131 lines
3.7 KiB
Solidity
131 lines
3.7 KiB
Solidity
// SPDX-License-Identifier: MIT
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/*
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Get funds from users
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Withdraw funds
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Set a minimum funding value in USD
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*/
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/***** 1. Pragma *****/
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pragma solidity ^0.8.0;
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/***** 2. Import *****/
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import "./PriceConverter.sol";
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// Save Gas by using constant, immutable for variables
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/***** 3. Error Codes *****/
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error FundMe__NotOwner();
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/***** 4. Interfaces *****/
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/***** 5. Libraries *****/
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/***** 6. Contracts *****/
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/**
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* @title A contract for crowd funding
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* @author hoelee
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* @notice This contract is to demo a sample funding contract
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* @dev This implements price feed as our library
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*/
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contract FundMe {
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/*
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Transaction Fields
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Nonce
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Gas Price
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Gas Limit - Max Gas that this TX can use
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To - Address
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Value - Amount of wei to send
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Data - What to send to the Address (Can Empty)
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v, r, s - components of TX signature
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*/
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/***** 6.1 Type Declarations *****/
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using PriceConverter for uint256;
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uint256 public constant MINIMUM_USD = 50 * 1e18;
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address[] public funders;
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address public immutable i_owner; // immutable only can declare 1 time at contructor
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AggregatorV3Interface public priceFeed;
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/***** 6.2 State Variable *****/
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mapping(address => uint256) public addressToAmountFunded;
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/***** 6.3 Modifier *****/
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modifier onlyOwner() {
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// require(msg.sender == i_owner, "Sender is not owner!");
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if (msg.sender != i_owner) {
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revert FundMe__NotOwner();
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}
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_; // doing the rest of the code
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}
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/***** Function Orders:
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* Constructor
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* Receive
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* Fallback
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* External
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* Public Internal
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* Private
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* View / Pure
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* *****/
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constructor(address priceFeedAddress) {
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i_owner = msg.sender;
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priceFeed = AggregatorV3Interface(priceFeedAddress);
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}
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// What happens if someone send this contract ETH without calling the fund function
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receive() external payable {
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// people send money / empty money into this contract
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fund();
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}
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fallback() external payable {
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// cannot identify which function to run
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fund();
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}
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/**
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* @notice Minimum sending USD50, Check Conversion In Real Time
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* @dev This implements price feed as our library
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*/
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function fund() public payable {
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//require (msg.value >= 1e18, "Didn't send enough"); // 1e18 = 1 * 10 * 18 = 1000000000000000000
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require(
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msg.value.getConversionRate(priceFeed) >= MINIMUM_USD,
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"Didn't send enough"
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);
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funders.push(msg.sender);
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addressToAmountFunded[msg.sender] = msg.value;
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}
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// Owner of this contract only can withdraw
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function withdraw() public onlyOwner {
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// Can use modifier to replace
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// require(msg.sender == owner, "Sender is not owner");
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/* starting index, eding index, step amount */
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for (
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uint256 funderIndex = 0;
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funderIndex < funders.length;
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funderIndex++
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) {
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address funder = funders[funderIndex];
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addressToAmountFunded[funder] = 0;
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}
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// reset the array
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funders = new address[](0);
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/*
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// transfer - over 2300 gas will cause exception
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payable(msg.sender).transfer(address(this).balance);
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// send - over 2300 gas will not cause exception, only will return true or false
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bool sendSuccess = payable(msg.sender).send(address(this).balance);
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require(sendSuccess, "Send failed");
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*/
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// call - lower level
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(bool callSuccess, ) = payable(msg.sender).call{
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value: address(this).balance
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}("");
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require(callSuccess, "Call failed");
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}
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}
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