#pragma once

#include "envoy/formatter/http_formatter_context.h"

#include "envoy/http/header_map.h"

#include "envoy/stream_info/stream_info.h"

namespace Envoy {

namespace Http {

// The interface of applying operations to a header map.

class HeaderEvaluator {

public:

  /**

   * Apply the header operations that are saved in the HeaderEvaluator. An example of the operation

   * is to add a new header name `foo` to the target header map and the header value is extracted

   * from the `bar` field in the stream_info, request headers or response headers.

   *

   * @param headers the target header map to be mutated.

   * @param context context to format the header value.

   * @param stream_info the source of values that can be used in the evaluation.

   */

  virtual void evaluateHeaders(Http::HeaderMap& headers, const Formatter::Context& context,

                               const StreamInfo::StreamInfo& stream_info) const PURE;

};

} // namespace Http

} // namespace Envoy