Managed_files in drupal forms

calendar_admin.module.php

<?php
/**
* @file
* Admin module for managing builds
*/

function calendar_admin_menu() {
  $items = array();

  $items['calendar/admin/sponsor/new'] = array(
    'title' => "Add new sponsor",
    'page callback' => 'calendar_admin_add_sponsor_page',
    'access callback' => TRUE,
    );
  return $items;
}

function sponsor_load($sponsorID) {
  return db_query('SELECT sponsorID, sponsorName, sponsorBio, logo, sageID FROM {calSponsor} WHERE sponsorid = :sponsorid', array(':sponsorid' => $sponsorID))->fetchObject();
}

function calendar_admin_add_sponsor_page() {
  $item = new StdClass;
  $item->sponsorID = FALSE;
  $item->sponsorName = '';
  $item->sponsorBio = '';
  $item->logo = '';
  $item->sageID = '';

  return drupal_get_form('calendar_admin_sponsor_form', $item);
}

function calendar_admin_sponsor_form($form, &$form_state, $item) {
  $form['#item'] = $item;
  $form['sponsorName'] = array(
    '#title' => t('Enter sponsor name'),
    '#type' => 'textfield',
    '#default_value' => $item->sponsorName,
    );
  $form['sponsorBio'] = array(
    '#title' => t('Enter sponsor bio'),
    '#type' => 'textfield',
    '#default_value' => $item->sponsorBio,
    );
  $form['logo_fid'] = array(
    '#type' => 'managed_file',
    '#title' => t('Logo'),
    '#progress_message' => t('Please wait...'),
    '#progress_indicator' => 'bar',
    '#description' => t('Upload a file, allowed extensions: jpg, jpeg, png, gif'),
    '#default_value' => variable_get('logo_fid', ''),
    '#upload_location' => 'public://logos/',
    );
  $form['logo'] = array(
    '#title' => t('Logo file name'),
    '#type' => 'hidden,
    '#default_value' => $item->logo,
    );
  $form['sageID'] = array(
    '#title' => t('Enter sageID'),
    '#type' => 'textfield',
    '#default_value' => $item->sageID,
    );
  $form['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Save'),
    );
  return $form;
}

// function calendar_admin_sponsor_form_validate($form, &$form_state, $item) {
//     $file = file_save_upload('file', array(
//     // Validates file is really an image.
//     'file_validate_is_image' => array(),
//     // Validate extensions.
//     'file_validate_extensions' => array('png gif jpg jpeg'),
//   ));
//     // If the file passed validation:
//     if ($file) {
//       // Move the file into the Drupal file system.
//       if ($file = file_move($file, 'public://')) {
//         // Save the file for use in the submit handler.
//         $form_state['storage']['file'] = $file;
//       }
//       else {
//         form_set_error('file', t("Failed to write the uploaded file to the site's file folder."));
//       }
//     }
//     else {
//       form_set_error('file', t('No file was uploaded.'));
//     }
//   }

function calendar_admin_sponsor_form_submit($form, &$form_state) {
  $item = $form['#item'];
  $managed_file = (!empty($form['logo_fid']['#default_value'])) ? $form['logo_fid']['#default_value'] : 0;
  if (isset($form_state['values']['logo_fid']) && $form_state['values']['logo_fid']) {
     if (isset($managed_file_example) && $managed_file_example != $form_state['values']['logo_fid']) {
       mf_remove_managed_file($managed_file_example, 'one');
        mf_add_managed_file($form_state['values']['logo_fid'], 'example');
     } else {
       mf_add_managed_file($form_state['values']['logo_fid'], 'example');
     }
  } elseif ($managed_file_one) {
    mf_remove_managed_file($managed_file_example, 'example');
  }
  if(isset($item->sponsorID) && $item->sponsorID) {
    db_update('calSponsor')
      ->fields(array(
        'sponsorName' => $form_state['values']['sponsorName'],
        'sponsorBio' => $form_state['values']['sponsorBio'],
        'logo' => $form_state['values']['logo'],
        'sageID' => $form_state['values']['sageID'],
        ))
      ->condition('sponsorid', $item->sponsorID)
      ->execute();
      $form_state['redirect'] = 'calendar/admin/sponsor/'. $item->sponsorID;
  } else {
    $sponsor = $sponsorID = db_insert('calSponsor')
    ->fields(array(
        'sponsorName' => $form_state['values']['sponsorName'],
        'sponsorBio' => $form_state['values']['sponsorBio'],
        'logo' => $form_state['values']['logo_fid'],
        'sageID' => $form_state['values']['sageID'],
        ))
    ->execute();
    $file = file_load($form_state['values']['file']);
    $file->status = FILE_STATUS_PERMANENT;
    // file_usage_add($file, 'calendar_admin', 'user', $sponsor->sponsorID);
    file_save($file);
    $form_state['redirect'] = 'calendar/admin/sponsor/'. $sponsorID;
  }
}

function mf_remove_managed_file($managed_file, $which) { 
  // Retrieve the old file's id.
  $file = $managed_file ? file_load($managed_file) : FALSE;
  if ($file) {
    // When a module is managing a file, it must manage the usage count.
    // Here we decrement the usage count with file_usage_delete().
    file_usage_delete($file, 'mf', $which, $file->fid);
 
    // The file_delete() function takes a file object and checks to see if
    // the file is being used by any other modules. If it is the delete
    // operation is cancelled, otherwise the file is deleted.
    file_delete($file);
    drupal_set_message(t('The image @image_name was removed.', array('@image_name' => $file->filename)));
  }
}

function mf_add_managed_file($managed_file, $which) {
  /* if our file is already in use, then we don't need to re-do this and increase the count */
  $count = db_query('SELECT `count` FROM {file_usage} WHERE fid=:fid', array('fid' => $managed_file))->fetchField();
  if (empty($count)) {
    /* load the file via fid */
    $file = file_load($managed_file);
    /* change status to permanent */
    $file->status = FILE_STATUS_PERMANENT;
    /* save the file */
    file_save($file);
    /* record the file as in use */
    file_usage_add($file, 'mf', $which, $managed_file);
    unset($file);
  }
}