// File: contracts/StakingHelper.sol



// SPDX-License-Identifier: AGPL-3.0-or-later
pragma solidity 0.7.5;

import "./interfaces/IERC20.sol";
import "./interfaces/IStaking.sol";

contract StakingHelper {

    address public immutable staking;
    address public immutable PSI;

    constructor (address _staking, address _PSI) {
        require(_staking != address(0));
        staking = _staking;
        require(_PSI != address(0));
        PSI = _PSI;
    }

    function stake(uint _amount) external {
        IERC20(PSI).transferFrom(msg.sender, address(this), _amount);
        IERC20(PSI).approve(staking, _amount);
        IStaking(staking).stake(_amount, msg.sender);
        IStaking(staking).claim(msg.sender);
    }
}
// File: contracts/interfaces/IStaking.sol



// SPDX-License-Identifier: AGPL-3.0-or-later
pragma solidity 0.7.5;

interface IStaking {

    function stake(uint _amount, address _recipient) external returns (bool);

    function claim(address _recipient) external;
}
// File: contracts/interfaces/IERC20.sol



// SPDX-License-Identifier: AGPL-3.0-or-later
pragma solidity 0.7.5;

/**
 * @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 amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

    /**
     * @dev Moves `amount` 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 amount) 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 `amount` 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 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` 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 amount
    ) external returns (bool);
}