/** @file

  A brief file description

  @section license License

  Licensed to the Apache Software Foundation (ASF) under one
  or more contributor license agreements.  See the NOTICE file
  distributed with this work for additional information
  regarding copyright ownership.  The ASF licenses this file
  to you under the Apache License, Version 2.0 (the
  "License"); you may not use this file except in compliance
  with the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
 */

#pragma once

#include "iocore/eventsystem/VConnection.h"
#include "proxy/ProxyTransaction.h"
#include "iocore/net/quic/QUICStreamVCAdapter.h"
#include "proxy/http3/Http3FrameDispatcher.h"
#include "proxy/http3/Http3FrameCollector.h"
#include "proxy/http3/Http3HeaderFramer.h"
#include "proxy/http3/Http3DataFramer.h"
#include "proxy/http3/Http3ProtocolEnforcer.h"
#include "proxy/http3/Http3HeaderVIOAdaptor.h"
#include "proxy/http3/Http3StreamDataVIOAdaptor.h"

#include <functional>

class QUICStreamIO;
class HQSession;
class Http09Session;
class Http3Session;

class HQTransaction : public ProxyTransaction
{
public:
  using super = ProxyTransaction;

  HQTransaction(HQSession *session, QUICStreamVCAdapter::IOInfo &info);
  virtual ~HQTransaction();

  // Implement ProxyClienTransaction interface
  void set_active_timeout(ink_hrtime timeout_in) override;
  void set_inactivity_timeout(ink_hrtime timeout_in) override;
  void cancel_inactivity_timeout() override;
  void transaction_done() override;
  void release() override;
  int  get_transaction_id() const override;
  void stream_closed();
  void set_stream_cleanup(std::function<void()> cleanup);
  void increment_transactions_stat() override;
  void decrement_transactions_stat() override;

  // VConnection interface
  virtual VIO *do_io_read(Continuation *c, int64_t nbytes = INT64_MAX, MIOBuffer *buf = 0) override;
  virtual VIO *do_io_write(Continuation *c = nullptr, int64_t nbytes = INT64_MAX, IOBufferReader *buf = 0,
                           bool owner = false) override;
  virtual void do_io_close(int lerrno = -1) override;
  virtual void do_io_shutdown(ShutdownHowTo_t) override;
  virtual void reenable(VIO *) override;

  // HQTransaction
  virtual int             state_stream_open(int event, Event *data)   = 0;
  virtual int             state_stream_closed(int event, Event *data) = 0;
  NetVConnectionContext_t direction() const;

  /** Full-width QUIC stream identifier for this transaction.
   *
   *  @c get_transaction_id returns @c int and exists primarily for compact log
   *  fields and probe arguments; QUIC stream IDs are 62-bit values, so callers
   *  that route or compare by stream ID must use this accessor to avoid
   *  truncation.
   *
   *  @return The QUIC stream ID owned by this transaction.
   */
  QUICStreamId get_quic_stream_id() const;

  // For Queue from tscore/Link.h
  LINK(HQTransaction, link);

protected:
  virtual int64_t _process_read_vio()  = 0;
  virtual int64_t _process_write_vio() = 0;
  void            _schedule_read_ready_event();
  void            _unschedule_read_ready_event();
  void            _close_read_ready_event(Event *e);
  void            _schedule_read_complete_event();
  void            _unschedule_read_complete_event();
  void            _close_read_complete_event(Event *e);
  void            _schedule_read_event();
  void            _schedule_write_ready_event();
  void            _unschedule_write_ready_event();
  void            _close_write_ready_event(Event *e);
  void            _schedule_write_complete_event();
  void            _unschedule_write_complete_event();
  void            _close_write_complete_event(Event *e);
  void            _signal_event(int event, Event *e);
  void            _signal_read_event();
  void            _signal_write_event();
  bool            _is_write_buffer_flushed();
  virtual bool    _is_closed() const = 0;
  bool            _is_stream_closed() const;
  void            _delete_if_possible();

  EThread *_thread = nullptr;

  MIOBuffer                    _read_vio_buf{BUFFER_SIZE_INDEX_4K};
  QUICStreamVCAdapter::IOInfo &_info;
  QUICStreamId                 _stream_id = 0;

  size_t _sent_bytes = 0;

  VIO    _read_vio;
  VIO    _write_vio;
  Event *_read_ready_event     = nullptr;
  Event *_read_complete_event  = nullptr;
  Event *_write_ready_event    = nullptr;
  Event *_write_complete_event = nullptr;

  bool _transaction_done     = false;
  bool _event_handler_active = false;

  std::function<void()> _stream_cleanup;
};

class Http3Transaction : public HQTransaction
{
public:
  using super = HQTransaction;

  Http3Transaction(Http3Session *session, QUICStreamVCAdapter::IOInfo &info);
  virtual ~Http3Transaction();

  VIO *do_io_write(Continuation *c = nullptr, int64_t nbytes = INT64_MAX, IOBufferReader *buf = nullptr,
                   bool owner = false) override;
  int  state_stream_open(int event, Event *data) override;
  int  state_stream_closed(int event, Event *data) override;

  void do_io_close(int lerrno = -1) override;
  void on_header_decode_complete();

  bool is_response_header_sent() const;
  bool is_response_body_sent() const;

  // TODO:  Just a place holder for now
  bool has_request_body(int64_t content_length, bool is_chunked_set) const override;

private:
  int64_t _process_read_vio() override;
  int64_t _process_write_vio() override;
  bool    _is_closed() const override;
  void    _handle_error(const Http3Error &error);

  // These are for HTTP/3
  Http3FrameDispatcher      _frame_dispatcher;
  Http3FrameCollector       _frame_collector;
  Http3ProtocolEnforcer     _protocol_enforcer;
  Http3HeaderFramer         _header_framer;
  Http3DataFramer           _data_framer;
  Http3HeaderVIOAdaptor     _header_handler;
  Http3StreamDataVIOAdaptor _data_handler;
};

/**
   Only for interop. Will be removed.
 */
class Http09Transaction : public HQTransaction
{
public:
  using super = HQTransaction;

  Http09Transaction(Http09Session *session, QUICStreamVCAdapter::IOInfo &info);
  ~Http09Transaction();

  int state_stream_open(int event, Event *data) override;
  int state_stream_closed(int event, Event *data) override;

  void do_io_close(int lerrno = -1) override;

private:
  int64_t _process_read_vio() override;
  int64_t _process_write_vio() override;
  bool    _is_closed() const override;

  // These are for HTTP/0.9
  bool _protocol_detected          = false;
  bool _legacy_request             = false;
  bool _client_req_header_complete = false;
};