#pragma once

#include <chrono>

#include <cstdint>

#include <string>

#include "envoy/http/codes.h"

#include "envoy/http/header_map.h"

#include "envoy/stats/scope.h"

#include "source/common/common/thread.h"

#include "source/common/stats/symbol_table.h"

namespace Envoy {

namespace Http {

struct CodeStats::ResponseStatInfo {

  Stats::Scope& global_scope_;

  Stats::Scope& cluster_scope_;

  Stats::StatName prefix_;

  uint64_t response_status_code_;

  bool internal_request_;

  Stats::StatName request_vhost_name_;

  Stats::StatName request_vcluster_name_;

  Stats::StatName request_route_name_;

  Stats::StatName from_zone_;

  Stats::StatName to_zone_;

  bool upstream_canary_;

};

struct CodeStats::ResponseTimingInfo {

  Stats::Scope& global_scope_;

  Stats::Scope& cluster_scope_;

  Stats::StatName prefix_;

  std::chrono::milliseconds response_time_;

  bool upstream_canary_;

  bool internal_request_;

  Stats::StatName request_vhost_name_;

  Stats::StatName request_vcluster_name_;

  Stats::StatName request_route_name_;

  Stats::StatName from_zone_;

  Stats::StatName to_zone_;

};

class CodeStatsImpl : public CodeStats {

public:

  explicit CodeStatsImpl(Stats::SymbolTable& symbol_table);

  // CodeStats

  void chargeBasicResponseStat(Stats::Scope& scope, Stats::StatName prefix, Code response_code,

                               bool exclude_http_code_stats) const override;

  void chargeResponseStat(const ResponseStatInfo& info,

                          bool exclude_http_code_stats) const override;

  void chargeResponseTiming(const ResponseTimingInfo& info) const override;

private:

  friend class CodeStatsTest;

  void writeCategory(const ResponseStatInfo& info, Stats::StatName rq_group,

                     Stats::StatName rq_code, Stats::StatName category) const;

  void incCounter(Stats::Scope& scope, const Stats::StatNameVec& names) const;

  void incCounter(Stats::Scope& scope, Stats::StatName a, Stats::StatName b) const;

  void recordHistogram(Stats::Scope& scope, const Stats::StatNameVec& names,

                       Stats::Histogram::Unit unit, uint64_t count) const;

  Stats::StatName upstreamRqGroup(Code response_code) const;

  Stats::StatName upstreamRqStatName(Code response_code) const;

  mutable Stats::StatNamePool stat_name_pool_;

  Stats::SymbolTable& symbol_table_;

  const Stats::StatName canary_;

  const Stats::StatName empty_; // Used for the group-name for invalid http codes.

  const Stats::StatName external_;

  const Stats::StatName internal_;

  const Stats::StatName upstream_;

  const Stats::StatName upstream_rq_1xx_;

  const Stats::StatName upstream_rq_2xx_;

  const Stats::StatName upstream_rq_3xx_;

  const Stats::StatName upstream_rq_4xx_;

  const Stats::StatName upstream_rq_5xx_;

  const Stats::StatName upstream_rq_unknown_;

  const Stats::StatName upstream_rq_completed_;

  const Stats::StatName upstream_rq_time_;

  const Stats::StatName vcluster_;

  const Stats::StatName vhost_;

  const Stats::StatName route_;

  const Stats::StatName zone_;

  // Use an array of atomic pointers to hold StatNameStorage objects for

  // every conceivable HTTP response code. In the hot-path we'll reference

  // these with a null-check, and if we need to allocate a symbol for a

  // new code, we'll take a mutex to avoid duplicate allocations and

  // subsequent leaks. This is similar in principle to a ReaderMutexLock,

  // but should be faster, as ReaderMutexLocks appear to be too expensive for

  // fine-grained controls. Another option would be to use a lock per

  // stat-name, which might have similar performance to atomics with default

  // barrier policy.

  //

  // We don't allocate these all up front during construction because

  // SymbolTable greedily encodes the first 128 names it discovers in one

  // byte. We don't want those high-value single-byte codes to go to fully

  // enumerating the 4 prefixes combined with HTTP codes that are seldom used,

  // so we allocate these on demand.

  //

  // There can be multiple symbol tables in a server. The one passed into the

  // Codes constructor should be the same as the one passed to

  // Stats::ThreadLocalStore. Note that additional symbol tables can be created

  // from IsolatedStoreImpl's default constructor.

  //

  // The Codes object is global to the server.

  static constexpr uint32_t NumHttpCodes = 500;

  static constexpr uint32_t HttpCodeOffset = 100; // code 100 is at index 0.

  mutable Thread::AtomicPtrArray<const uint8_t, NumHttpCodes,

                                 Thread::AtomicPtrAllocMode::DoNotDelete>

      rc_stat_names_;

};

/**

 * General utility routines for HTTP codes.

 */

class CodeUtility {

public:

  /**

   * Convert an HTTP response code to a descriptive string.

   * @param code supplies the code to convert.

   * @return const char* the string.

   */

  static const char* toString(Code code);

  static std::string groupStringForResponseCode(Code response_code);

};

} // namespace Http

} // namespace Envoy