// SPDX-License-Identifier: MIT
pragma solidity 0.8.26;

/// @title HYPE/USD price for Ambrosia mints
/// @notice Elysium has no trusted feed yet. Two fixed feeders post the median of several venues.
///         The contract bounds how fast and how far they can move it, and refuses stale prices.
///         Price has 8 decimals (73.12 USD = 7_312_000_000).
contract HypeUsdOracle {
    uint256 public constant MAX_MOVE_BPS = 500; // 5% per update
    uint256 public constant MIN_INTERVAL = 60;
    uint256 public constant MAX_AGE = 15 minutes;
    uint256 public constant FLOOR = 5e8; // $5
    uint256 public constant CEIL = 500e8; // $500

    address public immutable feederA;
    address public immutable feederB;

    uint128 public price;
    uint64 public updatedAt;

    event Price(uint256 price, uint256 at, address feeder);

    error NotFeeder();
    error TooSoon();
    error OutOfBand();
    error MoveTooLarge();
    error StalePrice();

    constructor(address a, address b, uint256 initialPrice) {
        if (initialPrice < FLOOR || initialPrice > CEIL) revert OutOfBand();
        feederA = a;
        feederB = b;
        price = uint128(initialPrice);
        updatedAt = uint64(block.timestamp);
        emit Price(initialPrice, block.timestamp, msg.sender);
    }

    function post(uint256 p) external {
        if (msg.sender != feederA && msg.sender != feederB) revert NotFeeder();
        if (block.timestamp < updatedAt + MIN_INTERVAL) revert TooSoon();
        if (p < FLOOR || p > CEIL) revert OutOfBand();
        uint256 last = price;
        uint256 diff = p > last ? p - last : last - p;
        if (diff * 10_000 > last * MAX_MOVE_BPS) revert MoveTooLarge();
        price = uint128(p);
        updatedAt = uint64(block.timestamp);
        emit Price(p, block.timestamp, msg.sender);
    }

    /// @notice Reverts when the last update is older than 15 minutes.
    function fresh() external view returns (uint256) {
        if (block.timestamp > updatedAt + MAX_AGE) revert StalePrice();
        return price;
    }
}