// SPDX-License-Identifier: MIT
pragma solidity 0.6.6;

import "./interfaces/AggregatorV2V3Interface.sol";

/**
 * @title A facade forAggregator versions to conform to the new v0.6
 * Aggregator V3 interface.
 */
contract AggregatorFacade is AggregatorV2V3Interface {

  AggregatorInterface public aggregator;
  uint8 public override decimals;
  string public override description;

  uint256 constant public override version = 2;

  // An error specific to the Aggregator V3 Interface, to prevent possible
  // confusion around accidentally reading unset values as reported values.
  string constant private V3_NO_DATA_ERROR = "No data present";

  constructor(
    address _aggregator,
    uint8 _decimals,
    string memory _description
  ) public {
    aggregator = AggregatorInterface(_aggregator);
    decimals = _decimals;
    description = _description;
  }

  /**
   * @notice get the latest completed round where the answer was updated
   * @dev #[deprecated]. Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestRound()
    external
    view
    virtual
    override
    returns (uint256)
  {
    return aggregator.latestRound();
  }

  /**
   * @notice Reads the current answer from aggregator delegated to.
   *
   * @dev #[deprecated] Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestAnswer()
    external
    view
    virtual
    override
    returns (int256)
  {
    return aggregator.latestAnswer();
  }

  /**
   * @notice Reads the last updated height from aggregator delegated to.
   *
   * @dev #[deprecated] Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestTimestamp()
    external
    view
    virtual
    override
    returns (uint256)
  {
    return aggregator.latestTimestamp();
  }

  /**
   * @notice get data about the latest round. Consumers are encouraged to check
   * that they're receiving fresh data by inspecting the updatedAt value.
   * @return roundId is the round ID for which data was retrieved
   * @return answer is the answer for the given round
   * @return startedAt is always equal to updatedAt because the underlying
   * Aggregator contract does not expose this information.
   * @return updatedAt is the timestamp when the round last was updated (i.e.
   * answer was last computed)
   * @return answeredInRound is always equal to roundId because the underlying
   * Aggregator contract does not expose this information.
   * @dev Note that for rounds that haven't yet received responses from all
   * oracles, answer and updatedAt may change between queries.
   */
  function latestRoundData()
    external
    view
    virtual
    override
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    return _getRoundData(uint80(aggregator.latestRound()));
  }

  /**
   * @notice get past rounds answers
   * @param _roundId the answer number to retrieve the answer for
   *
   * @dev #[deprecated] Use getRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended getRoundData
   * instead which includes better verification information.
   */
  function getAnswer(uint256 _roundId)
    external
    view
    virtual
    override
    returns (int256)
  {
    return aggregator.getAnswer(_roundId);
  }

  /**
   * @notice get block timestamp when an answer was last updated
   * @param _roundId the answer number to retrieve the updated timestamp for
   *
   * @dev #[deprecated] Use getRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended getRoundData
   * instead which includes better verification information.
   */
  function getTimestamp(uint256 _roundId)
    external
    view
    virtual
    override
    returns (uint256)
  {
    return aggregator.getTimestamp(_roundId);
  }

  /**
   * @notice get data about a round. Consumers are encouraged to check
   * that they're receiving fresh data by inspecting the updatedAt value.
   * @param _roundId the round ID to retrieve the round data for
   * @return roundId is the round ID for which data was retrieved
   * @return answer is the answer for the given round
   * @return startedAt is always equal to updatedAt because the underlying
   * Aggregator contract does not expose this information.
   * @return updatedAt is the timestamp when the round last was updated (i.e.
   * answer was last computed)
   * @return answeredInRound is always equal to roundId because the underlying
   * Aggregator contract does not expose this information.
   * @dev Note that for rounds that haven't yet received responses from all
   * oracles, answer and updatedAt may change between queries.
   */
  function getRoundData(uint80 _roundId)
    external
    view
    virtual
    override
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    return _getRoundData(_roundId);
  }


  /*
   * Internal
   */

  function _getRoundData(uint80 _roundId)
    internal
    view
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    answer = aggregator.getAnswer(_roundId);
    updatedAt = uint64(aggregator.getTimestamp(_roundId));

    require(updatedAt > 0, V3_NO_DATA_ERROR);

    return (_roundId, answer, updatedAt, updatedAt, _roundId);
  }

}