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// SPDX-License-Identifier: UNLICENSED
// openzeppelin-contracts-upgradeable v3.0.0

pragma solidity 0.6.10;

/**
 * @title Proxy
 * @dev Gives the possibility to delegate any call to a foreign implementation.
 */
abstract contract Proxy {
    /**
     * @dev Tells the address of the implementation where every call will be delegated.
     * @return address of the implementation to which it will be delegated
     */
    function implementation() public view virtual returns (address);

    /**
     * @dev Fallback function allowing to perform a delegatecall to the given implementation.
     * This function will return whatever the implementation call returns
     */
    fallback() external payable {
        address _impl = implementation();
        require(_impl != address(0));

        assembly {
            let ptr := mload(0x40)
            calldatacopy(ptr, 0, calldatasize())
            let result := delegatecall(gas(), _impl, ptr, calldatasize(), 0, 0)
            let size := returndatasize()
            returndatacopy(ptr, 0, size)

            switch result
            case 0 {
                revert(ptr, size)
            }
            default {
                return(ptr, size)
            }
        }
    }
}

// SPDX-License-Identifier: UNLICENSED
// openzeppelin-contracts-upgradeable v3.0.0

pragma solidity 0.6.10;

import "./Proxy.sol";

/**
 * @title UpgradeabilityProxy
 * @dev This contract represents a proxy where the implementation address to which it will delegate can be upgraded
 */
contract UpgradeabilityProxy is Proxy {
    /**
     * @dev This event will be emitted every time the implementation gets upgraded
     * @param implementation representing the address of the upgraded implementation
     */
    event Upgraded(address indexed implementation);

    /// @dev Storage position of the address of the current implementation
    bytes32 private constant implementationPosition = keccak256("org.zeppelinos.proxy.implementation");

    /**
     * @dev Tells the address of the current implementation
     * @return impl address of the current implementation
     */
    function implementation() public view override returns (address impl) {
        bytes32 position = implementationPosition;
        assembly {
            impl := sload(position)
        }
    }

    /**
     * @dev Sets the address of the current implementation
     * @param _newImplementation address representing the new implementation to be set
     */
    function setImplementation(address _newImplementation) internal {
        bytes32 position = implementationPosition;
        assembly {
            sstore(position, _newImplementation)
        }
    }

    /**
     * @dev Upgrades the implementation address
     * @param _newImplementation representing the address of the new implementation to be set
     */
    function _upgradeTo(address _newImplementation) internal {
        address currentImplementation = implementation();
        require(currentImplementation != _newImplementation);
        setImplementation(_newImplementation);
        emit Upgraded(_newImplementation);
    }
}

// SPDX-License-Identifier: UNLICENSED
// openzeppelin-contracts-upgradeable v3.0.0

pragma solidity 0.6.10;

import "./UpgradeabilityProxy.sol";

/**
 * @title OwnedUpgradeabilityProxy
 * @dev This contract combines an upgradeability proxy with basic authorization control functionalities
 */
contract OwnedUpgradeabilityProxy is UpgradeabilityProxy {
    /**
     * @dev Event to show ownership has been transferred
     * @param previousOwner representing the address of the previous owner
     * @param newOwner representing the address of the new owner
     */
    event ProxyOwnershipTransferred(address previousOwner, address newOwner);

    /// @dev Storage position of the owner of the contract
    bytes32 private constant proxyOwnerPosition = keccak256("org.zeppelinos.proxy.owner");

    /**
     * @dev the constructor sets the original owner of the contract to the sender account.
     */
    constructor() public {
        setUpgradeabilityOwner(msg.sender);
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyProxyOwner() {
        require(msg.sender == proxyOwner());
        _;
    }

    /**
     * @dev Tells the address of the owner
     * @return owner the address of the owner
     */
    function proxyOwner() public view returns (address owner) {
        bytes32 position = proxyOwnerPosition;
        assembly {
            owner := sload(position)
        }
    }

    /**
     * @dev Sets the address of the owner
     * @param _newProxyOwner address of new proxy owner
     */
    function setUpgradeabilityOwner(address _newProxyOwner) internal {
        bytes32 position = proxyOwnerPosition;
        assembly {
            sstore(position, _newProxyOwner)
        }
    }

    /**
     * @dev Allows the current owner to transfer control of the contract to a newOwner.
     * @param _newOwner The address to transfer ownership to.
     */
    function transferProxyOwnership(address _newOwner) public onlyProxyOwner {
        require(_newOwner != address(0));
        emit ProxyOwnershipTransferred(proxyOwner(), _newOwner);
        setUpgradeabilityOwner(_newOwner);
    }

    /**
     * @dev Allows the proxy owner to upgrade the current version of the proxy.
     * @param _implementation representing the address of the new implementation to be set.
     */
    function upgradeTo(address _implementation) public onlyProxyOwner {
        _upgradeTo(_implementation);
    }

    /**
     * @dev Allows the proxy owner to upgrade the current version of the proxy and call the new implementation
     * to initialize whatever is needed through a low level call.
     * @param _implementation representing the address of the new implementation to be set.
     * @param _data represents the msg.data to bet sent in the low level call. This parameter may include the function
     * signature of the implementation to be called with the needed payload
     */
    function upgradeToAndCall(address _implementation, bytes calldata _data) public payable onlyProxyOwner {
        upgradeTo(_implementation);
        (bool success, ) = address(this).call{value: msg.value}(_data);
        require(success);
    }
}