/**
 * Copyright Microsoft Corporation. All rights reserved.
 *
 * 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 assert from 'assert';
import debug from 'debug';
import * as net from 'net';
import { EventEmitter } from 'events';
import { Backend, DeviceBackend, SocketBackend } from './android';
import { createGuid } from '../../utils/utils';

export class AdbBackend implements Backend {
  async devices(): Promise<DeviceBackend[]> {
    const result = await runCommand('host:devices');
    const lines = result.toString().trim().split('\n');
    return lines.map(line => {
      const [serial, status] = line.trim().split('\t');
      return new AdbDevice(serial, status);
    });
  }
}

class AdbDevice implements DeviceBackend {
  readonly serial: string;
  readonly status: string;

  constructor(serial: string, status: string) {
    this.serial = serial;
    this.status = status;
  }

  async init() {
  }

  async close() {
  }

  runCommand(command: string): Promise<Buffer> {
    return runCommand(command, this.serial);
  }

  async open(command: string): Promise<SocketBackend> {
    const result = await open(command, this.serial);
    result.becomeSocket();
    return result;
  }
}

async function runCommand(command: string, serial?: string): Promise<Buffer> {
  debug('pw:adb:runCommand')(command, serial);
  const socket = new BufferedSocketWrapper(command, net.createConnection({ port: 5037 }));
  if (serial) {
    await socket.write(encodeMessage(`host:transport:${serial}`));
    const status = await socket.read(4);
    assert(status.toString() === 'OKAY', status.toString());
  }
  await socket.write(encodeMessage(command));
  const status = await socket.read(4);
  assert(status.toString() === 'OKAY', status.toString());
  let commandOutput: Buffer;
  if (!command.startsWith('shell:')) {
    const remainingLength = parseInt((await socket.read(4)).toString(), 16);
    commandOutput = await socket.read(remainingLength);
  } else {
    commandOutput = await socket.readAll();
  }
  socket.close();
  return commandOutput;
}

async function open(command: string, serial?: string): Promise<BufferedSocketWrapper> {
  const socket = new BufferedSocketWrapper(command, net.createConnection({ port: 5037 }));
  if (serial) {
    await socket.write(encodeMessage(`host:transport:${serial}`));
    const status = await socket.read(4);
    assert(status.toString() === 'OKAY', status.toString());
  }
  await socket.write(encodeMessage(command));
  const status = await socket.read(4);
  assert(status.toString() === 'OKAY', status.toString());
  return socket;
}

function encodeMessage(message: string): Buffer {
  let lenHex = (message.length).toString(16);
  lenHex = '0'.repeat(4 - lenHex.length) + lenHex;
  return Buffer.from(lenHex + message);
}

class BufferedSocketWrapper extends EventEmitter implements SocketBackend {
  readonly guid = createGuid();
  private _socket: net.Socket;
  private _buffer = Buffer.from([]);
  private _isSocket = false;
  private _notifyReader: (() => void) | undefined;
  private _connectPromise: Promise<void>;
  private _isClosed = false;
  private _command: string;

  constructor(command: string, socket: net.Socket) {
    super();
    this._command = command;
    this._socket = socket;
    this._connectPromise = new Promise(f => this._socket.on('connect', f));
    this._socket.on('data', data => {
      debug('pw:adb:data')(data.toString());
      if (this._isSocket) {
        this.emit('data', data);
        return;
      }
      this._buffer = Buffer.concat([this._buffer, data]);
      if (this._notifyReader)
        this._notifyReader();
    });
    this._socket.on('close', () => {
      this._isClosed = true;
      if (this._notifyReader)
        this._notifyReader();
      this.close();
      this.emit('close');
    });
    this._socket.on('error', error => this.emit('error', error));
  }

  async write(data: Buffer) {
    debug('pw:adb:send')(data.toString().substring(0, 100) + '...');
    await this._connectPromise;
    await new Promise(f => this._socket.write(data, f));
  }

  close() {
    if (this._isClosed)
      return;
    debug('pw:adb')('Close ' + this._command);
    this._socket.destroy();
  }

  async read(length: number): Promise<Buffer> {
    await this._connectPromise;
    assert(!this._isSocket, 'Can not read by length in socket mode');
    while (this._buffer.length < length)
      await new Promise<void>(f => this._notifyReader = f);
    const result = this._buffer.slice(0, length);
    this._buffer = this._buffer.slice(length);
    debug('pw:adb:recv')(result.toString().substring(0, 100) + '...');
    return result;
  }

  async readAll(): Promise<Buffer> {
    while (!this._isClosed)
      await new Promise<void>(f => this._notifyReader = f);
    return this._buffer;
  }

  becomeSocket() {
    assert(!this._buffer.length);
    this._isSocket = true;
  }
}
