const { chmodSync } = require('fs');
const { EventEmitter } = require('events');
const path = require('path');
const { execFile } = require('child_process');

class ClipboardEventListener extends EventEmitter {
  constructor() {
    super();
    this.child = null;
  }
  startListening() {
    const { platform } = process;
    if (platform === 'win32') {
      this.child = execFile(path.join(__dirname, 'platform/clipboard-event-handler-win32.exe'));
    }
    else if (platform === 'linux') {
      const p = path.join(__dirname, 'platform/clipboard-event-handler-linux');
      chmodSync(p, 0o111); // modify file permission: everyone can execute, or it will fail
      this.child = execFile();
    }
    else if (platform === 'darwin') {
      this.child = execFile(path.join(__dirname, 'platform/clipboard-event-handler-mac'));
    }
    else {
      throw 'Not yet supported';
    }
    this.child.stdout.on('data', (data) => {
      if (data.trim() === 'CLIPBOARD_CHANGE') {
        this.emit('change');
      }
    });
  }
  stopListening() {
    const res = this.child.kill();
    return res;
  }
}

module.exports = new ClipboardEventListener();