'use strict';

const assert = require('node:assert');
const { pipeline } = require('node:stream');
const util = require('../core/util.js');
const {
  RequestContentLengthMismatchError,
  RequestAbortedError,
  SocketError,
  InformationalError,
} = require('../core/errors.js');
const {
  kUrl,
  kReset,
  kClient,
  kRunning,
  kPending,
  kQueue,
  kPendingIdx,
  kRunningIdx,
  kError,
  kSocket,
  kStrictContentLength,
  kOnError,
  kMaxConcurrentStreams,
  kHTTP2Session,
  kResume,
  kSize,
  kHTTPContext,
  kClosed,
  kBodyTimeout,
} = require('../core/symbols.js');
const { channels } = require('../core/diagnostics.js');

const kOpenStreams = Symbol('open streams');

let extractBody;

/** @type {import('http2')} */
let http2;
try {
  http2 = require('node:http2');
} catch {
  // @ts-ignore
  http2 = { constants: {} };
}

const {
  constants: {
    HTTP2_HEADER_AUTHORITY,
    HTTP2_HEADER_METHOD,
    HTTP2_HEADER_PATH,
    HTTP2_HEADER_SCHEME,
    HTTP2_HEADER_CONTENT_LENGTH,
    HTTP2_HEADER_EXPECT,
    HTTP2_HEADER_STATUS,
  },
} = http2;

function parseH2Headers(headers) {
  const result = [];

  for (const [name, value] of Object.entries(headers)) {
    // h2 may concat the header value by array
    // e.g. Set-Cookie
    if (Array.isArray(value)) {
      for (const subvalue of value) {
        // we need to provide each header value of header name
        // because the headers handler expect name-value pair
        result.push(Buffer.from(name), Buffer.from(subvalue));
      }
    } else {
      result.push(Buffer.from(name), Buffer.from(value));
    }
  }

  return result;
}

async function connectH2(client, socket) {
  client[kSocket] = socket;

  const session = http2.connect(client[kUrl], {
    createConnection: () => socket,
    peerMaxConcurrentStreams: client[kMaxConcurrentStreams],
    settings: {
      // TODO(metcoder95): add support for PUSH
      enablePush: false,
    },
  });

  session[kOpenStreams] = 0;
  session[kClient] = client;
  session[kSocket] = socket;
  session[kHTTP2Session] = null;

  util.addListener(session, 'error', onHttp2SessionError);
  util.addListener(session, 'frameError', onHttp2FrameError);
  util.addListener(session, 'end', onHttp2SessionEnd);
  util.addListener(session, 'goaway', onHttp2SessionGoAway);
  util.addListener(session, 'close', onHttp2SessionClose);

  session.unref();

  client[kHTTP2Session] = session;
  socket[kHTTP2Session] = session;

  util.addListener(socket, 'error', onHttp2SocketError);
  util.addListener(socket, 'end', onHttp2SocketEnd);
  util.addListener(socket, 'close', onHttp2SocketClose);

  socket[kClosed] = false;
  socket.on('close', onSocketClose);

  return {
    version: 'h2',
    defaultPipelining: Infinity,
    write(request) {
      return writeH2(client, request);
    },
    resume() {
      resumeH2(client);
    },
    destroy(err, callback) {
      if (socket[kClosed]) {
        queueMicrotask(callback);
      } else {
        socket.destroy(err).on('close', callback);
      }
    },
    get destroyed() {
      return socket.destroyed;
    },
    busy() {
      return false;
    },
  };
}

function resumeH2(client) {
  const socket = client[kSocket];

  if (socket?.destroyed === false) {
    if (client[kSize] === 0 || client[kMaxConcurrentStreams] === 0) {
      socket.unref();
      client[kHTTP2Session].unref();
    } else {
      socket.ref();
      client[kHTTP2Session].ref();
    }
  }
}

function onHttp2SessionError(err) {
  assert(err.code !== 'ERR_TLS_CERT_ALTNAME_INVALID');

  this[kSocket][kError] = err;
  this[kClient][kOnError](err);
}

function onHttp2FrameError(type, code, id) {
  if (id === 0) {
    const err = new InformationalError(
      `HTTP/2: "frameError" received - type ${type}, code ${code}`
    );
    this[kSocket][kError] = err;
    this[kClient][kOnError](err);
  }
}

function onHttp2SessionEnd() {
  const err = new SocketError(
    'other side closed',
    util.getSocketInfo(this[kSocket])
  );
  this.destroy(err);
  util.destroy(this[kSocket], err);
}

/**
 * This is the root cause of #3011
 * We need to handle GOAWAY frames properly, and trigger the session close
 * along with the socket right away
 *
 * @this {import('http2').ClientHttp2Session}
 * @param {number} errorCode
 */
function onHttp2SessionGoAway(errorCode) {
  // TODO(mcollina): Verify if GOAWAY implements the spec correctly:
  // https://datatracker.ietf.org/doc/html/rfc7540#section-6.8
  // Specifically, we do not verify the "valid" stream id.

  const err =
    this[kError] ||
    new SocketError(
      `HTTP/2: "GOAWAY" frame received with code ${errorCode}`,
      util.getSocketInfo(this[kSocket])
    );
  const client = this[kClient];

  client[kSocket] = null;
  client[kHTTPContext] = null;

  // this is an HTTP2 session
  this.close();
  this[kHTTP2Session] = null;

  util.destroy(this[kSocket], err);

  // Fail head of pipeline.
  if (client[kRunningIdx] < client[kQueue].length) {
    const request = client[kQueue][client[kRunningIdx]];
    client[kQueue][client[kRunningIdx]++] = null;
    util.errorRequest(client, request, err);
    client[kPendingIdx] = client[kRunningIdx];
  }

  assert(client[kRunning] === 0);

  client.emit('disconnect', client[kUrl], [client], err);

  client[kResume]();
}

function onHttp2SessionClose() {
  const { [kClient]: client } = this;
  const { [kSocket]: socket } = client;

  const err =
    this[kSocket][kError] ||
    this[kError] ||
    new SocketError('closed', util.getSocketInfo(socket));

  client[kSocket] = null;
  client[kHTTPContext] = null;

  if (client.destroyed) {
    assert(client[kPending] === 0);

    // Fail entire queue.
    const requests = client[kQueue].splice(client[kRunningIdx]);
    for (let i = 0; i < requests.length; i++) {
      const request = requests[i];
      util.errorRequest(client, request, err);
    }
  }
}

function onHttp2SocketClose() {
  const err =
    this[kError] || new SocketError('closed', util.getSocketInfo(this));

  const client = this[kHTTP2Session][kClient];

  client[kSocket] = null;
  client[kHTTPContext] = null;

  if (this[kHTTP2Session] !== null) {
    this[kHTTP2Session].destroy(err);
  }

  client[kPendingIdx] = client[kRunningIdx];

  assert(client[kRunning] === 0);

  client.emit('disconnect', client[kUrl], [client], err);

  client[kResume]();
}

function onHttp2SocketError(err) {
  assert(err.code !== 'ERR_TLS_CERT_ALTNAME_INVALID');

  this[kError] = err;

  this[kClient][kOnError](err);
}

function onHttp2SocketEnd() {
  util.destroy(
    this,
    new SocketError('other side closed', util.getSocketInfo(this))
  );
}

function onSocketClose() {
  this[kClosed] = true;
}

// https://www.rfc-editor.org/rfc/rfc7230#section-3.3.2
function shouldSendContentLength(method) {
  return (
    method !== 'GET' &&
    method !== 'HEAD' &&
    method !== 'OPTIONS' &&
    method !== 'TRACE' &&
    method !== 'CONNECT'
  );
}

function writeH2(client, request) {
  const requestTimeout = request.bodyTimeout ?? client[kBodyTimeout];
  const session = client[kHTTP2Session];
  const {
    method,
    path,
    host,
    upgrade,
    expectContinue,
    signal,
    headers: reqHeaders,
  } = request;
  let { body } = request;

  if (upgrade) {
    util.errorRequest(
      client,
      request,
      new Error('Upgrade not supported for H2')
    );
    return false;
  }

  const headers = {};
  for (let n = 0; n < reqHeaders.length; n += 2) {
    const key = reqHeaders[n + 0];
    const val = reqHeaders[n + 1];

    if (Array.isArray(val)) {
      for (let i = 0; i < val.length; i++) {
        if (headers[key]) {
          headers[key] += `,${val[i]}`;
        } else {
          headers[key] = val[i];
        }
      }
    } else {
      headers[key] = val;
    }
  }

  /** @type {import('node:http2').ClientHttp2Stream} */
  let stream = null;

  const { hostname, port } = client[kUrl];

  headers[HTTP2_HEADER_AUTHORITY] =
    host || `${hostname}${port ? `:${port}` : ''}`;
  headers[HTTP2_HEADER_METHOD] = method;

  const abort = (err) => {
    if (request.aborted || request.completed) {
      return;
    }

    err = err || new RequestAbortedError();

    util.errorRequest(client, request, err);

    if (stream != null) {
      // Some chunks might still come after abort,
      // let's ignore them
      stream.removeAllListeners('data');

      // On Abort, we close the stream to send RST_STREAM frame
      stream.close();

      // We move the running index to the next request
      client[kOnError](err);
      client[kResume]();
    }

    // We do not destroy the socket as we can continue using the session
    // the stream gets destroyed and the session remains to create new streams
    util.destroy(body, err);
  };

  try {
    // We are already connected, streams are pending.
    // We can call on connect, and wait for abort
    request.onConnect(abort);
  } catch (err) {
    util.errorRequest(client, request, err);
  }

  if (request.aborted) {
    return false;
  }

  if (method === 'CONNECT') {
    session.ref();
    // We are already connected, streams are pending, first request
    // will create a new stream. We trigger a request to create the stream and wait until
    // `ready` event is triggered
    // We disabled endStream to allow the user to write to the stream
    stream = session.request(headers, { endStream: false, signal });

    if (!stream.pending) {
      request.onUpgrade(null, null, stream);
      ++session[kOpenStreams];
      client[kQueue][client[kRunningIdx]++] = null;
    } else {
      stream.once('ready', () => {
        request.onUpgrade(null, null, stream);
        ++session[kOpenStreams];
        client[kQueue][client[kRunningIdx]++] = null;
      });
    }

    stream.once('close', () => {
      session[kOpenStreams] -= 1;
      if (session[kOpenStreams] === 0) session.unref();
    });
    stream.setTimeout(requestTimeout);

    return true;
  }

  // https://tools.ietf.org/html/rfc7540#section-8.3
  // :path and :scheme headers must be omitted when sending CONNECT

  headers[HTTP2_HEADER_PATH] = path;
  headers[HTTP2_HEADER_SCHEME] = 'https';

  // https://tools.ietf.org/html/rfc7231#section-4.3.1
  // https://tools.ietf.org/html/rfc7231#section-4.3.2
  // https://tools.ietf.org/html/rfc7231#section-4.3.5

  // Sending a payload body on a request that does not
  // expect it can cause undefined behavior on some
  // servers and corrupt connection state. Do not
  // re-use the connection for further requests.

  const expectsPayload =
    method === 'PUT' || method === 'POST' || method === 'PATCH';

  if (body && typeof body.read === 'function') {
    // Try to read EOF in order to get length.
    body.read(0);
  }

  let contentLength = util.bodyLength(body);

  if (util.isFormDataLike(body)) {
    extractBody ??= require('../web/fetch/body.js').extractBody;

    const [bodyStream, contentType] = extractBody(body);
    headers['content-type'] = contentType;

    body = bodyStream.stream;
    contentLength = bodyStream.length;
  }

  if (contentLength == null) {
    contentLength = request.contentLength;
  }

  if (contentLength === 0 || !expectsPayload) {
    // https://tools.ietf.org/html/rfc7230#section-3.3.2
    // A user agent SHOULD NOT send a Content-Length header field when
    // the request message does not contain a payload body and the method
    // semantics do not anticipate such a body.

    contentLength = null;
  }

  // https://github.com/nodejs/undici/issues/2046
  // A user agent may send a Content-Length header with 0 value, this should be allowed.
  if (
    shouldSendContentLength(method) &&
    contentLength > 0 &&
    request.contentLength != null &&
    request.contentLength !== contentLength
  ) {
    if (client[kStrictContentLength]) {
      util.errorRequest(
        client,
        request,
        new RequestContentLengthMismatchError()
      );
      return false;
    }

    process.emitWarning(new RequestContentLengthMismatchError());
  }

  if (contentLength != null) {
    assert(body, 'no body must not have content length');
    headers[HTTP2_HEADER_CONTENT_LENGTH] = `${contentLength}`;
  }

  session.ref();

  if (channels.sendHeaders.hasSubscribers) {
    let header = '';
    for (const key in headers) {
      header += `${key}: ${headers[key]}\r\n`;
    }
    channels.sendHeaders.publish({
      request,
      headers: header,
      socket: session[kSocket],
    });
  }

  // TODO(metcoder95): add support for sending trailers
  const shouldEndStream =
    method === 'GET' || method === 'HEAD' || body === null;
  if (expectContinue) {
    headers[HTTP2_HEADER_EXPECT] = '100-continue';
    stream = session.request(headers, { endStream: shouldEndStream, signal });

    stream.once('continue', writeBodyH2);
  } else {
    stream = session.request(headers, {
      endStream: shouldEndStream,
      signal,
    });

    writeBodyH2();
  }

  // Increment counter as we have new streams open
  ++session[kOpenStreams];
  stream.setTimeout(requestTimeout);

  stream.once('response', (headers) => {
    const { [HTTP2_HEADER_STATUS]: statusCode, ...realHeaders } = headers;
    request.onResponseStarted();

    // Due to the stream nature, it is possible we face a race condition
    // where the stream has been assigned, but the request has been aborted
    // the request remains in-flight and headers hasn't been received yet
    // for those scenarios, best effort is to destroy the stream immediately
    // as there's no value to keep it open.
    if (request.aborted) {
      stream.removeAllListeners('data');
      return;
    }

    if (
      request.onHeaders(
        Number(statusCode),
        parseH2Headers(realHeaders),
        stream.resume.bind(stream),
        ''
      ) === false
    ) {
      stream.pause();
    }
  });

  stream.on('data', (chunk) => {
    if (request.onData(chunk) === false) {
      stream.pause();
    }
  });

  stream.once('end', (err) => {
    stream.removeAllListeners('data');
    // When state is null, it means we haven't consumed body and the stream still do not have
    // a state.
    // Present specially when using pipeline or stream
    if (stream.state?.state == null || stream.state.state < 6) {
      // Do not complete the request if it was aborted
      // Not prone to happen for as safety net to avoid race conditions with 'trailers'
      if (!request.aborted && !request.completed) {
        request.onComplete({});
      }

      client[kQueue][client[kRunningIdx]++] = null;
      client[kResume]();
    } else {
      // Stream is closed or half-closed-remote (6), decrement counter and cleanup
      // It does not have sense to continue working with the stream as we do not
      // have yet RST_STREAM support on client-side
      --session[kOpenStreams];
      if (session[kOpenStreams] === 0) {
        session.unref();
      }

      abort(
        err ?? new InformationalError('HTTP/2: stream half-closed (remote)')
      );
      client[kQueue][client[kRunningIdx]++] = null;
      client[kPendingIdx] = client[kRunningIdx];
      client[kResume]();
    }
  });

  stream.once('close', () => {
    stream.removeAllListeners('data');
    session[kOpenStreams] -= 1;
    if (session[kOpenStreams] === 0) {
      session.unref();
    }
  });

  stream.once('error', function (err) {
    stream.removeAllListeners('data');
    abort(err);
  });

  stream.once('frameError', (type, code) => {
    stream.removeAllListeners('data');
    abort(
      new InformationalError(
        `HTTP/2: "frameError" received - type ${type}, code ${code}`
      )
    );
  });

  stream.on('aborted', () => {
    stream.removeAllListeners('data');
  });

  stream.on('timeout', () => {
    const err = new InformationalError(
      `HTTP/2: "stream timeout after ${requestTimeout}"`
    );
    stream.removeAllListeners('data');
    session[kOpenStreams] -= 1;

    if (session[kOpenStreams] === 0) {
      session.unref();
    }

    abort(err);
  });

  stream.once('trailers', (trailers) => {
    if (request.aborted || request.completed) {
      return;
    }

    request.onComplete(trailers);
  });

  return true;

  function writeBodyH2() {
    /* istanbul ignore else: assertion */
    if (!body || contentLength === 0) {
      writeBuffer(
        abort,
        stream,
        null,
        client,
        request,
        client[kSocket],
        contentLength,
        expectsPayload
      );
    } else if (util.isBuffer(body)) {
      writeBuffer(
        abort,
        stream,
        body,
        client,
        request,
        client[kSocket],
        contentLength,
        expectsPayload
      );
    } else if (util.isBlobLike(body)) {
      if (typeof body.stream === 'function') {
        writeIterable(
          abort,
          stream,
          body.stream(),
          client,
          request,
          client[kSocket],
          contentLength,
          expectsPayload
        );
      } else {
        writeBlob(
          abort,
          stream,
          body,
          client,
          request,
          client[kSocket],
          contentLength,
          expectsPayload
        );
      }
    } else if (util.isStream(body)) {
      writeStream(
        abort,
        client[kSocket],
        expectsPayload,
        stream,
        body,
        client,
        request,
        contentLength
      );
    } else if (util.isIterable(body)) {
      writeIterable(
        abort,
        stream,
        body,
        client,
        request,
        client[kSocket],
        contentLength,
        expectsPayload
      );
    } else {
      assert(false);
    }
  }
}

function writeBuffer(
  abort,
  h2stream,
  body,
  client,
  request,
  socket,
  contentLength,
  expectsPayload
) {
  try {
    if (body != null && util.isBuffer(body)) {
      assert(
        contentLength === body.byteLength,
        'buffer body must have content length'
      );
      h2stream.cork();
      h2stream.write(body);
      h2stream.uncork();
      h2stream.end();

      request.onBodySent(body);
    }

    if (!expectsPayload) {
      socket[kReset] = true;
    }

    request.onRequestSent();
    client[kResume]();
  } catch (error) {
    abort(error);
  }
}

function writeStream(
  abort,
  socket,
  expectsPayload,
  h2stream,
  body,
  client,
  request,
  contentLength
) {
  assert(
    contentLength !== 0 || client[kRunning] === 0,
    'stream body cannot be pipelined'
  );

  // For HTTP/2, is enough to pipe the stream
  const pipe = pipeline(body, h2stream, (err) => {
    if (err) {
      util.destroy(pipe, err);
      abort(err);
    } else {
      util.removeAllListeners(pipe);
      request.onRequestSent();

      if (!expectsPayload) {
        socket[kReset] = true;
      }

      client[kResume]();
    }
  });

  util.addListener(pipe, 'data', onPipeData);

  function onPipeData(chunk) {
    request.onBodySent(chunk);
  }
}

async function writeBlob(
  abort,
  h2stream,
  body,
  client,
  request,
  socket,
  contentLength,
  expectsPayload
) {
  assert(contentLength === body.size, 'blob body must have content length');

  try {
    if (contentLength != null && contentLength !== body.size) {
      throw new RequestContentLengthMismatchError();
    }

    const buffer = Buffer.from(await body.arrayBuffer());

    h2stream.cork();
    h2stream.write(buffer);
    h2stream.uncork();
    h2stream.end();

    request.onBodySent(buffer);
    request.onRequestSent();

    if (!expectsPayload) {
      socket[kReset] = true;
    }

    client[kResume]();
  } catch (err) {
    abort(err);
  }
}

async function writeIterable(
  abort,
  h2stream,
  body,
  client,
  request,
  socket,
  contentLength,
  expectsPayload
) {
  assert(
    contentLength !== 0 || client[kRunning] === 0,
    'iterator body cannot be pipelined'
  );

  let callback = null;
  function onDrain() {
    if (callback) {
      const cb = callback;
      callback = null;
      cb();
    }
  }

  const waitForDrain = () =>
    new Promise((resolve, reject) => {
      assert(callback === null);

      if (socket[kError]) {
        reject(socket[kError]);
      } else {
        callback = resolve;
      }
    });

  h2stream.on('close', onDrain).on('drain', onDrain);

  try {
    // It's up to the user to somehow abort the async iterable.
    for await (const chunk of body) {
      if (socket[kError]) {
        throw socket[kError];
      }

      const res = h2stream.write(chunk);
      request.onBodySent(chunk);
      if (!res) {
        await waitForDrain();
      }
    }

    h2stream.end();

    request.onRequestSent();

    if (!expectsPayload) {
      socket[kReset] = true;
    }

    client[kResume]();
  } catch (err) {
    abort(err);
  } finally {
    h2stream.off('close', onDrain).off('drain', onDrain);
  }
}

module.exports = connectH2;