#pragma once

#include "envoy/stats/stats_macros.h"

namespace Envoy {

namespace Extensions {

namespace HttpFilters {

namespace Cache {

namespace FileSystemHttpCache {

/**

 * All cache stats. @see stats_macros.h

 *

 * Note that size_bytes and size_count may drift away from true values, due to:

 * - Changes to the filesystem may be made outside of the process, which will not be

 *   accounted for. (Including, during hot restart, overlapping envoy processes.)

 * - Files completed while pre-cache-purge measurement is in progress may not be counted.

 * - Changes in file size due to header updates are assumed to be negligible, and are ignored.

 *

 * Drift will eventually be reconciled at the next pre-cache-purge measurement.

 *

 * There are also cache_hit_ and cache_miss_, defined separately to accommodate extra tags;

 * these two both go into the stat with key `event`, and with tag `event_type=(hit|miss)`

 **/

#define ALL_CACHE_STATS(COUNTER, GAUGE, HISTOGRAM, TEXT_READOUT, STATNAME)                         \

  COUNTER(eviction_runs)                                                                           \

  GAUGE(size_bytes, NeverImport)                                                                   \

  GAUGE(size_count, NeverImport)                                                                   \

  GAUGE(size_limit_bytes, NeverImport)                                                             \

  GAUGE(size_limit_count, NeverImport)                                                             \

  STATNAME(cache)                                                                                  \

  STATNAME(cache_path)                                                                             \

  STATNAME(event)                                                                                  \

  STATNAME(event_type)                                                                             \

  STATNAME(hit)                                                                                    \

  STATNAME(miss)

// TODO(ravenblack): Add other stats from DESIGN.md

#define COUNTER_HELPER_(NAME)                                                                      \

  , NAME##_(                                                                                       \

#define GAUGE_HELPER_(NAME, MODE)                                                                  \

#define STATNAME_HELPER_(NAME)

MAKE_STAT_NAMES_STRUCT(CacheStatNames, ALL_CACHE_STATS);

struct CacheStats {

  CacheStats(const CacheStatNames& stat_names, Envoy::Stats::Scope& scope,

             Stats::StatName cache_path)

            ALL_CACHE_STATS(COUNTER_HELPER_, GAUGE_HELPER_, HISTOGRAM_HELPER_, TEXT_READOUT_HELPER_,

                            STATNAME_HELPER_),

private:

  const CacheStatNames& stat_names_;

  const Stats::StatName prefix_;

  const Stats::StatName cache_path_;

  Stats::StatNameTagVector tags_;

  Stats::StatNameTagVector tags_hit_;

  Stats::StatNameTagVector tags_miss_;

public:

  ALL_CACHE_STATS(GENERATE_COUNTER_STRUCT, GENERATE_GAUGE_STRUCT, GENERATE_HISTOGRAM_STRUCT,

                  GENERATE_TEXT_READOUT_STRUCT, GENERATE_STATNAME_STRUCT);

  Stats::Counter& cache_hit_;

  Stats::Counter& cache_miss_;

};

CacheStats generateStats(CacheStatNames& stat_names, Stats::Scope& scope,

                         absl::string_view cache_path);

} // namespace FileSystemHttpCache

} // namespace Cache

} // namespace HttpFilters

} // namespace Extensions

} // namespace Envoy