<?php

/**
 * @file
 * Defines options to control how the Read more link is displayed on teasers.
 */

/**
 * Implements hook_help().
 */
function readmorecontrol_help($path, $arg) {
  switch ($path) {
    case 'admin/help#readmorecontrol':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('The Read More Control module can add and control the read more link in many different content types, including nodes, terms and even users.') . '</p>';
      return $output;
  }
}

/**
 * Implements hook_theme().
 */
function readmorecontrol_theme($existing, $type, $theme, $path) {
  return array(
    'readmorecontrol_link' => array(
      'variables' => array(
        'entity_type' => NULL,
        'entity' => NULL,
        'bundle' => NULL,
        'link' => NULL,
      ),
    ),
  );
}

/**
 * Implements hook_menu().
 */
function readmorecontrol_menu() {
  $items['admin/config/content/read-more-control'] = array(
    'title' => 'Read more settings',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('readmorecontrol_admin_settings_form', 'node'),
    'description' => 'Configure the Read more link settings.',
    'access arguments' => array('administer site configuration'),
    'file' => 'readmorecontrol.admin.inc',
  );

  $entity_info = entity_get_info();
  foreach ($entity_info as $entity_type => $info) {
    if (readmorecontrol_supported_entity($entity_type, $info)) {
      if ($entity_type == 'node') {
        $items['admin/config/content/read-more-control/' . $entity_type] = array(
          'title' => $info['label'],
          'type' => MENU_DEFAULT_LOCAL_TASK,
          'weight' => -10,
        );
      }
      else {
        $items['admin/config/content/read-more-control/' . $entity_type] = array(
          'title' => $info['label'],
          'page callback' => 'drupal_get_form',
          'page arguments' => array('readmorecontrol_admin_settings_form', $entity_type),
          'description' => 'Configure the Read more link settings.',
          'access arguments' => array('administer site configuration'),
          'file' => 'readmorecontrol.admin.inc',
          'type' => MENU_LOCAL_TASK,
        );
      }
    }
  }
  return $items;
}

/**
 * Implements hook_node_type_update().
 */
function readmorecontrol_node_type_update($info) {
  if (!empty($info->old_type) && $info->old_type != $info->type) {
    variable_set('readmorecontrol_behaviour__node__' . $info->type, variable_get('readmorecontrol_behaviour__node__' . $info->old_type, 'always'));
    variable_del('readmorecontrol_behaviour__node__' . $info->old_type);

    variable_set('readmorecontrol_format__node__' . $info->type, variable_get('readmorecontrol_format__node__' . $info->old_type, array()));
    variable_del('readmorecontrol_format__node__' . $info->old_type);

    // Update all of the view modes if required.
    $entity_info = entity_get_info('node');
    foreach ($entity_info['view modes'] as $view_mode => $view_mode_settings) {
      if ($old_settings = variable_get('readmorecontrol_behaviour__node__' . $info->old_type . '__' . $view_mode, FALSE)) {
        variable_set('readmorecontrol_behaviour__node__' . $info->type . '__' . $view_mode, $old_settings);
        variable_del('readmorecontrol_behaviour__node__' . $info->old_type);
      }
      if ($old_settings = variable_get('readmorecontrol_format__node__' . $info->old_type . '__' . $view_mode, FALSE)) {
        variable_set('readmorecontrol_format__node__' . $info->type . '__' . $view_mode, $old_settings);
        variable_del('readmorecontrol_format__node__' . $info->old_type);
      }
    }

  }
}

/**
 * Implements hook_node_type_delete().
 */
function readmorecontrol_node_type_delete($info) {
  variable_del('readmorecontrol_behaviour__node__' . $info->type);
  variable_del('readmorecontrol_format__node__' . $info->type);
}

/**
 * Implements hook_form_FORM_ID_alter().
 */
function readmorecontrol_form_field_ui_field_edit_form_alter(&$form, &$form_state, $form_id) {
  module_load_include('admin.inc', 'readmorecontrol');
  _readmorecontrol_form_field_ui_field_edit_form_alter($form, $form_state, $form_id);
}

function readmorecontrol_form_field_ui_display_overview_form_alter_submit(&$form, &$form_state) {
  module_load_include('admin.inc', 'readmorecontrol');
  _readmorecontrol_form_field_ui_display_overview_form_alter_submit($form, $form_state);
}

/**
 * Implements hook_form_FORM_ID_alter().
 */
function readmorecontrol_form_field_ui_display_overview_form_alter(&$form, &$form_state, $display_overview = FALSE) {
  module_load_include('admin.inc', 'readmorecontrol');
  _readmorecontrol_form_field_ui_display_overview_form_alter($form, $form_state, $display_overview);
}

/**
 * Preprocessor for search result.
 *
 * @see search-result.tpl.php
 */
function readmorecontrol_preprocess_search_result(&$variables) {
  // Best guess here, e.g. node or user.
  $type = $variables['module'];
  if (isset($variables['result'][$type]) && readmorecontrol_supported_entity($type)) {
    $entity = $variables['result'][$type];
    if (is_object($entity) && !empty($entity->readmorelink)) {
      if ($entity->readmore_required) {
        switch ($entity->readmorelink_placement) {
          case 'search_info':
            $variables['info_split'][] = $entity->readmorelink;
            if (empty($variables['info'])) {
              $variables['info'] = $entity->readmorelink;
            }
            else {
              $variables['info'] .= ' - ' . $entity->readmorelink;
            }
            break;

          default:
            $elm = strpos($entity->readmorelink_placement, '_inline') ? 'span' : 'div';
            $variables['snippet'] .= " <{$elm} class=\"read-more-link\">" . $entity->readmorelink . "</{$elm}>";
            break;
        }
      }
    }
  }
}

################################################################################
#  Helper functions for parsing various settings and options.                  #
################################################################################

/**
 * Helper function to get a list of view modes that should not have a Read more
 * link applied to these.
 */
function readmorecontrol_excluded_view_modes() {
  return array(
    'search_index',
    'token',
    'diff_standard',
    'diff_complete',
  );
}

/**
 * Determines if the entity can support a Read more link.
 */
function readmorecontrol_supported_entity($entity_type, $info = NULL) {
  if (!$info) {
    $info = entity_get_info($entity_type);
  }
  if ((!empty($info['label callback']) || !empty($info['entity keys']['label']))
      && !empty($info['uri callback'])) {
    if (!empty($info['view modes'])) {
      $excluded_modes = variable_get('readmorecontrol_disabled_view_modes', readmorecontrol_excluded_view_modes());
      $excluded_modes[] = 'default';
      $excluded_modes[] = 'full';
      $modes = array_keys($info['view modes']);
      $target_modes = array_diff($modes, $excluded_modes);
      return !empty($target_modes);
    }
  }
  return FALSE;
}

/**
 * Helper function to determine the Read more link behaviour.
 */
function readmorecontrol_entity_behaviour($entity_type, $bundle, $view_mode) {
  // This blocks all processing within entity_view().
  if (in_array($view_mode, readmorecontrol_excluded_view_modes())) {
    // Defaulting to none rather than never to prevent any additional processing.
    return 'none';
  }
  else {
    $node_teaser = $entity_type == 'node' && $view_mode == 'teaser';
    $behaviour = variable_get("readmorecontrol_behaviour__{$entity_type}__{$bundle}__{$view_mode}", $node_teaser ? 'default' : 'none');
    if ($behaviour == 'default') {
      $behaviour = variable_get("readmorecontrol_behaviour__{$entity_type}__{$bundle}", 'default');
      if ($behaviour == 'default') {
        $system_default = $node_teaser ? 'always' : 'none';
        $behaviour = variable_get("readmorecontrol_behaviour__{$entity_type}", $system_default);
      }
    }
    return $behaviour;
  }
}

/**
 * Helper function to get any formatting settings.
 */
function readmorecontrol_format_settings($entity_type, $bundle = NULL, $view_mode = NULL, $is_edit = FALSE) {
  $settings = array();
  if ($is_edit) {
    if ($view_mode && $view_mode != 'default') {
      $settings += (array) variable_get('readmorecontrol_format__' . $entity_type . '__' . $bundle. '__' . $view_mode, array('enabled' => 'global'));
    }
    elseif ($bundle) {
      $settings += (array) variable_get('readmorecontrol_format__' . $entity_type . '__' . $bundle, array('enabled' => 'global'));
    }
    else {
      $settings += (array) variable_get('readmorecontrol_format__' . $entity_type, array('enabled' => 'none'));
    }
  }
  else {
    // Find the setting with the highest precesion, but discard if the use
    // global setting is selected.
    if ($view_mode) {
      $settings += (array) variable_get('readmorecontrol_format__' . $entity_type . '__' . $bundle. '__' . $view_mode, array('enabled' => 'global'));
      if (!$is_edit && $settings['enabled'] == 'global') {
        $settings = array();
      }
    }
    if ($bundle) {
      $settings += (array) variable_get('readmorecontrol_format__' . $entity_type . '__' . $bundle, array('enabled' => 'global'));
      if ($settings['enabled'] == 'global') {
        $settings = array();
      }
    }
    $settings += (array) variable_get('readmorecontrol_format__' . $entity_type, array('enabled' => 'none'));
  }

  $settings += array(
    'enabled' => 'none',
    'text' => '',
    'href' => '',
    'query' => '',
    'fragment' => '',
    'title' => '',
    'class' => '',
    'rel' => '',
    'target' => '',
    'placement' => readmorecontrol_default_placement($entity_type, $view_mode),
  );
  return $settings;
}

/**
 * Helper function to determine the best placement default value.
 */
function readmorecontrol_default_placement($entity_type, $view_mode) {
  switch ($view_mode) {
    case 'search_result':
      return 'search_snippet';

    default:
      return 'none';
  }
}

/**
 * A helper function to help determine if a field should be tested.
 *
 * Checks the instance settings and field view access rights.
 */
function readmorecontrol_field_requires_processing($entity_type, $entity, $field, $instance) {
  if (field_access('view', $field, $entity_type, $entity)) {
    // Test the default action to determine if we should use this field.
    switch ($entity->readmorebehaviour) {
      case 'when_required':
        // Check the field settings to see if this field is to be ignored.
        if ($behaviour = readmorecontrol_instance_settings($instance)) {
          return $behaviour == 'process';
        }
        return TRUE;

      case 'when_required_text':
        if (in_array($field['type'], array('text_with_summary', 'text_long'))) {
          if ($behaviour = readmorecontrol_instance_settings($instance)) {
            return $behaviour == 'process';
          }
          return TRUE;
        }
        break;

      case 'when_required_body':
        if ($field['field_name'] == 'body') {
          if ($behaviour = readmorecontrol_instance_settings($instance)) {
            return $behaviour == 'process';
          }
          return TRUE;
        }
        break;
    }
  }
  return FALSE;
}

/**
 * Helper function to determine the instance readmore_behaviour setting.
 */
function readmorecontrol_instance_settings($instance) {
  // Check the field settings to see if this field is to be ignored.
  if (isset($instance['readmore_behaviour'])) {
    if ($instance['readmore_behaviour'] != 'default') {
      return $instance['readmore_behaviour'];
    }
  }
  return FALSE;
}

################################################################################
#  Core processing functions.                                                  #
################################################################################

/**
 * Extract, update or construct the read more link.
 */
function readmorecontrol_entity_view($entity, $entity_type, $view_mode, $langcode) {
  // The module makes the assumption that these are the only two "full" view
  // modes to compare against.
  if ($view_mode == 'full' || $view_mode == 'default') {
    return;
  }

  // Ensure that this entity is actually supported.
  $entity_info = entity_get_info($entity_type);
  if (!readmorecontrol_supported_entity($entity_type, $entity_info)) {
    return;
  }

  // Only process enabled view modes.
  list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);

  $behaviour = readmorecontrol_entity_behaviour($entity_type, $bundle, $view_mode);
  if ($behaviour == 'none') {
    return;
  }
  $full_mode = empty($entity_info['view modes']['full']) ? 'default' : 'full';
  $view_mode_settings = field_view_mode_settings($entity_type, $bundle);
  $actual_mode = empty($view_mode_settings[$view_mode]['custom_settings']) ? 'default' : $view_mode;
  $actual_full_mode = empty($view_mode_settings[$full_mode]['custom_settings']) ? 'default' : $full_mode;

  // Determine the behaviour of the modules processing of the link.
  $entity->readmorebehaviour = $behaviour;
  switch ($entity->readmorebehaviour) {
    case 'always':
      $entity->readmore_required = TRUE;
      break;

    case 'never':
      $entity->readmore_required = FALSE;
      break;

    default:
      // Test the view mode to see really different.
      if ($actual_mode == $actual_full_mode) {
        $entity->readmore_required = FALSE;
      }
      else {
        foreach (field_info_instances($entity_type, $bundle) as $field_name => $instance) {
          // Get the field display info for full view mode.
          $display = field_get_display($instance, $view_mode, $entity);
          $display_full = field_get_display($instance, $full_mode, $entity);

          // If the full view mode is hidden, we can ignore this field.
          if ($display_full['type'] == 'hidden') {
            continue;
          }
          $field = field_info_field($field_name);
          if (readmorecontrol_field_requires_processing($entity_type, $entity, $field, $instance)) {
            // Only test fields that have data.
            $items = field_get_items($entity_type, $entity, $field_name, $langcode);
            if (!empty($items)) {
              // If current view is hidden, we can assume that the main view
              // has values.
              if ($display['type'] == 'hidden') {
                $entity->readmore_required = TRUE;
                break;
              }

              $func = "readmorecontrol_{$display['module']}_compare_items";
              if (function_exists($func)) {
                $content = array(
                  'display' => $display,
                  'display_full' => $display_full,
                  'instance' => $instance,
                  'field' => $field,
                  'langcode' => $langcode,
                );
                if ($func($items, $content)) {
                  $entity->readmore_required = TRUE;
                  break;
                }
              }
              else {
                if ($display_full['type'] != $display['type'] || $display_full['settings'] !== $display['settings']) {
                  $entity->readmore_required = TRUE;
                  break;
                }
              }
            }
          }
        }
      }
      break;
  }

  // No differences were found.
  if (!isset($entity->readmore_required)) {
    $entity->readmore_required = FALSE;
  }

  // Apply the settings.
  $format = readmorecontrol_format_settings($entity_type, $bundle, $view_mode);

  // Create and append a copy of the Read More link to the entity itself.
  $has_readmore = !empty($entity->content['links']) && !empty($entity->content['links'][$entity_type])
      && !empty($entity->content['links'][$entity_type]['#links'][$entity_type . '-readmore']);

  if ($has_readmore) {
    $readmorelink = $entity->content['links'][$entity_type]['#links'][$entity_type . '-readmore'];
  }
  else {
    $title = entity_label($entity_type, $entity);
    $title_stripped = strip_tags($title);
    $uri = entity_uri($entity_type, $entity);
    $readmorelink = array(
      'title' => t('Read more<span class="element-invisible"> about @title</span>', array('@title' => $title_stripped)),
      'href' => $uri['path'],
      'html' => TRUE,
      'attributes' => array('title' => $title_stripped),
    );
    if (in_array($view_mode, variable_get('readmodecontrol_external_view_modes', array('rss')))) {
      $readmorelink['absolute'] = 1;
    }
  }

  if (!empty($format['text'])) {
    if ($title = filter_xss_admin(_rmc_token_replace($format['text'], $entity_type, $entity))) {
      $readmorelink['title'] = $title;
      $readmorelink['html'] = 1;
    }
  }

  // The generated URL is passed through check_plain() internally.
  if (!empty($format['href'])) {
    if ($format['href'] == '<none>') {
      unset($readmorelink['href']);
    }
    else {
      $readmorelink['href'] = _rmc_token_replace($format['href'], $entity_type, $entity);
    }
  }
  if (!empty($format['query'])) {
    if ($query_string = _rmc_token_replace($format['query'], $entity_type, $entity)) {
      $query = array();
      foreach (explode('&', $query_string) as $query_argument) {
        list($key, $value) = explode('=', $query_argument . '=1');
        $query[$key] = $value;
      }
      $readmorelink['query'] = $query;
    }
  }
  if (!empty($format['fragment'])) {
    if ($fragment = _rmc_token_replace($format['fragment'], $entity_type, $entity)) {
      $readmorelink['fragment'] = $fragment;
    }
  }

  // Append any link attributes. Like the link options, these have are also
  // passed through check_plain() internally.
  $attributes = empty($readmorelink['attributes']) ? array() : $readmorelink['attributes'];
  if (!empty($format['title'])) {
    if ($attr_title = _rmc_token_replace($format['title'], $entity_type, $entity)) {
      $attributes['title'] = $attr_title;
    }
  }
  if (!empty($attributes['class'])) {
    $attributes['class'] = is_array($attributes['class']) ? $attributes['class'] : explode(' ', $attributes['class']);
    if (!in_array('read-more', $attributes['class'])) {
      $attributes['class'][] = 'read-more';
    }
  }
  else {
    $attributes['class'] = array('read-more');
  }
  if (!empty($format['class'])) {
    if ($classes = _rmc_token_replace($format['class'], $entity_type, $entity)) {
      $attributes['class'][] = $classes;
    }
  }

  if (!empty($format['rel'])) {
    if ($rel_title = _rmc_token_replace($format['rel'], $entity_type, $entity)) {
      $attributes['rel'] = $rel_title;
    }
  }
  if (!empty($format['target'])) {
    $attributes['target'] = $format['target'];
  }
  $readmorelink['attributes'] = $attributes;

  $entity->readmorelink = theme('readmorecontrol_link__' . $entity_type, array(
    'entity' => $entity,
    'entity_type' => $entity_type,
    'bundle' => $bundle,
    'link' => $readmorelink,
  ));

  $entity->readmorelink_raw = $readmorelink;
  $entity->readmorelink_placement = $format['placement'];

  if (!$entity->readmore_required || $view_mode == 'search_result') {
    if ($has_readmore) {
      unset($entity->content['links'][$entity_type]['#links'][$entity_type . '-readmore']);
    }
    return;
  }

  // If required, process the placement.
  if ($format['placement'] != 'none') {
    $field_item = NULL;
    if (strpos($format['placement'], 'body_') === 0) {
      if (isset($entity->content['body'])) {
        $field_item = &$entity->content['body'];
      }
    }
    else {
      $rendered_fields = array();
      foreach (field_info_instances($entity_type, $bundle) as $field_name => $instance) {
        if (isset($entity->content[$field_name])) {
          $display = $instance['display'][$actual_mode];
          $rendered_fields[$field_name] = $display['weight'];
        }
      }
      // This places the field last
      if ($format['placement'] == 'append') {
        $extra_fields = field_extra_fields_get_display($entity_type, $bundle, $view_mode);
        foreach ($extra_fields as $name => $settings) {
          if (isset($entity->content[$name])) {
            $rendered_fields[$name] = $settings['weight'];
          }
        }
      }
      asort($rendered_fields);
      foreach ($rendered_fields as $key => $weight) {
        if ($format['placement'] == 'append') {
          $field_item = &$entity->content[$key];
        }
        elseif ($format['placement'] == 'field_append' || $format['placement'] == 'field_inline') {
          $field_item = &$entity->content[$key];
        }
        elseif (isset($entity->content[$key]['#field_type'])) {
          if (in_array($entity->content[$key]['#field_type'], array('text_with_summary', 'text_long'))) {
            $field_item = &$entity->content[$key];
          }
        }
      }
    }

    if (isset($field_item)) {
      $deltas = element_children($field_item);
      $last_delta = array_pop($deltas);
      if (isset($last_delta)) {
        $item = &$field_item[$last_delta];
        if (strpos($format['placement'], '_inline') && isset($item['#markup'])) {
          $link = ' <span class="read-more-link">' . $entity->readmorelink . '</span>';
          if (preg_match('!</?(?:p|div)[^>]*>\s*$!i', $item['#markup'], $match, PREG_OFFSET_CAPTURE)) {
            $insert_point = strpos('teaser', $item['#markup']) + $match[0][1];
            $item['#markup'] = substr_replace($item['#markup'], $link, $insert_point, 0);
          }
          else {
            $item['#markup'] .= $link;
          }
        }
        else {
          $field_item[$last_delta]['#suffix'] = '<div class="read-more-link">' . $entity->readmorelink . '</div>';
        }
      }
      else {
        $field_item['#suffix'] = '<div class="read-more-link">' . $entity->readmorelink . '</div>';
      }
      if ($has_readmore) {
        unset($entity->content['links'][$entity_type]['#links'][$entity_type . '-readmore']);
      }
      return;
    }
  }

  // Fallen though, apply as a links element.
  if (empty($entity->content['links'])) {
    $entity->content['links'] = array(
      '#theme' => 'links__' . $entity_type,
      '#pre_render' => array('drupal_pre_render_links'),
      '#attributes' => array('class' => array('links', 'inline')),
      $entity_type => array(
        '#theme' => 'links__' . $entity_type . '__' . $bundle,
        '#links' => array(),
        '#attributes' => array('class' => array('links', 'inline')),
      ),
    );
  }
  $entity->content['links'][$entity_type]['#links'][$entity_type . '-readmore'] = $readmorelink;
}

function theme_readmorecontrol_link($variables) {
  $readmore = $variables['link'];

  // Also available.
  $entity_type = $variables['entity_type'];
  $entity = $variables['entity'];
  $bundle = $variables['bundle'];

  if (isset($readmore['href'])) {
    // Pass in $readmore as $options, they share the same keys.
    return l($readmore['title'], $readmore['href'], $readmore);
  }
  elseif (!empty($readmore['title'])) {
    // Some links are actually not links, but we wrap these in <span> for adding title and class attributes.
    if (empty($readmore['html'])) {
      $readmore['title'] = check_plain($readmore['title']);
    }
    $span_attributes = '';
    if (isset($readmore['attributes'])) {
      $span_attributes = drupal_attributes($readmore['attributes']);
    }
    return '<span' . $span_attributes . '>' . $readmore['title'] . '</span>';
  }
  return '';
}

/**
 * Wrapper function for token_replace().
 *
 * Returned text is not sanitized.
 */
function _rmc_token_replace($text, $entity_type, $entity) {
  // Only process if there is a hint that a token present.
  if (strpos($text, ']')) {
    return token_replace($text, array(
      $entity_type => $entity,
      array('clear' => 1, 'sanitize' => 0),
    ));
  }
  return $text;
}

################################################################################
#  Core field comparison callbacks.                                            #
################################################################################

/**
 * Implements the callback readmorecontrol_MODULE_compare_items().
 */
function readmorecontrol_text_compare_items($items, $content) {
  extract($content, EXTR_SKIP);

  // We can bypass processing of some combinations.
  if ($display['type'] == $display_full['type']) {
    switch ($display['type']) {
      case 'text_default':
      case 'text_plain':
        return FALSE;
    }
  }

  // Avoid additional processing, do this once for both if required.
  $needs_sanitization = $display['type'] != 'text_plain' || $display_full['type'] != 'text_plain';
  $has_summary = $display['type'] == 'text_summary_or_trimmed' || $display_full['type'] == 'text_summary_or_trimmed';

  foreach ($items as $delta => $item) {
    $sanitized_text = $needs_sanitization ? _text_sanitize($instance, $langcode, $item, 'value') : '';
    $sanitized_summary = $has_summary ? _text_sanitize($instance, $langcode, $item, 'summary') : '';
    $display_text = '';
    $full_display_text = '';
    foreach (array('display_text', 'full_display_text') as $var) {
      $test_display = $var == 'display_text' ? $display : $display_full;
      switch ($test_display['type']) {
        case 'text_default':
        case 'text_trimmed':
          $$var = $sanitized_text;
          if ($test_display['type'] == 'text_trimmed') {
            $$var = text_summary($$var, $instance['settings']['text_processing'] ? $item['format'] : NULL, $test_display['settings']['trim_length']);
          }
          break;

        case 'text_summary_or_trimmed':
          if (!empty($item['summary'])) {
            $$var = $sanitized_summary;
          }
          else {
            $$var = text_summary($sanitized_text, $instance['settings']['text_processing'] ? $item['format'] : NULL, $test_display['settings']['trim_length']);
          }
          break;

        case 'text_plain':
          $$var = strip_tags($item['value']);
          break;
      }
    }

    if ($display_text != $full_display_text) {
      return TRUE;
    }

  }
  return FALSE;
}