/** Returns a PDF object based on the contents of the 'invoicing' sheet */
function invoiceToPDF(invDetails) 
{
  var spreadsheet = SpreadsheetApp.getActiveSpreadsheet();
  ssID = spreadsheet.getId();
  var sheet = spreadsheet.getSheetByName(INVOICES_SHEETNAME);
  var gid = sheet.getSheetId();
 
  // &gid=x at the end of above url if you only want a particular sheet
  var url2 = "http://spreadsheets.google.com/feeds/download/spreadsheets/Export?key=" + ssID + 
            "&gid=" + gid + 
            "&fmcmd=12&size=7&fzr=true&portrait=true&fitw=true&locale=en&gridlines=false&printtitle=false&sheetnames=false&pagenum=UNDEFINED&attachment=true";
 
  // AUTH TOKEN required to access the UrlFetchApp call below.  You can receive it 
  // from https://appscripts.appspot.com/getAuthToken
  var AUTH_TOKEN = "your_token_goes_here"; 
  var auth = "AuthSub token=\"" + AUTH_TOKEN + "\"";
  
  var res = UrlFetchApp.fetch(url2, {headers: {Authorization: auth}}).getBlob();  
  return res; 
}



/** 
  * Creates an invoice in the Invoices drive folder
  */
function createInvoiceAsGDriveDocsFile(pdfBlob)
{
  var details = getInvoiceDetails();
  filename = "Invoice_xyz";  
  
  var spreadsheet = SpreadsheetApp.getActiveSpreadsheet();
 
  // get or create the base folder  
  var theFolder = getInvoicesBaseFolder();  
  
  // Create the invoice file based on the filename
  try 
  {
    var matchingFileList = theFolder.find(filename);

    // guard against duplicates
    if (matchingFileList == undefined || matchingFileList.length == 0)
    {   
      pdfBlob.setName(filename);  
      var f = theFolder.createFile(pdfBlob);
      // check file created ok
      if (f != undefined)
      {   
        f.setDescription("TBD some blurb from the invoice perhaps");
        spreadsheet.toast("Created invoice " + f.getName() + " " + f.getSize() + " bytes" + " in " + theFolder.getName());
      }
      else
      {
        Browser.msgBox("ERROR: creating document: " + filename);
      }
    }
    else
    {
      Browser.msgBox("ERROR: New invoice not created. " + filename + " already exists. " + filename); 
    }
  }
  catch (fileCreateError)
  {
    Browser.msgBox("ERROR: couldn't create invoice pdf " + filename);
  }
}