function onCardClick(event) {
  if (event.action.actionMethodName === 'handleFormSubmit') {
    const recipients = getFieldValue_(event.common.formInputs, 'email');
    const subject = getFieldValue_(event.common.formInputs, 'subject');
    const body = getFieldValue_(event.common.formInputs, 'body');

    // Assumes dialog card inputs for date and times are in the correct format. mm/dd/yyy HH:MM
    const dateTimeInput = getFieldValue_(event.common.formInputs, 'date');
    const startTime = getStartTimeAsDateObject_(dateTimeInput);
    const duration = Number(getFieldValue_(event.common.formInputs, 'duration'));

    // Handles instances of missing or invalid input parameters.
    const errors = [];

    if (!recipients) {
      errors.push('Missing or invalid recipient email address.');
    }
    if (!subject) {
      errors.push('Missing subject line.');
    }
    if (!body) {
      errors.push('Missing event description.');
    }
    if (!startTime) {
      errors.push('Missing or invalid start time.');
    }
    if (!duration || isNaN(duration)) {
      errors.push('Missing or invalid duration');
    }
    if (errors.length) {
      // Redisplays the form if missing or invalid inputs exist.
      return getInputFormAsDialog_({
        errors,
        invitee: recipients,
        startTime: dateTimeInput,
        duration,
        subject,
        body
      });
    }

    //  Calculates the end time via duration.
    const endTime = new Date(startTime.valueOf());
    endTime.setMinutes(endTime.getMinutes() + duration);

    // Creates calendar event with notification.
    const calendar = CalendarApp.getDefaultCalendar()
    const scheduledEvent = calendar.createEvent(subject,
      startTime,
      endTime,
      {
        guests: recipients,
        sendInvites: true,
        description: body + '\nThis meeting scheduled by a Google Chat App!'
      });

    // Gets a link to the Calendar event.
    const url = getCalendarEventURL_(scheduledEvent, calendar)
        
    return getConfirmationDialog_(url);

  } else if (event.action.actionMethodName === 'closeDialog') {

    // Returns this dialog as success.
    return {
      actionResponse: {
        type: 'DIALOG',
        dialog_action: {
          actionStatus: 'OK'
        }
      }
    }
  }
}
Responds to a CARD_CLICKED event triggered in Chat.
@param {object} event the event object from Chat
@return {object} JSON-formatted response
@see https://developers.google.com/chat/api/guides/message-formats/events