/// @dev get the quote token address (immutable)
/// @return address of quote token
function quoteToken() external view returns (address);
/// @dev Query the amount for selling the base token amount.
/// @param baseToken the base token to sell
/// @param baseAmount the amount to sell
/// @return quoteAmount the swapped quote amount
function querySellBase(address baseToken, uint256 baseAmount) external view returns (uint256 quoteAmount);
/// @dev Query the amount for selling the quote token.
/// @param baseToken the base token to receive (buy)
/// @param quoteAmount the amount to sell
/// @return baseAmount the swapped base token amount
function querySellQuote(address baseToken, uint256 quoteAmount) external view returns (uint256 baseAmount);
/// @dev Swap baseToken into quoteToken
/// @param baseToken the base token
/// @param baseAmount amount of baseToken that user want to swap
/// @param minQuoteAmount minimum amount of quoteToken that user accept to receive
/// @param to quoteToken receiver address
/// @param rebateTo the wallet address for rebate
/// @return quoteAmount the swapped amount of quote token
) external returns (uint256 quoteAmount);
/// @dev Swap quoteToken into baseToken
/// @param baseToken the base token
/// @param quoteAmount amount of quoteToken that user want to swap
/// @param minBaseAmount minimum amount of baseToken that user accept to receive
/// @param to baseToken receiver address
/// @param rebateTo the wallet address for rebate
/// @return baseAmount the swapped amount of base token
) external returns (uint256 baseAmount);