How to add a disabled button to alert ion 2

Question

I created an ionic2 warning and I have to disable the button according to the condition.

This is a simple structure of my code:

import { AlertController } from 'ionic-angular';

export class MyPage {
  constructor(public alertCtrl: AlertController) {
  }

  showCheckbox(condition) {
    let alert = this.alertCtrl.create();
    alert.setTitle('Which planets have you visited?');

    alert.addInput({
      type: 'checkbox',
      label: 'Alderaan',
      value: 'value1',
      checked: true
    });

    alert.addInput({
      type: 'checkbox',
      label: 'Bespin',
      value: 'value2'
    });

    alert.addButton('Cancel');
    alert.addButton({
      text: 'Okay',

      handler: data => {
        console.log('Checkbox data:', data);
        this.testCheckboxOpen = false;
        this.testCheckboxResult = data;
      }
    });
    alert.present();
  }
}

I need to disable the button Okayif the specified condition true(parameter 'condition' passed to the function showCheckbox()).