/**
 * Message Notes - saves the sermon notes from email into Google Drive.
 *
 * Runs every 10 minutes in the Google account it is installed in (media@waterschurch.org).
 * When a "Notes/Slides - ..." email arrives with notes attached, it saves the attachment(s)
 * plus the email text (used to know who is preaching) into the Drive folder "Message Notes".
 * Google Drive on the ProPresenter Mac syncs that folder, and the Message Notes tool picks
 * up the newest file from it.
 *
 * Setup: paste this into a new project at https://script.google.com (signed in as media@),
 * save, choose the function "install" and click Run, then click Allow.
 */
var FOLDER_NAME = 'Message Notes';
var QUERY = '(subject:"Notes/Slides" OR to:sermonslides@waterschurch.org) has:attachment newer_than:21d';
var KEEP = 300;   // how many processed message ids to remember

function saveSermonNotes() {
  var props = PropertiesService.getScriptProperties();
  var done = JSON.parse(props.getProperty('done') || '[]');
  var folder = getFolder_();
  var threads = GmailApp.search(QUERY, 0, 30);
  threads.forEach(function (thread) {
    thread.getMessages().forEach(function (msg) {
      var id = msg.getId();
      if (done.indexOf(id) >= 0) return;
      var saved = false;
      msg.getAttachments({includeInlineImages: false}).forEach(function (att) {
        var name = att.getName();
        if (!/\.(rtf|docx?)$/i.test(name)) return;
        replaceFile_(folder, name, att.copyBlob());
        var base = name.replace(/\.[^.]+$/, '');
        var info = 'Subject: ' + msg.getSubject() + '\nFrom: ' + msg.getFrom() + '\nDate: ' +
                   msg.getDate().toISOString() + '\n\n' + msg.getPlainBody();
        replaceFile_(folder, base + '.email.txt', Utilities.newBlob(info, 'text/plain', base + '.email.txt'));
        saved = true;
      });
      done.push(id);
    });
  });
  props.setProperty('done', JSON.stringify(done.slice(-KEEP)));
}

function getFolder_() {
  var it = DriveApp.getRootFolder().getFoldersByName(FOLDER_NAME);
  return it.hasNext() ? it.next() : DriveApp.getRootFolder().createFolder(FOLDER_NAME);
}

function replaceFile_(folder, name, blob) {
  var old = folder.getFilesByName(name);
  while (old.hasNext()) old.next().setTrashed(true);
  folder.createFile(blob.setName(name));
}

/** Run once: saves anything recent now and checks every 10 minutes from then on. */
function install() {
  ScriptApp.getProjectTriggers().forEach(function (t) {
    if (t.getHandlerFunction() === 'saveSermonNotes') ScriptApp.deleteTrigger(t);
  });
  ScriptApp.newTrigger('saveSermonNotes').timeBased().everyMinutes(10).create();
  saveSermonNotes();
}