ERC-7947: Account Abstraction Recovery Interface

pragma solidity ^0.8.20;

/**
 * @notice Defines a common account recovery interface for smart accounts to implement.
 */
interface IAccountRecovery {
    /**
     * MUST be emitted whenever the owner of the account changes as a result 
     * of account recovery (e.g. in the `recoverOwnership` function).
     */
    event OwnershipRecovered(address indexed oldOwner, address indexed newOwner);
    
    /**
     * MUST be emitted whenever a new recovery provider is added to
     * the account (e.g. in the `addRecoveryProvider` function).
     */
    event RecoveryProviderAdded(address indexed provider);

    /**
     * MUST be emitted whenever a recovery provider is removed from
     * the account (e.g. in the `removeRecoveryProvider` function).
     */
    event RecoveryProviderRemoved(address indexed provider);

    /**
     * @notice A function to add a new recovery provider.
     * SHOULD be access controlled.
     * MUST check that `provider` is not `address(0)`.
     * MUST call `subscribe` on the `provider`.
     * MUST pass `recoveryData` to the `subscribe` function.
     * 
     * @param provider the address of a recovery provider (ZKP verifier) to add.
     * @param recoveryData custom data (commitment) for the recovery provider.
     */
    function addRecoveryProvider(address provider, bytes memory recoveryData) external;

    /**
     * @notice A function to remove an existing recovery provider.
     * SHOULD be access controlled.
     * MUST call `unsubscribe` on the `provider`.
     * 
     * @param provider the address of a previously added recovery provider to remove.
     */
    function removeRecoveryProvider(address provider) external;

    /**
     * @notice A view function to check if a provider has been previously added.
     * 
     * @param provider the provider to check.
     * @return true if the provider exists in the account, false otherwise.
     */
    function recoveryProviderAdded(address provider) external view returns (bool);

    /**
     * @notice A non-view function to recover ownership of a smart account.
     * MUST check that `provider` exists in the account.
     * MUST call `recover` on the `provider`.
     * MUST update the account owner to `newOwner` if `proof` verification succeeds.
     * MUST return `true` if the ownership recovery is successful.
     * 
     * @param newOwner the address of a new owner.
     * @param provider the address of a recovery provider.
     * @param proof an encoded proof of recovery (ZKP/ZKAI, signature, etc).
     * @return `true` if recovery is successful, `false` (or revert) otherwise.
     */
    function recoverOwnership(
        address newOwner,
        address provider,
        bytes memory proof
    ) external returns (bool);
}

/**
 * @notice Defines a common recovery provider interface.
 */
interface IRecoveryProvider {
    /**
     * MUST be emitted whenever a new account subscribes to
     * the recovery provider (e.g. in the `subscribe` function).
     */
    event AccountSubscribed(address indexed account);

    /**
     * MUST be emitted whenever an account unsubscribes from
     * the recovery provider (e.g. in the `unsubscribe` function).
     */
    event AccountUnsubscribed(address indexed account);

    /**
     * @notice A function that "subscribes" a smart account (msg.sender) to a recovery provider.
     * SHOULD process and assign the `recoveryData` to the `msg.sender`.
     * 
     * @param recoveryData a recovery commitment (hash/ZKP public output) to be used 
     * in the `recover` function to check a recovery proof validity.
     */
    function subscribe(bytes memory recoveryData) external;

    /**
     * @notice A function that revokes a smart account subscription.
     * MUST delete all the recovery data associated with the `msg.sender`.
     */
    function unsubscribe() external;

    /**
     * @notice A function to get a recovery data (commitment) of an account.
     * 
     * @param account the account to get the recovery data of.
     * @return the associated recovery data.
     */
    function getRecoveryData(address account) external view returns (bytes memory);

    /**
     * @notice A function that checks if a recovery of a smart account (msg.sender)
     * to the `newOwner` is possible.
     * SHOULD use `msg.sender`'s `recoveryData` to check the `proof` validity.
     * MUST ensure that the `proof` can't be reused, e.g. update nonce.
     * 
     * @param newOwner the new owner to recover the `msg.sender` ownership to.
     * @param proof the recovery proof.
     */
    function recover(address newOwner, bytes memory proof) external;
}