code.gs

/***************************************************
Script will send an email notification to you or other email addresses
when a file in a given Google folder has been added, or modified.
To create a copy, use https://docs.google.com/spreadsheets/d/13z6ExSxdhrAfjppSIrGw6yLvByRjTIA3iWWpi97dgsQ/edit?usp=sharing
***************************************************/
function checkForChangedFiles() {

  var config = loadConfiguration();

  var folderSearch = '"' + config["folderID"] + '" ' + 'in parents';
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(config["sheetName"]);

  var startTime = getLastUpdatedFileTime(config["sheetName"]);
  Logger.log("Looking for files posted since: " + startTime)

  var search = '(trashed = true or trashed = false) and '+ folderSearch +' and (modifiedDate > "' + startTime + '")';   
  var files  = DriveApp.searchFiles(search);
    
  var row = "", count=0;
  Logger.log("Found " + countFiles(files) + " files to report.")
  
  // Didn't find a reset() method for unwinding the iteration, so we'll waste some GCP cycles.
  var files  = DriveApp.searchFiles(search);
  
  while(files.hasNext()) {
    var file = files.next();
    var fileName = file.getName();
    var fileURL  = file.getUrl();
    var lastUpdated =  Moment.moment(file.getLastUpdated()).toISOString();
    var dateCreated =  Moment.moment(file.getDateCreated()).toISOString();
    
    row += "<li>" + lastUpdated + " <a href='" + fileURL + "'>" + fileName + "</a></li>";
    
    sheet.appendRow([dateCreated, lastUpdated, fileName, fileURL]);
    
    count++;
  }
  
  if (row !== "") {
    row = "<p>" + count + " file(s) changed. Here's the list:</p><ol>" + row + "</ol>";
    row +=  config["emailBody"]+"<br>" + "<br><small> "+config["emailFooter"]+" </a>.</small>";     
    MailApp.sendEmail(config["emailFromAddr"], config["emailSubject"], "", {name: config["emailFromName"], htmlBody: row, cc: config["emailCC"]});
  }  
}

function loadConfiguration() {
  // Ideas on how to pull config from the spreadsheet
  //var ss = SpreadsheetApp.getActiveSpreadsheet(); 
  //var sheet = ss.getActiveSheet();
  //var email = sheet.getRange("E1").getValue();
  
  var config = {
    "folderID": "11cpkbtpxWexample-example4pJGrYxApm",
    "sheetName": "File Change Report",
    "emailFromAddr": "[email protected]",
    "emailFromName": "Bob Example",
    "emailCC": "Other Dude <[email protected]>",
    "emailSubject": "[FileUpdates] New file uploaded",
    "emailBody": "New file has been uploaded, get to it!",
    "emailFooter": "To stop these notifications, please contact [email protected]"
  };
  
  Logger.log("### Configuration Start ###:");
  for( c in config) {
    Logger.log(c + ": " + config[c]);
  };
  Logger.log("### Configuration End ###:");
    
  return config;
};

function countFiles(files) {
  var count,file;

  count = 0;

  while (files.hasNext()) {
   count++;
   file = files.next();
   Logger.log(file.getName());
  };
  
  return count;
};

function getLastUpdatedFileTime(sheetName) {
  var ss = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(sheetName);
  var dateModifiedRange = ss.getRange("B1:B");
  var dateModifieds = dateModifiedRange.getValues();  
  var lastModifiedRowNum = dateModifieds.filter(String).length;
  var lastModifiedTimestamp = dateModifieds[lastModifiedRowNum - 1][0]
  Logger.log("Raw:    " + lastModifiedTimestamp)
  // To get access to Moment.js libraries, you need to add the library as a resource using the ID MHMchiX6c1bwSqGM1PZiW_PxhMjh3Sh48
  var lastModifiedTimestamp = Moment.moment(lastModifiedTimestamp).toISOString();
  Logger.log("Parsed(ISO8601): " + lastModifiedTimestamp);
  
  return lastModifiedTimestamp
}