#pragma once

#include "envoy/config/route/v3/route_components.pb.h"

#include "envoy/http/hash_policy.h"

#include "envoy/stream_info/filter_state.h"

namespace Envoy {

namespace Regex {

class Engine;

}

namespace Http {

/**

 * Implementation of HashPolicy that reads from the proto route config.

 */

class HashPolicyImpl : public HashPolicy {

public:

  static absl::StatusOr<std::unique_ptr<HashPolicyImpl>>

  create(absl::Span<const envoy::config::route::v3::RouteAction::HashPolicy* const> hash_policy,

         Regex::Engine& regex_engine);

  // Http::HashPolicy

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

                                        OptRef<const StreamInfo::StreamInfo> info,

                                        AddCookieCallback add_cookie = nullptr) const override;

  class HashMethod {

  public:

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

                                              OptRef<const StreamInfo::StreamInfo> info,

                                              AddCookieCallback add_cookie = nullptr) const PURE;

    // If the method is a terminal method, ignore rest of the hash policy chain.

    virtual bool terminal() const PURE;

  };

  using HashMethodPtr = std::unique_ptr<HashMethod>;

protected:

  explicit HashPolicyImpl(

      absl::Span<const envoy::config::route::v3::RouteAction::HashPolicy* const> hash_policy,

      Regex::Engine& regex_engine, absl::Status& creation_status);

private:

  std::vector<HashMethodPtr> hash_impls_;

};

} // namespace Http

} // namespace Envoy