import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

contract Week22Exercise3 is Ownable {
	using ECDSA for bytes32;

	mapping(address => uint256) public nonceForAddress;

	function claimAirdrop(
        uint256 amount,
        address to,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public {
        bytes32 hash_ = keccak256(abi.encodePacked(nonceForAddress[to], amount, to));
		nonceForAddress[to]++;

		address recovered = ecrecover(hash_, v, r, s);
		require(recovered == owner(), "invalid signature");

		// claim airdrop
    }
}