// Copyright 2022 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef QUICHE_QUIC_CONNECT_PROXY_CONNECT_SERVER_BACKEND_H_
#define QUICHE_QUIC_CONNECT_PROXY_CONNECT_SERVER_BACKEND_H_

#include <cstdint>
#include <memory>
#include <string>
#include <utility>

#include "absl/container/flat_hash_map.h"
#include "absl/container/flat_hash_set.h"
#include "quiche/quic/core/io/socket_factory.h"
#include "quiche/quic/core/quic_types.h"
#include "quiche/quic/tools/connect_tunnel.h"
#include "quiche/quic/tools/quic_simple_server_backend.h"

namespace quic {

// QUIC server backend that handles CONNECT requests. Non-CONNECT requests are
// delegated to a separate backend.
class ConnectServerBackend : public QuicSimpleServerBackend {
 public:
  ConnectServerBackend(
      std::unique_ptr<QuicSimpleServerBackend> non_connect_backend,
      absl::flat_hash_set<ConnectTunnel::HostAndPort> acceptable_destinations);

  ConnectServerBackend(const ConnectServerBackend&) = delete;
  ConnectServerBackend& operator=(const ConnectServerBackend&) = delete;

  ~ConnectServerBackend() override;

  // QuicSimpleServerBackend:
  bool InitializeBackend(const std::string& backend_url) override;
  bool IsBackendInitialized() const override;
  void SetSocketFactory(SocketFactory* socket_factory) override;
  void FetchResponseFromBackend(const spdy::Http2HeaderBlock& request_headers,
                                const std::string& request_body,
                                RequestHandler* request_handler) override;
  void HandleConnectHeaders(const spdy::Http2HeaderBlock& request_headers,
                            RequestHandler* request_handler) override;
  void HandleConnectData(absl::string_view data, bool data_complete,
                         RequestHandler* request_handler) override;
  void CloseBackendResponseStream(
      QuicSimpleServerBackend::RequestHandler* request_handler) override;

 private:
  std::unique_ptr<QuicSimpleServerBackend> non_connect_backend_;
  const absl::flat_hash_set<ConnectTunnel::HostAndPort>
      acceptable_destinations_;

  SocketFactory* socket_factory_;  // unowned
  absl::flat_hash_map<QuicStreamId, std::unique_ptr<ConnectTunnel>> tunnels_;
};

}  // namespace quic

#endif  // QUICHE_QUIC_CONNECT_PROXY_CONNECT_SERVER_BACKEND_H_