// File: /contracts/D4APRB.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.8.10;
import "@openzeppelin/contracts/access/Ownable.sol";
import "./interface/ID4APRB.sol";

contract D4APRB is Ownable, ID4APRB{
  uint256 public start_block;
  uint256 public period_block;
  constructor(uint256 _start_block, uint256 _period_block){
    start_block = _start_block;
    period_block = _period_block;
  }

  event D4APRBChangeStartBlock(uint256 old_start_block, uint256 new_start_block);
  function changeStartBlock(uint256 _start_block) public onlyOwner{
    emit D4APRBChangeStartBlock(start_block, _start_block);
    start_block = _start_block;
  }

  event D4APRBChangePeriodBlock(uint256 old_period_block, uint256 new_period_block);
  function changePeriodBlock(uint256 _period_block) public onlyOwner{
    emit D4APRBChangePeriodBlock(period_block, _period_block);
    period_block = _period_block;
  }

  function isStart() public view returns(bool){
    return block.number >=start_block;
  }

  function currentRound() public view returns(uint256){
    return (block.number - start_block)/period_block;
  }

}

// File: /contracts/interface/ID4APRB.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.8.10;

interface ID4APRB{
  function isStart() external view returns(bool);
  function currentRound() external view returns(uint256);
}

// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// File: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}