/**
 * Copyright (c) 2018 blockimmo AG license@blockimmo.ch
 * Non-Profit Open Software License 3.0 (NPOSL-3.0)
 * https://opensource.org/licenses/NPOSL-3.0
 */


pragma solidity 0.4.25;


/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
contract Ownable {
  address public owner;


  event OwnershipRenounced(address indexed previousOwner);
  event OwnershipTransferred(
    address indexed previousOwner,
    address indexed newOwner
  );


  /**
   * @dev The Ownable constructor sets the original `owner` of the contract to the sender
   * account.
   */
  constructor() public {
    owner = msg.sender;
  }

  /**
   * @dev Throws if called by any account other than the owner.
   */
  modifier onlyOwner() {
    require(msg.sender == owner);
    _;
  }

  /**
   * @dev Allows the current owner to relinquish control of the contract.
   * @notice Renouncing to ownership will leave the contract without an owner.
   * It will not be possible to call the functions with the `onlyOwner`
   * modifier anymore.
   */
  function renounceOwnership() public onlyOwner {
    emit OwnershipRenounced(owner);
    owner = address(0);
  }

  /**
   * @dev Allows the current owner to transfer control of the contract to a newOwner.
   * @param _newOwner The address to transfer ownership to.
   */
  function transferOwnership(address _newOwner) public onlyOwner {
    _transferOwnership(_newOwner);
  }

  /**
   * @dev Transfers control of the contract to a newOwner.
   * @param _newOwner The address to transfer ownership to.
   */
  function _transferOwnership(address _newOwner) internal {
    require(_newOwner != address(0));
    emit OwnershipTransferred(owner, _newOwner);
    owner = _newOwner;
  }
}


/**
 * @title Claimable
 * @dev Extension for the Ownable contract, where the ownership needs to be claimed.
 * This allows the new owner to accept the transfer.
 */
contract Claimable is Ownable {
  address public pendingOwner;

  /**
   * @dev Modifier throws if called by any account other than the pendingOwner.
   */
  modifier onlyPendingOwner() {
    require(msg.sender == pendingOwner);
    _;
  }

  /**
   * @dev Allows the current owner to set the pendingOwner address.
   * @param newOwner The address to transfer ownership to.
   */
  function transferOwnership(address newOwner) public onlyOwner {
    pendingOwner = newOwner;
  }

  /**
   * @dev Allows the pendingOwner address to finalize the transfer.
   */
  function claimOwnership() public onlyPendingOwner {
    emit OwnershipTransferred(owner, pendingOwner);
    owner = pendingOwner;
    pendingOwner = address(0);
  }
}

/**
 * @title LandRegistryProxy
 * @dev Points to `LandRegistry`, enabling it to be upgraded if absolutely necessary.
 *
 * Contracts reference `this.landRegistry` to locate `LandRegistry`.
 * They also reference `owner` to identify blockimmo's 'administrator' (currently blockimmo but ownership may be transferred to a
 * contract / DAO in the near-future, or even rescinded).
 *
 * `TokenizedProperty` references `this` to enforce the `LandRegistry` and route blockimmo's 1% transaction fee on dividend payouts.
 * `ShareholderDAO` references `this` to allow blockimmo's 'administrator' to extend proposals for any `TokenizedProperty`.
 * `TokenSale` references `this` to route blockimmo's 1% transaction fee on sales.
 *
 * For now this centralized 'administrator' provides an extra layer of control / security until our contracts are time and battle tested.
 *
 * This contract is never intended to be upgraded.
 */
contract LandRegistryProxy is Claimable {
  address public landRegistry;

  event Set(address indexed landRegistry);

  function set(address _landRegistry) public onlyOwner {
    landRegistry = _landRegistry;
    emit Set(landRegistry);
  }
}