// SPDX-License-Identifier: MIT
/*
    Get funds from users
    Withdraw funds
    Set a minimum funding value in USD
*/
pragma solidity ^0.8.0;

import "./PriceConverter.sol";
// Save Gas by using constant, immutable for variables

error NotOwner();

// 816914
contract FundMe {
    /*
        Transaction Fields
            Nonce
            Gas Price
            Gas Limit - Max Gas that this TX can use
            To - Address
            Value - Amount of wei to send
            Data - What to send to the Address (Can Empty)
            v, r, s - components of TX signature
    */

    using PriceConverter for uint256;
    uint256 public constant MINIMUM_USD = 50 * 1e18;

    address[] public funders;
    mapping(address => uint256) public addressToAmountFunded;

    // immutable only can declare 1 time at contructor
    address public immutable i_owner;

    AggregatorV3Interface public priceFeed;

    constructor(address priceFeedAddress) {
        i_owner = msg.sender;
        priceFeed = AggregatorV3Interface(priceFeedAddress);
    }

    function fund() public payable {
        /*
            Want to be able to set a minimum fund amount in USD
            1. How do we send ETH to this contract
        */
        //require (msg.value >= 1e18, "Didn't send enough"); // 1e18 = 1 * 10 * 18 = 1000000000000000000
        require(
            msg.value.getConversionRate(priceFeed) >= MINIMUM_USD,
            "Didn't send enough"
        );
        funders.push(msg.sender);
        addressToAmountFunded[msg.sender] = msg.value;
    }

    // Owner of this contract only can withdraw
    function withdraw() public onlyOwner {
        // Can use modifier to replace
        // require(msg.sender == owner, "Sender is not owner");

        /* starting index, eding index, step amount */
        for (
            uint256 funderIndex = 0;
            funderIndex < funders.length;
            funderIndex++
        ) {
            address funder = funders[funderIndex];
            addressToAmountFunded[funder] = 0;
        }
        // reset the array
        funders = new address[](0);

        /*
        // transfer - over 2300 gas will cause exception
        payable(msg.sender).transfer(address(this).balance);
        // send - over 2300 gas will not cause exception, only will return true or false
        bool sendSuccess = payable(msg.sender).send(address(this).balance);
        require(sendSuccess, "Send failed");
        */

        // call - lower level
        (bool callSuccess, ) = payable(msg.sender).call{
            value: address(this).balance
        }("");
        require(callSuccess, "Call failed");
    }

    modifier onlyOwner() {
        // require(msg.sender == i_owner, "Sender is not owner!");
        if (msg.sender != i_owner) {
            revert NotOwner();
        }

        _; // doing the rest of the code
    }

    // What happens if someone send this contract ETH without calling the fund fucntion
    /*
        receive - people send money / empty money into this contract
        fallback - cannot identify which function to run
    */
    receive() external payable {
        fund();
    }

    fallback() external payable {
        fund();
    }
}