// File: contracts/VaultProxy.sol



pragma solidity 0.5.16;

import "./hardworkInterface/IUpgradeSource.sol";
import "./BaseUpgradeabilityProxy.sol";

contract VaultProxy is BaseUpgradeabilityProxy {
    constructor(address _implementation) public {
        _setImplementation(_implementation);
    }

    /**
     * The main logic. If the timer has elapsed and there is a schedule upgrade,
     * the governance can upgrade the vault
     */
    function upgrade() external {
        (bool should, address newImplementation) =
            IUpgradeSource(address(this)).shouldUpgrade();
        require(should, "Upgrade not scheduled");
        _upgradeTo(newImplementation);

        // the finalization needs to be executed on itself to update the storage of this proxy
        // it also needs to be invoked by the governance, not by address(this), so delegatecall is needed
        (bool success, bytes memory result) =
            address(this).delegatecall(
                abi.encodeWithSignature("finalizeUpgrade()")
            );

        require(success, "Issue when finalizing the upgrade");
    }

    function implementation() external view returns (address) {
        return _implementation();
    }
}

// File: contracts/hardworkInterface/IUpgradeSource.sol



pragma solidity 0.5.16;

interface IUpgradeSource {
  function shouldUpgrade() external view returns (bool, address);
  function finalizeUpgrade() external;
}

// File: contracts/BaseUpgradeabilityProxy.sol



pragma solidity 0.5.16;

/**
 * @title Proxy
 * @dev Implements delegation of calls to other contracts, with proper
 * forwarding of return values and bubbling of failures.
 * It defines a fallback function that delegates all calls to the address
 * returned by the abstract _implementation() internal function.
 */
contract Proxy {
    /**
     * @dev Fallback function.
     * Implemented entirely in `_fallback`.
     */
    function() external payable {
        _fallback();
    }

    /**
     * @return The Address of the implementation.
     */
    function _implementation() internal view returns (address);

    /**
     * @dev Delegates execution to an implementation contract.
     * This is a low level function that doesn't return to its internal call site.
     * It will return to the external caller whatever the implementation returns.
     * @param implementation Address to delegate.
     */
    function _delegate(address implementation) internal {
        assembly {
            // Copy msg.data. We take full control of memory in this inline assembly
            // block because it will not return to Solidity code. We overwrite the
            // Solidity scratch pad at memory position 0.
            calldatacopy(0, 0, calldatasize)

            // Call the implementation.
            // out and outsize are 0 because we don't know the size yet.
            let result := delegatecall(
                gas,
                implementation,
                0,
                calldatasize,
                0,
                0
            )

            // Copy the returned data.
            returndatacopy(0, 0, returndatasize)

            switch result
                // delegatecall returns 0 on error.
                case 0 {
                    revert(0, returndatasize)
                }
                default {
                    return(0, returndatasize)
                }
        }
    }

    /**
     * @dev Function that is run as the first thing in the fallback function.
     * Can be redefined in derived contracts to add functionality.
     * Redefinitions must call super._willFallback().
     */
    function _willFallback() internal {}

    /**
     * @dev fallback implementation.
     * Extracted to enable manual triggering.
     */
    function _fallback() internal {
        _willFallback();
        _delegate(_implementation());
    }
}



/**
 * Utility library of inline functions on addresses
 *
 * Source https://raw.githubusercontent.com/OpenZeppelin/openzeppelin-solidity/v2.1.3/contracts/utils/Address.sol
 * This contract is copied here and renamed from the original to avoid clashes in the compiled artifacts
 * when the user imports a zos-lib contract (that transitively causes this contract to be compiled and added to the
 * build/artifacts folder) as well as the vanilla Address implementation from an openzeppelin version.
 */
library OpenZeppelinUpgradesAddress {
    /**
     * Returns whether the target address is a contract
     * @dev This function will return false if invoked during the constructor of a contract,
     * as the code is not actually created until after the constructor finishes.
     * @param account address of the account to check
     * @return whether the target address is a contract
     */
    function isContract(address account) internal view returns (bool) {
        uint256 size;
        // XXX Currently there is no better way to check if there is a contract in an address
        // than to check the size of the code at that address.
        // See https://ethereum.stackexchange.com/a/14016/36603
        // for more details about how this works.
        // TODO Check this again before the Serenity release, because all addresses will be
        // contracts then.
        // solhint-disable-next-line no-inline-assembly
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }
}

// File: @openzeppelin/upgrades/contracts/upgradeability/BaseUpgradeabilityProxy.sol


/**
 * @title BaseUpgradeabilityProxy
 * @dev This contract implements a proxy that allows to change the
 * implementation address to which it will delegate.
 * Such a change is called an implementation upgrade.
 */
contract BaseUpgradeabilityProxy is Proxy {
    /**
     * @dev Emitted when the implementation is upgraded.
     * @param implementation Address of the new implementation.
     */
    event Upgraded(address indexed implementation);

    /**
     * @dev Storage slot with the address of the current implementation.
     * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
     * validated in the constructor.
     */
    bytes32 internal constant IMPLEMENTATION_SLOT =
        0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;

    /**
     * @dev Returns the current implementation.
     * @return Address of the current implementation
     */
    function _implementation() internal view returns (address impl) {
        bytes32 slot = IMPLEMENTATION_SLOT;
        assembly {
            impl := sload(slot)
        }
    }

    /**
     * @dev Upgrades the proxy to a new implementation.
     * @param newImplementation Address of the new implementation.
     */
    function _upgradeTo(address newImplementation) internal {
        _setImplementation(newImplementation);
        emit Upgraded(newImplementation);
    }

    /**
     * @dev Sets the implementation address of the proxy.
     * @param newImplementation Address of the new implementation.
     */
    function _setImplementation(address newImplementation) internal {
        require(
            OpenZeppelinUpgradesAddress.isContract(newImplementation),
            "Cannot set a proxy implementation to a non-contract address"
        );

        bytes32 slot = IMPLEMENTATION_SLOT;

        assembly {
            sstore(slot, newImplementation)
        }
    }
}