// SPDX-License-Identifier: MIT

pragma solidity =0.8.18;

/**
 * @title SOMA Swap Factory Contract.
 * @author SOMA.finance
 * @notice Interface for the {SomaSwapFactory} contract.
 */
interface ISomaSwapFactory {
    /**
     * @notice Emitted when a pair is created via `createPair()`.
     * @param token0 The address of token0.
     * @param token1 The address of token1.
     * @param pair The address of the created pair.
     */
    event PairCreated(address indexed token0, address indexed token1, address pair, uint256);

    /**
     * @notice Emitted when the `feeTo` address is updated from `prevFeeTo` to `newFeeTo` by `sender`.
     * @param prevFeeTo The address of the previous fee to.
     * @param prevFeeTo The address of the new fee to.
     * @param sender The address of the message sender.
     */
    event FeeToUpdated(address indexed prevFeeTo, address indexed newFeeTo, address indexed sender);

    /**
     * @notice Emitted when a router is added by `sender`.
     * @param router The address of the router added.
     * @param sender The address of the message sender.
     */
    event RouterAdded(address indexed router, address indexed sender);

    /**
     * @notice Emitted when a router is removed by `sender`.
     * @param router The address of the router removed.
     * @param sender The address of the message sender.
     */
    event RouterRemoved(address indexed router, address indexed sender);

    /**
     * @notice Returns SOMA Swap Factory Create Pair Role.
     * @dev Returns `keccak256('SomaSwapFactory.CREATE_PAIR_ROLE')`.
     */
    function CREATE_PAIR_ROLE() external pure returns (bytes32);

    /**
     * @notice Returns SOMA Swap Factory Fee Setter Role.
     * @dev Returns `keccak256('SomaSwapFactory.FEE_SETTER_ROLE')`.
     */
    function FEE_SETTER_ROLE() external pure returns (bytes32);

    /**
     * @notice Returns SOMA Swap Factory Manage Router Role.
     * @dev Returns `keccak256('SomaSwapFactory.MANAGE_ROUTER_ROLE')`.
     */
    function MANAGE_ROUTER_ROLE() external pure returns (bytes32);

    /**
     * @notice Returns the address where fees from the exchange get transferred to.
     */
    function feeTo() external view returns (address);

    /**
     * @notice Returns the address of the pair contract for tokenA and tokenB if it exists, else returns address(0).
     * @dev Returns the address of the pair for `tokenA` and `tokenB` if it exists, else returns `address(0)`.
     * @param tokenA The token0 of the pair.
     * @param tokenB The token1 of the pair.
     * @return pair The address of the pair.
     */
    function getPair(address tokenA, address tokenB) external view returns (address pair);

    /**
     * @notice Returns the nth pair created through the factory, or address(0).
     * @dev Returns the `n-th` pair (0 indexed) created through the factory, or `address(0)`.
     * @return pair The address of the pair.
     */
    function allPairs(uint256) external view returns (address pair);

    /**
     * @notice Returns the total number of pairs created through the factory so far.
     */
    function allPairsLength() external view returns (uint256);

    /**
     * @notice Returns True if an address is an existing router, else returns False.
     * @param target The address to return true if it an existing router, or false if it is not.
     * @return Boolean value indicating if the address is an existing router.
     */
    function isRouter(address target) external view returns (bool);

    /**
     * @notice Adds an address as a new router. A router is able to tell a pair who is swapping.
     * @param router The address to add as a new router.
     * @custom:emits RouterAdded
     * @custom:requirement The function caller must have the MANAGE_ROUTER_ROLE.
     */
    function addRouter(address router) external;

    /**
     * @notice Removes an address from the list of routers. A router is able to tell a pair who is swapping.
     * @param router The address to remove from the list of routers.
     * @custom:emits RouterRemoved
     * @custom:requirement The function caller must have the MANAGE_ROUTER_ROLE.
     */
    function removeRouter(address router) external;

    /**
     * @notice Creates a new pair.
     * @dev Creates a pair for `tokenA` and `tokenB` if one does not exist already.
     * @param tokenA The address of token0 of the pair.
     * @param tokenB The address of token1 of the pair.
     * @custom:emits PairCreated
     * @custom:requirement The function caller must have the CREATE_PAIR_ROLE.
     * @custom:requirement `tokenA` must not be equal to `tokenB`.
     * @custom:requirement `tokenA` must not be equal to `address(0)`.
     * @custom:requirement `tokenA` and `tokenB` must not be an existing pair.
     * @custom:requirement The system must not be paused.
     * @return pair The address of the pair created.
     */
    function createPair(address tokenA, address tokenB) external returns (address pair);

    /**
     * @notice Sets a new `feeTo` address.
     * @param _feeTo The new address to receive the protocol fees.
     * @custom:emits FeeToUpdated
     * @custom:requirement The function caller must have the FEE_SETTER_ROLE.
     * @custom:requirement The system must not be paused.
     */
    function setFeeTo(address _feeTo) external;
}