Start an Android Virtual Device on Windows from a WSL shell

wsl-select-and-run-emulator.js

/* eslint-disable @typescript-eslint/no-var-requires */
const exec = require('child_process').exec;
const spawn = require('child_process').spawn;
const readline = require('readline');

// utility to add ansii escape codes to strings (external)
const { green, yellow, red } = require('./util/console-color');
// utility to shallow-validate the android sdk path (external)
const { validateAndroidHomeWin } = require('./util/validate-android-home');

/*
  ANDROID_HOME_WIN points to the mounted Windows Android SDK path
  e.g. /mnt/c/Users/<user>/AppData/Local/Android/Sdk
*/
const RUN_CMD = `${process.env.ANDROID_HOME_WIN}/emulator/emulator`;
const LIST_CMD = `${process.env.ANDROID_HOME_WIN}/emulator/emulator -avd -list-avds`;

if (validateAndroidHomeWin(process.env.ANDROID_HOME_WIN, false))
  (async () => {
    await runEmulator();
  })();

function getDevices() {
  return new Promise((resolve, reject) => {
    exec(LIST_CMD, (error, stdout) => {
      if (error) {
        if (error.message.includes('emulator/emulator:')) {
          console.error(
            'Error retrieving device list, unpatched Sdk directory. Please run wsl-setup first.' // <-- .exe files have not been copied to their non-exe counterparts
          );
        } else {
          console.error(`Error retrieving list of devices: ${error.message}`);
        }
        reject(error);
        return;
      }

      const result = stdout;
      const devices = result
        .split('\n')
        .map((name) => name.trim())
        .filter((name) => name);
      resolve(devices);
    });
  });
}

async function runEmulator() {
  const emulators = await getDevices();

  if (emulators.length === 0) {
    console.log('No devices available.');
    return;
  }

  console.log('Select an emulator:\n');
  emulators.forEach((emulator, index) => {
    console.log(`   [${index + 1}] ${emulator}`);
  });

  const selectedEmulatorIndex = await getUserInput('\nEmulator: ');

  if (isValidIndex(selectedEmulatorIndex, emulators.length)) {
    const selectedEmulator = emulators[selectedEmulatorIndex - 1];
    console.log(green(`\nStarting ${selectedEmulator}...`));
    try {
      const emulatorProcess = spawn(RUN_CMD, ['-avd', selectedEmulator]);

      emulatorProcess.on('close', (code) => {
        if (code !== 0)
          console.log(red(`${selectedEmulator} exited with error.`));
        else console.log(yellow(`${selectedEmulator} exited gracefully.`));
      });

      emulatorProcess.stderr.on('error', () => {
        console.log(
          red(
            `${selectedEmulator} encountered an error and had to be shut down.`
          )
        );
      });
    } catch (err) {
      console.error('Error running emulator.');
    }
  } else {
    console.log('Invalid selection.');
  }
}

function getUserInput(prompt) {
  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
  });

  return new Promise((resolve) => {
    rl.question(prompt, (answer) => {
      rl.close();
      resolve(answer.trim());
    });
  });
}

function isValidIndex(index, arrayLength) {
  return !isNaN(index) && index >= 1 && index <= arrayLength;
}