<?php
/**
 * @file
 * This file is essentially a copy/paste from the core image module:
 * image.module.
 * Applied the patch and few changes suggested at:
 * http://drupal.org/node/1570072
 */

/**
 * Implements hook_field_formatter_info().
 */
function image_link_formatter_field_formatter_info() {
  $formatters = array(
    'image_link_formatter' => array(
      'label' => t('Image Link Formatter'),
      'field types' => array('image'),
      'settings' => array('image_style' => '', 'image_link' => ''),
    ),
  );

  return $formatters;
}

/**
 * Implements hook_field_formatter_settings_form().
 */
function image_link_formatter_field_formatter_settings_form($field, $instance, $view_mode, $form, &$form_state) {
  $display = $instance['display'][$view_mode];
  $settings = $display['settings'];

  $image_styles = image_style_options(FALSE);
  $element['image_style'] = array(
    '#title' => t('Image style'),
    '#type' => 'select',
    '#default_value' => $settings['image_style'],
    '#empty_option' => t('None (original image)'),
    '#options' => $image_styles,
  );

  $link_types = image_link_formatter_image_field_link_types($instance);
  $element['image_link'] = array(
    '#title' => t('Link image to'),
    '#type' => 'select',
    '#default_value' => $settings['image_link'],
    '#empty_option' => t('Nothing'),
    '#options' => $link_types,
  );

  return $element;
}

/**
 * Implements hook_field_formatter_settings_summary().
 */
function image_link_formatter_field_formatter_settings_summary($field, $instance, $view_mode) {
  $display = $instance['display'][$view_mode];
  $settings = $display['settings'];

  $summary = array();

  $image_styles = image_style_options(FALSE);
  // Unset possible 'No defined styles' option.
  unset($image_styles['']);
  // Styles could be lost because of enabled/disabled modules that defines
  // their styles in code.
  if (isset($image_styles[$settings['image_style']])) {
    $summary[] = t('Image style: @style', array('@style' => $image_styles[$settings['image_style']]));
  }
  else {
    $summary[] = t('Original image');
  }

  $link_types = image_link_formatter_image_field_link_types($instance);
  // Display this setting only if image is linked.
  if (isset($link_types[$settings['image_link']])) {
    $summary[] = filter_xss_admin($link_types[$settings['image_link']]);
  }

  return implode('<br />', $summary);
}

/**
 * Implements hook_field_formatter_view().
 */
function image_link_formatter_field_formatter_view($entity_type, $entity, $field, $instance, $langcode, $items, $display) {
  $element = array();

  // Check if the formatter involves a link.
  $image_link = $display['settings']['image_link'];
  if ($image_link == 'content') {
    $uri = entity_uri($entity_type, $entity);
  }
  elseif ($image_link == 'file') {
    $link_file = TRUE;
  }
  elseif ($image_link) {
    if (isset($entity->$image_link)) {
      // Support for field translations.
      $language = field_language($entity_type, $entity, $field['field_name']);
      $link_field = $entity->$image_link;

      if (isset($link_field[$language])) {
        $link_values = $link_field[$language];
      }
    }
  }

  foreach ($items as $delta => $item) {
    if (isset($link_file)) {
      $uri = array(
        'path' => file_create_url($item['uri']),
        'options' => array(),
      );
    }
    // Handle multiple link with image values.
    if (isset($link_values)) {
      if (isset($link_values[$delta]['url'])) {
        $uri = array(
          'path' => $link_values[$delta]['url'],
          'options' => array('attributes' => $link_values[$delta]['attributes']),
        );
        // Handle query fragment if there is any.
        if (isset($link_values[$delta]['query']) && count($link_values[$delta]['query'])>0) {
          $uri['options']['query'] = $link_values[$delta]['query'];
        }
      }
      // If there are more image values than link values unset the link.
      else {
        unset($uri);
      }
    }
    $element[$delta] = array(
      '#theme' => 'image_formatter',
      '#item' => $item,
      '#image_style' => $display['settings']['image_style'],
      '#path' => isset($uri) ? $uri : '',
    );
  }

  return $element;
}

/**
 * Helper function to compute the list of possible link types.
 */
function image_link_formatter_image_field_link_types($instance) {
  $link_types = array(
    'content' => t('Content'),
    'file' => t('File'),
  );
  // If the link module is installed, also allow any link fields to be used.
  foreach (field_info_fields() as $field_key => $field_info) {
    if ($field_info['type'] == 'link_field') {
      $field_instance = field_info_instance($instance['entity_type'], $field_info['field_name'], $instance['bundle']);
      if ($field_instance) {
        $link_types[$field_key] = "$field_instance[label] ($field_info[field_name])";
      }
    }
  }
  return $link_types;
}