'use strict';

const binding = process.binding('http2');
const errors = require('internal/errors');

const {
  NGHTTP2_SESSION_CLIENT,
  NGHTTP2_SESSION_SERVER,

  HTTP2_HEADER_STATUS,
  HTTP2_HEADER_METHOD,
  HTTP2_HEADER_AUTHORITY,
  HTTP2_HEADER_SCHEME,
  HTTP2_HEADER_PATH,
  HTTP2_HEADER_ACCESS_CONTROL_ALLOW_CREDENTIALS,
  HTTP2_HEADER_ACCESS_CONTROL_MAX_AGE,
  HTTP2_HEADER_ACCESS_CONTROL_REQUEST_METHOD,
  HTTP2_HEADER_AGE,
  HTTP2_HEADER_AUTHORIZATION,
  HTTP2_HEADER_CONTENT_ENCODING,
  HTTP2_HEADER_CONTENT_LANGUAGE,
  HTTP2_HEADER_CONTENT_LENGTH,
  HTTP2_HEADER_CONTENT_LOCATION,
  HTTP2_HEADER_CONTENT_MD5,
  HTTP2_HEADER_CONTENT_RANGE,
  HTTP2_HEADER_CONTENT_TYPE,
  HTTP2_HEADER_COOKIE,
  HTTP2_HEADER_DATE,
  HTTP2_HEADER_DNT,
  HTTP2_HEADER_ETAG,
  HTTP2_HEADER_EXPIRES,
  HTTP2_HEADER_FROM,
  HTTP2_HEADER_IF_MATCH,
  HTTP2_HEADER_IF_NONE_MATCH,
  HTTP2_HEADER_IF_MODIFIED_SINCE,
  HTTP2_HEADER_IF_RANGE,
  HTTP2_HEADER_IF_UNMODIFIED_SINCE,
  HTTP2_HEADER_LAST_MODIFIED,
  HTTP2_HEADER_LOCATION,
  HTTP2_HEADER_MAX_FORWARDS,
  HTTP2_HEADER_PROXY_AUTHORIZATION,
  HTTP2_HEADER_RANGE,
  HTTP2_HEADER_REFERER,
  HTTP2_HEADER_RETRY_AFTER,
  HTTP2_HEADER_SET_COOKIE,
  HTTP2_HEADER_TK,
  HTTP2_HEADER_UPGRADE_INSECURE_REQUESTS,
  HTTP2_HEADER_USER_AGENT,
  HTTP2_HEADER_X_CONTENT_TYPE_OPTIONS,

  HTTP2_HEADER_CONNECTION,
  HTTP2_HEADER_UPGRADE,
  HTTP2_HEADER_HTTP2_SETTINGS,
  HTTP2_HEADER_TE,
  HTTP2_HEADER_TRANSFER_ENCODING,
  HTTP2_HEADER_HOST,
  HTTP2_HEADER_KEEP_ALIVE,
  HTTP2_HEADER_PROXY_CONNECTION,

  HTTP2_METHOD_DELETE,
  HTTP2_METHOD_GET,
  HTTP2_METHOD_HEAD
} = binding.constants;

// This set is defined strictly by the HTTP/2 specification. Only
// :-prefixed headers defined by that specification may be added to
// this set.
const kValidPseudoHeaders = new Set([
  HTTP2_HEADER_STATUS,
  HTTP2_HEADER_METHOD,
  HTTP2_HEADER_AUTHORITY,
  HTTP2_HEADER_SCHEME,
  HTTP2_HEADER_PATH
]);

// This set contains headers that are permitted to have only a single
// value. Multiple instances must not be specified.
const kSingleValueHeaders = new Set([
  HTTP2_HEADER_STATUS,
  HTTP2_HEADER_METHOD,
  HTTP2_HEADER_AUTHORITY,
  HTTP2_HEADER_SCHEME,
  HTTP2_HEADER_PATH,
  HTTP2_HEADER_ACCESS_CONTROL_ALLOW_CREDENTIALS,
  HTTP2_HEADER_ACCESS_CONTROL_MAX_AGE,
  HTTP2_HEADER_ACCESS_CONTROL_REQUEST_METHOD,
  HTTP2_HEADER_AGE,
  HTTP2_HEADER_AUTHORIZATION,
  HTTP2_HEADER_CONTENT_ENCODING,
  HTTP2_HEADER_CONTENT_LANGUAGE,
  HTTP2_HEADER_CONTENT_LENGTH,
  HTTP2_HEADER_CONTENT_LOCATION,
  HTTP2_HEADER_CONTENT_MD5,
  HTTP2_HEADER_CONTENT_RANGE,
  HTTP2_HEADER_CONTENT_TYPE,
  HTTP2_HEADER_DATE,
  HTTP2_HEADER_DNT,
  HTTP2_HEADER_ETAG,
  HTTP2_HEADER_EXPIRES,
  HTTP2_HEADER_FROM,
  HTTP2_HEADER_IF_MATCH,
  HTTP2_HEADER_IF_MODIFIED_SINCE,
  HTTP2_HEADER_IF_NONE_MATCH,
  HTTP2_HEADER_IF_RANGE,
  HTTP2_HEADER_IF_UNMODIFIED_SINCE,
  HTTP2_HEADER_LAST_MODIFIED,
  HTTP2_HEADER_LOCATION,
  HTTP2_HEADER_MAX_FORWARDS,
  HTTP2_HEADER_PROXY_AUTHORIZATION,
  HTTP2_HEADER_RANGE,
  HTTP2_HEADER_REFERER,
  HTTP2_HEADER_RETRY_AFTER,
  HTTP2_HEADER_TK,
  HTTP2_HEADER_UPGRADE_INSECURE_REQUESTS,
  HTTP2_HEADER_USER_AGENT,
  HTTP2_HEADER_X_CONTENT_TYPE_OPTIONS
]);

// The HTTP methods in this set are specifically defined as assigning no
// meaning to the request payload. By default, unless the user explicitly
// overrides the endStream option on the request method, the endStream
// option will be defaulted to true when these methods are used.
const kNoPayloadMethods = new Set([
  HTTP2_METHOD_DELETE,
  HTTP2_METHOD_GET,
  HTTP2_METHOD_HEAD
]);

// The following ArrayBuffer instances are used to share memory more efficiently
// with the native binding side for a number of methods. These are not intended
// to be used directly by users in any way. The ArrayBuffers are created on
// the native side with values that are filled in on demand, the js code then
// reads those values out. The set of IDX constants that follow identify the
// relevant data positions within these buffers.
const { settingsBuffer, optionsBuffer } = binding;

// Note that Float64Array is used here because there is no Int64Array available
// and these deal with numbers that can be beyond the range of Uint32 and Int32.
// The values set on the native side will always be integers. This is not a
// unique example of this, this pattern can be found in use in other parts of
// Node.js core as a performance optimization.
const { sessionState, streamState } = binding;

const IDX_SETTINGS_HEADER_TABLE_SIZE = 0;
const IDX_SETTINGS_ENABLE_PUSH = 1;
const IDX_SETTINGS_INITIAL_WINDOW_SIZE = 2;
const IDX_SETTINGS_MAX_FRAME_SIZE = 3;
const IDX_SETTINGS_MAX_CONCURRENT_STREAMS = 4;
const IDX_SETTINGS_MAX_HEADER_LIST_SIZE = 5;
const IDX_SETTINGS_FLAGS = 6;

const IDX_SESSION_STATE_EFFECTIVE_LOCAL_WINDOW_SIZE = 0;
const IDX_SESSION_STATE_EFFECTIVE_RECV_DATA_LENGTH = 1;
const IDX_SESSION_STATE_NEXT_STREAM_ID = 2;
const IDX_SESSION_STATE_LOCAL_WINDOW_SIZE = 3;
const IDX_SESSION_STATE_LAST_PROC_STREAM_ID = 4;
const IDX_SESSION_STATE_REMOTE_WINDOW_SIZE = 5;
const IDX_SESSION_STATE_OUTBOUND_QUEUE_SIZE = 6;
const IDX_SESSION_STATE_HD_DEFLATE_DYNAMIC_TABLE_SIZE = 7;
const IDX_SESSION_STATE_HD_INFLATE_DYNAMIC_TABLE_SIZE = 8;
const IDX_STREAM_STATE = 0;
const IDX_STREAM_STATE_WEIGHT = 1;
const IDX_STREAM_STATE_SUM_DEPENDENCY_WEIGHT = 2;
const IDX_STREAM_STATE_LOCAL_CLOSE = 3;
const IDX_STREAM_STATE_REMOTE_CLOSE = 4;
const IDX_STREAM_STATE_LOCAL_WINDOW_SIZE = 5;

const IDX_OPTIONS_MAX_DEFLATE_DYNAMIC_TABLE_SIZE = 0;
const IDX_OPTIONS_MAX_RESERVED_REMOTE_STREAMS = 1;
const IDX_OPTIONS_MAX_SEND_HEADER_BLOCK_LENGTH = 2;
const IDX_OPTIONS_PEER_MAX_CONCURRENT_STREAMS = 3;
const IDX_OPTIONS_PADDING_STRATEGY = 4;
const IDX_OPTIONS_FLAGS = 5;

function updateOptionsBuffer(options) {
  var flags = 0;
  if (typeof options.maxDeflateDynamicTableSize === 'number') {
    flags |= (1 << IDX_OPTIONS_MAX_DEFLATE_DYNAMIC_TABLE_SIZE);
    optionsBuffer[IDX_OPTIONS_MAX_DEFLATE_DYNAMIC_TABLE_SIZE] =
      options.maxDeflateDynamicTableSize;
  }
  if (typeof options.maxReservedRemoteStreams === 'number') {
    flags |= (1 << IDX_OPTIONS_MAX_RESERVED_REMOTE_STREAMS);
    optionsBuffer[IDX_OPTIONS_MAX_RESERVED_REMOTE_STREAMS] =
      options.maxReservedRemoteStreams;
  }
  if (typeof options.maxSendHeaderBlockLength === 'number') {
    flags |= (1 << IDX_OPTIONS_MAX_SEND_HEADER_BLOCK_LENGTH);
    optionsBuffer[IDX_OPTIONS_MAX_SEND_HEADER_BLOCK_LENGTH] =
      options.maxSendHeaderBlockLength;
  }
  if (typeof options.peerMaxConcurrentStreams === 'number') {
    flags |= (1 << IDX_OPTIONS_PEER_MAX_CONCURRENT_STREAMS);
    optionsBuffer[IDX_OPTIONS_PEER_MAX_CONCURRENT_STREAMS] =
      options.peerMaxConcurrentStreams;
  }
  if (typeof options.paddingStrategy === 'number') {
    flags |= (1 << IDX_OPTIONS_PADDING_STRATEGY);
    optionsBuffer[IDX_OPTIONS_PADDING_STRATEGY] =
      options.paddingStrategy;
  }
  optionsBuffer[IDX_OPTIONS_FLAGS] = flags;
}

function getDefaultSettings() {
  settingsBuffer[IDX_SETTINGS_FLAGS] = 0;
  binding.refreshDefaultSettings();
  const holder = Object.create(null);

  const flags = settingsBuffer[IDX_SETTINGS_FLAGS];

  if ((flags & (1 << IDX_SETTINGS_HEADER_TABLE_SIZE)) ===
      (1 << IDX_SETTINGS_HEADER_TABLE_SIZE)) {
    holder.headerTableSize =
      settingsBuffer[IDX_SETTINGS_HEADER_TABLE_SIZE];
  }

  if ((flags & (1 << IDX_SETTINGS_ENABLE_PUSH)) ===
      (1 << IDX_SETTINGS_ENABLE_PUSH)) {
    holder.enablePush =
      settingsBuffer[IDX_SETTINGS_ENABLE_PUSH] === 1;
  }

  if ((flags & (1 << IDX_SETTINGS_INITIAL_WINDOW_SIZE)) ===
      (1 << IDX_SETTINGS_INITIAL_WINDOW_SIZE)) {
    holder.initialWindowSize =
      settingsBuffer[IDX_SETTINGS_INITIAL_WINDOW_SIZE];
  }

  if ((flags & (1 << IDX_SETTINGS_MAX_FRAME_SIZE)) ===
      (1 << IDX_SETTINGS_MAX_FRAME_SIZE)) {
    holder.maxFrameSize =
      settingsBuffer[IDX_SETTINGS_MAX_FRAME_SIZE];
  }

  if ((flags & (1 << IDX_SETTINGS_MAX_CONCURRENT_STREAMS)) ===
      (1 << IDX_SETTINGS_MAX_CONCURRENT_STREAMS)) {
    holder.maxConcurrentStreams =
      settingsBuffer[IDX_SETTINGS_MAX_CONCURRENT_STREAMS];
  }

  if ((flags & (1 << IDX_SETTINGS_MAX_HEADER_LIST_SIZE)) ===
      (1 << IDX_SETTINGS_MAX_HEADER_LIST_SIZE)) {
    holder.maxHeaderListSize =
      settingsBuffer[IDX_SETTINGS_MAX_HEADER_LIST_SIZE];
  }

  return holder;
}

// remote is a boolean. true to fetch remote settings, false to fetch local.
// this is only called internally
function getSettings(session, remote) {
  const holder = Object.create(null);
  if (remote)
    binding.refreshRemoteSettings(session);
  else
    binding.refreshLocalSettings(session);

  holder.headerTableSize =
    settingsBuffer[IDX_SETTINGS_HEADER_TABLE_SIZE];
  holder.enablePush =
    !!settingsBuffer[IDX_SETTINGS_ENABLE_PUSH];
  holder.initialWindowSize =
    settingsBuffer[IDX_SETTINGS_INITIAL_WINDOW_SIZE];
  holder.maxFrameSize =
    settingsBuffer[IDX_SETTINGS_MAX_FRAME_SIZE];
  holder.maxConcurrentStreams =
    settingsBuffer[IDX_SETTINGS_MAX_CONCURRENT_STREAMS];
  holder.maxHeaderListSize =
    settingsBuffer[IDX_SETTINGS_MAX_HEADER_LIST_SIZE];
  return holder;
}

function updateSettingsBuffer(settings) {
  var flags = 0;
  if (typeof settings.headerTableSize === 'number') {
    flags |= (1 << IDX_SETTINGS_HEADER_TABLE_SIZE);
    settingsBuffer[IDX_SETTINGS_HEADER_TABLE_SIZE] =
      settings.headerTableSize;
  }
  if (typeof settings.maxConcurrentStreams === 'number') {
    flags |= (1 << IDX_SETTINGS_MAX_CONCURRENT_STREAMS);
    settingsBuffer[IDX_SETTINGS_MAX_CONCURRENT_STREAMS] =
      settings.maxConcurrentStreams;
  }
  if (typeof settings.initialWindowSize === 'number') {
    flags |= (1 << IDX_SETTINGS_INITIAL_WINDOW_SIZE);
    settingsBuffer[IDX_SETTINGS_INITIAL_WINDOW_SIZE] =
      settings.initialWindowSize;
  }
  if (typeof settings.maxFrameSize === 'number') {
    flags |= (1 << IDX_SETTINGS_MAX_FRAME_SIZE);
    settingsBuffer[IDX_SETTINGS_MAX_FRAME_SIZE] =
      settings.maxFrameSize;
  }
  if (typeof settings.maxHeaderListSize === 'number') {
    flags |= (1 << IDX_SETTINGS_MAX_HEADER_LIST_SIZE);
    settingsBuffer[IDX_SETTINGS_MAX_HEADER_LIST_SIZE] =
      settings.maxHeaderListSize;
  }
  if (typeof settings.enablePush === 'boolean') {
    flags |= (1 << IDX_SETTINGS_ENABLE_PUSH);
    settingsBuffer[IDX_SETTINGS_ENABLE_PUSH] = Number(settings.enablePush);
  }

  settingsBuffer[IDX_SETTINGS_FLAGS] = flags;
}

function getSessionState(session) {
  const holder = Object.create(null);
  binding.refreshSessionState(session);
  holder.effectiveLocalWindowSize =
    sessionState[IDX_SESSION_STATE_EFFECTIVE_LOCAL_WINDOW_SIZE];
  holder.effectiveRecvDataLength =
    sessionState[IDX_SESSION_STATE_EFFECTIVE_RECV_DATA_LENGTH];
  holder.nextStreamID =
    sessionState[IDX_SESSION_STATE_NEXT_STREAM_ID];
  holder.localWindowSize =
    sessionState[IDX_SESSION_STATE_LOCAL_WINDOW_SIZE];
  holder.lastProcStreamID =
    sessionState[IDX_SESSION_STATE_LAST_PROC_STREAM_ID];
  holder.remoteWindowSize =
    sessionState[IDX_SESSION_STATE_REMOTE_WINDOW_SIZE];
  holder.outboundQueueSize =
    sessionState[IDX_SESSION_STATE_OUTBOUND_QUEUE_SIZE];
  holder.deflateDynamicTableSize =
    sessionState[IDX_SESSION_STATE_HD_DEFLATE_DYNAMIC_TABLE_SIZE];
  holder.inflateDynamicTableSize =
    sessionState[IDX_SESSION_STATE_HD_INFLATE_DYNAMIC_TABLE_SIZE];
  return holder;
}

function getStreamState(session, stream) {
  const holder = Object.create(null);
  binding.refreshStreamState(session, stream);
  holder.state =
    streamState[IDX_STREAM_STATE];
  holder.weight =
    streamState[IDX_STREAM_STATE_WEIGHT];
  holder.sumDependencyWeight =
    streamState[IDX_STREAM_STATE_SUM_DEPENDENCY_WEIGHT];
  holder.localClose =
    streamState[IDX_STREAM_STATE_LOCAL_CLOSE];
  holder.remoteClose =
    streamState[IDX_STREAM_STATE_REMOTE_CLOSE];
  holder.localWindowSize =
    streamState[IDX_STREAM_STATE_LOCAL_WINDOW_SIZE];
  return holder;
}

function isIllegalConnectionSpecificHeader(name, value) {
  switch (name) {
    case HTTP2_HEADER_CONNECTION:
    case HTTP2_HEADER_UPGRADE:
    case HTTP2_HEADER_HOST:
    case HTTP2_HEADER_HTTP2_SETTINGS:
    case HTTP2_HEADER_KEEP_ALIVE:
    case HTTP2_HEADER_PROXY_CONNECTION:
    case HTTP2_HEADER_TRANSFER_ENCODING:
      return true;
    case HTTP2_HEADER_TE:
      const val = Array.isArray(value) ? value.join(', ') : value;
      return val !== 'trailers';
    default:
      return false;
  }
}

function assertValidPseudoHeader(key) {
  if (!kValidPseudoHeaders.has(key)) {
    const err = new errors.Error('ERR_HTTP2_INVALID_PSEUDOHEADER', key);
    Error.captureStackTrace(err, assertValidPseudoHeader);
    return err;
  }
}

function assertValidPseudoHeaderResponse(key) {
  if (key !== ':status') {
    const err = new errors.Error('ERR_HTTP2_INVALID_PSEUDOHEADER', key);
    Error.captureStackTrace(err, assertValidPseudoHeaderResponse);
    return err;
  }
}

function assertValidPseudoHeaderTrailer(key) {
  const err = new errors.Error('ERR_HTTP2_INVALID_PSEUDOHEADER', key);
  Error.captureStackTrace(err, assertValidPseudoHeaderTrailer);
  return err;
}

function mapToHeaders(map,
                      assertValuePseudoHeader = assertValidPseudoHeader) {
  let ret = '';
  let count = 0;
  const keys = Object.keys(map);
  const singles = new Set();
  for (var i = 0; i < keys.length; i++) {
    let key = keys[i];
    let value = map[key];
    let val;
    if (typeof key === 'symbol' || value === undefined || !key)
      continue;
    key = String(key).toLowerCase();
    const isArray = Array.isArray(value);
    if (isArray) {
      switch (value.length) {
        case 0:
          continue;
        case 1:
          value = String(value[0]);
          break;
        default:
          if (kSingleValueHeaders.has(key))
            return new errors.Error('ERR_HTTP2_HEADER_SINGLE_VALUE', key);
      }
    }
    if (key[0] === ':') {
      const err = assertValuePseudoHeader(key);
      if (err !== undefined)
        return err;
      ret = `${key}\0${String(value)}\0${ret}`;
      count++;
    } else {
      if (kSingleValueHeaders.has(key)) {
        if (singles.has(key))
          return new errors.Error('ERR_HTTP2_HEADER_SINGLE_VALUE', key);
        singles.add(key);
      }
      if (isIllegalConnectionSpecificHeader(key, value)) {
        return new errors.Error('ERR_HTTP2_INVALID_CONNECTION_HEADERS');
      }
      if (isArray) {
        for (var k = 0; k < value.length; k++) {
          val = String(value[k]);
          ret += `${key}\0${val}\0`;
        }
        count += value.length;
      } else {
        val = String(value);
        ret += `${key}\0${val}\0`;
        count++;
      }
    }
  }

  return [ret, count];
}

class NghttpError extends Error {
  constructor(ret) {
    super(binding.nghttp2ErrorString(ret));
    this.code = 'ERR_HTTP2_ERROR';
    this.name = 'Error [ERR_HTTP2_ERROR]';
    this.errno = ret;
  }
}

function assertIsObject(value, name, types = 'object') {
  if (value !== undefined &&
      (value === null ||
       typeof value !== 'object' ||
       Array.isArray(value))) {
    const err = new errors.TypeError('ERR_INVALID_ARG_TYPE', name, types);
    Error.captureStackTrace(err, assertIsObject);
    throw err;
  }
}

function assertWithinRange(name, value, min = 0, max = Infinity) {
  if (value !== undefined &&
      (typeof value !== 'number' || value < min || value > max)) {
    const err = new errors.RangeError('ERR_HTTP2_INVALID_SETTING_VALUE',
                                      name, value);
    err.min = min;
    err.max = max;
    err.actual = value;
    Error.captureStackTrace(err, assertWithinRange);
    throw err;
  }
}

function toHeaderObject(headers) {
  const obj = Object.create(null);
  for (var n = 0; n < headers.length; n = n + 2) {
    var name = headers[n];
    var value = headers[n + 1];
    if (name === HTTP2_HEADER_STATUS)
      value |= 0;
    var existing = obj[name];
    if (existing === undefined) {
      obj[name] = value;
    } else if (!kSingleValueHeaders.has(name)) {
      switch (name) {
        case HTTP2_HEADER_COOKIE:
          // https://tools.ietf.org/html/rfc7540#section-8.1.2.5
          // "...If there are multiple Cookie header fields after decompression,
          //  these MUST be concatenated into a single octet string using the
          //  two-octet delimiter of 0x3B, 0x20 (the ASCII string "; ") before
          //  being passed into a non-HTTP/2 context."
          obj[name] = `${existing}; ${value}`;
          break;
        case HTTP2_HEADER_SET_COOKIE:
          // https://tools.ietf.org/html/rfc7230#section-3.2.2
          // "Note: In practice, the "Set-Cookie" header field ([RFC6265]) often
          // appears multiple times in a response message and does not use the
          // list syntax, violating the above requirements on multiple header
          // fields with the same name.  Since it cannot be combined into a
          // single field-value, recipients ought to handle "Set-Cookie" as a
          // special case while processing header fields."
          if (Array.isArray(existing))
            existing.push(value);
          else
            obj[name] = [existing, value];
          break;
        default:
          // https://tools.ietf.org/html/rfc7230#section-3.2.2
          // "A recipient MAY combine multiple header fields with the same field
          // name into one "field-name: field-value" pair, without changing the
          // semantics of the message, by appending each subsequent field value
          // to the combined field value in order, separated by a comma."
          obj[name] = `${existing}, ${value}`;
          break;
      }
    }
  }
  return obj;
}

function isPayloadMeaningless(method) {
  return kNoPayloadMethods.has(method);
}

function sessionName(type) {
  switch (type) {
    case NGHTTP2_SESSION_CLIENT:
      return 'client';
    case NGHTTP2_SESSION_SERVER:
      return 'server';
    default:
      return '<invalid>';
  }
}

module.exports = {
  assertIsObject,
  assertValidPseudoHeaderResponse,
  assertValidPseudoHeaderTrailer,
  assertWithinRange,
  getDefaultSettings,
  getSessionState,
  getSettings,
  getStreamState,
  isPayloadMeaningless,
  mapToHeaders,
  NghttpError,
  sessionName,
  toHeaderObject,
  updateOptionsBuffer,
  updateSettingsBuffer
};