#pragma once

#include "envoy/http/filter.h"

#include "envoy/http/header_map.h"

#include "envoy/stats/scope.h"

#include "envoy/stats/stats_macros.h"

#include "envoy/stream_info/stream_info.h"

#include "envoy/upstream/cluster_manager.h"

#include "envoy/upstream/host_description.h"

namespace Envoy {

namespace Router {

class UpstreamRequest;

// This groups various per-stream timeouts conveniently together.

struct TimeoutData {

  std::chrono::milliseconds global_timeout_{0};

  std::chrono::milliseconds per_try_timeout_{0};

  std::chrono::milliseconds per_try_idle_timeout_{0};

};

// The interface the UpstreamRequest has to interact with the router filter.

class RouterFilterInterface {

public:

  /**

   * This will be called when upstream 1xx headers are ready to be processed by downstream code.

   * @param headers contains the 1xx headers

   * @param upstream_request inicates which UpstreamRequest the 1xx headers are from.

   *

   */

  virtual void onUpstream1xxHeaders(Http::ResponseHeaderMapPtr&& headers,

                                    UpstreamRequest& upstream_request) PURE;

  /**

   * This will be called when upstream non-1xx headers are ready to be processed by downstream code.

   * @param headers contains the headers

   * @param upstream_request inicates which UpstreamRequest the headers are from.

   * @param end_stream indicates if the response is complete.

   *

   */

  virtual void onUpstreamHeaders(uint64_t response_code, Http::ResponseHeaderMapPtr&& headers,

                                 UpstreamRequest& upstream_request, bool end_stream) PURE;

  /**

   * This will be called when upstream data is ready to be processed by downstream code.

   * @param data contains the data to process

   * @param upstream_request inicates which UpstreamRequest the data is from.

   * @param end_stream indicates if the response is complete.

   *

   */

  virtual void onUpstreamData(Buffer::Instance& data, UpstreamRequest& upstream_request,

                              bool end_stream) PURE;

  /**

   * This will be called when upstream trailers are ready to be processed by downstream code.

   * @param trailers contains the trailers to process

   * @param upstream_request inicates which UpstreamRequest the trailers are from.

   *

   */

  virtual void onUpstreamTrailers(Http::ResponseTrailerMapPtr&& trailers,

                                  UpstreamRequest& upstream_request) PURE;

  /**

   * This will be called when upstream metadata is ready to be processed by downstream code.

   * @param metadata contains the metadata to process

   * @param upstream_request inicates which UpstreamRequest the metadata is from.

   *

   */

  virtual void onUpstreamMetadata(Http::MetadataMapPtr&& metadata_map) PURE;

  /**

   * This will be called when an upstream reset is ready to be processed by downstream code.

   * @param reset_reason indicates the reason for the reset.

   * @param transport_failure optionally indicates any transport failure.

   * @param upstream_request inicates which UpstreamRequest the reset is from.

   *

   */

  virtual void onUpstreamReset(Http::StreamResetReason reset_reason,

                               absl::string_view transport_failure,

                               UpstreamRequest& upstream_request) PURE;

  /**

   * This will be called when an upstream host is selected. This is called both

   * if the host can accomodate the stream and if the host is selected but unusable.

   * @param host the host selected for the request

   * @param pool_success indicates if the host can be used for the request.

   */

  virtual void onUpstreamHostSelected(Upstream::HostDescriptionConstSharedPtr host,

                                      bool pool_success) PURE;

  /*

   * This will be called if a per-try timeout fails.

   * @param upstream_request inicates which UpstreamRequest which timed out

   */

  virtual void onPerTryTimeout(UpstreamRequest& upstream_request) PURE;

  /*

   * This will be called if a per-try idle timeout fails.

   * @param upstream_request inicates which UpstreamRequest which timed out

   */

  virtual void onPerTryIdleTimeout(UpstreamRequest& upstream_request) PURE;

  /*

   * This will be called if the max stream duration was reached.

   * @param upstream_request inicates which UpstreamRequest which timed out

   */

  virtual void onStreamMaxDurationReached(UpstreamRequest& upstream_request) PURE;

  /*

   * This will be called to set up the route timeout early for websocket upgrades.

   * This ensures the timeout is active during the upgrade negotiation phase.

   */

  virtual void setupRouteTimeoutForWebsocketUpgrade() PURE;

  /*

   * This will be called to disable the route timeout after websocket upgrade completes.

   * This prevents the timeout from firing after successful upgrade.

   */

  virtual void disableRouteTimeoutForWebsocketUpgrade() PURE;

  /*

   * @returns the Router filter's StreamDecoderFilterCallbacks.

   */

  virtual Http::StreamDecoderFilterCallbacks* callbacks() PURE;

  /*

   * @returns the cluster for this stream.

   */

  virtual Upstream::ClusterInfoConstSharedPtr cluster() PURE;

  /*

   * @returns the FilterConfig for this stream

   */

  virtual FilterConfig& config() PURE;

  /*

   * @returns the various timeouts for this stream.

   */

  virtual TimeoutData timeout() PURE;

  /*

   * @returns the dynamic max stream duraration for this stream, if set.

   */

  virtual absl::optional<std::chrono::milliseconds> dynamicMaxStreamDuration() const PURE;

  /*

   * @returns the request headers for the stream.

   */

  virtual Http::RequestHeaderMap* downstreamHeaders() PURE;

  /*

   * @returns the request trailers for the stream.

   */

  virtual Http::RequestTrailerMap* downstreamTrailers() PURE;

  /*

   * @returns true if the downstream response has started.

   */

  virtual bool downstreamResponseStarted() const PURE;

  /*

   * @returns true if end_stream has been sent from the upstream side to the downstream side.

   */

  virtual bool downstreamEndStream() const PURE;

  /*

   * @returns the number of attempts (e.g. retries) performed for this stream.

   */

  virtual uint32_t attemptCount() const PURE;

};

} // namespace Router

} // namespace Envoy