#include "source/common/router/metadatamatchcriteria_impl.h"

namespace Envoy {

namespace Router {

std::vector<MetadataMatchCriterionConstSharedPtr>

MetadataMatchCriteriaImpl::extractMetadataMatchCriteria(const MetadataMatchCriteriaImpl* parent,

                                                        const ProtobufWkt::Struct& matches) {

  std::vector<MetadataMatchCriterionConstSharedPtr> v;

  // Track locations of each name (from the parent) in v to make it

  // easier to replace them when the same name exists in matches.

  absl::node_hash_map<std::string, std::size_t> existing;

  if (parent) {

    for (const auto& it : parent->metadata_match_criteria_) {

      // v.size() is the index of the emplaced name.

      existing.emplace(it->name(), v.size());

      v.emplace_back(it);

    }

  }

  // Add values from matches, replacing name/values copied from parent.

  for (const auto& it : matches.fields()) {

    const auto index_it = existing.find(it.first);

    if (index_it != existing.end()) {

      v[index_it->second] = std::make_shared<MetadataMatchCriterionImpl>(it.first, it.second);

    } else {

      v.emplace_back(std::make_shared<MetadataMatchCriterionImpl>(it.first, it.second));

    }

  }

  // Sort criteria by name to speed matching in the subset load balancer.

  // See source/docs/subset_load_balancer.md.

  std::sort(

      v.begin(), v.end(),

      [](const MetadataMatchCriterionConstSharedPtr& a,

         const MetadataMatchCriterionConstSharedPtr& b) -> bool { return a->name() < b->name(); });

  return v;

}

MetadataMatchCriteriaConstPtr

MetadataMatchCriteriaImpl::filterMatchCriteria(const std::set<std::string>& names) const {

  std::vector<MetadataMatchCriterionConstSharedPtr> v;

  // iterating over metadata_match_criteria_ ensures correct order without sorting

  for (const auto& it : metadata_match_criteria_) {

    if (names.count(it->name()) == 1) {

      v.emplace_back(it);

    }

  }

  return MetadataMatchCriteriaImplConstPtr(new MetadataMatchCriteriaImpl(v));

};

} // namespace Router

} // namespace Envoy