day17. Solidity基本文法 – コントラクトの実装 –

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.13;


error Funding__NotOwner();
error Funding__NotEnoughETH();


/**
 * @title A contract for crowdfunding
 * @author simochan
 * @notice This contract is to demo a sample funding contract
 */
contract Funding {
    // State variables
    address[] private s_funders;
    mapping(address => uint256) private s_addressToAmountFunded;
    address private immutable i_owner;

    // Event
    event Funded(address indexed funder, uint256 indexed fundedAmount);

    // Modifiers
    modifier onlyOwner() {
        if (msg.sender != i_owner) {
            revert Funding__NotOwner();
        }
        _;
    }

    constructor() {
        i_owner = msg.sender;
    }

    function fund() public payable {
        if(msg.value <= 100000000000000000) {
            revert Funding__NotEnoughETH();
        }
        s_funders.push(msg.sender);
        s_addressToAmountFunded[msg.sender] += msg.value;
        emit Funded(msg.sender, msg.value);
    }

    function withdraw() public onlyOwner {
        for (uint256 i = 0; i < s_funders.length; i++) {
            address funder = s_funders[i];
            s_addressToAmountFunded[funder] = 0;
        }
        s_funders = new address[](0);
        (bool success, ) = i_owner.call{value: address(this).balance}("");
        require(success);
    }

    function getOwner() public view returns (address) {
        return i_owner;
    }

    function getFunder(uint256 index) public view returns (address) {
        return s_funders[index];
    }

    function getAddressToAmountFunded(address funder) public view returns(uint256) {
        return s_addressToAmountFunded[funder];
    }
}