// File: @chainlink/contracts/src/v0.6/interfaces/AggregatorV3Interface.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0;

interface AggregatorV3Interface {

  function decimals() external view returns (uint8);
  function description() external view returns (string memory);
  function version() external view returns (uint256);

  // getRoundData and latestRoundData should both raise "No data present"
  // if they do not have data to report, instead of returning unset values
  // which could be misinterpreted as actual reported values.
  function getRoundData(uint80 _roundId)
    external
    view
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    );
  function latestRoundData()
    external
    view
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    );

}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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 GSN 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 payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "../GSN/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 () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        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 {
        emit OwnershipTransferred(_owner, address(0));
        _owner = 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");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: @openzeppelin/contracts/introspection/IERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: contracts/oracles/ChainlinkOracle.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.7.5;

import "@chainlink/contracts/src/v0.6/interfaces/AggregatorV3Interface.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/introspection/IERC165.sol";

/**
 * @title Chainlink Oracle
 * @author Cryptex.finance
 * @notice Contract in charge or reading the information from a Chainlink Oracle. TCAP contracts read the price directly from this contract. More information can be found on Chainlink Documentation
 */
contract ChainlinkOracle is Ownable, IERC165 {
  AggregatorV3Interface internal aggregatorContract;

  /*
   * setReferenceContract.selector ^
   * getLatestAnswer.selector ^
   * getLatestTimestamp.selector ^
   * getPreviousAnswer.selector ^
   * getPreviousTimestamp.selector =>  0x85be402b
   */
  bytes4 private constant _INTERFACE_ID_CHAINLINK_ORACLE = 0x85be402b;

  /*
   * bytes4(keccak256('supportsInterface(bytes4)')) == 0x01ffc9a7
   */
  bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;

  /**
   * @notice Called once the contract is deployed.
   * Set the Chainlink Oracle as an aggregator.
   */
  constructor(address _aggregator) {
    aggregatorContract = AggregatorV3Interface(_aggregator);
  }

  /**
   * @notice Changes the reference contract.
   * @dev Only owner can call it.
   */
  function setReferenceContract(address _aggregator) public onlyOwner() {
    aggregatorContract = AggregatorV3Interface(_aggregator);
  }

  /**
   * @notice Returns the latest answer from the reference contract.
   * @return price
   */
  function getLatestAnswer() public view returns (int256) {
    (
      uint80 roundID,
      int256 price,
      ,
      uint256 timeStamp,
      uint80 answeredInRound
    ) = aggregatorContract.latestRoundData();
    require(
      timeStamp != 0,
      "ChainlinkOracle::getLatestAnswer: round is not complete"
    );
    require(
      answeredInRound >= roundID,
      "ChainlinkOracle::getLatestAnswer: stale data"
    );
    return price;
  }

  /**
   * @notice Returns the latest round from the reference contract.
   */
  function getLatestRound()
    public
    view
    returns (
      uint80,
      int256,
      uint256,
      uint256,
      uint80
    )
  {
    (
      uint80 roundID,
      int256 price,
      uint256 startedAt,
      uint256 timeStamp,
      uint80 answeredInRound
    ) = aggregatorContract.latestRoundData();

    return (roundID, price, startedAt, timeStamp, answeredInRound);
  }

  /**
   * @notice Returns a given round from the reference contract.
   * @param _id of round
   */
  function getRound(uint80 _id)
    public
    view
    returns (
      uint80,
      int256,
      uint256,
      uint256,
      uint80
    )
  {
    (
      uint80 roundID,
      int256 price,
      uint256 startedAt,
      uint256 timeStamp,
      uint80 answeredInRound
    ) = aggregatorContract.getRoundData(_id);

    return (roundID, price, startedAt, timeStamp, answeredInRound);
  }

  /**
   * @notice Returns the last time the Oracle was updated.
   */
  function getLatestTimestamp() public view returns (uint256) {
    (, , , uint256 timeStamp, ) = aggregatorContract.latestRoundData();
    return timeStamp;
  }

  /**
   * @notice Returns a previous answer updated on the Oracle.
   * @param _id of round
   * @return price
   */
  function getPreviousAnswer(uint80 _id) public view returns (int256) {
    (uint80 roundID, int256 price, , , ) = aggregatorContract.getRoundData(_id);
    require(
      _id <= roundID,
      "ChainlinkOracle::getPreviousAnswer: not enough history"
    );
    return price;
  }

  /**
   * @notice Returns a previous time the Oracle was updated.
   * @param _id of round
   * @return timeStamp
   */
  function getPreviousTimestamp(uint80 _id) public view returns (uint256) {
    (uint80 roundID, , , uint256 timeStamp, ) =
      aggregatorContract.getRoundData(_id);
    require(
      _id <= roundID,
      "ChainlinkOracle::getPreviousTimestamp: not enough history"
    );
    return timeStamp;
  }

  /**
   * @notice ERC165 Standard for support of interfaces.
   */
  function supportsInterface(bytes4 interfaceId)
    external
    pure
    override
    returns (bool)
  {
    return (interfaceId == _INTERFACE_ID_CHAINLINK_ORACLE ||
      interfaceId == _INTERFACE_ID_ERC165);
  }
}