/**
 * Implements hook_menu().
 */
function notification_menu() {
  $items = [];
  $items['admin/customize'] = [
    'title'            => 'Send Comment notifications',
    'discription'      => 'Admin will send notification to user about updates',
    'type'             => MENU_NORMAL_ITEM,
    'page callback'    => 'drupal_get_form',
    'page arguments'   => ['notification_form'],
    'access arguments' => ['access adminstration page'],
    'access callback'  => TRUE,
  ];
  return $items;
}
/**
 * Custom form.
 */
function notification_form($form, &$form_state) {
  $form['send_mail_to'] = [
    '#title'         => 'Send Mail To',
    '#discription'   => 'To whom you want to send form',
    '#size'          => 40,
    '#type'          => 'textfield',
    '#required'      => TRUE,
    '#default_value' => variable_get('send_mail_to'),
  ];
  //here the admin can wite subject for the mail.
  $form['mail_subject'] = [
    '#title'         => 'Subject',
    '#discription'   => 'the purpous of this mail',
    '#type'          => 'textfield',
    '#size'          => 40,
    '#maxlenght'     => 120,
    '#required'      => TRUE,
    '#default_value' => variable_get('mail_subject'),
  ];
  $form['mail_body'] = [
    '#title'         => 'Body',
    '#discription'   => 'the body of your mail.',
    '#type'          => 'textarea',
    '#row'           => 10,
    '#columns'       => 40,
    '#required'      => TRUE,
    '#default_value' => variable_get('mail_body'),
  ];
  $form['mail_bcc'] = [
    '#title' => 'BCC this mail to all',
    '#type'  => 'checkbox',
  ];
  return system_settings_form($form);
}