// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.0;

import "./PythStructs.sol";
import "./IPyth.sol";
import "./PythErrors.sol";

abstract contract AbstractPyth is IPyth {
    /// @notice Returns the price feed with given id.
    /// @dev Reverts if the price does not exist.
    /// @param id The Pyth Price Feed ID of which to fetch the PriceFeed.
    function queryPriceFeed(
        bytes32 id
    ) public view virtual returns (PythStructs.PriceFeed memory priceFeed);

    /// @notice Returns true if a price feed with the given id exists.
    /// @param id The Pyth Price Feed ID of which to check its existence.
    function priceFeedExists(
        bytes32 id
    ) public view virtual returns (bool exists);

    function getValidTimePeriod()
        public
        view
        virtual
        override
        returns (uint validTimePeriod);

    function getPrice(
        bytes32 id
    ) external view virtual override returns (PythStructs.Price memory price) {
        return getPriceNoOlderThan(id, getValidTimePeriod());
    }

    function getEmaPrice(
        bytes32 id
    ) external view virtual override returns (PythStructs.Price memory price) {
        return getEmaPriceNoOlderThan(id, getValidTimePeriod());
    }

    function getPriceUnsafe(
        bytes32 id
    ) public view virtual override returns (PythStructs.Price memory price) {
        PythStructs.PriceFeed memory priceFeed = queryPriceFeed(id);
        return priceFeed.price;
    }

    function getPriceNoOlderThan(
        bytes32 id,
        uint age
    ) public view virtual override returns (PythStructs.Price memory price) {
        price = getPriceUnsafe(id);

        if (diff(block.timestamp, price.publishTime) > age)
            revert PythErrors.StalePrice();

        return price;
    }

    function getEmaPriceUnsafe(
        bytes32 id
    ) public view virtual override returns (PythStructs.Price memory price) {
        PythStructs.PriceFeed memory priceFeed = queryPriceFeed(id);
        return priceFeed.emaPrice;
    }

    function getEmaPriceNoOlderThan(
        bytes32 id,
        uint age
    ) public view virtual override returns (PythStructs.Price memory price) {
        price = getEmaPriceUnsafe(id);

        if (diff(block.timestamp, price.publishTime) > age)
            revert PythErrors.StalePrice();

        return price;
    }

    function diff(uint x, uint y) internal pure returns (uint) {
        if (x > y) {
            return x - y;
        } else {
            return y - x;
        }
    }

    // Access modifier is overridden to public to be able to call it locally.
    function updatePriceFeeds(
        bytes[] calldata updateData
    ) public payable virtual override;

    function updatePriceFeedsIfNecessary(
        bytes[] calldata updateData,
        bytes32[] calldata priceIds,
        uint64[] calldata publishTimes
    ) external payable virtual override {
        if (priceIds.length != publishTimes.length)
            revert PythErrors.InvalidArgument();

        for (uint i = 0; i < priceIds.length; i++) {
            if (
                !priceFeedExists(priceIds[i]) ||
                queryPriceFeed(priceIds[i]).price.publishTime < publishTimes[i]
            ) {
                updatePriceFeeds(updateData);
                return;
            }
        }

        revert PythErrors.NoFreshUpdate();
    }

    function parsePriceFeedUpdates(
        bytes[] calldata updateData,
        bytes32[] calldata priceIds,
        uint64 minPublishTime,
        uint64 maxPublishTime
    )
        external
        payable
        virtual
        override
        returns (PythStructs.PriceFeed[] memory priceFeeds);
}