#pragma once

#include <regex>

#include <string>

#include "envoy/buffer/buffer.h"

#include "envoy/http/codes.h"

#include "envoy/http/header_map.h"

#include "envoy/server/admin.h"

#include "envoy/server/instance.h"

#include "source/server/admin/handler_ctx.h"

#include "source/server/admin/stats_request.h"

#include "source/server/admin/utils.h"

#include "absl/strings/string_view.h"

namespace Envoy {

namespace Server {

class StatsHandler : public HandlerContextBase {

public:

  StatsHandler(Server::Instance& server);

  Http::Code handlerResetCounters(Http::ResponseHeaderMap& response_headers,

                                  Buffer::Instance& response, AdminStream&);

  Http::Code handlerStatsRecentLookups(Http::ResponseHeaderMap& response_headers,

                                       Buffer::Instance& response, AdminStream&);

  Http::Code handlerStatsRecentLookupsClear(Http::ResponseHeaderMap& response_headers,

                                            Buffer::Instance& response, AdminStream&);

  Http::Code handlerStatsRecentLookupsDisable(Http::ResponseHeaderMap& response_headers,

                                              Buffer::Instance& response, AdminStream&);

  Http::Code handlerStatsRecentLookupsEnable(Http::ResponseHeaderMap& response_headers,

                                             Buffer::Instance& response, AdminStream&);

  Http::Code handlerPrometheusStats(Http::ResponseHeaderMap& response_headers,

                                    Buffer::Instance& response, AdminStream&);

  /**

   * Parses and executes a prometheus stats request.

   *

   * @param path_and_query the URL path and query

   * @param response buffer into which to write response

   * @return http response code

   */

  Http::Code prometheusStats(const Http::RequestHeaderMap& request_headers,

                             Http::ResponseHeaderMap& response_headers, Buffer::Instance& response);

  /**

   * Checks the server_ to see if a flush is needed, and then renders the

   * prometheus stats request.

   *

   * @params params the already-parsed parameters.

   * @param response buffer into which to write response

   */

  Http::Code prometheusFlushAndRender(const StatsParams& params,

                                      const Http::RequestHeaderMap& request_headers,

                                      Http::ResponseHeaderMap& response_headers,

                                      Buffer::Instance& response);

  /**

   * Renders the stats as prometheus. This is broken out as a separately

   * callable API to facilitate the benchmark

   * (test/server/admin/stats_handler_speed_test.cc) which does not have a

   * server object.

   *

   * @params stats the stats store to read

   * @param custom_namespaces namespace mappings used for prometheus

   * @params params the already-parsed parameters.

   * @param response buffer into which to write response

   */

  static void

  prometheusRender(Stats::Store& stats, const Stats::CustomStatNamespaces& custom_namespaces,

                   const Upstream::ClusterManager& cluster_manager, const StatsParams& params,

                   const Http::RequestHeaderMap& request_headers,

                   Http::ResponseHeaderMap& response_headers, Buffer::Instance& response);

  Http::Code handlerContention(Http::ResponseHeaderMap& response_headers,

                               Buffer::Instance& response, AdminStream&);

  /**

   * When stats are rendered in HTML mode, we want users to be able to tweak

   * parameters after the stats page is rendered, such as tweaking the filter or

   * `usedonly`. We use the same stats UrlHandler both for the admin home page

   * and for rendering in /stats?format=html. We share the same UrlHandler in

   * both contexts by defining an API for it here.

   *

   * @param active_mode skips rendering a form-field for 'usedonly', which we

   *        force-enable for active mode. It makes no sense to include stats

   *        that have never been written in a top-most-frequently-updated list.

   * @return a URL handler for stats.

   */

  Admin::UrlHandler statsHandler(bool active_mode);

  static Admin::RequestPtr makeRequest(Stats::Store& stats, const StatsParams& params,

                                       const Upstream::ClusterManager& cm,

                                       StatsRequest::UrlHandlerFn url_handler_fn = nullptr);

  Admin::RequestPtr makeRequest(AdminStream&);

};

} // namespace Server

} // namespace Envoy