// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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 `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, 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 `sender` to `recipient` 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 sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @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);
}

// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;

interface IGlpManager {
    function usdg() external view returns (address);
    function cooldownDuration() external returns (uint256);
    function getAumInUsdg(bool maximise) external view returns (uint256);
    function lastAddedAt(address _account) external returns (uint256);
    function addLiquidity(address _token, uint256 _amount, uint256 _minUsdg, uint256 _minGlp) external returns (uint256);
    function addLiquidityForAccount(address _fundingAccount, address _account, address _token, uint256 _amount, uint256 _minUsdg, uint256 _minGlp) external returns (uint256);
    function removeLiquidity(address _tokenOut, uint256 _glpAmount, uint256 _minOut, address _receiver) external returns (uint256);
    function removeLiquidityForAccount(address _account, address _tokenOut, uint256 _glpAmount, uint256 _minOut, address _receiver) external returns (uint256);
    function setShortsTrackerAveragePriceWeight(uint256 _shortsTrackerAveragePriceWeight) external;
    function setCooldownDuration(uint256 _cooldownDuration) external;
}

// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;

interface IRewardTracker {
    function depositBalances(address _account, address _depositToken) external view returns (uint256);
    function stakedAmounts(address _account) external view returns (uint256);
    function updateRewards() external;
    function stake(address _depositToken, uint256 _amount) external;
    function stakeForAccount(address _fundingAccount, address _account, address _depositToken, uint256 _amount) external;
    function unstake(address _depositToken, uint256 _amount) external;
    function unstakeForAccount(address _account, address _depositToken, uint256 _amount, address _receiver) external;
    function tokensPerInterval() external view returns (uint256);
    function claim(address _receiver) external returns (uint256);
    function claimForAccount(address _account, address _receiver) external returns (uint256);
    function claimable(address _account) external view returns (uint256);
    function averageStakedAmounts(address _account) external view returns (uint256);
    function cumulativeRewards(address _account) external view returns (uint256);
}

// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;

import "../libraries/math/SafeMath.sol";
import "../libraries/token/IERC20.sol";

import "../core/interfaces/IGlpManager.sol";

import "./interfaces/IRewardTracker.sol";
import "./interfaces/IRewardTracker.sol";

// provide a way to transfer staked GLP tokens by unstaking from the sender
// and staking for the receiver
// tests in RewardRouterV2.js
contract StakedGlp {
    using SafeMath for uint256;

    string public constant name = "StakedGlp";
    string public constant symbol = "sGLP";
    uint8 public constant decimals = 18;

    address public glp;
    IGlpManager public glpManager;
    address public stakedGlpTracker;
    address public feeGlpTracker;

    mapping (address => mapping (address => uint256)) public allowances;

    event Approval(address indexed owner, address indexed spender, uint256 value);

    constructor(
        address _glp,
        IGlpManager _glpManager,
        address _stakedGlpTracker,
        address _feeGlpTracker
    ) public {
        glp = _glp;
        glpManager = _glpManager;
        stakedGlpTracker = _stakedGlpTracker;
        feeGlpTracker = _feeGlpTracker;
    }

    function allowance(address _owner, address _spender) external view returns (uint256) {
        return allowances[_owner][_spender];
    }

    function approve(address _spender, uint256 _amount) external returns (bool) {
        _approve(msg.sender, _spender, _amount);
        return true;
    }

    function transfer(address _recipient, uint256 _amount) external returns (bool) {
        _transfer(msg.sender, _recipient, _amount);
        return true;
    }

    function transferFrom(address _sender, address _recipient, uint256 _amount) external returns (bool) {
        uint256 nextAllowance = allowances[_sender][msg.sender].sub(_amount, "StakedGlp: transfer amount exceeds allowance");
        _approve(_sender, msg.sender, nextAllowance);
        _transfer(_sender, _recipient, _amount);
        return true;
    }

    function balanceOf(address _account) external view returns (uint256) {
        return IRewardTracker(feeGlpTracker).depositBalances(_account, glp);
    }

    function totalSupply() external view returns (uint256) {
        return IERC20(stakedGlpTracker).totalSupply();
    }

    function _approve(address _owner, address _spender, uint256 _amount) private {
        require(_owner != address(0), "StakedGlp: approve from the zero address");
        require(_spender != address(0), "StakedGlp: approve to the zero address");

        allowances[_owner][_spender] = _amount;

        emit Approval(_owner, _spender, _amount);
    }

    function _transfer(address _sender, address _recipient, uint256 _amount) private {
        require(_sender != address(0), "StakedGlp: transfer from the zero address");
        require(_recipient != address(0), "StakedGlp: transfer to the zero address");

        require(
            glpManager.lastAddedAt(_sender).add(glpManager.cooldownDuration()) <= block.timestamp,
            "StakedGlp: cooldown duration not yet passed"
        );

        IRewardTracker(stakedGlpTracker).unstakeForAccount(_sender, feeGlpTracker, _amount, _sender);
        IRewardTracker(feeGlpTracker).unstakeForAccount(_sender, glp, _amount, _sender);

        IRewardTracker(feeGlpTracker).stakeForAccount(_sender, _recipient, glp, _amount);
        IRewardTracker(stakedGlpTracker).stakeForAccount(_recipient, _recipient, feeGlpTracker, _amount);
    }
}

{
  "compilationTarget": {
    "contracts/staking/StakedGlp.sol": "StakedGlp"
  },
  "evmVersion": "istanbul",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 1
  },
  "remappings": []
}