Drupal: SCORM & HTML 5 course link on node page

<?php

/**
  * @file
  * Add a link to node page after a SCORM or HTML5 course has been uploaded
  *
  * @author DrupalD <https://twitter.com/DrupalD>
*/

/**
 * Implementation of hook_menu
 *
 * @return array $items
 * @author DrupalD <https://twitter.com/DrupalD>
 */
function course_link_menu() {
    $items = array();
    $items['admin/config/content/course-link'] = array(
       'type' => MENU_NORMAL_ITEM,
       'title' => t('Course Link'),
       'description' => t('Configure file upload fields for Course Link'),
       'page callback' => 'drupal_get_form',
       'page arguments' => array('course_link_admin_form'),
       'access arguments' => array('administer site configuration'),
       'file' => 'course_link_admin.inc',
       'file path' => drupal_get_path('module', 'course_link'),
    );
    
    return $items;
}

/**
 * Implementation of hook_node_insert
 *
 * @param object $node
 * @author DrupalD <https://twitter.com/DrupalD>
 */
function course_link_node_insert($node) {
    $file_upload_fields = array();
    $file_field = array();
    $file_upload_fields = variable_get('course_link_field');
    //Default public directory path to extract zip files to
    $destination = _file_directory_path();
    if (!empty($file_upload_fields)) {
        foreach($file_upload_fields as $key => $value) {
            $file_field_info = field_info_field_by_id($value);
            $file_field  = array($file_field_info['field_name'] => $file_field_info['field_name']);
        }
    }

    if (!empty($file_field)) {
        foreach ($file_field as $key => $value) {
            //Get the correct field that is associated with existing node and exit the loop
            if (array_key_exists($key, (array) $node)) {
                $node_file_field = $key;
                break;
            }
        }
       // Check if the node has one of those file fields. If it does, get the URI of the uploaded file.
        $file_uri = _file_get_location($node->$node_file_field['und'][0]['fid']);
        if (!empty($file_uri)) {
            // Insert data in course_link_node_file to retrieve it on node page
            $data = array(
              'nid' => $node->nid,
              'fid' => $node->$node_file_field['und'][0]['fid'],
          );
         drupal_write_record('course_link_node_file', $data);
         
         //Unzip the file
         $zip = new ZipArchive();
         if ($zip->open($destination .'/'. basename($file_uri['uri'], '.zip') . '.zip') === TRUE) {
            $zip->extractTo($destination .'/courses/'. basename($file_uri['uri'], '.zip'));
            $zip->close();
         }
          else {
             drupal_set_message(t('Unable to  open zip file'), 'error');
          }
        }
    }
}

/**
 * Implemenation of hook_node_view
 *
 * @param object $node
 * @param string $view_mode
 * @param string $langcode
 * @author DrupalD <https://twitter.com/DrupalD>
 */
function course_link_node_view($node, $view_mode, $langcode) {
  $course_link = _get_course_link($node->nid);
  $node->content['course_link'] = array(
      '#markup' => $course_link,
  );
}

/**
 * _get_course_link
 * Get the link to the course to display on node page
 *
 * @param int $nid
 * @return string
 * @author DrupalD <https://twitter.com/DrupalD>
 */
function _get_course_link($nid) {
    $file_fid = array();
    $file_filename = array();
    //Get the fid from course_link_node_file table
    $record = db_select('course_link_node_file', 'cl')
                    ->fields('cl', array('fid'))
                    ->condition('nid', $nid, '=')
                    ->execute();
    while ($cl_fid = $record->fetchAssoc()) {
        $am_fid[] = $cl_fid;
    }
               
    if (count($am_fid) > 1) {
        $file_0_fid = array_slice($am_fid, -1,1) ;
        $file_fid = $file_0_fid[0];
    }
    else {
        $file_fid = $am_fid[0];
    }

    //Get the filename using the FID
    $file_filename = _file_get_location($file_fid['fid']);
    $course_directory = basename($file_filename['uri'], '.zip');
    $file_directory = _file_directory_path();
    $course_link_index_directory = scandir($file_directory .'/courses/'. $course_directory);
    $course_link_index_file = array_search('index.html', $course_link_index_directory) ?
        '/index.html' : '/res/index.html';
    //Add the link to node page
    $node = node_load($nid);
    $course_link = l($node->title, $file_directory .'/courses/'. $course_directory .
        $course_link_index_file, array('attributes' => array('target' => '_blank')));
    return $course_link;
}

/**
 * _file_get_location
 * Get the location of the uploaded zip file
 *
 * @param int $fid: Id of the file
 * @param bool $uri: Whether to fetch uri or not
 * @author DrupalD <https://twitter.com/DrupalD>
 */
function _file_get_location($fid) {
    //Get the URI of the uploaded file using the FID
    $result = db_select('file_managed', 'fm')
                 ->fields('fm', array('uri'))
                 ->condition('fid', $fid, '=')
                 ->execute()
                 ->fetchAssoc();
    return $result;
}

/**
 * _file_directory_path
 *
 * Path to files directory
 *
 * @author DrupalD <https://twitter.com/DrupalD>
 */
function _file_directory_path() {
    return variable_get('file_public_path', conf_path() . '/files');
}