// SPDX-License-Identifier: MIT
pragma solidity >=0.7.6 <0.9;

interface IFtso {
    enum PriceFinalizationType {
        // initial state
        NOT_FINALIZED,
        // median calculation used to find price
        WEIGHTED_MEDIAN,
        // low turnout - price calculated from median of trusted addresses
        TRUSTED_ADDRESSES,
        // low turnout + no votes from trusted addresses - price copied from previous epoch
        PREVIOUS_PRICE_COPIED,
        // price calculated from median of trusted addresses - triggered due to an exception
        TRUSTED_ADDRESSES_EXCEPTION,
        // previous price copied - triggered due to an exception
        PREVIOUS_PRICE_COPIED_EXCEPTION
    }

    event PriceRevealed(
        address indexed voter,
        uint256 indexed epochId,
        uint256 price,
        uint256 timestamp,
        uint256 votePowerNat,
        uint256 votePowerAsset
    );

    event PriceFinalized(
        uint256 indexed epochId,
        uint256 price,
        bool rewardedFtso,
        uint256 lowIQRRewardPrice,
        uint256 highIQRRewardPrice,
        uint256 lowElasticBandRewardPrice,
        uint256 highElasticBandRewardPrice,
        PriceFinalizationType finalizationType,
        uint256 timestamp
    );

    event PriceEpochInitializedOnFtso(
        uint256 indexed epochId,
        uint256 endTime,
        uint256 timestamp
    );

    event LowTurnout(
        uint256 indexed epochId,
        uint256 natTurnout,
        uint256 lowNatTurnoutThresholdBIPS,
        uint256 timestamp
    );

    /**
     * @notice Returns if FTSO is active
     */
    function active() external view returns (bool);

    /**
     * @notice Returns the FTSO symbol
     */
    function symbol() external view returns (string memory);

    /**
     * @notice Returns current epoch id
     */
    function getCurrentEpochId() external view returns (uint256);

    /**
     * @notice Returns id of the epoch which was opened for price submission at the specified timestamp
     * @param _timestamp            Timestamp as seconds from unix epoch
     */
    function getEpochId(uint256 _timestamp) external view returns (uint256);

    /**
     * @notice Returns random number of the specified epoch
     * @param _epochId              Id of the epoch
     */
    function getRandom(uint256 _epochId) external view returns (uint256);

    /**
     * @notice Returns asset price consented in specific epoch
     * @param _epochId              Id of the epoch
     * @return Price in USD multiplied by ASSET_PRICE_USD_DECIMALS
     */
    function getEpochPrice(uint256 _epochId) external view returns (uint256);

    /**
     * @notice Returns current epoch data
     * @return _epochId                 Current epoch id
     * @return _epochSubmitEndTime      End time of the current epoch price submission as seconds from unix epoch
     * @return _epochRevealEndTime      End time of the current epoch price reveal as seconds from unix epoch
     * @return _votePowerBlock          Vote power block for the current epoch
     * @return _fallbackMode            Current epoch in fallback mode - only votes from trusted addresses will be used
     * @dev half-closed intervals - end time not included
     */
    function getPriceEpochData()
        external
        view
        returns (
            uint256 _epochId,
            uint256 _epochSubmitEndTime,
            uint256 _epochRevealEndTime,
            uint256 _votePowerBlock,
            bool _fallbackMode
        );

    /**
     * @notice Returns current epoch data
     * @return _firstEpochStartTs           First epoch start timestamp
     * @return _submitPeriodSeconds         Submit period in seconds
     * @return _revealPeriodSeconds         Reveal period in seconds
     */
    function getPriceEpochConfiguration()
        external
        view
        returns (
            uint256 _firstEpochStartTs,
            uint256 _submitPeriodSeconds,
            uint256 _revealPeriodSeconds
        );

    /**
     * @notice Returns asset price submitted by voter in specific epoch
     * @param _epochId              Id of the epoch
     * @param _voter                Address of the voter
     * @return Price in USD multiplied by ASSET_PRICE_USD_DECIMALS
     */
    function getEpochPriceForVoter(
        uint256 _epochId,
        address _voter
    ) external view returns (uint256);

    /**
     * @notice Returns current asset price
     * @return _price               Price in USD multiplied by ASSET_PRICE_USD_DECIMALS
     * @return _timestamp           Time when price was updated for the last time
     */
    function getCurrentPrice()
        external
        view
        returns (uint256 _price, uint256 _timestamp);

    /**
     * @notice Returns current asset price and number of decimals
     * @return _price                   Price in USD multiplied by ASSET_PRICE_USD_DECIMALS
     * @return _timestamp               Time when price was updated for the last time
     * @return _assetPriceUsdDecimals   Number of decimals used for USD price
     */
    function getCurrentPriceWithDecimals()
        external
        view
        returns (
            uint256 _price,
            uint256 _timestamp,
            uint256 _assetPriceUsdDecimals
        );

    /**
     * @notice Returns current asset price calculated from trusted providers
     * @return _price               Price in USD multiplied by ASSET_PRICE_USD_DECIMALS
     * @return _timestamp           Time when price was updated for the last time
     */
    function getCurrentPriceFromTrustedProviders()
        external
        view
        returns (uint256 _price, uint256 _timestamp);

    /**
     * @notice Returns current asset price calculated from trusted providers and number of decimals
     * @return _price                   Price in USD multiplied by ASSET_PRICE_USD_DECIMALS
     * @return _timestamp               Time when price was updated for the last time
     * @return _assetPriceUsdDecimals   Number of decimals used for USD price
     */
    function getCurrentPriceWithDecimalsFromTrustedProviders()
        external
        view
        returns (
            uint256 _price,
            uint256 _timestamp,
            uint256 _assetPriceUsdDecimals
        );

    /**
     * @notice Returns current asset price details
     * @return _price                                   Price in USD multiplied by ASSET_PRICE_USD_DECIMALS
     * @return _priceTimestamp                          Time when price was updated for the last time
     * @return _priceFinalizationType                   Finalization type when price was updated for the last time
     * @return _lastPriceEpochFinalizationTimestamp     Time when last price epoch was finalized
     * @return _lastPriceEpochFinalizationType          Finalization type of last finalized price epoch
     */
    function getCurrentPriceDetails()
        external
        view
        returns (
            uint256 _price,
            uint256 _priceTimestamp,
            PriceFinalizationType _priceFinalizationType,
            uint256 _lastPriceEpochFinalizationTimestamp,
            PriceFinalizationType _lastPriceEpochFinalizationType
        );

    /**
     * @notice Returns current random number
     */
    function getCurrentRandom() external view returns (uint256);
}