BankContract.sol

pragma solidity ^0.6.6;

contract BankContract {
    
    struct client_account{
        int client_id;
        address client_address;
        uint client_balance_in_ether;
    }
    
    client_account[] clients;
    
    int clientCounter;
    address payable manager;
    mapping(address => uint) public interestDate;
    
    modifier onlyManager() {
        require(msg.sender == manager, "Only manager can call this!");
        _;
    }
    
    modifier onlyClients() {
        bool isclient = false;
        for(uint i=0;i<clients.length;i++){
            if(clients[i].client_address == msg.sender){
                isclient = true;
                break;
            }
        }
        require(isclient, "Only clients can call this!");
        _;
    }
    
    constructor() public{
        clientCounter = 0;
    }
    
    receive() external payable { }
    
    function setManager(address managerAddress) public returns(string memory){
        manager = payable(managerAddress);
        return "";
    }
   
    function joinAsClient() public payable returns(string memory){
        interestDate[msg.sender] = now;
        clients.push(client_account(clientCounter++, msg.sender, address(msg.sender).balance));
        return "";
    }
    
    function deposit() public payable onlyClients{
        payable(address(this)).transfer(msg.value);
    }
    
    function withdraw(uint amount) public payable onlyClients{
        msg.sender.transfer(amount * 1 ether);
    }
    
    function sendInterest() public payable onlyManager{
        for(uint i=0;i<clients.length;i++){
            address initialAddress = clients[i].client_address;
            uint lastInterestDate = interestDate[initialAddress];
            if(now < lastInterestDate + 10 seconds){
                revert("It's just been less than 10 seconds!");
            }
            payable(initialAddress).transfer(1 ether);
            interestDate[initialAddress] = now;
        }
    }
    
    function getContractBalance() public view returns(uint){
        return address(this).balance;
    }
}

contract