AE Prezzo

PREZZO.md

Presentation

SimpleBank.sol

// Declare the source file compiler version
pragma solidity ^0.5.0;

contract SimpleBank {
  // Declare state variables outside function, persist through life of contract

  mapping (address => uint) private balances;

  address public owner;

  event LogDepositMade(address accountAddress, uint amount);

  constructor() public {
    owner = msg.sender;
  }

  /// @notice Deposit ether into bank
  /// @return The balance of the user after the deposit is made
  function deposit() public payable returns (uint) {
    require((balances[msg.sender] + msg.value) >= msg.value);

    balances[msg.sender] += msg.value;

    emit LogDepositMade(msg.sender, msg.value); // fire event

    return balances[msg.sender];
  }

  /// @notice Withdraw ether from bank
  /// @dev This does not return any excess ether sent to it
  /// @param withdrawAmount amount you want to withdraw
  /// @return The balance remaining for the user
  function withdraw(uint withdrawAmount) public returns (uint remainingBal) {
    require(withdrawAmount <= balances[msg.sender]);

    balances[msg.sender] -= withdrawAmount;

    // this automatically throws on a failure, which means the updated balance is reverted
    msg.sender.transfer(withdrawAmount);

    return balances[msg.sender];
  }

  /// @notice Transfer to another address
  /// @param transferAmount amount you want to transfer
  /// @param recipient to which you want to transfer
  /// @return The balance remaining for the user
  function transfer(uint transferAmount, address recipient) public returns (uint remainingBal) {
    require(transferAmount <= balances[msg.sender]);
    require((balances[recipient] + transferAmount) >= transferAmount);

    balances[msg.sender] -= transferAmount;
    balances[recipient] += transferAmount;

    return balances[msg.sender];
  }

  /// @notice Get balance
  /// @return The balance of the user
  function balance() view public returns (uint) {
    return balances[msg.sender];
  }
}

STEPS.md

npm install -g truffle ganache-cli live-server
truffle init
truffle migrate -network development
ganache-cli
live-server

// js
window.web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));
await ethereum.enable();

const contractAddress = "0xF110Cca894a8c9EA63Bf935Fba56fE102fE29bE3"
contract = new web3.eth.Contract(abi, contractAddress);
let message = await contract.methods.balance().call();

accounts =  await web3.eth.getAccounts();

message = await contract.methods.deposit().send({value: 100, from: accounts[0]})
message = await contract.methods.transfer(20, "0x1C6b858D31B6b17d3910eEA642Bfb2C45491DeE8").send({from: "0x4d3DA1Cc86fe05057ea51f37D3DeCe480c4E4Bd2"});
message = await contract.methods.withdraw(5).send({from: "0x4d3DA1Cc86fe05057ea51f37D3DeCe480c4E4Bd2"});
message = await contract.methods.balance().call({from: "0x4d3DA1Cc86fe05057ea51f37D3DeCe480c4E4Bd2"});