// File: @openzeppelin/contracts/access/Ownable.sol



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

pragma solidity ^0.8.0;

import "../utils/Context.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 Ownable is Context {
    address private _owner;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _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);
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool);
}

// File: @openzeppelin/contracts/utils/Context.sol



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

pragma solidity ^0.8.0;

/**
 * @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 Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

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

// File: contracts/interfaces/IBasePriceOracle.sol



// SPDX-License-Identifier: Apache-2.0
pragma solidity 0.8.17;

interface IBasePriceOracle {
    event AssetStatusSet(address indexed baseAsset, bool indexed isEnabled);

    function supportsAsset(address, address) external view returns (bool);

    function getPrice(address, address) external view returns (bool, uint256);

    function setAssetStatus(address, bool) external;
}

// File: contracts/interfaces/IOracleManager.sol



// SPDX-License-Identifier: Apache-2.0
pragma solidity 0.8.17;

import "./IBasePriceOracle.sol";

interface IOracleManager {
    event SetOracles(address indexed _emitter, IBasePriceOracle[] _oracles);

    function setOracles(IBasePriceOracle[] memory) external;

    function getPrice(address) external view returns (uint256);

    function getOracles() external view returns (IBasePriceOracle[] memory);
}

// File: contracts/OracleManager.sol



// SPDX-License-Identifier: Apache-2.0
pragma solidity 0.8.17;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "./interfaces/IBasePriceOracle.sol";
import "./interfaces/IOracleManager.sol";

/**
 * @title OracleManager
 * @author LombardFi
 * @notice The Oracle Manager stores oracle implementations.
 * @dev External contracts can call `getPrice` to get the price of an asset.
 */
contract OracleManager is IOracleManager, Ownable {
    /**
     * @notice Active oracle implementations.
     * @dev Stored in priority order.
     */
    IBasePriceOracle[] public oracles;

    /**
     * @notice The number of active oracle implementations.
     */
    uint256 public numOracles;

    /**
     * @notice The ERC20 in which the price is quoted.
     */
    address public immutable quoteAsset;

    /**
     * @notice The minimum number of supported oracles.
     */
    uint256 public constant MIN_SUPPORTED_ORACLES = 1;

    /**
     * @notice The maximum number of supported oracles.
     */
    uint256 public constant MAX_SUPPORTED_ORACLES = 10;

    /**
     * @notice Sets the ERC20 in which the price is quoted.
     * @param _quoteAsset the address of the quote token.
     */
    constructor(address _quoteAsset) {
        require(
            _quoteAsset != address(0),
            "OracleManager::invalid quote asset"
        );
        quoteAsset = _quoteAsset;
    }

    /**
     * @notice Returns the price of the asset quoted in terms of the base asset.
     * @dev Iterates through `oracles` in order, and calls `IBasePriceOracle.getPrice()` if the oracle supports the asset.
     * Reverts if no oracle supports by asset.
     * @param _asset the address of the asset to quote.
     * @return The price of the asset in wad.
     */
    function getPrice(address _asset) external view returns (uint256) {
        // Base case
        address _quoteAsset = quoteAsset;
        if (_asset == _quoteAsset) {
            return 1e18;
        }

        // Iterate oracles ranked by priority
        uint256 _numOracles = numOracles;
        for (uint256 i = 0; i < _numOracles; ) {
            IBasePriceOracle oracle = oracles[i];

            // If the implementation supports the asset, use the oracle to get the price
            if (oracle.supportsAsset(_asset, _quoteAsset)) {
                (bool success, uint256 price) = oracle.getPrice(
                    _asset,
                    _quoteAsset
                );

                if (success) {
                    return price;
                }
            }

            unchecked {
                ++i;
            }
        }
        // If no oracle supports the asset, revert
        revert("OracleManager::not supported");
    }

    /**
     * @notice Sets the oracle implementations.
     * @dev First it zeroes out the `oracles` array in storage.
     * It copies elements from `_oracles` then updates `numOracles`.
     * 10 >= number of oracles > 0.
     * Can be called only by the owner.
     * @param _oracles an array of `IBasePriceOracle` implementations.
     */
    function setOracles(IBasePriceOracle[] memory _oracles) external onlyOwner {
        uint256 updatedNumOracles = _oracles.length;
        require(
            updatedNumOracles >= MIN_SUPPORTED_ORACLES,
            "OracleManager::too few oracles"
        );
        require(
            updatedNumOracles <= MAX_SUPPORTED_ORACLES,
            "OracleManager::too many oracles"
        );

        // Delete old storage
        // This loop is not required but is good for data sanity
        uint256 oldNumOracles = numOracles;
        for (uint256 i = 0; i < oldNumOracles; ) {
            // `pop()` removes the element and decrements the length
            oracles.pop();

            unchecked {
                ++i;
            }
        }

        // Now that the entire `oracles` array is zeroed out
        // Write the new implementations
        for (uint256 i = 0; i < updatedNumOracles; ) {
            require(
                address(_oracles[i]) != address(0),
                "OracleManager::zero address"
            );
            oracles.push(_oracles[i]);

            unchecked {
                ++i;
            }
        }

        // Update the number of oracles.
        numOracles = updatedNumOracles;

        emit SetOracles(msg.sender, _oracles);
    }

    /**
     * @notice Retrieves the oracle implementations.
     * @dev Used for off-chain data retrieval.
     * @return _oracles The current active oracle implementations in iteration order.
     */
    function getOracles()
        external
        view
        returns (IBasePriceOracle[] memory _oracles)
    {
        return oracles;
    }
}