/**
 * Copyright 2018 Google Inc. All rights reserved.
 * Modifications copyright (c) Microsoft Corporation.
 *
 * Licensed 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.
 */

import { debugError, helper, RegisteredListener } from '../helper';
import { ConnectionTransport } from '../transport';
import { makeWaitForNextTask } from '../platform';

export class PipeTransport implements ConnectionTransport {
  private _pipeWrite: NodeJS.WritableStream | null;
  private _pendingMessage = '';
  private _eventListeners: RegisteredListener[];
  private _waitForNextTask = makeWaitForNextTask();
  private readonly _closeCallback: () => void;

  onmessage?: (message: string) => void;
  onclose?: () => void;

  constructor(pipeWrite: NodeJS.WritableStream, pipeRead: NodeJS.ReadableStream, closeCallback: () => void) {
    this._pipeWrite = pipeWrite;
    this._closeCallback = closeCallback;
    this._eventListeners = [
      helper.addEventListener(pipeRead, 'data', buffer => this._dispatch(buffer)),
      helper.addEventListener(pipeRead, 'close', () => {
        helper.removeEventListeners(this._eventListeners);
        if (this.onclose)
          this.onclose.call(null);
      }),
      helper.addEventListener(pipeRead, 'error', debugError),
      helper.addEventListener(pipeWrite, 'error', debugError),
    ];
    this.onmessage = undefined;
    this.onclose = undefined;
  }

  send(message: string) {
    this._pipeWrite!.write(message);
    this._pipeWrite!.write('\0');
  }

  close() {
    this._closeCallback();
  }

  _dispatch(buffer: Buffer) {
    let end = buffer.indexOf('\0');
    if (end === -1) {
      this._pendingMessage += buffer.toString();
      return;
    }
    const message = this._pendingMessage + buffer.toString(undefined, 0, end);
    this._waitForNextTask(() => {
      if (this.onmessage)
        this.onmessage.call(null, message);
    });

    let start = end + 1;
    end = buffer.indexOf('\0', start);
    while (end !== -1) {
      const message = buffer.toString(undefined, start, end);
      this._waitForNextTask(() => {
        if (this.onmessage)
          this.onmessage.call(null, message);
      });
      start = end + 1;
      end = buffer.indexOf('\0', start);
    }
    this._pendingMessage = buffer.toString(undefined, start);
  }
}