#pragma once

#include <memory>

#include <string>

#include "envoy/buffer/buffer.h"

#include "envoy/http/codes.h"

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

#include "re2/re2.h"

namespace Envoy {

namespace Server {

namespace StatLabels {

constexpr absl::string_view All = "All";

constexpr absl::string_view Counters = "Counters";

constexpr absl::string_view Gauges = "Gauges";

constexpr absl::string_view Histograms = "Histograms";

constexpr absl::string_view TextReadouts = "TextReadouts";

} // namespace StatLabels

enum class StatsFormat {

#ifdef ENVOY_ADMIN_HTML

  Html,

  ActiveHtml,

#endif

  Json,

  Prometheus,

  Text,

};

// The order is used to linearize the ordering of stats of all types.

enum class StatsType {

  TextReadouts,

  Counters,

  Gauges,

  Histograms,

  All,

};

enum class HiddenFlag {

  Include,  // Will include hidden stats along side non-hidden stats

  ShowOnly, // Will only show hidden stats and exclude hidden stats

  Exclude,  // Default behavior. Will exclude all hidden stats

};

struct StatsParams {

  /**

   * Parses the URL's query parameter, populating this.

   *

   * @param url the URL from which to parse the query params.

   * @param response used to write error messages, if necessary.

   */

  Http::Code parse(absl::string_view url, Buffer::Instance& response);

  /**

   * @return a string representation for a type.

   */

  static absl::string_view typeToString(StatsType type);

  StatsType type_{StatsType::All};

  bool used_only_{false};

  bool prometheus_text_readouts_{false};

  bool pretty_{false};

  StatsFormat format_{StatsFormat::Text};

  HiddenFlag hidden_{HiddenFlag::Exclude};

  std::string filter_string_;

  std::shared_ptr<re2::RE2> re2_filter_;

  Utility::HistogramBucketsMode histogram_buckets_mode_{Utility::HistogramBucketsMode::Unset};

  // If set, emit native histograms with at most this many buckets per histogram.

  absl::optional<uint32_t> native_histogram_max_buckets_;

  Http::Utility::QueryParamsMulti query_;

  /**

   * Determines whether a metric should be shown based on the specified query-parameters. This

   * covers:

   * ``usedonly``, hidden, and filter.

   *

   * @param metric the metric to test

   * @param name_out if non-null, and the return value is true,

   *   will contain the metric name. This improves performance because computing the name is

   *   somewhat expensive, and in some cases it isn't needed.

   */

};

} // namespace Server

} // namespace Envoy