#pragma once

#include "envoy/http/header_map.h"

#include "envoy/stream_info/stream_info.h"

#include "absl/types/optional.h"

namespace Envoy {

namespace Http {

/**

 * CookieAttribute that stores the name and value of a cookie.

 */

class CookieAttribute {

public:

  std::string name_;

  std::string value_;

};

/**

 * Request hash policy. I.e., if using a hashing load balancer, how a request should be hashed onto

 * an upstream host.

 */

class HashPolicy {

public:

  /**

   * A callback used for requesting that a cookie be set with the given lifetime.

   * @param key the name of the cookie to be set

   * @param path the path of the cookie, or the empty string if no path should be set.

   * @param ttl the lifetime of the cookie

   * @return std::string the opaque value of the cookie that will be set

   */

  using AddCookieCallback = std::function<std::string(

      absl::string_view name, absl::string_view path, std::chrono::seconds ttl,

      absl::Span<const CookieAttribute> attributes)>;

  /**

   * @param headers stores the HTTP headers for the stream.

   * @param info stores the stream info for the stream.

   * @param add_cookie is called to add a set-cookie header on the reply sent to the downstream

   * host.

   * @return absl::optional<uint64_t> an optional hash value to route on. A hash value might not be

   * returned if for example the specified HTTP header does not exist.

   */

  virtual absl::optional<uint64_t> generateHash(OptRef<const RequestHeaderMap> headers,

                                                OptRef<const StreamInfo::StreamInfo> info,

                                                AddCookieCallback add_cookie = nullptr) const PURE;

};

} // namespace Http

} // namespace Envoy