#ifndef SRC_NODE_HTTP2_H_
#define SRC_NODE_HTTP2_H_

#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

// FIXME(joyeecheung): nghttp2.h needs stdint.h to compile on Windows
#include <cstdint>
#include "nghttp2/nghttp2.h"

#include "env.h"
#include "allocated_buffer.h"
#include "aliased_struct.h"
#include "node_http2_state.h"
#include "node_http_common.h"
#include "node_mem.h"
#include "node_perf.h"
#include "stream_base.h"
#include "string_bytes.h"

#include <algorithm>
#include <queue>

namespace node {
namespace http2 {

// Constants in all caps are exported as user-facing constants
// in JavaScript. Constants using the kName pattern are internal
// only.

// We strictly limit the number of outstanding unacknowledged PINGS a user
// may send in order to prevent abuse. The current default cap is 10. The
// user may set a different limit using a per Http2Session configuration
// option.
constexpr size_t kDefaultMaxPings = 10;

// Also strictly limit the number of outstanding SETTINGS frames a user sends
constexpr size_t kDefaultMaxSettings = 10;

// Default maximum total memory cap for Http2Session.
constexpr uint64_t kDefaultMaxSessionMemory = 10000000;

// These are the standard HTTP/2 defaults as specified by the RFC
constexpr uint32_t DEFAULT_SETTINGS_HEADER_TABLE_SIZE = 4096;
constexpr uint32_t DEFAULT_SETTINGS_ENABLE_PUSH = 1;
constexpr uint32_t DEFAULT_SETTINGS_MAX_CONCURRENT_STREAMS = 0xffffffffu;
constexpr uint32_t DEFAULT_SETTINGS_INITIAL_WINDOW_SIZE = 65535;
constexpr uint32_t DEFAULT_SETTINGS_MAX_FRAME_SIZE = 16384;
constexpr uint32_t DEFAULT_SETTINGS_MAX_HEADER_LIST_SIZE = 65535;
constexpr uint32_t DEFAULT_SETTINGS_ENABLE_CONNECT_PROTOCOL = 0;
constexpr uint32_t MAX_MAX_FRAME_SIZE = 16777215;
constexpr uint32_t MIN_MAX_FRAME_SIZE = DEFAULT_SETTINGS_MAX_FRAME_SIZE;
constexpr uint32_t MAX_INITIAL_WINDOW_SIZE = 2147483647;

// Stream is not going to have any DATA frames
constexpr int STREAM_OPTION_EMPTY_PAYLOAD = 0x1;

// Stream might have trailing headers
constexpr int STREAM_OPTION_GET_TRAILERS = 0x2;

// Http2Stream internal states
constexpr int kStreamStateNone = 0x0;
constexpr int kStreamStateShut = 0x1;
constexpr int kStreamStateReadStart = 0x2;
constexpr int kStreamStateReadPaused = 0x4;
constexpr int kStreamStateClosed = 0x8;
constexpr int kStreamStateDestroyed = 0x10;
constexpr int kStreamStateTrailers = 0x20;

// Http2Session internal states
constexpr int kSessionStateNone = 0x0;
constexpr int kSessionStateHasScope = 0x1;
constexpr int kSessionStateWriteScheduled = 0x2;
constexpr int kSessionStateClosed = 0x4;
constexpr int kSessionStateClosing = 0x8;
constexpr int kSessionStateSending = 0x10;
constexpr int kSessionStateWriteInProgress = 0x20;
constexpr int kSessionStateReadingStopped = 0x40;
constexpr int kSessionStateReceivePaused = 0x80;

// The Padding Strategy determines the method by which extra padding is
// selected for HEADERS and DATA frames. These are configurable via the
// options passed in to a Http2Session object.
enum PaddingStrategy {
 // No padding strategy. This is the default.
 PADDING_STRATEGY_NONE,
 // Attempts to ensure that the frame is 8-byte aligned
 PADDING_STRATEGY_ALIGNED,
 // Padding will ensure all data frames are maxFrameSize
 PADDING_STRATEGY_MAX,
 // Removed and turned into an alias because it is unreasonably expensive for
 // very little benefit.
 PADDING_STRATEGY_CALLBACK = PADDING_STRATEGY_ALIGNED
};

enum SessionType {
 NGHTTP2_SESSION_SERVER,
 NGHTTP2_SESSION_CLIENT
};

template <typename T, void(*fn)(T*)>
struct Nghttp2Deleter {
 void operator()(T* ptr) const noexcept { fn(ptr); }
};

using Nghttp2OptionPointer =
 std::unique_ptr<nghttp2_option,
 Nghttp2Deleter<nghttp2_option, nghttp2_option_del>>;

using Nghttp2SessionPointer =
 std::unique_ptr<nghttp2_session,
 Nghttp2Deleter<nghttp2_session, nghttp2_session_del>>;

using Nghttp2SessionCallbacksPointer =
 std::unique_ptr<nghttp2_session_callbacks,
 Nghttp2Deleter<nghttp2_session_callbacks,
 nghttp2_session_callbacks_del>>;

struct Http2HeadersTraits {
 typedef nghttp2_nv nv_t;
};

struct Http2RcBufferPointerTraits {
 typedef nghttp2_rcbuf rcbuf_t;
 typedef nghttp2_vec vector_t;

 static void inc(rcbuf_t* buf) {
 CHECK_NOT_NULL(buf);
 nghttp2_rcbuf_incref(buf);
 }
 static void dec(rcbuf_t* buf) {
 CHECK_NOT_NULL(buf);
 nghttp2_rcbuf_decref(buf);
 }
 static vector_t get_vec(rcbuf_t* buf) {
 CHECK_NOT_NULL(buf);
 return nghttp2_rcbuf_get_buf(buf);
 }
 static bool is_static(const rcbuf_t* buf) {
 CHECK_NOT_NULL(buf);
 return nghttp2_rcbuf_is_static(buf);
 }
};

using Http2Headers = NgHeaders<Http2HeadersTraits>;
using Http2RcBufferPointer = NgRcBufPointer<Http2RcBufferPointerTraits>;

struct NgHttp2StreamWrite : public MemoryRetainer {
 BaseObjectPtr<AsyncWrap> req_wrap;
 uv_buf_t buf;

 inline explicit NgHttp2StreamWrite(uv_buf_t buf_) : buf(buf_) {}
 inline NgHttp2StreamWrite(BaseObjectPtr<AsyncWrap> req_wrap, uv_buf_t buf_) :
 req_wrap(std::move(req_wrap)), buf(buf_) {}

 void MemoryInfo(MemoryTracker* tracker) const override;
 SET_MEMORY_INFO_NAME(NgHttp2StreamWrite)
 SET_SELF_SIZE(NgHttp2StreamWrite)
};

typedef uint32_t(*get_setting)(nghttp2_session* session,
 nghttp2_settings_id id);

class Http2Ping;
class Http2Session;
class Http2Settings;
class Http2Stream;
class Origins;

// This scope should be present when any call into nghttp2 that may schedule
// data to be written to the underlying transport is made, and schedules
// such a write automatically once the scope is exited.
class Http2Scope {
 public:
 explicit Http2Scope(Http2Stream* stream);
 explicit Http2Scope(Http2Session* session);
 ~Http2Scope();

 private:
 BaseObjectPtr<Http2Session> session_;
};

// The Http2Options class is used to parse the options object passed in to
// a Http2Session object and convert those into an appropriate nghttp2_option
// struct. This is the primary mechanism by which the Http2Session object is
// configured.
class Http2Options {
 public:
 Http2Options(Http2State* http2_state,
 SessionType type);

 ~Http2Options() = default;

 nghttp2_option* operator*() const {
 return options_.get();
 }

 void set_max_header_pairs(uint32_t max) {
 max_header_pairs_ = max;
 }

 uint32_t max_header_pairs() const {
 return max_header_pairs_;
 }

 void set_padding_strategy(PaddingStrategy val) {
 padding_strategy_ = val;
 }

 PaddingStrategy padding_strategy() const {
 return padding_strategy_;
 }

 void set_max_outstanding_pings(size_t max) {
 max_outstanding_pings_ = max;
 }

 size_t max_outstanding_pings() const {
 return max_outstanding_pings_;
 }

 void set_max_outstanding_settings(size_t max) {
 max_outstanding_settings_ = max;
 }

 size_t max_outstanding_settings() const {
 return max_outstanding_settings_;
 }

 void set_max_session_memory(uint64_t max) {
 max_session_memory_ = max;
 }

 uint64_t max_session_memory() const {
 return max_session_memory_;
 }

 private:
 Nghttp2OptionPointer options_;
 uint64_t max_session_memory_ = kDefaultMaxSessionMemory;
 uint32_t max_header_pairs_ = DEFAULT_MAX_HEADER_LIST_PAIRS;
 PaddingStrategy padding_strategy_ = PADDING_STRATEGY_NONE;
 size_t max_outstanding_pings_ = kDefaultMaxPings;
 size_t max_outstanding_settings_ = kDefaultMaxSettings;
};

struct Http2Priority : public nghttp2_priority_spec {
 Http2Priority(Environment* env,
 v8::Local<v8::Value> parent,
 v8::Local<v8::Value> weight,
 v8::Local<v8::Value> exclusive);
};

class Http2StreamListener : public StreamListener {
 public:
 uv_buf_t OnStreamAlloc(size_t suggested_size) override;
 void OnStreamRead(ssize_t nread, const uv_buf_t& buf) override;
};

struct Http2HeaderTraits {
 typedef Http2RcBufferPointer rcbufferpointer_t;
 typedef Http2Session allocator_t;

 // HTTP/2 does not support identifying header names by token id.
 // HTTP/3 will, however, so we prepare for that now.
 static const char* ToHttpHeaderName(int32_t token) { return nullptr; }
};

using Http2Header = NgHeader<Http2HeaderTraits>;

class Http2Stream : public AsyncWrap,
 public StreamBase {
 public:
 static Http2Stream* New(
 Http2Session* session,
 int32_t id,
 nghttp2_headers_category category = NGHTTP2_HCAT_HEADERS,
 int options = 0);
 ~Http2Stream() override;

 nghttp2_stream* operator*() const;

 nghttp2_stream* stream() const;

 Http2Session* session() { return session_.get(); }
 const Http2Session* session() const { return session_.get(); }

 // Required for StreamBase
 int ReadStart() override;

 // Required for StreamBase
 int ReadStop() override;

 // Required for StreamBase
 ShutdownWrap* CreateShutdownWrap(v8::Local<v8::Object> object) override;
 int DoShutdown(ShutdownWrap* req_wrap) override;

 bool HasWantsWrite() const override { return true; }

 // Initiate a response on this stream.
 int SubmitResponse(const Http2Headers& headers, int options);

 // Submit informational headers for this stream
 int SubmitInfo(const Http2Headers& headers);

 // Submit trailing headers for this stream
 int SubmitTrailers(const Http2Headers& headers);
 void OnTrailers();

 // Submit a PRIORITY frame for this stream
 int SubmitPriority(const Http2Priority& priority, bool silent = false);

 // Submits an RST_STREAM frame using the given code
 void SubmitRstStream(const uint32_t code);

 void FlushRstStream();

 // Submits a PUSH_PROMISE frame with this stream as the parent.
 Http2Stream* SubmitPushPromise(
 const Http2Headers& headers,
 int32_t* ret,
 int options = 0);


 void Close(int32_t code);

 // Destroy this stream instance and free all held memory.
 void Destroy();

 bool is_destroyed() const {
 return flags_ & kStreamStateDestroyed;
 }

 bool is_writable() const {
 return !(flags_ & kStreamStateShut);
 }

 bool is_paused() const {
 return flags_ & kStreamStateReadPaused;
 }

 bool is_closed() const {
 return flags_ & kStreamStateClosed;
 }

 bool has_trailers() const {
 return flags_ & kStreamStateTrailers;
 }

 void set_has_trailers(bool on = true) {
 if (on)
 flags_ |= kStreamStateTrailers;
 else
 flags_ &= ~kStreamStateTrailers;
 }

 void set_closed() {
 flags_ |= kStreamStateClosed;
 }

 void set_destroyed() {
 flags_ |= kStreamStateDestroyed;
 }

 void set_not_writable() {
 flags_ |= kStreamStateShut;
 }

 void set_reading(bool on = true) {
 if (on) {
 flags_ |= kStreamStateReadStart;
 set_paused(false);
 } else {}
 }

 void set_paused(bool on = true) {
 if (on)
 flags_ |= kStreamStateReadPaused;
 else
 flags_ &= ~kStreamStateReadPaused;
 }

 // Returns true if this stream is in the reading state, which occurs when
 // the kStreamStateReadStart flag has been set and the
 // kStreamStateReadPaused flag is *not* set.
 bool is_reading() const {
 return flags_ & kStreamStateReadStart && !is_paused();
 }

 // Returns the RST_STREAM code used to close this stream
 int32_t code() const { return code_; }

 // Returns the stream identifier for this stream
 int32_t id() const { return id_; }

 void IncrementAvailableOutboundLength(size_t amount);
 void DecrementAvailableOutboundLength(size_t amount);

 bool AddHeader(nghttp2_rcbuf* name, nghttp2_rcbuf* value, uint8_t flags);

 template <typename Fn>
 void TransferHeaders(Fn&& fn) {
 size_t i = 0;
 for (const auto& header : current_headers_ )
 fn(header, i++);
 current_headers_.clear();
 }

 size_t headers_count() const {
 return current_headers_.size();
 }

 nghttp2_headers_category headers_category() const {
 return current_headers_category_;
 }

 void StartHeaders(nghttp2_headers_category category);

 // Required for StreamBase
 bool IsAlive() override {
 return true;
 }

 // Required for StreamBase
 bool IsClosing() override {
 return false;
 }

 AsyncWrap* GetAsyncWrap() override { return this; }

 int DoWrite(WriteWrap* w, uv_buf_t* bufs, size_t count,
 uv_stream_t* send_handle) override;

 void MemoryInfo(MemoryTracker* tracker) const override;
 SET_MEMORY_INFO_NAME(Http2Stream)
 SET_SELF_SIZE(Http2Stream)

 std::string diagnostic_name() const override;

 // JavaScript API
 static void GetID(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void Destroy(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void Priority(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void PushPromise(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void RefreshState(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void Info(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void Trailers(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void Respond(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void RstStream(const v8::FunctionCallbackInfo<v8::Value>& args);

 class Provider;

 struct Statistics {
 uint64_t start_time;
 uint64_t end_time;
 uint64_t first_header; // Time first header was received
 uint64_t first_byte; // Time first DATA frame byte was received
 uint64_t first_byte_sent; // Time first DATA frame byte was sent
 uint64_t sent_bytes;
 uint64_t received_bytes;
 uint64_t id;
 };

 Statistics statistics_ = {};

 private:
 Http2Stream(Http2Session* session,
 v8::Local<v8::Object> obj,
 int32_t id,
 nghttp2_headers_category category,
 int options);

 void EmitStatistics();

 BaseObjectWeakPtr<Http2Session> session_; // The Parent HTTP/2 Session
 int32_t id_ = 0; // The Stream Identifier
 int32_t code_ = NGHTTP2_NO_ERROR; // The RST_STREAM code (if any)
 int flags_ = kStreamStateNone; // Internal state flags

 uint32_t max_header_pairs_ = DEFAULT_MAX_HEADER_LIST_PAIRS;
 uint32_t max_header_length_ = DEFAULT_SETTINGS_MAX_HEADER_LIST_SIZE;

 // The Current Headers block... As headers are received for this stream,
 // they are temporarily stored here until the OnFrameReceived is called
 // signalling the end of the HEADERS frame
 nghttp2_headers_category current_headers_category_ = NGHTTP2_HCAT_HEADERS;
 uint32_t current_headers_length_ = 0; // total number of octets
 std::vector<Http2Header> current_headers_;

 // This keeps track of the amount of data read from the socket while the
 // socket was in paused mode. When `ReadStart()` is called (and not before
 // then), we tell nghttp2 that we consumed that data to get proper
 // backpressure handling.
 size_t inbound_consumed_data_while_paused_ = 0;

 // Outbound Data... This is the data written by the JS layer that is
 // waiting to be written out to the socket.
 std::queue<NgHttp2StreamWrite> queue_;
 size_t available_outbound_length_ = 0;

 Http2StreamListener stream_listener_;

 friend class Http2Session;
};

class Http2Stream::Provider {
 public:
 Provider(Http2Stream* stream, int options);
 explicit Provider(int options);
 virtual ~Provider();

 nghttp2_data_provider* operator*() {
 return !empty_ ? &provider_ : nullptr;
 }

 class FD;
 class Stream;
 protected:
 nghttp2_data_provider provider_;

 private:
 bool empty_ = false;
};

class Http2Stream::Provider::Stream : public Http2Stream::Provider {
 public:
 Stream(Http2Stream* stream, int options);
 explicit Stream(int options);

 static ssize_t OnRead(nghttp2_session* session,
 int32_t id,
 uint8_t* buf,
 size_t length,
 uint32_t* flags,
 nghttp2_data_source* source,
 void* user_data);
};

struct SessionJSFields {
 uint8_t bitfield;
 uint8_t priority_listener_count;
 uint8_t frame_error_listener_count;
 uint32_t max_invalid_frames = 1000;
 uint32_t max_rejected_streams = 100;
};

// Indices for js_fields_, which serves as a way to communicate data with JS
// land fast. In particular, we store information about the number/presence
// of certain event listeners in JS, and skip calls from C++ into JS if they
// are missing.
enum SessionUint8Fields {
 kBitfield = offsetof(SessionJSFields, bitfield), // See below
 kSessionPriorityListenerCount =
 offsetof(SessionJSFields, priority_listener_count),
 kSessionFrameErrorListenerCount =
 offsetof(SessionJSFields, frame_error_listener_count),
 kSessionMaxInvalidFrames = offsetof(SessionJSFields, max_invalid_frames),
 kSessionMaxRejectedStreams = offsetof(SessionJSFields, max_rejected_streams),
 kSessionUint8FieldCount = sizeof(SessionJSFields)
};

enum SessionBitfieldFlags {
 kSessionHasRemoteSettingsListeners,
 kSessionRemoteSettingsIsUpToDate,
 kSessionHasPingListeners,
 kSessionHasAltsvcListeners
};

class Http2Session : public AsyncWrap,
 public StreamListener,
 public mem::NgLibMemoryManager<Http2Session, nghttp2_mem> {
 public:
 Http2Session(Http2State* http2_state,
 v8::Local<v8::Object> wrap,
 SessionType type = NGHTTP2_SESSION_SERVER);
 ~Http2Session() override;

 StreamBase* underlying_stream() {
 return static_cast<StreamBase*>(stream_);
 }

 void Close(uint32_t code = NGHTTP2_NO_ERROR,
 bool socket_closed = false);

 void Consume(v8::Local<v8::Object> stream);

 void Goaway(uint32_t code, int32_t lastStreamID,
 const uint8_t* data, size_t len);

 void AltSvc(int32_t id,
 uint8_t* origin,
 size_t origin_len,
 uint8_t* value,
 size_t value_len);

 void Origin(const Origins& origins);

 uint8_t SendPendingData();

 // Submits a new request. If the request is a success, assigned
 // will be a pointer to the Http2Stream instance assigned.
 // This only works if the session is a client session.
 Http2Stream* SubmitRequest(
 const Http2Priority& priority,
 const Http2Headers& headers,
 int32_t* ret,
 int options = 0);

 SessionType type() const { return session_type_; }

 nghttp2_session* session() const { return session_.get(); }

 nghttp2_session* operator*() { return session_.get(); }

 uint32_t max_header_pairs() const { return max_header_pairs_; }

 const char* TypeName() const;

 bool is_destroyed() {
 return (flags_ & kSessionStateClosed) || session_ == nullptr;
 }

 void set_destroyed() {
 flags_ |= kSessionStateClosed;
 }

#define IS_FLAG(name, flag) \
 bool is_##name() const { return flags_ & flag; } \
 void set_##name(bool on = true) { \
 if (on) \
 flags_ |= flag; \
 else \
 flags_ &= ~flag; \
 }

 IS_FLAG(in_scope, kSessionStateHasScope)
 IS_FLAG(write_scheduled, kSessionStateWriteScheduled)
 IS_FLAG(closing, kSessionStateClosing)
 IS_FLAG(sending, kSessionStateSending)
 IS_FLAG(write_in_progress, kSessionStateWriteInProgress)
 IS_FLAG(reading_stopped, kSessionStateReadingStopped)
 IS_FLAG(receive_paused, kSessionStateReceivePaused)

#undef IS_FLAG

 // Schedule a write if nghttp2 indicates it wants to write to the socket.
 void MaybeScheduleWrite();

 // Stop reading if nghttp2 doesn't want to anymore.
 void MaybeStopReading();

 // Returns pointer to the stream, or nullptr if stream does not exist
 BaseObjectPtr<Http2Stream> FindStream(int32_t id);

 bool CanAddStream();

 // Adds a stream instance to this session
 void AddStream(Http2Stream* stream);

 // Removes a stream instance from this session
 BaseObjectPtr<Http2Stream> RemoveStream(int32_t id);

 // Indicates whether there currently exist outgoing buffers for this stream.
 bool HasWritesOnSocketForStream(Http2Stream* stream);

 // Write data from stream_buf_ to the session.
 // This will call the error callback if an error occurs.
 void ConsumeHTTP2Data();

 void MemoryInfo(MemoryTracker* tracker) const override;
 SET_MEMORY_INFO_NAME(Http2Session)
 SET_SELF_SIZE(Http2Session)

 std::string diagnostic_name() const override;

 // Schedule an RstStream for after the current write finishes.
 void AddPendingRstStream(int32_t stream_id) {
 pending_rst_streams_.emplace_back(stream_id);
 }

 bool has_pending_rststream(int32_t stream_id) {
 return pending_rst_streams_.end() !=
 std::find(pending_rst_streams_.begin(),
 pending_rst_streams_.end(),
 stream_id);
 }

 // Handle reads/writes from the underlying network transport.
 uv_buf_t OnStreamAlloc(size_t suggested_size) override;
 void OnStreamRead(ssize_t nread, const uv_buf_t& buf) override;
 void OnStreamAfterWrite(WriteWrap* w, int status) override;

 // Implementation for mem::NgLibMemoryManager
 void CheckAllocatedSize(size_t previous_size) const;
 void IncreaseAllocatedSize(size_t size);
 void DecreaseAllocatedSize(size_t size);

 // The JavaScript API
 static void New(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void Consume(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void Receive(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void Destroy(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void Settings(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void Request(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void SetNextStreamID(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void SetLocalWindowSize(
 const v8::FunctionCallbackInfo<v8::Value>& args);
 static void Goaway(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void UpdateChunksSent(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void RefreshState(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void Ping(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void AltSvc(const v8::FunctionCallbackInfo<v8::Value>& args);
 static void Origin(const v8::FunctionCallbackInfo<v8::Value>& args);

 template <get_setting fn>
 static void RefreshSettings(const v8::FunctionCallbackInfo<v8::Value>& args);

 uv_loop_t* event_loop() const {
 return env()->event_loop();
 }

 Http2State* http2_state() const { return http2_state_.get(); }

 BaseObjectPtr<Http2Ping> PopPing();
 bool AddPing(const uint8_t* data, v8::Local<v8::Function> callback);

 BaseObjectPtr<Http2Settings> PopSettings();
 bool AddSettings(v8::Local<v8::Function> callback);

 void IncrementCurrentSessionMemory(uint64_t amount) {
 current_session_memory_ += amount;
 }

 void DecrementCurrentSessionMemory(uint64_t amount) {
 DCHECK_LE(amount, current_session_memory_);
 current_session_memory_ -= amount;
 }

 // Tell our custom memory allocator that this rcbuf is independent of
 // this session now, and may outlive it.
 void StopTrackingRcbuf(nghttp2_rcbuf* buf);

 // Returns the current session memory including memory allocated by nghttp2,
 // the current outbound storage queue, and pending writes.
 uint64_t current_session_memory() const {
 uint64_t total = current_session_memory_ + sizeof(Http2Session);
 total += current_nghttp2_memory_;
 total += outgoing_storage_.size();
 return total;
 }

 // Return true if current_session_memory + amount is less than the max
 bool has_available_session_memory(uint64_t amount) const {
 return current_session_memory() + amount <= max_session_memory_;
 }

 struct Statistics {
 uint64_t start_time;
 uint64_t end_time;
 uint64_t ping_rtt;
 uint64_t data_sent;
 uint64_t data_received;
 uint32_t frame_count;
 uint32_t frame_sent;
 int32_t stream_count;
 size_t max_concurrent_streams;
 double stream_average_duration;
 SessionType session_type;
 };

 Statistics statistics_ = {};

 private:
 void EmitStatistics();

 // Frame Padding Strategies
 ssize_t OnDWordAlignedPadding(size_t frameLength,
 size_t maxPayloadLen);
 ssize_t OnMaxFrameSizePadding(size_t frameLength,
 size_t maxPayloadLen);

 // Frame Handler
 int HandleDataFrame(const nghttp2_frame* frame);
 void HandleGoawayFrame(const nghttp2_frame* frame);
 void HandleHeadersFrame(const nghttp2_frame* frame);
 void HandlePriorityFrame(const nghttp2_frame* frame);
 void HandleSettingsFrame(const nghttp2_frame* frame);
 void HandlePingFrame(const nghttp2_frame* frame);
 void HandleAltSvcFrame(const nghttp2_frame* frame);
 void HandleOriginFrame(const nghttp2_frame* frame);

 // nghttp2 callbacks
 static int OnBeginHeadersCallback(
 nghttp2_session* session,
 const nghttp2_frame* frame,
 void* user_data);
 static int OnHeaderCallback(
 nghttp2_session* session,
 const nghttp2_frame* frame,
 nghttp2_rcbuf* name,
 nghttp2_rcbuf* value,
 uint8_t flags,
 void* user_data);
 static int OnFrameReceive(
 nghttp2_session* session,
 const nghttp2_frame* frame,
 void* user_data);
 static int OnFrameNotSent(
 nghttp2_session* session,
 const nghttp2_frame* frame,
 int error_code,
 void* user_data);
 static int OnFrameSent(
 nghttp2_session* session,
 const nghttp2_frame* frame,
 void* user_data);
 static int OnStreamClose(
 nghttp2_session* session,
 int32_t id,
 uint32_t code,
 void* user_data);
 static int OnInvalidHeader(
 nghttp2_session* session,
 const nghttp2_frame* frame,
 nghttp2_rcbuf* name,
 nghttp2_rcbuf* value,
 uint8_t flags,
 void* user_data);
 static int OnDataChunkReceived(
 nghttp2_session* session,
 uint8_t flags,
 int32_t id,
 const uint8_t* data,
 size_t len,
 void* user_data);
 static ssize_t OnSelectPadding(
 nghttp2_session* session,
 const nghttp2_frame* frame,
 size_t maxPayloadLen,
 void* user_data);
 static int OnNghttpError(
 nghttp2_session* session,
 const char* message,
 size_t len,
 void* user_data);
 static int OnSendData(
 nghttp2_session* session,
 nghttp2_frame* frame,
 const uint8_t* framehd,
 size_t length,
 nghttp2_data_source* source,
 void* user_data);
 static int OnInvalidFrame(
 nghttp2_session* session,
 const nghttp2_frame* frame,
 int lib_error_code,
 void* user_data);

 struct Callbacks {
 explicit Callbacks(bool kHasGetPaddingCallback);

 Nghttp2SessionCallbacksPointer callbacks;
 };

 /* Use callback_struct_saved[kHasGetPaddingCallback ? 1 : 0] */
 static const Callbacks callback_struct_saved[2];

 // The underlying nghttp2_session handle
 Nghttp2SessionPointer session_;

 // JS-accessible numeric fields, as indexed by SessionUint8Fields.
 AliasedStruct<SessionJSFields> js_fields_;

 // The session type: client or server
 SessionType session_type_;

 // The maximum number of header pairs permitted for streams on this session
 uint32_t max_header_pairs_ = DEFAULT_MAX_HEADER_LIST_PAIRS;

 // The maximum amount of memory allocated for this session
 uint64_t max_session_memory_ = kDefaultMaxSessionMemory;
 uint64_t current_session_memory_ = 0;
 // The amount of memory allocated by nghttp2 internals
 uint64_t current_nghttp2_memory_ = 0;

 // The collection of active Http2Streams associated with this session
 std::unordered_map<int32_t, BaseObjectPtr<Http2Stream>> streams_;

 int flags_ = kSessionStateNone;

 // The StreamBase instance being used for i/o
 PaddingStrategy padding_strategy_ = PADDING_STRATEGY_NONE;

 // use this to allow timeout tracking during long-lasting writes
 uint32_t chunks_sent_since_last_write_ = 0;

 uv_buf_t stream_buf_ = uv_buf_init(nullptr, 0);
 // When processing input data, either stream_buf_ab_ or stream_buf_allocation_
 // will be set. stream_buf_ab_ is lazily created from stream_buf_allocation_.
 v8::Global<v8::ArrayBuffer> stream_buf_ab_;
 AllocatedBuffer stream_buf_allocation_;
 size_t stream_buf_offset_ = 0;
 // Custom error code for errors that originated inside one of the callbacks
 // called by nghttp2_session_mem_recv.
 const char* custom_recv_error_code_ = nullptr;

 size_t max_outstanding_pings_ = kDefaultMaxPings;
 std::queue<BaseObjectPtr<Http2Ping>> outstanding_pings_;

 size_t max_outstanding_settings_ = kDefaultMaxSettings;
 std::queue<BaseObjectPtr<Http2Settings>> outstanding_settings_;

 std::vector<NgHttp2StreamWrite> outgoing_buffers_;
 std::vector<uint8_t> outgoing_storage_;
 size_t outgoing_length_ = 0;
 std::vector<int32_t> pending_rst_streams_;
 // Count streams that have been rejected while being opened. Exceeding a fixed
 // limit will result in the session being destroyed, as an indication of a
 // misbehaving peer. This counter is reset once new streams are being
 // accepted again.
 uint32_t rejected_stream_count_ = 0;
 // Also use the invalid frame count as a measure for rejecting input frames.
 uint32_t invalid_frame_count_ = 0;

 void PushOutgoingBuffer(NgHttp2StreamWrite&& write);

 BaseObjectPtr<Http2State> http2_state_;

 void CopyDataIntoOutgoing(const uint8_t* src, size_t src_length);
 void ClearOutgoing(int status);

 friend class Http2Scope;
 friend class Http2StreamListener;
};

struct Http2SessionPerformanceEntryTraits {
 static constexpr performance::PerformanceEntryType kType =
 performance::NODE_PERFORMANCE_ENTRY_TYPE_HTTP2;

 using Details = Http2Session::Statistics;

 static v8::MaybeLocal<v8::Object> GetDetails(
 Environment* env,
 const performance::PerformanceEntry<Http2SessionPerformanceEntryTraits>&
 entry);
};

struct Http2StreamPerformanceEntryTraits {
 static constexpr performance::PerformanceEntryType kType =
 performance::NODE_PERFORMANCE_ENTRY_TYPE_HTTP2;

 using Details = Http2Stream::Statistics;

 static v8::MaybeLocal<v8::Object> GetDetails(
 Environment* env,
 const performance::PerformanceEntry<Http2StreamPerformanceEntryTraits>&
 entry);
};

using Http2SessionPerformanceEntry =
 performance::PerformanceEntry<Http2SessionPerformanceEntryTraits>;
using Http2StreamPerformanceEntry =
 performance::PerformanceEntry<Http2StreamPerformanceEntryTraits>;

class Http2Ping : public AsyncWrap {
 public:
 explicit Http2Ping(
 Http2Session* session,
 v8::Local<v8::Object> obj,
 v8::Local<v8::Function> callback);

 void MemoryInfo(MemoryTracker* tracker) const override;
 SET_MEMORY_INFO_NAME(Http2Ping)
 SET_SELF_SIZE(Http2Ping)

 void Send(const uint8_t* payload);
 void Done(bool ack, const uint8_t* payload = nullptr);
 void DetachFromSession();

 v8::Local<v8::Function> callback() const;

 private:
 BaseObjectWeakPtr<Http2Session> session_;
 v8::Global<v8::Function> callback_;
 uint64_t startTime_;
};

// The Http2Settings class is used to parse the settings passed in for
// an Http2Session, converting those into an array of nghttp2_settings_entry
// structs.
class Http2Settings : public AsyncWrap {
 public:
 Http2Settings(Http2Session* session,
 v8::Local<v8::Object> obj,
 v8::Local<v8::Function> callback,
 uint64_t start_time = uv_hrtime());

 void MemoryInfo(MemoryTracker* tracker) const override;
 SET_MEMORY_INFO_NAME(Http2Settings)
 SET_SELF_SIZE(Http2Settings)

 void Send();
 void Done(bool ack);

 v8::Local<v8::Function> callback() const;

 // Returns a Buffer instance with the serialized SETTINGS payload
 v8::Local<v8::Value> Pack();

 static v8::Local<v8::Value> Pack(Http2State* state);

 // Resets the default values in the settings buffer
 static void RefreshDefaults(Http2State* http2_state);

 // Update the local or remote settings for the given session
 static void Update(Http2Session* session,
 get_setting fn);

 private:
 static size_t Init(
 Http2State* http2_state,
 nghttp2_settings_entry* entries);

 static v8::Local<v8::Value> Pack(
 Environment* env,
 size_t count,
 const nghttp2_settings_entry* entries);

 BaseObjectWeakPtr<Http2Session> session_;
 v8::Global<v8::Function> callback_;
 uint64_t startTime_;
 size_t count_ = 0;
 nghttp2_settings_entry entries_[IDX_SETTINGS_COUNT];
};

class Origins {
 public:
 Origins(Environment* env,
 v8::Local<v8::String> origin_string,
 size_t origin_count);
 ~Origins() = default;

 const nghttp2_origin_entry* operator*() const {
 return reinterpret_cast<const nghttp2_origin_entry*>(buf_.data());
 }

 size_t length() const {
 return count_;
 }

 private:
 size_t count_;
 AllocatedBuffer buf_;
};

#define HTTP2_HIDDEN_CONSTANTS(V) \
 V(NGHTTP2_HCAT_REQUEST) \
 V(NGHTTP2_HCAT_RESPONSE) \
 V(NGHTTP2_HCAT_PUSH_RESPONSE) \
 V(NGHTTP2_HCAT_HEADERS) \
 V(NGHTTP2_NV_FLAG_NONE) \
 V(NGHTTP2_NV_FLAG_NO_INDEX) \
 V(NGHTTP2_ERR_DEFERRED) \
 V(NGHTTP2_ERR_STREAM_ID_NOT_AVAILABLE) \
 V(NGHTTP2_ERR_INVALID_ARGUMENT) \
 V(NGHTTP2_ERR_STREAM_CLOSED) \
 V(NGHTTP2_ERR_NOMEM) \
 V(STREAM_OPTION_EMPTY_PAYLOAD) \
 V(STREAM_OPTION_GET_TRAILERS)

#define HTTP2_ERROR_CODES(V) \
 V(NGHTTP2_NO_ERROR) \
 V(NGHTTP2_PROTOCOL_ERROR) \
 V(NGHTTP2_INTERNAL_ERROR) \
 V(NGHTTP2_FLOW_CONTROL_ERROR) \
 V(NGHTTP2_SETTINGS_TIMEOUT) \
 V(NGHTTP2_STREAM_CLOSED) \
 V(NGHTTP2_FRAME_SIZE_ERROR) \
 V(NGHTTP2_REFUSED_STREAM) \
 V(NGHTTP2_CANCEL) \
 V(NGHTTP2_COMPRESSION_ERROR) \
 V(NGHTTP2_CONNECT_ERROR) \
 V(NGHTTP2_ENHANCE_YOUR_CALM) \
 V(NGHTTP2_INADEQUATE_SECURITY) \
 V(NGHTTP2_HTTP_1_1_REQUIRED) \

#define HTTP2_CONSTANTS(V) \
 V(NGHTTP2_ERR_FRAME_SIZE_ERROR) \
 V(NGHTTP2_SESSION_SERVER) \
 V(NGHTTP2_SESSION_CLIENT) \
 V(NGHTTP2_STREAM_STATE_IDLE) \
 V(NGHTTP2_STREAM_STATE_OPEN) \
 V(NGHTTP2_STREAM_STATE_RESERVED_LOCAL) \
 V(NGHTTP2_STREAM_STATE_RESERVED_REMOTE) \
 V(NGHTTP2_STREAM_STATE_HALF_CLOSED_LOCAL) \
 V(NGHTTP2_STREAM_STATE_HALF_CLOSED_REMOTE) \
 V(NGHTTP2_STREAM_STATE_CLOSED) \
 V(NGHTTP2_FLAG_NONE) \
 V(NGHTTP2_FLAG_END_STREAM) \
 V(NGHTTP2_FLAG_END_HEADERS) \
 V(NGHTTP2_FLAG_ACK) \
 V(NGHTTP2_FLAG_PADDED) \
 V(NGHTTP2_FLAG_PRIORITY) \
 V(DEFAULT_SETTINGS_HEADER_TABLE_SIZE) \
 V(DEFAULT_SETTINGS_ENABLE_PUSH) \
 V(DEFAULT_SETTINGS_MAX_CONCURRENT_STREAMS) \
 V(DEFAULT_SETTINGS_INITIAL_WINDOW_SIZE) \
 V(DEFAULT_SETTINGS_MAX_FRAME_SIZE) \
 V(DEFAULT_SETTINGS_MAX_HEADER_LIST_SIZE) \
 V(DEFAULT_SETTINGS_ENABLE_CONNECT_PROTOCOL) \
 V(MAX_MAX_FRAME_SIZE) \
 V(MIN_MAX_FRAME_SIZE) \
 V(MAX_INITIAL_WINDOW_SIZE) \
 V(NGHTTP2_SETTINGS_HEADER_TABLE_SIZE) \
 V(NGHTTP2_SETTINGS_ENABLE_PUSH) \
 V(NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS) \
 V(NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE) \
 V(NGHTTP2_SETTINGS_MAX_FRAME_SIZE) \
 V(NGHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE) \
 V(NGHTTP2_SETTINGS_ENABLE_CONNECT_PROTOCOL) \
 V(PADDING_STRATEGY_NONE) \
 V(PADDING_STRATEGY_ALIGNED) \
 V(PADDING_STRATEGY_MAX) \
 V(PADDING_STRATEGY_CALLBACK) \
 HTTP2_ERROR_CODES(V)

#define HTTP2_SETTINGS(V) \
 V(HEADER_TABLE_SIZE) \
 V(ENABLE_PUSH) \
 V(MAX_CONCURRENT_STREAMS) \
 V(INITIAL_WINDOW_SIZE) \
 V(MAX_FRAME_SIZE) \
 V(MAX_HEADER_LIST_SIZE) \
 V(ENABLE_CONNECT_PROTOCOL) \

} // namespace http2
} // namespace node

#endif // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#endif // SRC_NODE_HTTP2_H_