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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (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. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling 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);
    }
}

// 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: contracts/libraries/Burner.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "@openzeppelin/contracts/access/Ownable.sol";

contract Burner is Ownable {
  uint[] public dates;
  bool public started = false;
  bool public finalized = false;
  uint public burnStep = 0;
  uint public totalBurn = 0;
  uint public months = 0;

  event BurnTimestampsUpdated();
  event BurnStepUpdated();
  event MonthsUpdated();
  event DatesUpdated();
  event Started();
  event Finalized();

  error AlreadyStarted();

  constructor(uint[] memory _dates, uint _burnStep, uint _months) {
    dates = _dates;
    burnStep = _burnStep;
    totalBurn = _burnStep * _months;
  }

  /* @dev: Allows updating each burn step */
  function updateBurnStep(uint _burnStep) external onlyOwner {
    burnStep = _burnStep;
    emit BurnStepUpdated();
  }

  /* @dev: Allows updating of total months */
  function updateMonths(uint _months) external onlyOwner {
    months = _months;
    emit MonthsUpdated();
  }

  /* @dev: Allows updating the given dates for the loop */
  function updateDates(uint[] memory _dates) external onlyOwner {
    dates = _dates;
    emit DatesUpdated();
  }

  /* @dev: Returns the total burned amount, used to alter totalSupply() */
  function getTotalBurned() public view returns (uint) {
    if (!started) return 0;
    if (finalized) return totalBurn;
    uint i = 0;
    /* Increment burn by each step for a maximum of 12 months */
    unchecked {
      while (block.timestamp >= dates[i] && i <= (months - 1)) {
        i++;
      }
    }
    /* Calculate total burned one time to save gas */
    uint burned = burnStep * i;
    return burned < totalBurn ? burned : totalBurn;
  }

  /* @dev: Update whether burn has started */
  function updateStarted() external onlyOwner {
    if (started) revert AlreadyStarted();
    started = true;
    emit Started();
  }

  /* @dev: Finalize burn */
  function finalize() external onlyOwner {
    finalized = true;
    emit Finalized();
  }
}