// SPDX-License-Identifier: MIT
// Gearbox Protocol. Generalized leverage for DeFi protocols
// (c) Gearbox Holdings, 2022
pragma solidity ^0.8.10;
import { IVersion } from "./IVersion.sol";

interface IAccountFactoryEvents {
    /// @dev Emits when the account mining contract is changed
    /// @notice Not applicable to factories deployed after V2
    event AccountMinerChanged(address indexed miner);

    /// @dev Emits when a new Credit Account is created
    event NewCreditAccount(address indexed account);

    /// @dev Emits when a Credit Manager takes an account from the factory
    event InitializeCreditAccount(
        address indexed account,
        address indexed creditManager
    );

    /// @dev Emits when a Credit Manager returns an account to the factory
    event ReturnCreditAccount(address indexed account);

    /// @dev Emits when a Credit Account is taking out of the factory forever
    ///      by root
    event TakeForever(address indexed creditAccount, address indexed to);
}

interface IAccountFactoryGetters {
    /// @dev Gets the next available credit account after the passed one, or address(0) if the passed account is the tail
    /// @param creditAccount Credit Account previous to the one to retrieve
    function getNext(address creditAccount) external view returns (address);

    /// @dev Head of CA linked list
    function head() external view returns (address);

    /// @dev Tail of CA linked list
    function tail() external view returns (address);

    /// @dev Returns the number of unused credit accounts in stock
    function countCreditAccountsInStock() external view returns (uint256);

    /// @dev Returns the credit account address under the passed id
    /// @param id The index of the requested CA
    function creditAccounts(uint256 id) external view returns (address);

    /// @dev Returns the number of deployed credit accounts
    function countCreditAccounts() external view returns (uint256);
}

interface IAccountFactory is
    IAccountFactoryGetters,
    IAccountFactoryEvents,
    IVersion
{
    /// @dev Provides a new credit account to a Credit Manager
    function takeCreditAccount(
        uint256 _borrowedAmount,
        uint256 _cumulativeIndexAtOpen
    ) external returns (address);

    /// @dev Retrieves the Credit Account from the Credit Manager and adds it to the stock
    /// @param usedAccount Address of returned credit account
    function returnCreditAccount(address usedAccount) external;
}