ClickHouse/dbms/src/Common/XDBCBridgeHelper.h

#pragma once

#include <sstream>
#include <IO/ReadHelpers.h>
#include <IO/ReadWriteBufferFromHTTP.h>
#include <Interpreters/Context.h>
#include <Poco/File.h>
#include <Poco/Logger.h>
#include <Poco/Net/HTTPRequest.h>
#include <Poco/Path.h>
#include <Poco/URI.h>
#include <Poco/Util/AbstractConfiguration.h>
#include <Common/ShellCommand.h>
#include <Common/config.h>
#include <common/logger_useful.h>
#include <ext/range.h>

namespace DB
{
namespace ErrorCodes
{
    extern const int EXTERNAL_EXECUTABLE_NOT_FOUND;
    extern const int EXTERNAL_SERVER_IS_NOT_RESPONDING;
    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
}

/**
 * Class for Helpers for Xdbc-bridges, provide utility methods, not main request
 */
class IXDBCBridgeHelper
{
public:
    static constexpr inline auto DEFAULT_FORMAT = "RowBinary";

    virtual std::vector<std::pair<std::string, std::string>> getURLParams(const std::string & cols, size_t max_block_size) const = 0;
    virtual void startBridgeSync() const = 0;
    virtual Poco::URI getMainURI() const = 0;
    virtual Poco::URI getColumnsInfoURI() const = 0;
    virtual IdentifierQuotingStyle getIdentifierQuotingStyle() = 0;
    virtual String getName() const = 0;

    virtual ~IXDBCBridgeHelper() = default;
};

using BridgeHelperPtr = std::shared_ptr<IXDBCBridgeHelper>;

template <typename BridgeHelperMixin>
class XDBCBridgeHelper : public IXDBCBridgeHelper
{
private:
    Poco::Timespan http_timeout;

    std::string connection_string;

    Poco::URI ping_url;

    Poco::Logger * log = &Poco::Logger::get(BridgeHelperMixin::getName() + "BridgeHelper");

    std::optional<IdentifierQuotingStyle> quote_style;

protected:
    auto getConnectionString() const
    {
        return connection_string;
    }

public:
    using Configuration = Poco::Util::AbstractConfiguration;

    const Configuration & config;

    static constexpr inline auto DEFAULT_HOST = "localhost";
    static constexpr inline auto DEFAULT_PORT = BridgeHelperMixin::DEFAULT_PORT;
    static constexpr inline auto PING_HANDLER = "/ping";
    static constexpr inline auto MAIN_HANDLER = "/";
    static constexpr inline auto COL_INFO_HANDLER = "/columns_info";
    static constexpr inline auto IDENTIFIER_QUOTE_HANDLER = "/identifier_quote";
    static constexpr inline auto PING_OK_ANSWER = "Ok.";

    XDBCBridgeHelper(const Configuration & config_, const Poco::Timespan & http_timeout_, const std::string & connection_string_)
        : http_timeout(http_timeout_), connection_string(connection_string_), config(config_)
    {
        size_t bridge_port = config.getUInt(BridgeHelperMixin::configPrefix() + ".port", DEFAULT_PORT);
        std::string bridge_host = config.getString(BridgeHelperMixin::configPrefix() + ".host", DEFAULT_HOST);

        ping_url.setHost(bridge_host);
        ping_url.setPort(bridge_port);
        ping_url.setScheme("http");
        ping_url.setPath(PING_HANDLER);
    }
    
    String getName() const override
    {
        return BridgeHelperMixin::getName();
    }

    IdentifierQuotingStyle getIdentifierQuotingStyle() override
    {
        if (!quote_style.has_value())
        {
            startBridgeSync();

            auto uri = createBaseURI();
            uri.setPath(IDENTIFIER_QUOTE_HANDLER);
            uri.addQueryParameter("connection_string", getConnectionString());

            ReadWriteBufferFromHTTP buf(uri, Poco::Net::HTTPRequest::HTTP_POST, nullptr);
            std::string character;
            readStringBinary(character, buf);
            if (character.length() > 1)
                throw Exception("Failed to parse quoting style from '" + character + "' for service " + BridgeHelperMixin::serviceAlias(), ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
            else if (character.length() == 0)
                quote_style = IdentifierQuotingStyle::None;
            else if (character[0] == '`')
                quote_style = IdentifierQuotingStyle::Backticks;
            else if (character[0] == '"')
                quote_style = IdentifierQuotingStyle::DoubleQuotes;
            else
                throw Exception("Can not map quote identifier '" + character + "' to enum value", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
        }

        return *quote_style;
    }

    /**
     * @todo leaky abstraction - used by external API's
     */
    std::vector<std::pair<std::string, std::string>> getURLParams(const std::string & cols, size_t max_block_size) const override
    {
        std::vector<std::pair<std::string, std::string>> result;

        result.emplace_back("connection_string", connection_string); /// already validated
        result.emplace_back("columns", cols);
        result.emplace_back("max_block_size", std::to_string(max_block_size));

        return result;
    }

    /**
     * Performs spawn of external daemon
     */
    void startBridgeSync() const override
    {
        if (!checkBridgeIsRunning())
        {
            LOG_TRACE(log, BridgeHelperMixin::serviceAlias() + " is not running, will try to start it");
            startBridge();
            bool started = false;
            for (size_t counter : ext::range(1, 20))
            {
                LOG_TRACE(log, "Checking " + BridgeHelperMixin::serviceAlias() + " is running, try " << counter);
                if (checkBridgeIsRunning())
                {
                    started = true;
                    break;
                }
                std::this_thread::sleep_for(std::chrono::milliseconds(10));
            }
            if (!started)
                throw Exception(BridgeHelperMixin::getName() + "BridgeHelper: " + BridgeHelperMixin::serviceAlias() + " is not responding",
                    ErrorCodes::EXTERNAL_SERVER_IS_NOT_RESPONDING);
        }
    }

    /**
     * URI to fetch the data from external service
     */
    Poco::URI getMainURI() const override
    {
        auto uri = createBaseURI();
        uri.setPath(MAIN_HANDLER);
        return uri;
    }

    /**
     * URI to retrieve column description from external service
     */
    Poco::URI getColumnsInfoURI() const override
    {
        auto uri = createBaseURI();
        uri.setPath(COL_INFO_HANDLER);
        return uri;
    }

protected:
    Poco::URI createBaseURI() const
    {
        size_t bridge_port = config.getUInt(BridgeHelperMixin::serviceAlias() + ".port", DEFAULT_PORT);
        std::string bridge_host = config.getString(BridgeHelperMixin::serviceAlias() + ".host", DEFAULT_HOST);

        Poco::URI uri;
        uri.setHost(bridge_host);
        uri.setPort(bridge_port);
        uri.setScheme("http");
        return uri;
    }

private:
    bool checkBridgeIsRunning() const
    {
        try
        {
            ReadWriteBufferFromHTTP buf(ping_url, Poco::Net::HTTPRequest::HTTP_GET, nullptr);
            return checkString(XDBCBridgeHelper::PING_OK_ANSWER, buf);
        }
        catch (...)
        {
            return false;
        }
    }

    /* Contains logic for instantiation of the bridge instance */
    void startBridge() const
    {
        BridgeHelperMixin::startBridge(config, log, http_timeout);
    }
};

struct JDBCBridgeMixin
{
    static constexpr inline auto DEFAULT_PORT = 9019;
    static const String configPrefix()
    {
        return "jdbc_bridge";
    }
    static const String serviceAlias()
    {
        return "clickhouse-jdbc-bridge";
    }
    static const String getName()
    {
        return "JDBC";
    }

    static void startBridge(const Poco::Util::AbstractConfiguration &, const Poco::Logger *, const Poco::Timespan &)
    {
        throw Exception("jdbc-bridge is not running. Please, start it manually", ErrorCodes::EXTERNAL_SERVER_IS_NOT_RESPONDING);
    }
};

struct ODBCBridgeMixin
{
    static constexpr inline auto DEFAULT_PORT = 9018;

    static const String configPrefix()
    {
        return "odbc_bridge";
    }
    static const String serviceAlias()
    {
        return "clickhouse-odbc-bridge";
    }
    static const String getName()
    {
        return "ODBC";
    }

    static void startBridge(const Poco::Util::AbstractConfiguration & config, Poco::Logger * log, const Poco::Timespan & http_timeout)
    {
        Poco::Path path{config.getString("application.dir", "")};

        path.setFileName(
#if CLICKHOUSE_SPLIT_BINARY
            "clickhouse-odbc-bridge"
#else
            "clickhouse"
#endif
        );

        if (!Poco::File(path).exists())
            throw Exception("clickhouse binary (" + path.toString() + ") is not found", ErrorCodes::EXTERNAL_EXECUTABLE_NOT_FOUND);

        std::stringstream command;

        command << path.toString() <<
#if CLICKHOUSE_SPLIT_BINARY
            " "
#else
            " odbc-bridge "
#endif
            ;

        command << "--http-port " << config.getUInt(configPrefix() + ".port", DEFAULT_PORT) << ' ';
        command << "--listen-host " << config.getString(configPrefix() + ".listen_host", XDBCBridgeHelper<ODBCBridgeMixin>::DEFAULT_HOST)
                << ' ';
        command << "--http-timeout " << http_timeout.totalMicroseconds() << ' ';
        if (config.has("logger." + configPrefix() + "_log"))
            command << "--log-path " << config.getString("logger." + configPrefix() + "_log") << ' ';
        if (config.has("logger." + configPrefix() + "_errlog"))
            command << "--err-log-path " << config.getString("logger." + configPrefix() + "_errlog") << ' ';
        if (config.has("logger." + configPrefix() + "_level"))
            command << "--log-level " << config.getString("logger." + configPrefix() + "_level") << ' ';
        command << "&"; /// we don't want to wait this process

        auto command_str = command.str();

        std::cerr << command_str << std::endl;

        LOG_TRACE(log, "Starting " + serviceAlias() + " with command: " << command_str);

        auto cmd = ShellCommand::execute(command_str);
        cmd->wait();
    }
};
}