// SPDX-License-Identifier: MIT
pragma solidity 0.8.17;

/// @title IOwnable2StepUpgradeable
/// @author Rohan Kulkarni
/// @notice The external Ownable events, errors, and functions
interface IOwnable2StepUpgradeable {
    ///                                                          ///
    ///                            EVENTS                        ///
    ///                                                          ///

    /// @notice Emitted when ownership has been updated
    /// @param prevOwner The previous owner address
    /// @param newOwner The new owner address
    event OwnerUpdated(address indexed prevOwner, address indexed newOwner);

    /// @notice Emitted when an ownership transfer is pending
    /// @param owner The current owner address
    /// @param pendingOwner The pending new owner address
    event OwnerPending(address indexed owner, address indexed pendingOwner);

    /// @notice Emitted when a pending ownership transfer has been canceled
    /// @param owner The current owner address
    /// @param canceledOwner The canceled owner address
    event OwnerCanceled(address indexed owner, address indexed canceledOwner);

    ///                                                          ///
    ///                            ERRORS                        ///
    ///                                                          ///

    /// @dev Reverts if an unauthorized user calls an owner function
    error ONLY_OWNER();

    /// @dev Reverts if an unauthorized user calls a pending owner function
    error ONLY_PENDING_OWNER();

    /// @dev Owner cannot be the zero/burn address
    error OWNER_CANNOT_BE_ZERO_ADDRESS();

    ///                                                          ///
    ///                           FUNCTIONS                      ///
    ///                                                          ///

    /// @notice The address of the owner
    function owner() external view returns (address);

    /// @notice The address of the pending owner
    function pendingOwner() external view returns (address);

    /// @notice Forces an ownership transfer
    /// @param newOwner The new owner address
    function transferOwnership(address newOwner) external;

    /// @notice Initiates a two-step ownership transfer
    /// @param newOwner The new owner address
    function safeTransferOwnership(address newOwner) external;

    /// @notice Accepts an ownership transfer
    function acceptOwnership() external;

    /// @notice Cancels a pending ownership transfer
    function cancelOwnershipTransfer() external;
}