AcceleratedContract.sol

pragma solidity ^0.4.24;

/**
 * @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) {
    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;
  }
}


/**
 * @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 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));
    emit OwnershipTransferred(owner, newOwner);
    owner = newOwner;
  }

  /**
   * @dev Allows the current owner to relinquish control of the contract.
   */
  function renounceOwnership() public onlyOwner {
    emit OwnershipRenounced(owner);
    owner = address(0);
  }
}

contract AcceleratedContract is Ownable {
    using SafeMath for uint256;
    
    address public tenant;
    uint256 public totalMonth = 12;
    bool public start = false;
    uint256 public rentPerMonth = 12000;
    uint256 public totalMoney = totalMonth.mul(rentPerMonth);
    uint256 public currentMonth = 0;
    uint256 public currentPaid = 0;
    uint256 public deposit = 0;
    uint256 public timeoutPerMonth = 30 days;
    uint256 public lastDay = 0;
    uint256 public nextDeadline = 0;
    
    event StartRent();
    event PaidForMonth();
    event WithdrawDepositFromTenant();
    event WithdrawDepositFromLandlord();
    
    modifier contractNotStart {
        require(!start);
            _;
    }
    
    modifier contractStart {
        require(start);
            _;
    }
    
    modifier notTimeout {
        require(now <= nextDeadline);
            _;
    }
    
    modifier timeout {
        require(now > nextDeadline);
            _;
    }
    
    function startRent()
        contractNotStart
        public
        payable
    {
        uint firstPaid = msg.value;
        
        // 付二個月押金 + 第一個月房租
        require(firstPaid == rentPerMonth.mul(3));
        
        // 紀錄承租人
        tenant = msg.sender;
        
        // 第一個月付了
        currentMonth = 1;
        
        // 紀錄第一個月付了
        currentPaid = rentPerMonth;
        
        // 押金數量兩個月
        deposit = rentPerMonth.mul(2);
        
        // 下個月租金繳費期限
        nextDeadline = now.add(timeoutPerMonth);

        lastDay = now.add(365 days);
        
        start = true;
        emit StartRent();
    }
    
    function payRent()
        contractStart
        notTimeout
        public
        payable
    {
        uint paidForMonthRent = msg.value;
        
        // 付一個月房租
        require(paidForMonthRent == rentPerMonth);
        
        // 更新下次timeout，基於已付款的月份計算
        nextDeadline = nextDeadline.add(timeoutPerMonth);
        
        // 已繳月份加1
        currentMonth = currentMonth.add(1);

        // 已繳金額更新
        currentPaid = currentPaid.add(rentPerMonth);
        emit PaidForMonth();

        // 租金直接給房東
        owner.transfer(paidForMonthRent);
        
        if (currentMonth == 12) {
            // 繳滿房租，退押金給租客
            uint256 depositShouldReturn = deposit;
            deposit = 0;
            tenant.transfer(depositShouldReturn);
            emit WithdrawDepositFromTenant();
        }
    }

    function withdrawDeposit()
        timeout
        onlyOwner
        public
    {
        // 房租逾期押金歸房東
        owner.transfer(deposit);
        emit WithdrawDepositFromLandlord();
    }
}