// File: contracts/MedianOracle.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity 0.8.4;

import {OwnableUpgradeable} from "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import "./lib/Select.sol";

interface IOracle {
    function getData() external returns (uint256, bool);
}

/**
 * @title Median Oracle
 *
 * @notice Provides a value onchain that's aggregated from a whitelisted set of
 *         providers.
 */
contract MedianOracle is OwnableUpgradeable, IOracle {
    struct Report {
        uint256 timestamp;
        uint256 payload;
    }

    // Addresses of providers authorized to push reports.
    address[] public providers;

    // Reports indexed by provider address. Report[0].timestamp > 0
    // indicates provider existence.
    mapping(address => Report[2]) public providerReports;

    event ProviderAdded(address provider);
    event ProviderRemoved(address provider);
    event ReportTimestampOutOfRange(address provider);
    event ProviderReportPushed(address indexed provider, uint256 payload, uint256 timestamp);

    // The number of seconds after which the report is deemed expired.
    uint256 public reportExpirationTimeSec;

    // The number of seconds since reporting that has to pass before a report
    // is usable.
    uint256 public reportDelaySec;

    // The minimum number of providers with valid reports to consider the
    // aggregate report valid.
    uint256 public minimumProviders = 1;

    // Timestamp of 1 is used to mark uninitialized and invalidated data.
    // This is needed so that timestamp of 1 is always considered expired.
    uint256 private constant MAX_REPORT_EXPIRATION_TIME = 520 weeks;

    /**
     * @notice Contract state initialization.
     *
     * @param reportExpirationTimeSec_ The number of seconds after which the
     *                                 report is deemed expired.
     * @param reportDelaySec_ The number of seconds since reporting that has to
     *                        pass before a report is usable
     * @param minimumProviders_ The minimum number of providers with valid
     *                          reports to consider the aggregate report valid.
     */
    function init(
        uint256 reportExpirationTimeSec_,
        uint256 reportDelaySec_,
        uint256 minimumProviders_
    ) public initializer {
        require(reportExpirationTimeSec_ <= MAX_REPORT_EXPIRATION_TIME);
        require(minimumProviders_ > 0);
        reportExpirationTimeSec = reportExpirationTimeSec_;
        reportDelaySec = reportDelaySec_;
        minimumProviders = minimumProviders_;
        __Ownable_init();
    }

    /**
     * @notice Sets the report expiration period.
     * @param reportExpirationTimeSec_ The number of seconds after which the
     *        report is deemed expired.
     */
    function setReportExpirationTimeSec(uint256 reportExpirationTimeSec_) external onlyOwner {
        require(reportExpirationTimeSec_ <= MAX_REPORT_EXPIRATION_TIME);
        reportExpirationTimeSec = reportExpirationTimeSec_;
    }

    /**
     * @notice Sets the time period since reporting that has to pass before a
     *         report is usable.
     * @param reportDelaySec_ The new delay period in seconds.
     */
    function setReportDelaySec(uint256 reportDelaySec_) external onlyOwner {
        reportDelaySec = reportDelaySec_;
    }

    /**
     * @notice Sets the minimum number of providers with valid reports to
     *         consider the aggregate report valid.
     * @param minimumProviders_ The new minimum number of providers.
     */
    function setMinimumProviders(uint256 minimumProviders_) external onlyOwner {
        require(minimumProviders_ > 0);
        minimumProviders = minimumProviders_;
    }

    /**
     * @notice Pushes a report for the calling provider.
     * @param payload is expected to be 18 decimal fixed point number.
     */
    function pushReport(uint256 payload) external {
        address providerAddress = msg.sender;
        Report[2] storage reports = providerReports[providerAddress];
        uint256[2] memory timestamps = [reports[0].timestamp, reports[1].timestamp];

        require(timestamps[0] > 0);

        uint8 index_recent = timestamps[0] >= timestamps[1] ? 0 : 1;
        uint8 index_past = 1 - index_recent;

        // Check that the push is not too soon after the last one.
        require(timestamps[index_recent] + reportDelaySec <= block.timestamp);

        reports[index_past].timestamp = block.timestamp;
        reports[index_past].payload = payload;

        emit ProviderReportPushed(providerAddress, payload, block.timestamp);
    }

    /**
     * @notice Invalidates the reports of the calling provider.
     */
    function purgeReports() external {
        address providerAddress = msg.sender;
        require(providerReports[providerAddress][0].timestamp > 0);
        providerReports[providerAddress][0].timestamp = 1;
        providerReports[providerAddress][1].timestamp = 1;
    }

    /**
     * @notice Computes median of provider reports whose timestamps are in the
     *         valid timestamp range.
     * @return AggregatedValue: Median of providers reported values.
     *         valid: Boolean indicating an aggregated value was computed successfully.
     */
    function getData() external override returns (uint256, bool) {
        uint256 reportsCount = providers.length;
        uint256[] memory validReports = new uint256[](reportsCount);
        uint256 size = 0;
        uint256 minValidTimestamp = block.timestamp - reportExpirationTimeSec;
        uint256 maxValidTimestamp = block.timestamp - reportDelaySec;

        for (uint256 i = 0; i < reportsCount; i++) {
            address providerAddress = providers[i];
            Report[2] memory reports = providerReports[providerAddress];

            uint8 index_recent = reports[0].timestamp >= reports[1].timestamp ? 0 : 1;
            uint8 index_past = 1 - index_recent;
            uint256 reportTimestampRecent = reports[index_recent].timestamp;
            if (reportTimestampRecent > maxValidTimestamp) {
                // Recent report is too recent.
                uint256 reportTimestampPast = providerReports[providerAddress][index_past]
                    .timestamp;
                if (reportTimestampPast < minValidTimestamp) {
                    // Past report is too old.
                    emit ReportTimestampOutOfRange(providerAddress);
                } else if (reportTimestampPast > maxValidTimestamp) {
                    // Past report is too recent.
                    emit ReportTimestampOutOfRange(providerAddress);
                } else {
                    // Using past report.
                    validReports[size++] = providerReports[providerAddress][index_past].payload;
                }
            } else {
                // Recent report is not too recent.
                if (reportTimestampRecent < minValidTimestamp) {
                    // Recent report is too old.
                    emit ReportTimestampOutOfRange(providerAddress);
                } else {
                    // Using recent report.
                    validReports[size++] = providerReports[providerAddress][index_recent].payload;
                }
            }
        }

        if (size < minimumProviders) {
            return (0, false);
        }

        return (Select.computeMedian(validReports, size), true);
    }

    /**
     * @notice Authorizes a provider.
     * @param provider Address of the provider.
     */
    function addProvider(address provider) external onlyOwner {
        require(providerReports[provider][0].timestamp == 0);
        providers.push(provider);
        providerReports[provider][0].timestamp = 1;
        emit ProviderAdded(provider);
    }

    /**
     * @notice Revokes provider authorization.
     * @param provider Address of the provider.
     */
    function removeProvider(address provider) external onlyOwner {
        delete providerReports[provider];
        for (uint256 i = 0; i < providers.length; i++) {
            if (providers[i] == provider) {
                if (i + 1 != providers.length) {
                    providers[i] = providers[providers.length - 1];
                }
                providers.pop();
                emit ProviderRemoved(provider);
                break;
            }
        }
    }

    /**
     * @return The number of authorized providers.
     */
    function providersSize() external view returns (uint256) {
        return providers.length;
    }
}

// File: contracts/lib/Select.sol



// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity 0.8.4;

/**
 * @title Select
 * @dev Median Selection Library
 */
library Select {
    /**
     * @dev Sorts the input array up to the denoted size, and returns the median.
     * @param array Input array to compute its median.
     * @param size Number of elements in array to compute the median for.
     * @return Median of array.
     */
    function computeMedian(uint256[] memory array, uint256 size) internal pure returns (uint256) {
        require(size > 0 && array.length >= size);
        for (uint256 i = 1; i < size; i++) {
            for (uint256 j = i; j > 0 && array[j - 1] > array[j]; j--) {
                uint256 tmp = array[j];
                array[j] = array[j - 1];
                array[j - 1] = tmp;
            }
        }
        if (size % 2 == 1) {
            return array[size / 2];
        } else {
            return (array[size / 2] + array[size / 2 - 1]) / 2;
        }
    }
}

// File: @openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/ContextUpgradeable.sol";
import "../proxy/utils/Initializable.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 OwnableUpgradeable is Initializable, ContextUpgradeable {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    function __Ownable_init() internal onlyInitializing {
        __Ownable_init_unchained();
    }

    function __Ownable_init_unchained() internal onlyInitializing {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        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 {
        _transferOwnership(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");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }

    /**
     * @dev This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[49] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/utils/ContextUpgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;
import "../proxy/utils/Initializable.sol";

/**
 * @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 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 ContextUpgradeable is Initializable {
    function __Context_init() internal onlyInitializing {
    }

    function __Context_init_unchained() internal onlyInitializing {
    }
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }

    /**
     * @dev This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[50] private __gap;
}

// File: @openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (proxy/utils/Initializable.sol)

pragma solidity ^0.8.2;

import "../../utils/AddressUpgradeable.sol";

/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since proxied contracts do not make use of a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * The initialization functions use a version number. Once a version number is used, it is consumed and cannot be
 * reused. This mechanism prevents re-execution of each "step" but allows the creation of new initialization steps in
 * case an upgrade adds a module that needs to be initialized.
 *
 * For example:
 *
 * [.hljs-theme-light.nopadding]
 * ```
 * contract MyToken is ERC20Upgradeable {
 *     function initialize() initializer public {
 *         __ERC20_init("MyToken", "MTK");
 *     }
 * }
 * contract MyTokenV2 is MyToken, ERC20PermitUpgradeable {
 *     function initializeV2() reinitializer(2) public {
 *         __ERC20Permit_init("MyToken");
 *     }
 * }
 * ```
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {ERC1967Proxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 *
 * [CAUTION]
 * ====
 * Avoid leaving a contract uninitialized.
 *
 * An uninitialized contract can be taken over by an attacker. This applies to both a proxy and its implementation
 * contract, which may impact the proxy. To prevent the implementation contract from being used, you should invoke
 * the {_disableInitializers} function in the constructor to automatically lock it when it is deployed:
 *
 * [.hljs-theme-light.nopadding]
 * ```
 * /// @custom:oz-upgrades-unsafe-allow constructor
 * constructor() {
 *     _disableInitializers();
 * }
 * ```
 * ====
 */
abstract contract Initializable {
    /**
     * @dev Indicates that the contract has been initialized.
     * @custom:oz-retyped-from bool
     */
    uint8 private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Triggered when the contract has been initialized or reinitialized.
     */
    event Initialized(uint8 version);

    /**
     * @dev A modifier that defines a protected initializer function that can be invoked at most once. In its scope,
     * `onlyInitializing` functions can be used to initialize parent contracts. Equivalent to `reinitializer(1)`.
     */
    modifier initializer() {
        bool isTopLevelCall = !_initializing;
        require(
            (isTopLevelCall && _initialized < 1) || (!AddressUpgradeable.isContract(address(this)) && _initialized == 1),
            "Initializable: contract is already initialized"
        );
        _initialized = 1;
        if (isTopLevelCall) {
            _initializing = true;
        }
        _;
        if (isTopLevelCall) {
            _initializing = false;
            emit Initialized(1);
        }
    }

    /**
     * @dev A modifier that defines a protected reinitializer function that can be invoked at most once, and only if the
     * contract hasn't been initialized to a greater version before. In its scope, `onlyInitializing` functions can be
     * used to initialize parent contracts.
     *
     * `initializer` is equivalent to `reinitializer(1)`, so a reinitializer may be used after the original
     * initialization step. This is essential to configure modules that are added through upgrades and that require
     * initialization.
     *
     * Note that versions can jump in increments greater than 1; this implies that if multiple reinitializers coexist in
     * a contract, executing them in the right order is up to the developer or operator.
     */
    modifier reinitializer(uint8 version) {
        require(!_initializing && _initialized < version, "Initializable: contract is already initialized");
        _initialized = version;
        _initializing = true;
        _;
        _initializing = false;
        emit Initialized(version);
    }

    /**
     * @dev Modifier to protect an initialization function so that it can only be invoked by functions with the
     * {initializer} and {reinitializer} modifiers, directly or indirectly.
     */
    modifier onlyInitializing() {
        require(_initializing, "Initializable: contract is not initializing");
        _;
    }

    /**
     * @dev Locks the contract, preventing any future reinitialization. This cannot be part of an initializer call.
     * Calling this in the constructor of a contract will prevent that contract from being initialized or reinitialized
     * to any version. It is recommended to use this to lock implementation contracts that are designed to be called
     * through proxies.
     */
    function _disableInitializers() internal virtual {
        require(!_initializing, "Initializable: contract is initializing");
        if (_initialized < type(uint8).max) {
            _initialized = type(uint8).max;
            emit Initialized(type(uint8).max);
        }
    }
}

// File: @openzeppelin/contracts-upgradeable/utils/AddressUpgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library AddressUpgradeable {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly
                /// @solidity memory-safe-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}