joint_savings.sol

pragma solidity ^0.5.0;

// Define a new contract named `JointSavings`
contract JointSavings{
    /*
    Inside the new contract define the following variables:
    - Two variables of type `address payable` named `accountOne` and `accountTwo`
    - A variable of type `address public` named `lastToWithdraw`
    - Two variables of type `uint public` named `lastWithdrawAmount` and `contractBalance`.
    */

    address payable accountOne;
    address payable accountTwo;
    address public lastToWithdraw;
    uint public lastWithdrawAmount;
    uint public contractBalance;

    /*
    Define a function named **withdraw** that will accept two arguments.
    - A `uint` variable named `amount`
    - A `payable address` named `recipient`
    */
    function withdraw(uint amount, address payable recipient) public {

        //Define a `require` statement that checks if the `recipient` is equal to either `accountOne` or `accountTwo`. 
        //The `requiere` statement returns the text `"You don't own this account!"` if it does not.
        require(recipient == accountOne || recipient == accountTwo, "You don't own this account!");

        //Define a `require` statement that checks if the `balance` is sufficient to accomplish the withdraw operation.
        // If there are insufficient funds, the text `Insufficient funds!` is returned.
        require(address(this).balance >= amount, "Insufficient funds!");

        //Add and `if` statement to check if the `lastToWithdraw` is not equal to (`!=`) to `recipient`
        // If `lastToWithdraw` is not equal, then set it to the current value of `recipient`.
        if (lastToWithdraw != recipient) {
            lastToWithdraw = recipient;
        }

        // Call the `transfer` function of the `recipient` and pass it the `amount` to transfer as an argument.
        recipient.transfer(amount);    

        // Set  `lastWithdrawAmount` equal to `amount`      
        lastWithdrawAmount = amount;

        // Call the `contractBalance` variable and set it equal to the balance of the contract by using `address(this).balance` to reflect the new balance of the contract.
        contractBalance = address(this).balance; 
    }

    // Define a `public payable` function named `deposit`.
    function deposit() public payable {
        
        //Call the `contractBalance` variable and set it equal to the balance of the contract by using `address(this).balance`.
        contractBalance = address(this).balance;
    }

    //Define a `public` function named `setAccounts` that receive two `address payable` arguments named `account1` and `account2`.
    function setAccounts(address payable account1, address payable account2) public {

        // Set the values of `accountOne` and `accountTwo` to `account1` and `account2` respectively.
        accountOne = account1; 
        accountTwo = account2;
    }

    //Finally, add the **default fallback function** so that your contract can store Ether sent from outside the deposit function.
    function () external payable{}

}