#include "HTTPHandlerFactory.h"

#include <re2/re2.h>
#include <re2/stringpiece.h>
#include <common/find_symbols.h>
#include <Poco/StringTokenizer.h>

#include "HTTPHandler.h"
#include "NotFoundHandler.h"
#include "StaticRequestHandler.h"
#include "ReplicasStatusHandler.h"
#include "InterserverIOHTTPHandler.h"
#include "PrometheusRequestHandler.h"


namespace DB
{

namespace ErrorCodes
{
    extern const int LOGICAL_ERROR;
    extern const int UNKNOWN_ELEMENT_IN_CONFIG;
    extern const int INVALID_CONFIG_PARAMETER;
}

HTTPRequestHandlerFactoryMain::HTTPRequestHandlerFactoryMain(const std::string & name_)
    : log(&Logger::get(name_)), name(name_)
{
}

Poco::Net::HTTPRequestHandler * HTTPRequestHandlerFactoryMain::createRequestHandler(const Poco::Net::HTTPServerRequest & request) // override
{
    LOG_TRACE(log, "HTTP Request for " << name << ". "
        << "Method: " << request.getMethod()
        << ", Address: " << request.clientAddress().toString()
        << ", User-Agent: " << (request.has("User-Agent") ? request.get("User-Agent") : "none")
        << (request.hasContentLength() ? (", Length: " + std::to_string(request.getContentLength())) : (""))
        << ", Content Type: " << request.getContentType()
        << ", Transfer Encoding: " << request.getTransferEncoding());

    for (auto & handler_factory : child_factories)
    {
        auto handler = handler_factory->createRequestHandler(request);
        if (handler != nullptr)
            return handler;
    }

    if (request.getMethod() == Poco::Net::HTTPRequest::HTTP_GET
        || request.getMethod() == Poco::Net::HTTPRequest::HTTP_HEAD
        || request.getMethod() == Poco::Net::HTTPRequest::HTTP_POST)
    {
        return new NotFoundHandler;
    }

    return nullptr;
}

HTTPRequestHandlerFactoryMain::~HTTPRequestHandlerFactoryMain()
{
    while (!child_factories.empty())
    {
        delete child_factories.back();
        child_factories.pop_back();
    }
}

HTTPRequestHandlerFactoryMain::TThis * HTTPRequestHandlerFactoryMain::addHandler(Poco::Net::HTTPRequestHandlerFactory * child_factory)
{
    child_factories.emplace_back(child_factory);
    return this;
}

static inline auto createHandlersFactoryFromConfig(IServer & server, const std::string & name, const String & prefix)
{
    auto main_handler_factory = new HTTPRequestHandlerFactoryMain(name);

    try
    {
        Poco::Util::AbstractConfiguration::Keys keys;
        server.config().keys(prefix, keys);

        for (const auto & key : keys)
        {
            if (!startsWith(key, "rule"))
                throw Exception("Unknown element in config: " + prefix + "." + key + ", must be 'rule'", ErrorCodes::UNKNOWN_ELEMENT_IN_CONFIG);

            const auto & handler_type = server.config().getString(prefix + "." + key + ".handler.type", "");

            if (handler_type == "static")
                main_handler_factory->addHandler(createStaticHandlerFactory(server, prefix + "." + key));
            else if (handler_type == "dynamic_query_handler")
                main_handler_factory->addHandler(createDynamicHandlerFactory(server, prefix + "." + key));
            else if (handler_type == "predefined_query_handler")
                main_handler_factory->addHandler(createPredefinedHandlerFactory(server, prefix + "." + key));
            else if (handler_type.empty())
                throw Exception("Handler type in config is not specified here: " +
                                prefix + "." + key + ".handler.type", ErrorCodes::INVALID_CONFIG_PARAMETER);
            else
                throw Exception("Unknown handler type '" + handler_type +"' in config here: " +
                                prefix + "." + key + ".handler.type",ErrorCodes::INVALID_CONFIG_PARAMETER);
        }

        return main_handler_factory;
    }
    catch (...)
    {
        delete main_handler_factory;
        throw;
    }
}

static const auto ping_response_expression = "Ok.\n";
static const auto root_response_expression = "config://http_server_default_response";

static inline Poco::Net::HTTPRequestHandlerFactory * createHTTPHandlerFactory(IServer & server, const std::string & name, AsynchronousMetrics & async_metrics)
{
    if (server.config().has("http_handlers"))
        return createHandlersFactoryFromConfig(server, name, "http_handlers");
    else
    {
        auto factory = (new HTTPRequestHandlerFactoryMain(name))
            ->addHandler((new HandlingRuleHTTPHandlerFactory<StaticRequestHandler>(server, root_response_expression))
                ->attachStrictPath("/")->allowGetAndHeadRequest())
            ->addHandler((new HandlingRuleHTTPHandlerFactory<StaticRequestHandler>(server, ping_response_expression))
                ->attachStrictPath("/ping")->allowGetAndHeadRequest())
            ->addHandler((new HandlingRuleHTTPHandlerFactory<ReplicasStatusHandler>(server))
                ->attachNonStrictPath("/replicas_status")->allowGetAndHeadRequest())
            ->addHandler((new HandlingRuleHTTPHandlerFactory<DynamicQueryHandler>(server, "query"))->allowPostAndGetParamsRequest());

        if (server.config().has("prometheus") && server.config().getInt("prometheus.port", 0) == 0)
            factory->addHandler((new HandlingRuleHTTPHandlerFactory<PrometheusRequestHandler>(
                server, PrometheusMetricsWriter(server.config(), "prometheus", async_metrics)))
                    ->attachStrictPath(server.config().getString("prometheus.endpoint", "/metrics"))->allowGetAndHeadRequest());

        return factory;
    }
}

static inline Poco::Net::HTTPRequestHandlerFactory * createInterserverHTTPHandlerFactory(IServer & server, const std::string & name)
{
    return (new HTTPRequestHandlerFactoryMain(name))
        ->addHandler((new HandlingRuleHTTPHandlerFactory<StaticRequestHandler>(server, root_response_expression))
            ->attachStrictPath("/")->allowGetAndHeadRequest())
        ->addHandler((new HandlingRuleHTTPHandlerFactory<StaticRequestHandler>(server, ping_response_expression))
            ->attachStrictPath("/ping")->allowGetAndHeadRequest())
        ->addHandler((new HandlingRuleHTTPHandlerFactory<ReplicasStatusHandler>(server))
            ->attachNonStrictPath("/replicas_status")->allowGetAndHeadRequest())
        ->addHandler((new HandlingRuleHTTPHandlerFactory<InterserverIOHTTPHandler>(server))->allowPostAndGetParamsRequest());
}

Poco::Net::HTTPRequestHandlerFactory * createHandlerFactory(IServer & server, AsynchronousMetrics & async_metrics, const std::string & name)
{
    if (name == "HTTPHandler-factory" || name == "HTTPSHandler-factory")
        return createHTTPHandlerFactory(server, name, async_metrics);
    else if (name == "InterserverIOHTTPHandler-factory" || name == "InterserverIOHTTPSHandler-factory")
        return createInterserverHTTPHandlerFactory(server, name);
    else if (name == "PrometheusHandler-factory")
        return (new HTTPRequestHandlerFactoryMain(name))->addHandler((new HandlingRuleHTTPHandlerFactory<PrometheusRequestHandler>(
            server, PrometheusMetricsWriter(server.config(), "prometheus", async_metrics)))
                ->attachStrictPath(server.config().getString("prometheus.endpoint", "/metrics"))->allowGetAndHeadRequest());

    throw Exception("LOGICAL ERROR: Unknown HTTP handler factory name.", ErrorCodes::LOGICAL_ERROR);
}

}