#pragma once

#include "envoy/config/typed_config.h"

#include "envoy/stream_info/filter_state.h"

#include "source/common/common/logger.h"

#include "absl/strings/string_view.h"

namespace Envoy {

namespace Router {

/**

 * Used to decide if an internal redirect is allowed to be followed based on the target route.

 * Subclassing Logger::Loggable so that implementations can log details.

 */

class InternalRedirectPredicate : Logger::Loggable<Logger::Id::router> {

public:

  /**

   * A FilterState is provided so that predicate implementation can use it to preserve state across

   * internal redirects.

   * @param filter_state supplies the filter state associated with the current request so that the

   *        predicates can use it to persist states across filter chains.

   * @param target_route_name indicates the route that an internal redirect is targeting.

   * @param downstream_is_https indicates the downstream request is using https.

   * @param target_is_https indicates the internal redirect target url has https in the url.

   * @return whether the route specified by target_route_name is allowed to be followed. Any

   *         predicate returning false will prevent the redirect from being followed, causing the

   *         response to be proxied downstream.

   */

  virtual bool acceptTargetRoute(StreamInfo::FilterState& filter_state,

                                 absl::string_view target_route_name, bool downstream_is_https,

                                 bool target_is_https) PURE;

  /**

   * @return the name of the current predicate.

   */

  virtual absl::string_view name() const PURE;

};

using InternalRedirectPredicateSharedPtr = std::shared_ptr<InternalRedirectPredicate>;

/**

 * Factory for InternalRedirectPredicate.

 */

class InternalRedirectPredicateFactory : public Config::TypedFactory {

public:

  /**

   * @param config contains the proto stored in TypedExtensionConfig.typed_config for the predicate.

   * @param current_route_name stores the route name of the route where the predicate is installed.

   * @return an InternalRedirectPredicate. The given current_route_name is useful for predicates

   *         that need to create per-route FilterState.

   */

  virtual InternalRedirectPredicateSharedPtr

  createInternalRedirectPredicate(const Protobuf::Message& config,

                                  absl::string_view current_route_name) PURE;

};

} // namespace Router

} // namespace Envoy