Logic to generate pdf from archived invoices stored in s3

generate_pdf_archived_invoice.php

// CONSTANTS defined in whiteboard_migration.module.
// Will be accessible when this module is installed on whiteboard.
define('WHITEBOARD_INVOICE_HEADER_START_COMMENT', 'Header begins here for invoice #');
define('WHITEBOARD_INVOICE_HEADER_END_COMMENT', 'Header ends here for invoice #');
define('WHITEBOARD_INVOICE_BODY_START_COMMENT', 'Body begins here for invoice #');
define('WHITEBOARD_INVOICE_BODY_END_COMMENT', 'Body ends here for invoice #');
define('WHITEBOARD_INVOICE_FOOTER_START_COMMENT', 'Footer begins here for invoice #');
define('WHITEBOARD_INVOICE_FOOTER_END_COMMENT', 'Footer ends here for invoice #');

$header_start_comment = '<!--' . WHITEBOARD_INVOICE_HEADER_START_COMMENT . $invoice_vid . '-->';
$header_end_comment = '<!--' . WHITEBOARD_INVOICE_HEADER_END_COMMENT . $invoice_vid . '-->';
$body_start_comment = '<!--' . WHITEBOARD_INVOICE_BODY_START_COMMENT . $invoice_vid . '-->';
$body_end_comment = '<!--' . WHITEBOARD_INVOICE_BODY_END_COMMENT_COMMENT . $invoice_vid . '-->';
$footer_start_comment = '<!--' . WHITEBOARD_INVOICE_FOOTER_START_COMMENT . $invoice_vid . '-->';
$footer_end_comment = '<!--' . WHITEBOARD_INVOICE_FOOTER_END_COMMENT . $invoice_vid . '-->';

// Fetch list of archived invoice nids.
$query_archived_invoices = "SELECT DISTINCT invoice_nid FROM {whiteboard_migration_map}";
while ($row = db_fetch_array($result)) {
  $archived_invoice_nids[] = $result['invoice_nid'];
}

// Check if the current invoice being generated is archived.
if (in_array($nid, $archived_invoice_nids) {
  $invoice_node = node_load($nid, $vid);
  $invoice_markup = file_get_contents($invoice_node->field_invoice_content_online[0]['value']);
  
  preg_match('/' . $header_start_comment . '[a-z|A-Z|\s|\S|\d|\D]*' . $header_end_comment . '/', $invoice_markup, $header_matches);
  preg_match('/' . $body_start_comment . '[a-z|A-Z|\s|\S|\d|\D]*' . $body_end_comment . '/', $invoice_markup, $body_matches);
  preg_match('/' . $footer_start_comment . '[a-z|A-Z|\s|\S|\d|\D]*' . $footer_end_comment . '/', $invoice_markup, $footer_matches);
  
  /**
   * $header_matches[0]: will have the same content that should be in $headerHTML @L#2069 global.inc
   * $body_matches[0]: will have the same content that should be in $htmlData @L#2068 global.inc
   * $footer_matches[0]: will have the same content that should be in $footerHTML @L#2070 global.inc
   * We need to prefix CSS being appended in the pdf generator function to this file as well.
   */
}