#include "request_stats.hpp"

#include <chrono>  // NOLINT
#include <cstdint>
#include <sstream>
#include <string>

#include "logging.hpp"
#include <nlohmann/json.hpp>
#include "managed_store_clock.hpp"

namespace managedStore {

/** the linear constants below are a good start, we can revisit them as we find
 * value in this histogram */
/** num of buckets */
constexpr static int64_t kHistNumBuckets = 50;
/** size of each bucket in milliseconds */
constexpr static int64_t kHistBucketSizeMillisec = 100;

/** global stats store config */
RequestStatsStoreConfig statsStoreConfigDefault;  // NOLINT
/** global stats store */
RequestStatsStore statsStore(statsStoreConfigDefault);  // NOLINT

RequestStatsContext::RequestStatsContext(
    const std::string& key, const std::chrono::steady_clock::time_point& now)
    : queryURLKey(key), timepointStart(now), rdeStats() {
  BMCWEB_LOG_DEBUG << "RequestStatsContext: start: " << this->toJson();
}

RequestStatsContext::~RequestStatsContext() {
  BMCWEB_LOG_DEBUG << "RequestStatsContext: done: " << this->toJson();
}

std::string RequestStatsContext::queryURLKeyFor(
    const boost::beast::http::verb& method, const boost::urls::url_view& qURL) {
  std::stringstream key;
  key << method << kSep << qURL;
  return key.str();
}

nlohmann::json RequestStatsContext::toJson() const {
  nlohmann::json obj;
  obj["queryURLKey"] = this->queryURLKey;
  if (managedStore::RequestStatsStore::isRdeRateLimitEnabled()) {
    obj["rdeStats"] = nlohmann::json::object();
    obj["rdeStats"]["rdeReqs"] = getRdeReqs();
    obj["rdeStats"]["rdeDbusErrors"] = getRdeDbusErrors();
    obj["rdeStats"]["rdeSkips"] = getRdeSkips();
    obj["rdeStats"]["rdeRateLimitToggles"] = getRdeRateLimitToggles();
  }
  obj["ageMillisec"] =
      managedStore::clockSinceMilliseconds(this->timepointStart);
  return obj;
}

std::string RequestStatsContext::getQueryURLKey() const {
  return this->queryURLKey;
};

std::chrono::steady_clock::time_point RequestStatsContext::getTimepointStart()
    const {
  return this->timepointStart;
};

void RequestStatsContext::setOK(bool ok) { this->isOK = ok; }

bool RequestStatsContext::ok() const { return this->isOK; }
void RequestStatsContext::updateRdeReqs() { this->rdeStats.totalReqs += 1; }
void RequestStatsContext::updateRdeDbusErrors() {
  this->rdeStats.totalDbusErrors += 1;
}
void RequestStatsContext::updateRdeSkips() { this->rdeStats.totalSkips += 1; }
void RequestStatsContext::updateRdeRateLimitToggles() {
  this->rdeStats.totalRateLimitToggles += 1;
}
int RequestStatsContext::getRdeReqs() const { return this->rdeStats.totalReqs; }
int RequestStatsContext::getRdeDbusErrors() const {
  return this->rdeStats.totalDbusErrors;
}
int RequestStatsContext::getRdeSkips() const {
  return this->rdeStats.totalSkips;
}
int RequestStatsContext::getRdeRateLimitToggles() const {
  return this->rdeStats.totalRateLimitToggles;
}
nlohmann::json RequestStatsStoreConfig::toJson() const {
  nlohmann::json obj;
  obj["enable"] = this->enable;
  obj["enableRdeRateLimit"] = this->enableRdeRateLimit;
  obj["rdeDbusErrorThreshold"] = this->rdeDbusErrorThreshold;
  obj["rdeMaxSkips"] = this->rdeMaxSkips;
  obj["bucket_num"] = kHistNumBuckets;
  obj["bucket_millisec"] = kHistBucketSizeMillisec;

  return obj;
}

void RequestStatsStore::initialize(const RequestStatsStoreConfig& config) {
  BMCWEB_LOG_INFO << "RequestStatsStore::initialize: config: "
                  << config.toJson();
  statsStore.config = config;
}

RequestStatsStore& RequestStatsStore::instance() { return statsStore; }

RequestStatsStore::RequestStatsStore(const RequestStatsStoreConfig& conf)
    : config(conf) {}

RequestStatsStore::~RequestStatsStore() = default;

nlohmann::json RequestStatsStore::toJson() const {
  nlohmann::json obj;
  obj["config"] = this->config.toJson();

  if (isRdeRateLimitEnabled()) {
    obj["rdeStats"] = nlohmann::json::object();
    obj["rdeStats"]["totalReqs"] = this->rdeStats.totalReqs;
    obj["rdeStats"]["totalDbusErrors"] = this->rdeStats.totalDbusErrors;
    obj["rdeStats"]["totalSkips"] = this->rdeStats.totalSkips;
    obj["rdeStats"]["totalRateLimitToggles"] =
        this->rdeStats.totalRateLimitToggles;
    obj["rdeStats"]["CurrentRdeDbusErrorCount"] =
        this->rdeStats.rdeDbusErrorCount;
    obj["rdeStats"]["CurrentRdeRequestSkips"] = this->rdeStats.rdeRequestSkips;
  }

  // TODO: pick on of these:
  // obj["statsList"] = nlohmann::json::array();
  obj["statsMap"] = nlohmann::json::object();

  for (const auto& query_stats : this->requestURLStats) {
    auto query_stats_json = query_stats.second.toJson();
    query_stats_json["target"] = query_stats.first;
    // obj["statsList"].push_back(query_stats_json);
    obj["statsMap"][query_stats.first] = query_stats_json;
  }
  return obj;
}

void RequestStatsStore::clear() {
  this->requestURLStats.clear();
  this->rdeStats.clear();
}

void RequestStatsStore::logRequestStats(
    std::chrono::steady_clock::time_point now,
    const RequestStatsContext& requestStatsContext) {
  BMCWEB_LOG_DEBUG << "logRequestStats: " << requestStatsContext.toJson();

  // auto iter =
  //     this->requestURLStats.find(requestStatsContext.getQueryURLKey());
  // if (iter == this->requestURLStats.end())
  // {
  //     this->requestURLStats[requestStatsContext.getQueryURLKey()] =
  //         RequestStats();
  //     iter =
  //     this->requestURLStats.find(requestStatsContext.getQueryURLKey());
  // }

  auto insert_ret = this->requestURLStats.insert(
      {requestStatsContext.getQueryURLKey(), RequestStats()});
  auto insert_ret_iter = insert_ret.first;

  // check again, just in case
  if (insert_ret_iter == this->requestURLStats.end()) {
    BMCWEB_LOG_ERROR << "failed to allocate stats for: "
                     << requestStatsContext.getQueryURLKey();
    return;
  }

  RequestStats& request_stats = insert_ret_iter->second;

  // log returned status code:
  if (requestStatsContext.ok()) {
    request_stats.countOK += 1;
  } else {
    request_stats.countError += 1;
  }

  // calculate and export latency:
  const int64_t latency_milliseconds = managedStore::clockSinceMilliseconds(
      requestStatsContext.getTimepointStart(), now);

  if (latency_milliseconds >= 0) {
    int64_t bucket_index = latency_milliseconds / kHistBucketSizeMillisec;

    // last bucket is "catch all":
    if (bucket_index >= kHistNumBuckets) {
      bucket_index = kHistNumBuckets;
    }
    // increment the right histogram bucket:
    request_stats.latencyHistogramMilliseconds[kHistBucketSizeMillisec *
                                               (1 + bucket_index)] += 1;
  } else {
    BMCWEB_LOG_ERROR << "logRequestStats:"
                     << " context: " << requestStatsContext.toJson()
                     << " latency_milliseconds: " << latency_milliseconds
                     << " negative";
  }

  BMCWEB_LOG_INFO << "logRequestStats: iter: "
                  << insert_ret_iter->second.toJson()
                  << " requestStatsContext: " << requestStatsContext.toJson();
}

void RequestStatsStore::logRdeRequestStats(
    const RequestStatsContext& requestStatsContext) {
  BMCWEB_LOG_DEBUG << "logRdeRequestStats: " << requestStatsContext.toJson();
  this->rdeStats.totalReqs += requestStatsContext.getRdeReqs();
  this->rdeStats.totalDbusErrors += requestStatsContext.getRdeDbusErrors();
  this->rdeStats.totalSkips += requestStatsContext.getRdeSkips();
  this->rdeStats.totalRateLimitToggles +=
      requestStatsContext.getRdeRateLimitToggles();
}

void RequestStatsStore::updateCurrentRdeDbusErrors() {
  this->rdeStats.rdeDbusErrorCount += 1;
}
int RequestStatsStore::getCurrentRdeDbusErrors() const {
  return this->rdeStats.rdeDbusErrorCount;
}
void RequestStatsStore::setCurrentRdeDbusErrors(int errCount) {
  this->rdeStats.rdeDbusErrorCount = errCount;
}

void RequestStatsStore::updateCurrentRdeRequestSkips() {
  if (this->rdeStats.rdeRequestSkips > 0) {
    this->rdeStats.rdeRequestSkips -= 1;
  }
}
int RequestStatsStore::getCurrentRdeRequestSkips() const {
  return this->rdeStats.rdeRequestSkips;
}
void RequestStatsStore::setCurrentRdeRequestSkips(int skipCount) {
  this->rdeStats.rdeRequestSkips = skipCount;
}

}  // namespace managedStore