pragma solidity ^0.8.13;

contract BloomReceiptAttestor {
    uint256[8] private bloom;

    event ReceiptAdded(bytes32 indexed receiptId);

    function _position(bytes32 receiptId, uint256 salt) private view returns (uint256) {
        return uint256(keccak256(abi.encodePacked(block.chainid, receiptId, salt))) & 2047;
    }

    function add(bytes32 receiptId) external {
        for (uint256 i = 0; i < 3; i++) {
            uint256 p = _position(receiptId, i);
            bloom[p >> 8] |= uint256(1) << uint8(p & 255);
        }
        emit ReceiptAdded(receiptId);
    }

    function contains(bytes32 receiptId) external view returns (bool) {
        for (uint256 i = 0; i < 3; i++) {
            uint256 p = _position(receiptId, i);
            if ((bloom[p >> 8] & (uint256(1) << uint8(p & 255))) == 0) return false;
        }
        return true;
    }
}