<?php

/**
 * @file
 * Exposes global functionality for creating image styles.
 */

use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpFoundation\StreamedResponse;
use Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException;
use Drupal\Core\File\File;

/**
 * Image style constant for user presets in the database.
 */
const IMAGE_STORAGE_NORMAL = 1;

/**
 * Image style constant for user presets that override module-defined presets.
 */
const IMAGE_STORAGE_OVERRIDE = 2;

/**
 * Image style constant for module-defined presets in code.
 */
const IMAGE_STORAGE_DEFAULT = 4;

/**
 * Image style constant to represent an editable preset.
 */
define('IMAGE_STORAGE_EDITABLE', IMAGE_STORAGE_NORMAL | IMAGE_STORAGE_OVERRIDE);

/**
 * Image style constant to represent any module-based preset.
 */
define('IMAGE_STORAGE_MODULE', IMAGE_STORAGE_OVERRIDE | IMAGE_STORAGE_DEFAULT);

// Load all Field module hooks for Image.
require_once DRUPAL_ROOT . '/core/modules/image/image.field.inc';

/**
 * Implements hook_help().
 */
function image_help($path, $arg) {
  switch ($path) {
    case 'admin/help#image':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('The Image module allows you to manipulate images on your website. It exposes a setting for using the <em>Image toolkit</em>, allows you to configure <em>Image styles</em> that can be used for resizing or adjusting images on display, and provides an <em>Image</em> field for attaching images to content. For more information, see the online handbook entry for <a href="@image">Image module</a>.', array('@image' => 'http://drupal.org/documentation/modules/image')) . '</p>';
      $output .= '<h3>' . t('Uses') . '</h3>';
      $output .= '<dl>';
      $output .= '<dt>' . t('Manipulating images') . '</dt>';
      $output .= '<dd>' . t('With the Image module you can scale, crop, resize, rotate and desaturate images without affecting the original image using <a href="@image">image styles</a>. When you change an image style, the module automatically refreshes all created images. Every image style must have a name, which will be used in the URL of the generated images. There are two common approaches to naming image styles (which you use will depend on how the image style is being applied):',array('@image' => url('admin/config/media/image-styles')));
      $output .= '<ul><li>' . t('Based on where it will be used: eg. <em>profile-picture</em>') . '</li>';
      $output .= '<li>' . t('Describing its appearance: eg. <em>square-85x85</em>') . '</li></ul>';
      $output .=  t('After you create an image style, you can add effects: crop, scale, resize, rotate, and desaturate (other contributed modules provide additional effects). For example, by combining effects as crop, scale, and desaturate, you can create square, grayscale thumbnails.') . '<dd>';
      $output .= '<dt>' . t('Attaching images to content as fields') . '</dt>';
      $output .= '<dd>' . t("Image module also allows you to attach images to content as fields. To add an image field to a <a href='@content-type'>content type</a>, go to the content type's <em>manage fields</em> page, and add a new field of type <em>Image</em>. Attaching images to content this way allows image styles to be applied and maintained, and also allows you more flexibility when theming.", array('@content-type' => url('admin/structure/types'))) . '</dd>';
      $output .= '</dl>';
      return $output;
    case 'admin/config/media/image-styles':
      return '<p>' . t('Image styles commonly provide thumbnail sizes by scaling and cropping images, but can also add various effects before an image is displayed. When an image is displayed with a style, a new file is created and the original image is left unchanged.') . '</p>';
    case 'admin/config/media/image-styles/edit/%/add/%':
      $effect = image_effect_definition_load($arg[7]);
      return isset($effect['help']) ? ('<p>' . $effect['help'] . '</p>') : NULL;
    case 'admin/config/media/image-styles/edit/%/effects/%':
      $effect = ($arg[5] == 'add') ? image_effect_definition_load($arg[6]) : image_effect_load($arg[6], $arg[4]);
      return isset($effect['help']) ? ('<p>' . $effect['help'] . '</p>') : NULL;
  }
}

/**
 * Implements hook_menu().
 */
function image_menu() {
  $items = array();

  // Generate image derivatives of publicly available files.
  // If clean URLs are disabled, image derivatives will always be served
  // through the menu system.
  // If clean URLs are enabled and the image derivative already exists,
  // PHP will be bypassed.
  $directory_path = file_stream_wrapper_get_instance_by_scheme('public')->getDirectoryPath();
  $items[$directory_path . '/styles/%image_style'] = array(
    'title' => 'Generate image style',
    'page callback' => 'image_style_deliver',
    'page arguments' => array(count(explode('/', $directory_path)) + 1),
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
  );
  // Generate and deliver image derivatives of private files.
  // These image derivatives are always delivered through the menu system.
  $items['system/files/styles/%image_style'] = array(
    'title' => 'Generate image style',
    'page callback' => 'image_style_deliver',
    'page arguments' => array(3),
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
  );
  $items['admin/config/media/image-styles'] = array(
    'title' => 'Image styles',
    'description' => 'Configure styles that can be used for resizing or adjusting images on display.',
    'page callback' => 'image_style_list',
    'access arguments' => array('administer image styles'),
    'file' => 'image.admin.inc',
  );
  $items['admin/config/media/image-styles/list'] = array(
    'title' => 'List',
    'description' => 'List the current image styles on the site.',
    'page callback' => 'image_style_list',
    'access arguments' => array('administer image styles'),
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => 1,
    'file' => 'image.admin.inc',
  );
  $items['admin/config/media/image-styles/add'] = array(
    'title' => 'Add style',
    'description' => 'Add a new image style.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('image_style_add_form'),
    'access arguments' => array('administer image styles'),
    'type' => MENU_LOCAL_ACTION,
    'weight' => 2,
    'file' => 'image.admin.inc',
  );
  $items['admin/config/media/image-styles/edit/%image_style'] = array(
    'title' => 'Edit style',
    'description' => 'Configure an image style.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('image_style_form', 5),
    'access arguments' => array('administer image styles'),
    'file' => 'image.admin.inc',
  );
  $items['admin/config/media/image-styles/delete/%image_style'] = array(
    'title' => 'Delete style',
    'description' => 'Delete an image style.',
    'load arguments' => array(NULL, (string) IMAGE_STORAGE_NORMAL),
    'page callback' => 'drupal_get_form',
    'page arguments' => array('image_style_delete_form', 5),
    'access arguments' => array('administer image styles'),
    'file' => 'image.admin.inc',
  );
  $items['admin/config/media/image-styles/edit/%image_style/effects/%image_effect'] = array(
    'title' => 'Edit image effect',
    'description' => 'Edit an existing effect within a style.',
    'load arguments' => array(5, (string) IMAGE_STORAGE_EDITABLE),
    'page callback' => 'drupal_get_form',
    'page arguments' => array('image_effect_form', 5, 7),
    'access arguments' => array('administer image styles'),
    'file' => 'image.admin.inc',
  );
  $items['admin/config/media/image-styles/edit/%image_style/effects/%image_effect/delete'] = array(
    'title' => 'Delete image effect',
    'description' => 'Delete an existing effect from a style.',
    'load arguments' => array(5, (string) IMAGE_STORAGE_EDITABLE),
    'page callback' => 'drupal_get_form',
    'page arguments' => array('image_effect_delete_form', 5, 7),
    'access arguments' => array('administer image styles'),
    'file' => 'image.admin.inc',
  );
  $items['admin/config/media/image-styles/edit/%image_style/add/%image_effect_definition'] = array(
    'title' => 'Add image effect',
    'description' => 'Add a new effect to a style.',
    'load arguments' => array(5),
    'page callback' => 'drupal_get_form',
    'page arguments' => array('image_effect_form', 5, 7),
    'access arguments' => array('administer image styles'),
    'file' => 'image.admin.inc',
  );

  return $items;
}

/**
 * Implements hook_theme().
 */
function image_theme() {
  return array(
    // Theme functions in image.module.
    'image_style' => array(
      'variables' => array(
        'style_name' => NULL,
        'uri' => NULL,
        'width' => NULL,
        'height' => NULL,
        'alt' => '',
        'title' => NULL,
        'attributes' => array(),
      ),
    ),

    // Theme functions in image.admin.inc.
    'image_style_list' => array(
      'variables' => array('styles' => NULL),
    ),
    'image_style_effects' => array(
      'render element' => 'form',
    ),
    'image_style_preview' => array(
      'variables' => array('style' => NULL),
    ),
    'image_anchor' => array(
      'render element' => 'element',
    ),
    'image_resize_summary' => array(
      'variables' => array('data' => NULL),
    ),
    'image_scale_summary' => array(
      'variables' => array('data' => NULL),
    ),
    'image_crop_summary' => array(
      'variables' => array('data' => NULL),
    ),
    'image_rotate_summary' => array(
      'variables' => array('data' => NULL),
    ),

    // Theme functions in image.field.inc.
    'image_widget' => array(
      'render element' => 'element',
    ),
    'image_formatter' => array(
      'variables' => array('item' => NULL, 'path' => NULL, 'image_style' => NULL),
    ),
  );
}

/**
 * Implements hook_permission().
 */
function image_permission() {
  return array(
    'administer image styles' => array(
      'title' => t('Administer image styles'),
      'description' => t('Create and modify styles for generating image modifications such as thumbnails.'),
    ),
  );
}

/**
 * Implements hook_form_FORM_ID_alter().
 */
function image_form_system_file_system_settings_alter(&$form, &$form_state) {
  $form['#submit'][] = 'image_system_file_system_settings_submit';
}

/**
 * Submit handler for the file system settings form.
 *
 * Adds a menu rebuild after the public file path has been changed, so that the
 * menu router item depending on that file path will be regenerated.
 */
function image_system_file_system_settings_submit($form, &$form_state) {
  if ($form['file_public_path']['#default_value'] !== $form_state['values']['file_public_path']) {
    variable_set('menu_rebuild_needed', TRUE);
  }
}

/**
 * Implements hook_file_download().
 *
 * Control the access to files underneath the styles directory.
 */
function image_file_download($uri) {
  $path = file_uri_target($uri);

  // Private file access for image style derivatives.
  if (strpos($path, 'styles/') === 0) {
    $args = explode('/', $path);
    // Discard the first part of the path (styles).
    array_shift($args);
    // Get the style name from the second part.
    $style_name = array_shift($args);
    // Remove the scheme from the path.
    array_shift($args);

    // Then the remaining parts are the path to the image.
    $original_uri = file_uri_scheme($uri) . '://' . implode('/', $args);

    // Check that the file exists and is an image.
    if ($info = image_get_info($uri)) {
      // Check the permissions of the original to grant access to this image.
      $headers = module_invoke_all('file_download', $original_uri);
      if (!in_array(-1, $headers)) {
        return array(
          // Send headers describing the image's size, and MIME-type...
          'Content-Type' => $info['mime_type'],
          'Content-Length' => $info['file_size'],
          // By not explicitly setting them here, this uses normal Drupal
          // Expires, Cache-Control and ETag headers to prevent proxy or
          // browser caching of private images.
        );
      }
    }
    return -1;
  }

  // Private file access for the original files. Note that we only
  // check access for non-temporary images, since file.module will
  // grant access for all temporary files.
  $files = entity_load_multiple_by_properties('file', array('uri' => $uri));
  if (count($files)) {
    $file = reset($files);
    if ($file->status) {
      return file_file_download($uri, 'image');
    }
  }
}

/**
 * Implements hook_file_move().
 */
function image_file_move(File $file, File $source) {
  // Delete any image derivatives at the original image path.
  image_path_flush($source->uri);
}

/**
 * Implements hook_file_predelete().
 */
function image_file_predelete(File $file) {
  // Delete any image derivatives of this image.
  image_path_flush($file->uri);
}

/**
 * Implements hook_image_style_save().
 */
function image_image_style_save($style) {
  if (isset($style['old_name']) && $style['old_name'] != $style['name']) {
    $instances = field_read_instances();
    // Loop through all fields searching for image fields.
    foreach ($instances as $instance) {
      if ($instance['widget']['module'] == 'image') {
        $instance_changed = FALSE;
        foreach ($instance['display'] as $view_mode => $display) {
          // Check if the formatter involves an image style.
          if ($display['type'] == 'image' && $display['settings']['image_style'] == $style['old_name']) {
            // Update display information for any instance using the image
            // style that was just deleted.
            $instance['display'][$view_mode]['settings']['image_style'] = $style['name'];
            $instance_changed = TRUE;
          }
        }
        if ($instance['widget']['settings']['preview_image_style'] == $style['old_name']) {
          $instance['widget']['settings']['preview_image_style'] = $style['name'];
          $instance_changed = TRUE;
        }
        if ($instance_changed) {
          field_update_instance($instance);
        }
      }
    }
  }
}

/**
 * Implements hook_image_style_delete().
 */
function image_image_style_delete($style) {
  image_image_style_save($style);
}

/**
 * Implements hook_field_delete_field().
 */
function image_field_delete_field($field) {
  if ($field['type'] != 'image') {
    return;
  }

  // The value of a managed_file element can be an array if #extended == TRUE.
  $fid = (is_array($field['settings']['default_image']) ? $field['settings']['default_image']['fid'] : $field['settings']['default_image']);
  if ($fid && ($file = file_load($fid))) {
    file_usage_delete($file, 'image', 'default_image', $field['id']);
  }
}

/**
 * Implements hook_field_update_field().
 */
function image_field_update_field($field, $prior_field, $has_data) {
  if ($field['type'] != 'image') {
    return;
  }

  // The value of a managed_file element can be an array if #extended == TRUE.
  $fid_new = (is_array($field['settings']['default_image']) ? $field['settings']['default_image']['fid'] : $field['settings']['default_image']);
  $fid_old = (is_array($prior_field['settings']['default_image']) ? $prior_field['settings']['default_image']['fid'] : $prior_field['settings']['default_image']);

  $file_new = $fid_new ? file_load($fid_new) : FALSE;

  if ($fid_new != $fid_old) {

    // Is there a new file?
    if ($file_new) {
      $file_new->status = FILE_STATUS_PERMANENT;
      $file_new->save();
      file_usage_add($file_new, 'image', 'default_image', $field['id']);
    }

    // Is there an old file?
    if ($fid_old && ($file_old = file_load($fid_old))) {
      file_usage_delete($file_old, 'image', 'default_image', $field['id']);
    }
  }

  // If the upload destination changed, then move the file.
  if ($file_new && (file_uri_scheme($file_new->uri) != $field['settings']['uri_scheme'])) {
    $directory = $field['settings']['uri_scheme'] . '://default_images/';
    file_prepare_directory($directory, FILE_CREATE_DIRECTORY);
    file_move($file_new, $directory . $file_new->filename);
  }
}

/**
 * Implements hook_field_delete_instance().
 */
function image_field_delete_instance($instance) {
  // Only act on image fields.
  $field = field_read_field($instance['field_name']);
  if ($field['type'] != 'image') {
    return;
  }

  // The value of a managed_file element can be an array if the #extended
  // property is set to TRUE.
  $fid = $instance['settings']['default_image'];
  if (is_array($fid)) {
    $fid = $fid['fid'];
  }

  // Remove the default image when the instance is deleted.
  if ($fid && ($file = file_load($fid))) {
    file_usage_delete($file, 'image', 'default_image', $instance['id']);
  }
}

/**
 * Implements hook_field_update_instance().
 */
function image_field_update_instance($instance, $prior_instance) {
  // Only act on image fields.
  $field = field_read_field($instance['field_name']);
  if ($field['type'] != 'image') {
    return;
  }

  // The value of a managed_file element can be an array if the #extended
  // property is set to TRUE.
  $fid_new = $instance['settings']['default_image'];
  if (is_array($fid_new)) {
    $fid_new = $fid_new['fid'];
  }
  $fid_old = $prior_instance['settings']['default_image'];
  if (is_array($fid_old)) {
    $fid_old = $fid_old['fid'];
  }

  // If the old and new files do not match, update the default accordingly.
  $file_new = $fid_new ? file_load($fid_new) : FALSE;
  if ($fid_new != $fid_old) {
    // Save the new file, if present.
    if ($file_new) {
      $file_new->status = FILE_STATUS_PERMANENT;
      $file_new->save();
      file_usage_add($file_new, 'image', 'default_image', $instance['id']);
    }
    // Delete the old file, if present.
    if ($fid_old && ($file_old = file_load($fid_old))) {
      file_usage_delete($file_old, 'image', 'default_image', $instance['id']);
    }
  }

  // If the upload destination changed, then move the file.
  if ($file_new && (file_uri_scheme($file_new->uri) != $field['settings']['uri_scheme'])) {
    $directory = $field['settings']['uri_scheme'] . '://default_images/';
    file_prepare_directory($directory, FILE_CREATE_DIRECTORY);
    file_move($file_new, $directory . $file_new->filename);
  }
}

/**
 * Clear cached versions of a specific file in all styles.
 *
 * @param $path
 *   The Drupal file path to the original image.
 */
function image_path_flush($path) {
  $styles = image_styles();
  foreach ($styles as $style) {
    $image_path = image_style_path($style['name'], $path);
    if (file_exists($image_path)) {
      file_unmanaged_delete($image_path);
    }
  }
}

/**
 * Implements MODULE_config_import_create().
 */
function image_config_import_create($name, $new_config, $old_config) {
  // Only image styles require custom handling. Any other module settings can be
  // synchronized directly.
  if (strpos($name, 'image.style.') !== 0) {
    return FALSE;
  }
  $style = $new_config->get();
  return image_style_save($style);
}

/**
 * Implements MODULE_config_import_change().
 */
function image_config_import_change($name, $new_config, $old_config) {
  // Only image styles require custom handling. Any other module settings can be
  // synchronized directly.
  if (strpos($name, 'image.style.') !== 0) {
    return FALSE;
  }
  $style = $new_config->get();
  return image_style_save($style);
}

/**
 * Implements MODULE_config_import_delete().
 */
function image_config_import_delete($name, $new_config, $old_config) {
  // Only image styles require custom handling. Any other module settings can be
  // synchronized directly.
  if (strpos($name, 'image.style.') !== 0) {
    return FALSE;
  }
  // @todo image_style_delete() supports the notion of a "replacement style"
  //   to be used by other modules instead of the deleted style. Essential!
  //   But that is impossible currently, since the config system only knows
  //   about deleted and added changes. Introduce an 'old_ID' key within
  //   config objects as a standard?
  $style = $old_config->get();
  return image_style_delete($style);
}

/**
 * Get an array of all styles and their settings.
 *
 * @return
 *   An array of styles keyed by the image style ID (isid).
 * @see image_style_load()
 */
function image_styles() {
  // @todo Configuration must not be statically cached nor cache-system cached.
  //   However, there's a drupal_alter() involved here.

//  $styles = &drupal_static(__FUNCTION__);
//
//  // Grab from cache or build the array.
//  if (!isset($styles)) {
//    if ($cache = cache()->get('image_styles')) {
//      $styles = $cache->data;
//    }
//    else {
      $styles = array();

      // Select the styles we have configured.
      $configured_styles = config_get_storage_names_with_prefix('image.style');
      foreach ($configured_styles as $config_name) {
        // @todo Allow to retrieve the name without prefix only.
        $style = image_style_load(str_replace('image.style.', '', $config_name));
        $styles[$style['name']] = $style;
      }
      drupal_alter('image_styles', $styles);
//      cache()->set('image_styles', $styles);
//    }
//  }

  return $styles;
}

/**
 * Load a style by style name or ID. May be used as a loader for menu items.
 *
 * @param $name
 *   The name of the style.
 * @return
 *   An image style array containing the following keys:
 *   - "name": The unique image style name.
 *   - "effects": An array of image effects within this image style.
 *   If the image style name is not valid, an empty array is returned.
 * @see image_effect_load()
 */
function image_style_load($name) {
  $config = config('image.style.' . $name);
  if ($config->isNew()) {
    return FALSE;
  }
  $style = $config->get();

  if (!empty($style['effects'])) {
    foreach ($style['effects'] as $ieid => $effect) {
      $definition = image_effect_definition_load($effect['name']);
      $effect = array_merge($definition, $effect);
      $style['effects'][$ieid] = $effect;
    }
    // Sort effects by weight.
    uasort($style['effects'], 'drupal_sort_weight');
  }

  return $style;
}

/**
 * Save an image style.
 *
 * @param style
 *   An image style array.
 * @return
 *   An image style array.
 */
function image_style_save($style) {
  $config = config('image.style.' . $style['name']);
  $is_new = $config->isNew();

  $config->set('name', $style['name']);
  if (isset($style['effects'])) {
    $config->set('effects', $style['effects']);
  }
  else {
    $config->set('effects', array());
  }
  $config->save();

  // Let other modules update as necessary on save.
  $style['is_new'] = $is_new;
  module_invoke_all('image_style_save', $style);

  // Clear all caches and flush.
  image_style_flush($style);

  return $style;
}

/**
 * Delete an image style.
 *
 * @param $style
 *   An image style array.
 * @param $replacement_style_name
 *   (optional) When deleting a style, specify a replacement style name so
 *   that existing settings (if any) may be converted to a new style.
 * @return
 *   TRUE on success.
 */
function image_style_delete($style, $replacement_style_name = '') {
  image_style_flush($style);

  $config = config('image.style.' . $style['name']);
  $config->delete();

  // Let other modules update as necessary on save.
  $style['old_name'] = $style['name'];
  $style['name'] = $replacement_style_name;
  module_invoke_all('image_style_delete', $style);

  return TRUE;
}

/**
 * Load all the effects for an image style.
 *
 * @param $style
 *   An image style array.
 * @return
 *   An array of image effects associated with specified image style in the
 *   format array('isid' => array()), or an empty array if the specified style
 *   has no effects.
 *
 * @todo Remove this function; it's entirely obsolete.
 */
function image_style_effects($style) {
  return $style['effects'];
}

/**
 * Get an array of image styles suitable for using as select list options.
 *
 * @param $include_empty
 *   If TRUE a <none> option will be inserted in the options array.
 * @return
 *   Array of image styles both key and value are set to style name.
 */
function image_style_options($include_empty = TRUE) {
  $styles = image_styles();
  $options = array();
  if ($include_empty && !empty($styles)) {
    $options[''] = t('<none>');
  }
  // Use the array concatenation operator '+' here instead of array_merge(),
  // because the latter loses the datatype of the array keys, turning
  // associative string keys into numeric ones without warning.
  $options = $options + drupal_map_assoc(array_keys($styles));
  if (empty($options)) {
    $options[''] = t('No defined styles');
  }
  return $options;
}

/**
 * Menu callback; Given a style and image path, generate a derivative.
 *
 * After generating an image, transfer it to the requesting agent.
 *
 * @param $style
 *   The image style
 */
function image_style_deliver($style, $scheme) {
  // Check that the style is defined and the scheme is valid.
  if (!$style || !file_stream_wrapper_valid_scheme($scheme)) {
    drupal_exit();
  }

  $args = func_get_args();
  array_shift($args);
  array_shift($args);
  $target = implode('/', $args);

  $image_uri = $scheme . '://' . $target;
  $derivative_uri = image_style_path($style['name'], $image_uri);

  // If using the private scheme, let other modules provide headers and
  // control access to the file.
  if ($scheme == 'private') {
    if (file_exists($derivative_uri)) {
      file_download($scheme, file_uri_target($derivative_uri));
    }
    else {
      $headers = module_invoke_all('file_download', $image_uri);
      if (in_array(-1, $headers) || empty($headers)) {
        throw new AccessDeniedHttpException();
      }
      if (count($headers)) {
        foreach ($headers as $name => $value) {
          drupal_add_http_header($name, $value);
        }
      }
    }
  }

  // Don't try to generate file if source is missing.
  if (!file_exists($image_uri)) {
    watchdog('image', 'Unable to generate the derived image from image at %path.', array('%path' => $derivative_uri));
    return new Response(t('Error generating image, missing source file.'), 404);
  }

  // Don't start generating the image if the derivative already exists or if
  // generation is in progress in another thread.
  $lock_name = 'image_style_deliver:' . $style['name'] . ':' . drupal_hash_base64($image_uri);
  if (!file_exists($derivative_uri)) {
    $lock_acquired = lock_acquire($lock_name);
    if (!$lock_acquired) {
      // Tell client to retry again in 3 seconds. Currently no browsers are known
      // to support Retry-After.
      drupal_add_http_header('Status', '503 Service Unavailable');
      drupal_add_http_header('Retry-After', 3);
      print t('Image generation in progress. Try again shortly.');
      drupal_exit();
    }
  }

  // Try to generate the image, unless another thread just did it while we were
  // acquiring the lock.
  $success = file_exists($derivative_uri) || image_style_create_derivative($style, $image_uri, $derivative_uri);

  if (!empty($lock_acquired)) {
    lock_release($lock_name);
  }

  if ($success) {
    $image = image_load($derivative_uri);
    $uri = $image->source;
    $headers = array(
      'Content-Type' => $image->info['mime_type'],
      'Content-Length' => $image->info['file_size'],
    );
    return file_transfer($uri, $headers);
  }
  else {
    watchdog('image', 'Unable to generate the derived image located at %path.', array('%path' => $derivative_uri));
    return new Response(t('Error generating image.'), 500);
  }
}

/**
 * Creates a new image derivative based on an image style.
 *
 * Generates an image derivative by creating the destination folder (if it does
 * not already exist), applying all image effects defined in $style['effects'],
 * and saving a cached version of the resulting image.
 *
 * @param $style
 *   An image style array.
 * @param $source
 *   Path of the source file.
 * @param $destination
 *   Path or URI of the destination file.
 *
 * @return
 *   TRUE if an image derivative was generated, or FALSE if the image derivative
 *   could not be generated.
 *
 * @see image_style_load()
 */
function image_style_create_derivative($style, $source, $destination) {
  // Get the folder for the final location of this style.
  $directory = drupal_dirname($destination);

  // Build the destination folder tree if it doesn't already exist.
  if (!file_prepare_directory($directory, FILE_CREATE_DIRECTORY | FILE_MODIFY_PERMISSIONS)) {
    watchdog('image', 'Failed to create style directory: %directory', array('%directory' => $directory), WATCHDOG_ERROR);
    return FALSE;
  }

  if (!$image = image_load($source)) {
    return FALSE;
  }

  if (!empty($style['effects'])) {
    foreach ($style['effects'] as $effect) {
      image_effect_apply($image, $effect);
    }
  }

  if (!image_save($image, $destination)) {
    if (file_exists($destination)) {
      watchdog('image', 'Cached image file %destination already exists. There may be an issue with your rewrite configuration.', array('%destination' => $destination), WATCHDOG_ERROR);
    }
    return FALSE;
  }

  return TRUE;
}

/**
 * Determines the dimensions of the styled image.
 *
 * Applies all of an image style's effects to $dimensions.
 *
 * @param $style_name
 *   The name of the style to be applied.
 * @param $dimensions
 *   Dimensions to be modified - an array with components width and height, in
 *   pixels.
 */
function image_style_transform_dimensions($style_name, array &$dimensions) {
  module_load_include('inc', 'image', 'image.effects');
  $style = image_style_load($style_name);

  if (!is_array($style)) {
    return;
  }

  if (!empty($style['effects'])) {
    foreach ($style['effects'] as $effect) {
      if (isset($effect['dimensions passthrough'])) {
        continue;
      }

      if (isset($effect['dimensions callback'])) {
        $effect['dimensions callback']($dimensions, $effect['data']);
      }
      else {
        $dimensions['width'] = $dimensions['height'] = NULL;
      }
    }
  }
}

/**
 * Flush cached media for a style.
 *
 * @param $style
 *   An image style array.
 */
function image_style_flush($style) {
  $style_directory = drupal_realpath(file_default_scheme() . '://styles/' . $style['name']);
  if (is_dir($style_directory)) {
    file_unmanaged_delete_recursive($style_directory);
  }

  // Let other modules update as necessary on flush.
  module_invoke_all('image_style_flush', $style);

//  // Clear image style and effect caches.
//  cache()->delete('image_styles');
//  cache()->deletePrefix('image_effects:');
//  drupal_static_reset('image_styles');
//  drupal_static_reset('image_effects');

  // Clear field caches so that formatters may be added for this style.
  field_info_cache_clear();
  drupal_theme_rebuild();

  // Clear page caches when flushing.
  if (module_exists('block')) {
    cache('block')->flush();
  }
  cache('page')->flush();
}

/**
 * Return the URL for an image derivative given a style and image path.
 *
 * @param $style_name
 *   The name of the style to be used with this image.
 * @param $path
 *   The path to the image.
 * @return
 *   The absolute URL where a style image can be downloaded, suitable for use
 *   in an <img> tag. Requesting the URL will cause the image to be created.
 * @see image_style_deliver()
 */
function image_style_url($style_name, $path) {
  $uri = image_style_path($style_name, $path);

  // If not using clean URLs, the image derivative callback is only available
  // with the script path. If the file does not exist, use url() to ensure
  // that it is included. Once the file exists it's fine to fall back to the
  // actual file path, this avoids bootstrapping PHP once the files are built.
  if ($GLOBALS['script_path'] && file_uri_scheme($uri) == 'public' && !file_exists($uri)) {
    $directory_path = file_stream_wrapper_get_instance_by_uri($uri)->getDirectoryPath();
    return url($directory_path . '/' . file_uri_target($uri), array('absolute' => TRUE));
  }

  return file_create_url($uri);
}

/**
 * Return the URI of an image when using a style.
 *
 * The path returned by this function may not exist. The default generation
 * method only creates images when they are requested by a user's browser.
 *
 * @param $style_name
 *   The name of the style to be used with this image.
 * @param $uri
 *   The URI or path to the image.
 * @return
 *   The URI to an image style image.
 * @see image_style_url()
 */
function image_style_path($style_name, $uri) {
  $scheme = file_uri_scheme($uri);
  if ($scheme) {
    $path = file_uri_target($uri);
  }
  else {
    $path = $uri;
    $scheme = file_default_scheme();
  }
  return $scheme . '://styles/' . $style_name . '/' . $scheme . '/' . $path;
}

/**
 * Pull in image effects exposed by modules implementing hook_image_effect_info().
 *
 * @return
 *   An array of image effects to be used when transforming images.
 * @see hook_image_effect_info()
 * @see image_effect_definition_load()
 */
function image_effect_definitions() {
  $language_interface = language(LANGUAGE_TYPE_INTERFACE);

  // hook_image_effect_info() includes translated strings, so each language is
  // cached separately.
  $langcode = $language_interface->langcode;

  $effects = &drupal_static(__FUNCTION__);

  if (!isset($effects)) {
    if ($cache = cache()->get("image_effects:$langcode") && !empty($cache->data)) {
      $effects = $cache->data;
    }
    else {
      $effects = array();
      include_once DRUPAL_ROOT . '/core/modules/image/image.effects.inc';
      foreach (module_implements('image_effect_info') as $module) {
        foreach (module_invoke($module, 'image_effect_info') as $name => $effect) {
          // Ensure the current toolkit supports the effect.
          $effect['module'] = $module;
          $effect['name'] = $name;
          $effect['data'] = isset($effect['data']) ? $effect['data'] : array();
          $effects[$name] = $effect;
        }
      }
      uasort($effects, '_image_effect_definitions_sort');
      drupal_alter('image_effect_info', $effects);
      cache()->set("image_effects:$langcode", $effects);
    }
  }

  return $effects;
}

/**
 * Load the definition for an image effect.
 *
 * The effect definition is a set of core properties for an image effect, not
 * containing any user-settings. The definition defines various functions to
 * call when configuring or executing an image effect. This loader is mostly for
 * internal use within image.module. Use image_effect_load() or
 * image_style_load() to get image effects that contain configuration.
 *
 * @param $effect
 *   The name of the effect definition to load.
 * @return
 *   An array containing the image effect definition with the following keys:
 *   - "effect": The unique name for the effect being performed. Usually prefixed
 *     with the name of the module providing the effect.
 *   - "module": The module providing the effect.
 *   - "help": A description of the effect.
 *   - "function": The name of the function that will execute the effect.
 *   - "form": (optional) The name of a function to configure the effect.
 *   - "summary": (optional) The name of a theme function that will display a
 *     one-line summary of the effect. Does not include the "theme_" prefix.
 */
function image_effect_definition_load($effect) {
  $definitions = image_effect_definitions();
  return isset($definitions[$effect]) ? $definitions[$effect] : FALSE;
}

/**
 * Load all image effects from the database.
 *
 * @return
 *   An array of all image effects.
 * @see image_effect_load()
 *
 * @todo Remove after moving/resolving the todo.
 */
function image_effects() {
  $effects = &drupal_static(__FUNCTION__);

  if (!isset($effects)) {
    $effects = array();

    // Add database image effects.
    // @todo Strictly speaking, this is obsolete. However, it demonstrates a
    //   use-case for retrieving/listing configuration objects using a wildcard
    //   within the name (instead of only the suffix).
    $result = db_select('image_effects', NULL, array('fetch' => PDO::FETCH_ASSOC))
      ->fields('image_effects')
      ->orderBy('image_effects.weight', 'ASC')
      ->execute();
    foreach ($result as $effect) {
      $effect['data'] = unserialize($effect['data']);
      $definition = image_effect_definition_load($effect['name']);
      // Do not load image effects whose definition cannot be found.
      if ($definition) {
        $effect = array_merge($definition, $effect);
        $effects[$effect['ieid']] = $effect;
      }
    }
  }

  return $effects;
}

/**
 * Load a single image effect.
 *
 * @param $ieid
 *   The image effect ID.
 * @param $style_name
 *   The image style name.
 *
 * @return
 *   An image effect array, consisting of the following keys:
 *   - "ieid": The unique image effect ID.
 *   - "weight": The weight of this image effect within the image style.
 *   - "name": The name of the effect definition that powers this image effect.
 *   - "data": An array of configuration options for this image effect.
 *   Besides these keys, the entirety of the image definition is merged into
 *   the image effect array. Returns FALSE if the specified effect cannot be
 *   found.
 * @see image_style_load()
 * @see image_effect_definition_load()
 */
function image_effect_load($ieid, $style_name) {
  if (($style = image_style_load($style_name)) && isset($style['effects'][$ieid])) {
    $effect = $style['effects'][$ieid];
    $definition = image_effect_definition_load($effect['name']);
    $effect = array_merge($definition, $effect);
    // @todo The effect's key name within the style is unknown. It *should* be
    //   identical to the ieid, but that is in no way guaranteed. And of course,
    //   the ieid key *within* the effect is senseless duplication in the first
    //   place. This problem can be eliminated in many places, but especially
    //   for loaded menu arguments like %image_effect, the actual router
    //   callbacks don't have access to 'ieid' anymore (unless resorting to
    //   dirty %index and %map tricks).
    $effect['ieid'] = $ieid;
    return $effect;
  }
  return FALSE;
}

/**
 * Save an image effect.
 *
 * @param $style_name
 *   The image style this effect belongs to.
 * @param $effect
 *   An image effect array.
 * @return
 *   An image effect array. In the case of a new effect, 'ieid' will be set.
 */
function image_effect_save($style_name, $effect) {
  $config = config('image.style.' . $style_name);

  if (!isset($effect['ieid']) || empty($effect['ieid'])) {
    // We need to generate the ieid and save the new effect.
    // The machine name is all the elements of the data array concatenated
    // together, delimited by underscores.
    $effect['ieid'] = $effect['name'];
    foreach ($effect['data'] as $key => $value) {
      $effect['ieid'] .= '_' . $value;
    }
    // @todo The machine name must not use any special non-alphanumeric
    //   characters, and may also not contain dots/periods, as that is the
    //   config system's nested key syntax.
    $effect['ieid'] = preg_replace('@[^a-zA-Z0-9_-]@', '', $effect['ieid']);
  }
  $config->set('effects.' . $effect['ieid'], $effect);
  $config->save();
  $style = image_style_load($style_name);
  image_style_flush($style);
  return $effect;
}

/**
 * Delete an image effect.
 *
 * @param $style_name
 *   The image style this effect belongs to.
 * @param $effect
 *   An image effect array.
 */
function image_effect_delete($style_name, $effect) {
  $config = config('image.style.' . $style_name);
  $config->clear('effects.' . $effect['ieid']);
  $config->save();
  $style = image_style_load($style_name);
  image_style_flush($style);
}

/**
 * Given an image object and effect, perform the effect on the file.
 *
 * @param $image
 *   An image object returned by image_load().
 * @param $effect
 *   An image effect array.
 * @return
 *   TRUE on success. FALSE if unable to perform the image effect on the image.
 */
function image_effect_apply($image, $effect) {
  module_load_include('inc', 'image', 'image.effects');
  $function = $effect['effect callback'];
  return $function($image, $effect['data']);
}

/**
 * Returns HTML for an image using a specific image style.
 *
 * @param $variables
 *   An associative array containing:
 *   - style_name: The name of the style to be used to alter the original image.
 *   - uri: The path of the image file relative to the Drupal files directory.
 *     This function does not work with images outside the files directory nor
 *     with remotely hosted images. This should be in a format such as
 *     'images/image.jpg', or using a stream wrapper such as
 *     'public://images/image.jpg'.
 *   - width: The width of the source image (if known).
 *   - height: The height of the source image (if known).
 *   - alt: The alternative text for text-based browsers.
 *   - title: The title text is displayed when the image is hovered in some
 *     popular browsers.
 *   - attributes: Associative array of attributes to be placed in the img tag.
 *
 * @ingroup themeable
 */
function theme_image_style($variables) {
  // Determine the dimensions of the styled image.
  $dimensions = array(
    'width' => $variables['width'],
    'height' => $variables['height'],
  );

  image_style_transform_dimensions($variables['style_name'], $dimensions);

  $variables['width'] = $dimensions['width'];
  $variables['height'] = $dimensions['height'];

  // Determine the url for the styled image.
  $variables['uri'] = image_style_url($variables['style_name'], $variables['uri']);
  return theme('image', $variables);
}

/**
 * Accept a keyword (center, top, left, etc) and return it as a pixel offset.
 *
 * @param $value
 * @param $current_pixels
 * @param $new_pixels
 */
function image_filter_keyword($value, $current_pixels, $new_pixels) {
  switch ($value) {
    case 'top':
    case 'left':
      return 0;

    case 'bottom':
    case 'right':
      return $current_pixels - $new_pixels;

    case 'center':
      return $current_pixels / 2 - $new_pixels / 2;
  }
  return $value;
}

/**
 * Internal function for sorting image effect definitions through uasort().
 *
 * @see image_effect_definitions()
 */
function _image_effect_definitions_sort($a, $b) {
  return strcasecmp($a['name'], $b['name']);
}