/* -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
 *   Copyright 2024. Couchbase, Inc.
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 */

#include "meter_wrapper.hxx"

#include <couchbase/error_codes.hxx>

#include <mutex>
#include <system_error>

namespace couchbase::core::metrics
{
namespace
{
auto
snake_case_to_camel_case(const std::string& s) -> std::string
{
  std::string res{};
  bool capitalize{ true }; // First letter should be capitalized
  for (const char c : s) {
    if (c == '_') {
      capitalize = true; // Next letter should be capitalized
      continue;
    }
    if (capitalize) {
      res += static_cast<char>(std::toupper(c));
      capitalize = false;
    } else {
      res += c;
    }
  }
  return res;
}

auto
extract_error_name(std::error_code ec) -> std::string
{
  const std::string::size_type pos = ec.message().find(' ');
  if (pos != std::string::npos) {
    return ec.message().substr(0, pos);
  }
  return ec.message();
}

auto
service_to_string(service_type s) -> std::string
{
  switch (s) {
    case service_type::analytics:
      return "analytics";
    case service_type::search:
      return "search";
    case service_type::key_value:
      return "kv";
    case service_type::management:
      return "management";
    case service_type::eventing:
      return "eventing";
    case service_type::query:
      return "query";
    case service_type::view:
      return "views";
  }
  return {};
}

auto
get_standardized_outcome(std::error_code ec) -> std::string
{
  if (!ec) {
    return "Success";
  }

  // SDK-specific errors
  if (ec.value() >= 1000) {
    return "CouchbaseError";
  }

  // Errors where message and RFC-message don't match
  if (ec == errc::field_level_encryption::generic_cryptography_failure) {
    return "CryptoError";
  }

  return snake_case_to_camel_case(extract_error_name(ec));
}
} // namespace

auto
metric_attributes::encode() const -> std::map<std::string, std::string>
{
  std::map<std::string, std::string> tags = { { "db.couchbase.service",
                                                service_to_string(service) },
                                              { "db.operation", operation },
                                              { "outcome", get_standardized_outcome(ec) } };

  if (internal.cluster_name.has_value()) {
    tags.emplace("db.couchbase.cluster_name", internal.cluster_name.value());
  }
  if (internal.cluster_uuid.has_value()) {
    tags.emplace("db.couchbase.cluster_uuid", internal.cluster_uuid.value());
  }
  if (bucket_name) {
    tags.emplace("db.name", bucket_name.value());
  }
  if (scope_name) {
    tags.emplace("db.couchbase.scope", scope_name.value());
  }
  if (collection_name) {
    tags.emplace("db.couchbase.collection", collection_name.value());
  }

  return tags;
}

meter_wrapper::meter_wrapper(std::shared_ptr<couchbase::metrics::meter> meter)
  : meter_{ std::move(meter) }
{
}

void
meter_wrapper::start()
{
  meter_->start();
}

void
meter_wrapper::stop()
{
  meter_->stop();
}

void
meter_wrapper::record_value(metric_attributes attrs,
                            std::chrono::steady_clock::time_point start_time)
{
  static const std::string meter_name{ "db.couchbase.operations" };

  {
    const std::shared_lock lock{ cluster_labels_mutex_ };

    if (cluster_name_) {
      attrs.internal.cluster_name = cluster_name_;
    }
    if (cluster_uuid_) {
      attrs.internal.cluster_uuid = cluster_uuid_;
    }
  }

  auto tags = attrs.encode();
  meter_->get_value_recorder(meter_name, tags)
    ->record_value(std::chrono::duration_cast<std::chrono::microseconds>(
                     std::chrono::steady_clock::now() - start_time)
                     .count());
}

void
meter_wrapper::update_config(topology::configuration config)
{
  const std::scoped_lock<std::shared_mutex> lock{ cluster_labels_mutex_ };
  if (config.cluster_uuid.has_value()) {
    cluster_uuid_ = config.cluster_uuid;
  }
  if (config.cluster_name.has_value()) {
    cluster_name_ = config.cluster_name;
  }
}

auto
meter_wrapper::create(std::shared_ptr<couchbase::metrics::meter> meter)
  -> std::shared_ptr<meter_wrapper>
{
  return std::make_shared<meter_wrapper>(std::move(meter));
}
} // namespace couchbase::core::metrics