Check and\or Create a Folder in Shared Drive - get

Question

I'm trying to work with this ready-made script to create files in a specific folder upon Calendar Event creation.
The script works well for my needs but, due to my company policies, I need to modify the first part in order to target a specific folder inside a Shared Drive.
Any idea how I could do that? I know that I need to use Drive API instead of DriveApp but so far I couldn't find any example to follow.
Sorry i'm very new to this and missing some basics..
Thanks in advance
Diego
/**
* Checks if the folder for Agenda docs exists, and creates it if it doesn't.
*
* #return {*} Drive folder ID for the app.
*/
function checkFolder() {
const folders = DriveApp.getFoldersByName('Agenda Maker - App');
// Finds the folder if it exists
while (folders.hasNext()) {
let folder = folders.next();
if (
folder.getDescription() ==
'Apps Script App - Do not change this description' &&
folder.getOwner().getEmail() == Session.getActiveUser().getEmail()
) {
return folder.getId();
}
}
// If the folder doesn't exist, creates one
let folder = DriveApp.createFolder('Agenda Maker - App');
folder.setDescription('Apps Script App - Do not change this description');
return folder.getId();
}
/**
* Finds the template agenda doc, or creates one if it doesn't exist.
*/
function getTemplateId(folderId) {
const folder = DriveApp.getFolderById(folderId);
const files = folder.getFilesByName('Agenda TEMPLATE##');
// If there is a file, returns the ID.
while (files.hasNext()) {
const file = files.next();
return file.getId();
}
// Otherwise, creates the agenda template.
// You can adjust the default template here
const doc = DocumentApp.create('Agenda TEMPLATE##');
const body = doc.getBody();
body
.appendParagraph('##Attendees##')
.setHeading(DocumentApp.ParagraphHeading.HEADING1)
.editAsText()
.setBold(true);
body.appendParagraph(' ').editAsText().setBold(false);
body
.appendParagraph('Overview')
.setHeading(DocumentApp.ParagraphHeading.HEADING1)
.editAsText()
.setBold(true);
body.appendParagraph(' ');
body.appendParagraph('- Topic 1: ').editAsText().setBold(true);
body.appendParagraph(' ').editAsText().setBold(false);
body.appendParagraph('- Topic 2: ').editAsText().setBold(true);
body.appendParagraph(' ').editAsText().setBold(false);
body.appendParagraph('- Topic 3: ').editAsText().setBold(true);
body.appendParagraph(' ').editAsText().setBold(false);
body
.appendParagraph('Next Steps')
.setHeading(DocumentApp.ParagraphHeading.HEADING1)
.editAsText()
.setBold(true);
body.appendParagraph('- Takeaway 1: ').editAsText().setBold(true);
body.appendParagraph('- Responsible: ').editAsText().setBold(false);
body.appendParagraph('- Accountable: ');
body.appendParagraph('- Consult: ');
body.appendParagraph('- Inform: ');
body.appendParagraph(' ');
body.appendParagraph('- Takeaway 2: ').editAsText().setBold(true);
body.appendParagraph('- Responsible: ').editAsText().setBold(false);
body.appendParagraph('- Accountable: ');
body.appendParagraph('- Consult: ');
body.appendParagraph('- Inform: ');
body.appendParagraph(' ');
body.appendParagraph('- Takeaway 3: ').editAsText().setBold(true);
body.appendParagraph('- Responsible: ').editAsText().setBold(false);
body.appendParagraph('- Accountable: ');
body.appendParagraph('- Consult: ');
body.appendParagraph('- Inform: ');
doc.saveAndClose();
folder.addFile(DriveApp.getFileById(doc.getId()));
return doc.getId();
}
/**
* When there is a change to the calendar, searches for events that include "#agenda"
* in the decrisption.
*
*/
function onCalendarChange() {
// Gets recent events with the #agenda tag
const now = new Date();
const events = CalendarApp.getEvents(
now,
new Date(now.getTime() + 2 * 60 * 60 * 1000000),
{search: '#agenda'},
);
const folderId = checkFolder();
const templateId = getTemplateId(folderId);
const folder = DriveApp.getFolderById(folderId);
// Loops through any events found
for (i = 0; i < events.length; i++) {
const event = events[i];
// Confirms whether the event has the #agenda tag
let description = event.getDescription();
if (description.search('#agenda') == -1) continue;
// Only works with events created by the owner of this calendar
{
// Creates a new document from the template for an agenda for this event
const newDoc = DriveApp.getFileById(templateId).makeCopy();
newDoc.setName(event.getTitle() + ' - Agenda');
const file = DriveApp.getFileById(newDoc.getId());
folder.addFile(file);
const doc = DocumentApp.openById(newDoc.getId());
const body = doc.getBody();
// !!!MMA!!! Fills in the template with information about the attendees from the
// calendar event
const conf = body.findText('##Attendees##');
if (conf) {
const ref = conf.getStartOffset();
for (let i in event.getGuestList()) {
let guest = event.getGuestList()[i];
body.insertParagraph(ref + 11, guest.getEmail());
}
body.replaceText('##Attendees##', 'Attendees:');
body.replaceText('##Meeting_Name##', event.getTitle());
body.replaceText('##Person_In_Charge##', event.getCreators());
body.replaceText('##Description##', event.getDescription());
body.replaceText('##Location##', event.getLocation());
body.replaceText('##Time##', Utilities.formatDate(event.getStartTime(), Session.getScriptTimeZone(),"dd/MM/yyyy" + " # " + "HH:mm"));
}
// Replaces the tag with a link to the agenda document
const agendaUrl = 'https://docs.google.com/document/d/' + newDoc.getId();
description = description.replace(
'#agenda',
'<a href=' + agendaUrl + '>Link to Meeting Agenda</a>',
);
event.setDescription(description);
// Invites attendees to the Google doc so they automatically receive access to the agenda
newDoc.addEditor(newDoc.getOwner());
for (let i in event.getGuestList()) {
let guest = event.getGuestList()[i];
newDoc.addEditor(guest.getEmail());
}
}
}
return;
}
/**
* Creates an event-driven trigger that fires whenever there's a change to the calendar.
*/
function setUp() {
let email = Session.getActiveUser().getEmail();
ScriptApp.newTrigger("onCalendarChange").forUserCalendar(email).onEventUpdated().create();
}