Cryo Explorer Ethereum Mainnet

pragma solidity ^0.4.24;

/**
 * @title IRegistry
 * @dev This contract represents the interface of a registry contract
 */
interface ITwoKeySingletonesRegistry {

    /**
    * @dev This event will be emitted every time a new proxy is created
    * @param proxy representing the address of the proxy created
    */
    event ProxyCreated(address proxy);


    /**
    * @dev This event will be emitted every time a new implementation is registered
    * @param version representing the version name of the registered implementation
    * @param implementation representing the address of the registered implementation
    * @param contractName is the name of the contract we added new version
    */
    event VersionAdded(string version, address implementation, string contractName);

    /**
    * @dev Registers a new version with its implementation address
    * @param version representing the version name of the new implementation to be registered
    * @param implementation representing the address of the new implementation to be registered
    */
    function addVersion(string _contractName, string version, address implementation) public;

    /**
    * @dev Tells the address of the implementation for a given version
    * @param _contractName is the name of the contract we're querying
    * @param version to query the implementation of
    * @return address of the implementation registered for the given version
    */
    function getVersion(string _contractName, string version) public view returns (address);
}


/**
 * @title Proxy
 */
contract Proxy {


    // Gives the possibility to delegate any call to a foreign implementation.


    /**
    * @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 returns (address);

    /**
    * @dev Fallback function allowing to perform a delegatecall to the given implementation.
    * This function will return whatever the implementation call returns
    */
    function () payable public {
        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) }
        }
    }
}


/**
 * @author Nikola Madjarevic
 * @dev This contract holds all the necessary state variables to support the upgrade functionality
 */
contract UpgradeabilityStorage {
    // Versions registry
    ITwoKeySingletonesRegistry internal registry;

    // Address of the current implementation
    address internal _implementation;

    /**
    * @dev Tells the address of the current implementation
    * @return address of the current implementation
    */
    function implementation() public view returns (address) {
        return _implementation;
    }
}

/**
 * @title UpgradeabilityProxy
 * @dev This contract represents a proxy where the implementation address to which it will delegate can be upgraded
 */
contract UpgradeabilityProxy is Proxy, UpgradeabilityStorage {

    //TODO: Add event through event source whenever someone calls upgradeTo
    /**
    * @dev Constructor function
    */
    constructor (string _contractName, string _version) public {
        registry = ITwoKeySingletonesRegistry(msg.sender);
        _implementation = registry.getVersion(_contractName, _version);
    }

    /**
    * @dev Upgrades the implementation to the requested version
    * @param _version representing the version name of the new implementation to be set
    */
    function upgradeTo(string _contractName, string _version, address _impl) public {
        require(msg.sender == address(registry));
        require(_impl != address(0));
        _implementation = _impl;
    }

}