SpreadSheetNotifier

var months = ['January','February','March','April','May','June','July','August','September','October', 'November','December']

function main() {
  var currentDate = new Date();
  var day = currentDate.getDate();
  var month = months[currentDate.getMonth()]
  var tasks = getTasksToBeNotified(day,month)
  tasks = orderTasks(tasks)
  createDocumentAndNotify(tasks,day,month) 
}

var collTask = 1;
var collFrom = 2;
var collTill = 3;
var collDone = 4;

function getTasksToBeNotified(day, month){
 var sheet = SpreadsheetApp.getActive().getSheetByName(month)
 var tasks = [];
 for (var row=3;row<=sheet.getLastRow();row++){
   var from = sheet.getRange(row,collFrom).getValue();
   var till = sheet.getRange(row,collTill).getValue();
   var isCompleted = sheet.getRange(row,collDone).getValue();
   if (isCompleted!="Si" && day>=from && day<=till){
      var pendingDays= till-day // Pending days to be completed
      var taskDescription = sheet.getRange(row,collTask).getValue()
      tasks.push({name: taskDescription, pending:pendingDays, from:from, till:till})
    }
 } 
 return tasks 
}


function compareTasks(task1,task2) {
  if (task1.pending < task2.pending)
    return -1;
  if (task1.pending > task2.pending)
    return 1;
  return 0;
}

function orderTasks(tasks){
  var orderedTasks = [];
  tasks.sort(compareTasks).forEach(function(task){
    orderedTasks.push(task);
  });
  return orderedTasks;
}

var emailTo = 'youremail@gmail.com'

function createDocumentAndNotify(tasks, day, month) {
  Logger.log('Creating document')
  var doc = DocumentApp.create(day.toString() +' of '+month);
  doc.addHeader().setText("Tasks for day "+day.toString() +"th of "+month) 
  doc.getBody().appendParagraph('Tasks')   
  tasks.forEach(function(task){
    var item ='Task "'+task.name + '"needs to be done before day '+task.till+'th'
    Logger.log('Adding tassk '+item+' to document')
    doc.getBody().appendListItem(item)  
  });
  doc.saveAndClose()
  Logger.log('Document with id '+doc.getId()+' is gonna be deleted')
  sendEmail(doc)
  DriveApp.getFileById(doc.getId()).setTrashed(true)
}

function sendEmail(doc){
  var message = "Please find attached the document with the pending tasks.";
  var subject = 'Tasks for tody ';
  var pdf = DriveApp.getFileById(doc.getId()).getAs('application/pdf').getBytes();
  var attach = {fileName:'Tasks.pdf',content:pdf, mimeType:'application/pdf'};
  Logger.log('Sending email with tasks to be done')
  MailApp.sendEmail(emailTo, subject, message, {attachments:[attach]});
}