/**
Circularity.finance Team Vesting contract
Circular economics applied to decentralized assets

Web:
https://circularity.finance

Twitter:
https://twitter.com/CircularityFin

Telegram:
https://t.me/CircularityFinance
*/


pragma solidity ^0.4.24;

/**
 * @title ERC20Basic
 * @dev Simpler version of ERC20 interface
 * @dev 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);
}

/**
 * @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;

  uint256 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(_to != address(0));
    require(_value <= balances[msg.sender]);

    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];
  }

}

/**
 * @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));
  }
}


/**
 * @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.
   */
  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 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;
  }
}


contract CircularityTeamVesting is Ownable {
  using SafeMath for uint256;
  using SafeERC20 for ERC20Basic;

  event Released(address beneficiary, uint256 amount);

  ERC20Basic public token;
  uint256 public cliff;
  uint256 public start;
  uint256 public duration;

  mapping (address => uint256) public shares;

  uint256 released = 0;

  address[] public beneficiaries;

  modifier onlyBeneficiaries {
    require(msg.sender == owner || shares[msg.sender] > 0, "You cannot release tokens!");
    _;
  }

  constructor(
    ERC20Basic _token,
    uint256 _start,
    uint256 _cliff,
    uint256 _duration
  )
  public
  {
    require(_cliff <= _duration, "Cliff has to be lower or equal to duration");
    token = _token;
    duration = _duration;
    cliff = _start.add(_cliff);
    start = _start;
  }

  function addBeneficiary(address _beneficiary, uint256 _sharesAmount) onlyOwner public {
    require(_beneficiary != address(0), "The beneficiary's address cannot be 0");
    require(_sharesAmount > 0, "Shares amount has to be greater than 0");

    releaseAllTokens();

    if (shares[_beneficiary] == 0) {
      beneficiaries.push(_beneficiary);
    }

    shares[_beneficiary] = shares[_beneficiary].add(_sharesAmount);
  }

  function releaseAllTokens() onlyBeneficiaries public {
    uint256 unreleased = releasableAmount();

    if (unreleased > 0) {
      uint beneficiariesCount = beneficiaries.length;

      released = released.add(unreleased);

      for (uint i = 0; i < beneficiariesCount; i++) {
        release(beneficiaries[i], calculateShares(unreleased, beneficiaries[i]));
      }
    }
  }

  function releasableAmount() public view returns (uint256) {
    return vestedAmount().sub(released);
  }

  function calculateShares(uint256 _amount, address _beneficiary) public view returns (uint256) {
    return _amount.mul(shares[_beneficiary]).div(totalShares());
  }

  function totalShares() public view returns (uint256) {
    uint sum = 0;
    uint beneficiariesCount = beneficiaries.length;

    for (uint i = 0; i < beneficiariesCount; i++) {
      sum = sum.add(shares[beneficiaries[i]]);
    }

    return sum;
  }

  function vestedAmount() public view returns (uint256) {
    uint256 currentBalance = token.balanceOf(this);
    uint256 totalBalance = currentBalance.add(released);

    // solium-disable security/no-block-members
    if (block.timestamp < cliff) {
      return 0;
    } else if (block.timestamp >= start.add(duration)) {
      return totalBalance;
    } else {
      return totalBalance.mul(block.timestamp.sub(start)).div(duration);
    }
    // solium-enable security/no-block-members
  }

  function release(address _beneficiary, uint256 _amount) private {
    token.safeTransfer(_beneficiary, _amount);
    emit Released(_beneficiary, _amount);
  }
}