to] = balances[_to].add(_amount);
    emit Mint(_to, _amount);
    emit Transfer(address(0), _to, _amount);
    return true;
  }

  /**
   * @dev Function to stop minting new tokens.
   * @return True if the operation was successful.
   */
  function finishMinting() public onlyOwner canMint returns (bool) {
    mintingFinished = true;
    emit MintFinished();
    return true;
  }
}

// File: openzeppelin-solidity/contracts/token/ERC20/CappedToken.sol

/**
 * @title Capped token
 * @dev Mintable token with a token cap.
 */
contract CappedToken is MintableToken {

  uint256 public cap;

  constructor(uint256 _cap) public {
    require(_cap > 0);
    cap = _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
    returns (bool)
  {
    require(totalSupply_.add(_amount) <= cap);

    return super.mint(_to, _amount);
  }

}

// File: openzeppelin-solidity/contracts/lifecycle/Pausable.sol

/**
 * @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() public onlyOwner whenNotPaused {
    paused = true;
    emit Pause();
  }

  /**
   * @dev called by the owner to unpause, returns to normal state
   */
  function unpause() public onlyOwner whenPaused {
    paused = false;
    emit Unpause();
  }
}

// File: openzeppelin-solidity/contracts/token/ERC20/PausableToken.sol

/**
 * @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);
  }
}

// File: openzeppelin-solidity/contracts/token/ERC20/SafeERC20.sol

/**
 * @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
  {
    require(_token.transfer(_to, _value));
  }

  function safeTransferFrom(
    ERC20 _token,
    address _from,
    address _to,
    uint256 _value
  )
    internal
  {
    require(_token.transferFrom(_from, _to, _value));
  }

  function safeApprove(
    ERC20 _token,
    address _spender,
    uint256 _value
  )
    internal
  {
    require(_token.approve(_spender, _value));
  }
}

// File: openzeppelin-solidity/contracts/token/ERC20/TokenTimelock.sol

/**
 * @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
  uint256 public releaseTime;

  constructor(
    ERC20Basic _token,
    address _beneficiary,
    uint256 _releaseTime
  )
    public
  {
    // solium-disable-next-line security/no-block-members
    require(_releaseTime > block.timestamp);
    token = _token;
    beneficiary = _beneficiary;
    releaseTime = _releaseTime;
  }

  /**
   * @notice Transfers tokens held by timelock to beneficiary.
   */
  function release() public {
    // solium-disable-next-line security/no-block-members
    require(block.timestamp >= releaseTime);

    uint256 amount = token.balanceOf(address(this));
    require(amount > 0);

    token.safeTransfer(beneficiary, amount);
  }
}

// File: contracts/SocialGoodToken.sol

/// @title Token contract - ERC20 compatible SocialGood token contract.
/// @author Social Good Foundation Inc. - <info@socialgood-foundation.com>
contract SocialGoodToken is CappedToken(210000000e18), PausableToken, Superuser { // capped at 210 mil
    using SafeMath for uint256;

    /*
     *  Constants / Token meta data
     */
    string constant public name = 'SocialGood'; // Token name
    string constant public symbol = 'SG';       // Token symbol
    uint8 constant public decimals = 18;
    uint256 constant public totalTeamTokens = 3100000e18;  // 3.1 mil reserved tokens for the team
    uint256 constant private secsInYear = 365 * 86400 + 21600;  // including the extra seconds in a leap year

    /*
     *  Timelock contracts for team's tokens
     */
    address public timelock1;
    address public timelock2;
    address public timelock3;
    address public timelock4;

    /*
     *  Events
     */
    event Burn(address indexed burner, uint256 value);

    /*
     *  Contract functions
     */
    /**
     * @dev Contract constructor function
     */
    constructor() public {
        paused = true; // not to allow token transfers initially
    }

    /**
     * @dev Initialize this contract
     * @param socialGoodTeamAddr Address to receive unlocked team tokens
     * @param startTimerAt Time to start counting the lock-up periods
     */
    function initializeTeamTokens(address socialGoodTeamAddr, uint256 startTimerAt) external {
        require(socialGoodTeamAddr != 0 && startTimerAt > 0);

        // Tokens for the SocialGood team (loked-up initially)
        // 25% tokens will be released every year
        timelock1 = new TokenTimelock(ERC20Basic(this), socialGoodTeamAddr, startTimerAt.add(secsInYear));
        timelock2 = new TokenTimelock(ERC20Basic(this), socialGoodTeamAddr, startTimerAt.add(secsInYear.mul(2)));
        timelock3 = new TokenTimelock(ERC20Basic(this), socialGoodTeamAddr, startTimerAt.add(secsInYear.mul(3)));
        timelock4 = new TokenTimelock(ERC20Basic(this), socialGoodTeamAddr, startTimerAt.add(secsInYear.mul(4)));
        mint(timelock1, totalTeamTokens / 4);
        mint(timelock2, totalTeamTokens / 4);
        mint(timelock3, totalTeamTokens / 4);
        mint(timelock4, totalTeamTokens / 4);
    }

    /**
     * @dev Burns a specific amount of tokens.
     * @param _value The amount of token to be burned.
     */
    function burn(uint256 _value) public onlyOwner {
        _burn(msg.sender, _value);
    }

    // save some gas by making only one contract call
    function burnFrom(address _from, uint256 _value)
        public
        onlyOwner
    {
        assert(transferFrom(_from, msg.sender, _value));
        _burn(msg.sender, _value);
    }

    // this inherited function is disabled to prevent centralized pausing
    function pause() public { revert(); }

    function _burn(address _who, uint256 _value) internal {
        require(_value <= balances[_who]);
        // 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

        balances[_who] = balances[_who].sub(_value);
        totalSupply_ = totalSupply_.sub(_value);
        emit Burn(_who, _value);
        emit Transfer(_who, address(0), _value);
    }
}