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

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

#include "source/common/http/headers.h"

namespace Envoy {

namespace Server {

namespace Utility {

void populateFallbackResponseHeaders(Http::Code code, Http::ResponseHeaderMap& header_map) {

  header_map.setStatus(std::to_string(enumToInt(code)));

  if (header_map.ContentType() == nullptr) {

    // Default to text-plain if unset.

    header_map.setReferenceContentType(Http::Headers::get().ContentTypeValues.TextUtf8);

  }

  // Default to 'no-cache' if unset, but not 'no-store' which may break the back button.

  if (header_map.get(Http::CustomHeaders::get().CacheControl).empty()) {

    header_map.setReference(Http::CustomHeaders::get().CacheControl,

                            Http::CustomHeaders::get().CacheControlValues.NoCacheMaxAge0);

  }

  // Under no circumstance should browsers sniff content-type.

  header_map.addReference(Http::Headers::get().XContentTypeOptions,

                          Http::Headers::get().XContentTypeOptionValues.Nosniff);

}

// Helper method to get the histogram_buckets parameter. Returns false if histogram_buckets query

// param is found and value is not "cumulative" or "disjoint", true otherwise.

absl::Status histogramBucketsParam(const Http::Utility::QueryParams& params,

                                   HistogramBucketsMode& histogram_buckets_mode) {

  absl::optional<std::string> histogram_buckets_query_param =

      queryParam(params, "histogram_buckets");

  histogram_buckets_mode = HistogramBucketsMode::NoBuckets;

  if (histogram_buckets_query_param.has_value()) {

    if (histogram_buckets_query_param.value() == "cumulative") {

      histogram_buckets_mode = HistogramBucketsMode::Cumulative;

    } else if (histogram_buckets_query_param.value() == "disjoint") {

      histogram_buckets_mode = HistogramBucketsMode::Disjoint;

    } else if (histogram_buckets_query_param.value() == "detailed") {

      histogram_buckets_mode = HistogramBucketsMode::Detailed;

    } else if (histogram_buckets_query_param.value() != "none") {

      return absl::InvalidArgumentError(

          "usage: /stats?histogram_buckets=(cumulative|disjoint|none)\n");

    }

  }

  return absl::OkStatus();

}

// Helper method to get the format parameter.

absl::optional<std::string> formatParam(const Http::Utility::QueryParams& params) {

  return queryParam(params, "format");

}

// Helper method to get a query parameter.

absl::optional<std::string> queryParam(const Http::Utility::QueryParams& params,

                                       const std::string& key) {

  const auto iter = params.find(key);

  if (iter != params.end()) {

    const std::string& value = iter->second;

    if (!value.empty()) {

      return value;

    }

  }

  return absl::nullopt;

}

} // namespace Utility

} // namespace Server

} // namespace Envoy