// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.1) (utils/Context.sol)

pragma solidity ^0.8.20;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }

    function _contextSuffixLength() internal view virtual returns (uint256) {
        return 0;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (access/IAccessControl.sol)

pragma solidity ^0.8.20;

/**
 * @dev External interface of AccessControl declared to support ERC165 detection.
 */
interface IAccessControl {
    /**
     * @dev The `account` is missing a role.
     */
    error AccessControlUnauthorizedAccount(address account, bytes32 neededRole);

    /**
     * @dev The caller of a function is not the expected one.
     *
     * NOTE: Don't confuse with {AccessControlUnauthorizedAccount}.
     */
    error AccessControlBadConfirmation();

    /**
     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
     *
     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
     * {RoleAdminChanged} not being emitted signaling this.
     */
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);

    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {AccessControl-_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) external view returns (bool);

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {AccessControl-_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) external view returns (bytes32);

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) external;

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) external;

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `callerConfirmation`.
     */
    function renounceRole(bytes32 role, address callerConfirmation) external;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.20;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the value of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the value of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves a `value` amount of tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 value) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
     * caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the
     * allowance mechanism. `value` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 value) external returns (bool);
}

/**
 * SPDX-License-Identifier: MIT
 */
pragma solidity 0.8.20;

import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import {IAccessControl} from "@openzeppelin/contracts/access/IAccessControl.sol";

interface ILingoToken is IERC20, IAccessControl {
    function INTERNAL_ROLE() external view returns (bytes32);
    function MINTER_ROLE() external view returns (bytes32);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (access/Ownable.sol)

pragma solidity ^0.8.20;

import {Context} from "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * The initial owner is set to the address provided by the deployer. This can
 * later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    /**
     * @dev The caller account is not authorized to perform an operation.
     */
    error OwnableUnauthorizedAccount(address account);

    /**
     * @dev The owner is not a valid owner account. (eg. `address(0)`)
     */
    error OwnableInvalidOwner(address owner);

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the address provided by the deployer as the initial owner.
     */
    constructor(address initialOwner) {
        if (initialOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(initialOwner);
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        if (owner() != _msgSender()) {
            revert OwnableUnauthorizedAccount(_msgSender());
        }
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        if (newOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (access/Ownable2Step.sol)

pragma solidity ^0.8.20;

import {Ownable} from "./Ownable.sol";

/**
 * @dev Contract module which provides access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * The initial owner is specified at deployment time in the constructor for `Ownable`. This
 * can later be changed with {transferOwnership} and {acceptOwnership}.
 *
 * This module is used through inheritance. It will make available all functions
 * from parent (Ownable).
 */
abstract contract Ownable2Step is Ownable {
    address private _pendingOwner;

    event OwnershipTransferStarted(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Returns the address of the pending owner.
     */
    function pendingOwner() public view virtual returns (address) {
        return _pendingOwner;
    }

    /**
     * @dev Starts the ownership transfer of the contract to a new account. Replaces the pending transfer if there is one.
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual override onlyOwner {
        _pendingOwner = newOwner;
        emit OwnershipTransferStarted(owner(), newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`) and deletes any pending owner.
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual override {
        delete _pendingOwner;
        super._transferOwnership(newOwner);
    }

    /**
     * @dev The new owner accepts the ownership transfer.
     */
    function acceptOwnership() public virtual {
        address sender = _msgSender();
        if (pendingOwner() != sender) {
            revert OwnableUnauthorizedAccount(sender);
        }
        _transferOwnership(sender);
    }
}

// SPDX-License-Identifier: MIT
pragma solidity 0.8.20;

import {ILingoToken} from "./ILingoToken.sol";
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
import {Ownable2Step} from "@openzeppelin/contracts/access/Ownable2Step.sol";

/**
 * @author wepee
 * @title Lingo Token Staking
 * @dev Implements the Lingo Token staking mechanism.
 */
contract TokenStaking is Ownable2Step {
    struct Position {
        uint128 amount;
        uint128 unlockBlock;
    }

    ILingoToken public immutable LINGO_TOKEN;
    uint256 public constant MIN_DEPOSIT = 10 ** 18;
    uint256[] public lockDurations; // In blocks
    uint256 public lockDurationsCount;
    mapping(address => Position[]) private userPositions;

    /// @notice Emitted when a user stakes tokens.
    /// @param user Address of the user who staked.
    /// @param amount Amount of tokens staked.
    /// @param duration Duration of the lock period in blocks.
    event Staked(address indexed user, uint256 amount, uint256 duration);

    /// @notice Emitted when a user withdraws staked tokens.
    /// @param user Address of the user who withdrew.
    /// @param amount Amount of tokens withdrawn.
    /// @param unlockBlock Block number at which the tokens were unlocked.
    event Unstaked(address indexed user, uint256 amount, uint256 unlockBlock);

    /// @notice Emitted when the owner updates the lock durations.
    /// @param durations New lock durations in blocks.
    event LockDurationsUpdated(uint256[] durations);

    // Custom errors
    error InvalidDuration();
    error StakeStillLocked();
    error MissingInternalRole();
    error InsufficientAmount();
    error UnauthorizedStakingOnBehalf();
    /**
     * @dev Sets the initial contract parameters.
     * @param _lingoToken Address of the Lingo ERC20 token.
     */
    constructor(
        address _initialOwner,
        ILingoToken _lingoToken,
        uint256[] memory _lockDurations
    ) Ownable(_initialOwner) {
        LINGO_TOKEN = ILingoToken(_lingoToken);
        lockDurations = _lockDurations;
        lockDurationsCount = _lockDurations.length;
    }

    /**
     * @notice Allows a user to stake tokens.
     * @param _amount The amount of tokens to stake.
     * @param _durationIndex The chosen duration index for staking.
     * @param _expectedDuration This ensures that any changes to the lock durations by the admin cannot affect ongoing user staking operations without their knowledge.
     * @param _user The address of the user on whose behalf tokens are staked.
     */
    function stake(
        uint256 _amount,
        uint256 _durationIndex,
        uint256 _expectedDuration,
        address _user
    ) external {
        if (_amount < MIN_DEPOSIT) revert InsufficientAmount();
        if (!LINGO_TOKEN.hasRole(LINGO_TOKEN.INTERNAL_ROLE(), address(this)))
            revert MissingInternalRole();
        if (lockDurations.length < _durationIndex) revert InvalidDuration();

        if (msg.sender != _user) {
            if (!LINGO_TOKEN.hasRole(LINGO_TOKEN.MINTER_ROLE(), msg.sender)) {
                revert UnauthorizedStakingOnBehalf();
            }
        }

        uint256 duration = lockDurations[_durationIndex];

        if (duration != _expectedDuration) revert InvalidDuration();

        uint256 unlockBlock = block.number + duration;

        userPositions[_user].push(
            Position(uint128(_amount), uint128(unlockBlock))
        );

        emit Staked(_user, _amount, duration);

        LINGO_TOKEN.transferFrom(msg.sender, address(this), _amount);
    }

    /**
     * @notice Allows a user to unstake tokens after the lock period has passed.
     * @param _stakeIndex The index of the position to be unstaked.
     */
    function unstake(uint256 _stakeIndex) external {
        Position memory stakeDetails = userPositions[msg.sender][_stakeIndex];
        if (block.number < stakeDetails.unlockBlock) revert StakeStillLocked();

        uint256 amount = stakeDetails.amount;

        uint256 positionLength = userPositions[msg.sender].length;

        if (_stakeIndex < positionLength - 1) {
            userPositions[msg.sender][_stakeIndex] = userPositions[msg.sender][
                positionLength - 1
            ];
        }
        userPositions[msg.sender].pop();

        emit Unstaked(msg.sender, amount, stakeDetails.unlockBlock);

        LINGO_TOKEN.transfer(msg.sender, amount);
    }

    /**
     * @notice Allows the owner to update the lock durations.
     * @param _durations The new lock durations in blocks.
     */
    function updateLockDurations(
        uint256[] calldata _durations
    ) external onlyOwner {
        lockDurations = _durations;
        lockDurationsCount = _durations.length;

        emit LockDurationsUpdated(_durations);
    }

    /**
     * @notice Returns the stakes of a user.
     * @param _user The address of the user.
     * @return Array of Stake structures.
     */
    function getStakes(
        address _user
    ) external view returns (Position[] memory) {
        return userPositions[_user];
    }
}

{
  "compilationTarget": {
    "contracts/TokenStaking.sol": "TokenStaking"
  },
  "evmVersion": "paris",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}