#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 "common/stats/histogram_impl.h"

#include "server/admin/handler_ctx.h"

#include "absl/strings/string_view.h"

namespace Envoy {
namespace Server {

class StatsHandler : public HandlerContextBase {

public:
  StatsHandler(Server::Instance& server);

  Http::Code handlerResetCounters(absl::string_view path_and_query,
                                  Http::ResponseHeaderMap& response_headers,
                                  Buffer::Instance& response, AdminStream&);
  Http::Code handlerStatsRecentLookups(absl::string_view path_and_query,
                                       Http::ResponseHeaderMap& response_headers,
                                       Buffer::Instance& response, AdminStream&);
  Http::Code handlerStatsRecentLookupsClear(absl::string_view path_and_query,
                                            Http::ResponseHeaderMap& response_headers,
                                            Buffer::Instance& response, AdminStream&);
  Http::Code handlerStatsRecentLookupsDisable(absl::string_view path_and_query,
                                              Http::ResponseHeaderMap& response_headers,
                                              Buffer::Instance& response, AdminStream&);
  Http::Code handlerStatsRecentLookupsEnable(absl::string_view path_and_query,
                                             Http::ResponseHeaderMap& response_headers,
                                             Buffer::Instance& response, AdminStream&);
  Http::Code handlerStats(absl::string_view path_and_query,
                          Http::ResponseHeaderMap& response_headers, Buffer::Instance& response,
                          AdminStream&);
  Http::Code handlerPrometheusStats(absl::string_view path_and_query,
                                    Http::ResponseHeaderMap& response_headers,
                                    Buffer::Instance& response, AdminStream&);
  Http::Code handlerContention(absl::string_view path_and_query,
                               Http::ResponseHeaderMap& response_headers,
                               Buffer::Instance& response, AdminStream&);

private:
  template <class StatType>
  static bool shouldShowMetric(const StatType& metric, const bool used_only,
                               const absl::optional<std::regex>& regex) {
    return ((!used_only || metric.used()) &&
            (!regex.has_value() || std::regex_search(metric.name(), regex.value())));
  }

  friend class AdminStatsTest;

  static std::string statsAsJson(const std::map<std::string, uint64_t>& all_stats,
                                 const std::map<std::string, std::string>& text_readouts,
                                 const std::vector<Stats::ParentHistogramSharedPtr>& all_histograms,
                                 bool used_only,
                                 const absl::optional<std::regex> regex = absl::nullopt,
                                 bool pretty_print = false);
};

} // namespace Server
} // namespace Envoy