#pragma once

#include <memory>

#include <string>

#include <vector>

#include "envoy/common/pure.h"

#include "envoy/stats/tag.h"

#include "absl/strings/string_view.h"

namespace Envoy {

namespace Stats {

class TagProducer {

public:

  /**

   * Take a metric name and a vector then add proper tags into the vector and

   * return an extracted metric name. The tags array will be populated with

   * name/value pairs extracted from the full metric name, using the regular

   * expressions in source/common/config/well_known_names.cc. For example, the

   * stat name "vhost.foo.vcluster.bar.c1" would have "foo" extracted as the

   * value of tag "vhost" and "bar" extracted as the value of tag

   * "vcluster", so this will populate tags with {"vhost", "foo"} and

   * {"vcluster", "bar"}, and return "vhost.vcluster.c1".

   *

   * @param metric_name std::string a name of Stats::Metric (Counter, Gauge, Histogram).

   * @param tags TagVector a set of Stats::Tag.

   */

  virtual std::string produceTags(absl::string_view metric_name, TagVector& tags) const PURE;

  virtual const TagVector& fixedTags() const PURE;

};

using TagProducerPtr = std::unique_ptr<const TagProducer>;

} // namespace Stats

} // namespace Envoy