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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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 () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        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 {
        emit OwnershipTransferred(_owner, address(0));
        _owner = 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");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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 GSN 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 payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: contracts/Registry.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "@openzeppelin/contracts/access/Ownable.sol";

contract Registry is Ownable {
    // Map asset addresses to indexes.
    mapping(address => uint32) public assetAddressToIndex;
    mapping(uint32 => address) public assetIndexToAddress;
    uint32 numAssets = 0;

    // Valid strategies.
    mapping(address => uint32) public strategyAddressToIndex;
    mapping(uint32 => address) public strategyIndexToAddress;
    uint32 numStrategies = 0;

    event AssetRegistered(address asset, uint32 assetId);
    event StrategyRegistered(address strategy, uint32 strategyId);
    event StrategyUpdated(address previousStrategy, address newStrategy, uint32 strategyId);

    /**
     * @notice Register a asset
     * @param _asset The asset token address;
     */
    function registerAsset(address _asset) external onlyOwner {
        require(_asset != address(0), "Invalid asset");
        require(assetAddressToIndex[_asset] == 0, "Asset already registered");

        // Register asset with an index >= 1 (zero is reserved).
        numAssets++;
        assetAddressToIndex[_asset] = numAssets;
        assetIndexToAddress[numAssets] = _asset;

        emit AssetRegistered(_asset, numAssets);
    }

    /**
     * @notice Register a strategy
     * @param _strategy The strategy contract address;
     */
    function registerStrategy(address _strategy) external onlyOwner {
        require(_strategy != address(0), "Invalid strategy");
        require(strategyAddressToIndex[_strategy] == 0, "Strategy already registered");

        // Register strategy with an index >= 1 (zero is reserved).
        numStrategies++;
        strategyAddressToIndex[_strategy] = numStrategies;
        strategyIndexToAddress[numStrategies] = _strategy;

        emit StrategyRegistered(_strategy, numStrategies);
    }

    /**
     * @notice Update the address of an existing strategy
     * @param _strategy The strategy contract address;
     * @param _strategyId The strategy ID;
     */
    function updateStrategy(address _strategy, uint32 _strategyId) external onlyOwner {
        require(_strategy != address(0), "Invalid strategy");
        require(strategyIndexToAddress[_strategyId] != address(0), "Strategy doesn't exist");

        address previousStrategy = strategyIndexToAddress[_strategyId];
        strategyAddressToIndex[previousStrategy] = 0;
        strategyAddressToIndex[_strategy] = _strategyId;
        strategyIndexToAddress[_strategyId] = _strategy;

        emit StrategyUpdated(previousStrategy, _strategy, _strategyId);
    }
}