<?php

/**
 * @file
 * Adds ical functionality to Views, and an iCal parser to Feeds.
 */

/**
 * The version number of the current release. This is inserted into the PRODID
 * value of the iCal feeds created by Date iCal. It's primarily used for
 * debugging.
 */
define('DATE_ICAL_VERSION', '3.1-dev');

/**
 * Exception class for generic exceptions thrown by this module.
 */
class DateIcalException extends Exception {}

/**
 * Exception used by iCal Fields for when a date field is blank.
 */
class BlankDateFieldException extends DateIcalException {}

/**
 * Exception thrown when the Feeds parser plugin fails.
 */
class DateIcalParseException extends DateIcalException {}

/**
 * Implements hook_hook_info().
 */
function date_ical_hook_info() {
  $hooks = array(
    'date_ical_export_html_alter',
    'date_ical_export_raw_event_alter',
    'date_ical_export_vevent_alter',
    'date_ical_export_vcalendar_alter',
    'date_ical_export_post_render_alter',
    'date_ical_import_vcalendar_alter',
    'date_ical_import_component_alter',
    'date_ical_import_timezone_alter',
  );

  return array_fill_keys($hooks, array('group' => 'date_ical'));
}

/**
 * Implements hook_views_api().
 */
function date_ical_views_api() {
  return array(
    'api' => 3,
    'path' => drupal_get_path('module', 'date_ical') . '/includes',
  );
}

/**
 * Implements hook_feeds_plugins().
 */
function date_ical_feeds_plugins() {
  $path = drupal_get_path('module', 'date_ical') . '/includes';
  $info = array();
  $info['DateiCalFeedsParser'] = array(
    'name' => 'iCal parser',
    'description' => t('Parse iCal feeds.'),
    'handler' => array(
      'parent' => 'FeedsParser',
      'class' => 'DateiCalFeedsParser',
      'file' => 'DateiCalFeedsParser.inc',
      'path' => $path,
    ),
  );
  return $info;
}

/**
 * Implements hook_theme().
 */
function date_ical_theme($existing, $type, $theme, $path) {
  return array(
    'date_ical_icon' => array(
      'variables' => array('url' => NULL, 'tooltip' => NULL),
    ),
  );
}

/**
 * Theme function for the ical icon used by attached iCal feed.
 *
 * Available variables are:
 * $variables['tooltip'] - The tooltip to be used for the ican feed icon.
 * $variables['url'] - The url to the actual iCal feed.
 * $variables['view'] - The view object from which the iCal feed is being
 *   built (useful for contextual information).
 */
function theme_date_ical_icon($variables) {
  if (empty($variables['tooltip'])) {
    $variables['tooltip'] = t('Add this event to my calendar');
  }
  $variables['path'] = drupal_get_path('module', 'date_ical') . '/images/ical-feed-icon-34x14.png';
  $variables['alt'] = $variables['title'] = $variables['tooltip'];
  if ($image = theme('image', $variables)) {
    return "<a href='{$variables['url']}' class='ical-icon'>$image</a>";
  }
  else {
    return "<a href='{$variables['url']}' class='ical-icon'>{$variables['tooltip']}</a>";
  }
}

/**
 * Implements hook_preprocess_HOOK().
 *
 * Hides the page elements which don't belong in an iCal DESCRIPTION element.
 * The display of the body and other fields is controlled by the Manage
 * Display settings for the nodes' iCal view mode.
 */
function date_ical_preprocess_node(&$variables) {
  if (isset($variables['view_mode']) && $variables['view_mode'] == 'ical') {
    // Trick the default node template into not displaying the page title, by
    // telling it that this *is* a page.
    $variables['page'] = TRUE;
    $variables['title_prefix'] = '';
    $variables['title_suffix'] = '';
    
    // We don't want to see the author information in our feed.
    $variables['display_submitted'] = FALSE;
    
    // Comments and links don't belong in an iCal feed.
    if (isset($variables['content']['comments'])) {
      unset($variables['content']['comments']);
    }
    if (isset($variables['content']['links'])) {
      unset($variables['content']['links']);
    }
  }
}

/**
 * Implements hook_entity_info_alter().
 *
 * Adds an 'iCal' view mode for entities, which is used by the iCal Entity
 * View plugin.
 */
function date_ical_entity_info_alter(&$entity_info) {
  foreach ($entity_info as $entity_type => $info) {
    if (!isset($entity_info[$entity_type]['view modes'])) {
      $entity_info[$entity_type]['view modes'] = array();
    }
    $entity_info[$entity_type]['view modes'] += array(
      'ical' => array(
        'label' => t('iCal'),
        // Set the iCal view mode to default to same settings as the "default"
        // view mode, so it won't pollute Features.
        'custom settings' => FALSE,
      ),
    );
  }
}

/**
 * Implements hook_libraries_info().
 */
function date_ical_libraries_info() {
  $libraries['iCalcreator'] = array(
    'name' => 'iCalcreator',
    'vendor url' => 'http://github.com/iCalcreator/iCalcreator',
    'download url' => 'http://github.com/iCalcreator/iCalcreator',
    'version arguments' => array(
      'file' => 'iCalcreator.class.php',
      'pattern' => "/define\( 'ICALCREATOR_VERSION', 'iCalcreator ([\d\.]+)' \);/",
      'lines' => 100,
    ),
    'files' => array(
      'php' => array('iCalcreator.class.php'),
    ),
  );
  
  return $libraries;
}

/**
 * Implements hook_ctools_plugin_api().
 */
function date_ical_ctools_plugin_api($owner, $api) {
  if ($owner == 'feeds' && $api == 'plugins') {
    return array('version' => 2);
  }
}

/**
 * Implements hook_feeds_processor_targets_alter().
 *
 * Adds the "Field Name: Repeat Rule" target to Date Repeat fields.
 *
 * @see FeedsNodeProcessor::getMappingTargets()
 */
function date_ical_feeds_processor_targets_alter(&$targets, $entity_type, $bundle_name) {
  foreach (field_info_instances($entity_type, $bundle_name) as $name => $instance) {
    $info = field_info_field($name);
    if (in_array($info['type'], array('date', 'datestamp', 'datetime')) && isset($info['settings']['repeat']) && $info['settings']['repeat']) {
      $targets[$name . ':rrule'] = array(
        'name' => t('@name: Repeat Rule', array('@name' => $instance['label'])),
        'callback' => 'date_ical_feeds_set_rrule',
        'description' => t('The repeat rule for the @name field.', array('@name' => $instance['label'])),
        'real_target' => $name,
      );
    }
  }
}

/**
 * Reformats the provided text to be compliant with the iCal spec.
 *
 * If the text contains HTML tags, those tags will be stripped (with <p> tags
 * converted to "\n\n" and link tags converted to footnotes), and uneeded
 * whitespace will be cleaned up.
 *
 * @param string $text
 *   The text to be sanitized.
 */
function date_ical_sanitize_text($text = '') {
  // Use Drupal's built-in HTML to Text converter, which does a mostly
  // adequate job of making the text iCal-compliant.
  $text = trim(drupal_html_to_text($text));
  // Replace instances of more than one space with exactly one space. This
  // cleans up the whitespace mess that drupal_html_to_text() leaves behind.
  $text = preg_replace("/  +/", " ", $text);
  // The call to drupal_html_to_text() above converted <p> to \n\n, and also
  // shoved a \n into the string every 80 characters. We don't want those
  // single \n's lying around, because iCalcreator will properly "fold" long
  // text fields for us. So, we need to remove all instances of \n which
  // are neither immediately preceeded, nor followed, by another \n.
  // However, \n's which are followed immediately by a > character should
  // remain, because of how drupal_html_to_text() converts <blockquote>.
  $text = preg_replace("/(?<!\n)\n(?![\n\>])/", " ", $text);
  return $text;
}

/**
 * Callback specified in date_ical_feeds_processor_targets_alter() for RRULEs.
 *
 * @param object $source
 *   The FeedsSource object.
 * @param object $entity
 *   The node that's being built from the iCal element that's being parsed.
 * @param string $target
 *   The machine name of the field into which this RRULE shall be parsed,
 *   with ":rrule" appended to the end.
 * @param string $repeat_rule
 *   The repeat rule string, formatted like "$rrule|$rdate|$exrule|$exdate".
 */
function date_ical_feeds_set_rrule($source, $entity, $target, $repeat_rule) {
  if (empty($repeat_rule)) {
    // Don't alter the entity if there's no repeat rule.
    return;
  }
  // $target looks like <field_name>:rrule, but we only need <field_name>.
  $field_name = current(explode(':', $target, 2));
  // Parse the repeat rule into RRULE, RDATE, EXRULE, and EXDATE strings.
  $repeat_data = array_combine(
    array('RRULE', 'RDATE', 'EXRULE', 'EXDATE'),
    explode('|', $repeat_rule)
  );
  
  module_load_include('inc', 'date_ical', 'date_ical.utils');
  // This "loop" is really just to make sure we get the right array keys. It
  // souldn't ever execute more than once.
  foreach ($entity->{$field_name} as $lang => $date_values) {
    $values = _date_ical_get_repeat_dates($field_name, $repeat_data, $date_values[0], $source);
    foreach ($values as $key => $value) {
      $entity->{$field_name}[$lang][$key] = $value;
    }
  }
}

/**
 * Identify all potential fields which could be used as an iCal LOCATION.
 */
function date_ical_get_location_fields($base = 'node', $reset = FALSE) {
  static $fields = array();
  $empty = array('name' => array(), 'alias' => array());
  
  if (empty($fields[$base]) || $reset) {
    $cid = 'date_ical_location_fields_' . $base;
    if (!$reset && $cached = cache_get($cid, 'cache_views')) {
      $fields[$base] = $cached->data;
    }
    else {
      $fields[$base] = _date_ical_get_location_fields($base);
    }
  }
  // Make sure that empty values will be arrays in the expected format.
  return !empty($fields) && !empty($fields[$base]) ? $fields[$base] : $empty;
}

/**
 * Internal helper function for date_ical_get_location_fields().
 *
 * This is a cut down version of _date_views_fields() from
 * date_views_fields.inc in date_views module.
 *
 * @return array
 *   array with fieldname, type, and table.
 *
 * @see date_views_date_views_fields()
 */
function _date_ical_get_location_fields($base = 'node') {
  // Make sure $base is never empty.
  if (empty($base)) {
    $base = 'node';
  }
  
  $cid = 'date_ical_location_fields_' . $base;
  cache_clear_all($cid, 'cache_views');
  
  // Iterate over all the fields that Views knows about.
  $all_fields = date_views_views_fetch_fields($base, 'field');
  $fields = array();
  foreach ($all_fields as $alias => $val) {
    $name = $alias;
    $tmp = explode('.', $name);
    $field_name = $tmp[1];
    $table_name = $tmp[0];
    
    // Skip unsupported field types and fields that weren't defined through
    // the Field module.
    $info = field_info_field($field_name);
    $supported_location_fields = array(
      'text',
      'text_long',
      'text_with_summary',
      'node_reference',
      'addressfield',
      'location'
    );
    if (!$info || !in_array($info['type'], $supported_location_fields)) {
      continue;
    }
    
    // Build an array of the field info that we'll need.
    $alias = str_replace('.', '_', $alias);
    $fields['name'][$name] = array(
      'label' => "{$val['group']}: {$val['title']} ($field_name)",
      'table_name' => $table_name,
      'field_name' => $field_name,
      'type' => $info['type'],
    );
    
    // These are here only to make this $field array conform to the same format
    // as the one returned by _date_views_fields(). They're probably not needed,
    // but I thought that consistency would be a good idea.
    $fields['name'][$name]['real_field_name'] = $field_name;
    $fields['alias'][$alias] = $fields['name'][$name];
  }
  
  cache_set($cid, $fields, 'cache_views');
  return $fields;
}


/**
 * Identify all potential fields which could be used as an iCal SUMMARY.
 */
function date_ical_get_summary_fields($base = 'node', $reset = FALSE) {
  static $fields = array();
  $empty = array('name' => array(), 'alias' => array());

  if (empty($fields[$base]) || $reset) {
    $cid = 'date_ical_summary_fields_' . $base;
    if (!$reset && $cached = cache_get($cid, 'cache_views')) {
      $fields[$base] = $cached->data;
    }
    else {
      $fields[$base] = _date_ical_get_summary_fields($base);
    }
  }
  // Make sure that empty values will be arrays in the expected format.
  return !empty($fields) && !empty($fields[$base]) ? $fields[$base] : $empty;
}

/**
 * Internal helper function for date_ical_get_summary_fields().
 *
 * This is a cut down version of _date_views_fields() from
 * date_views_fields.inc in date_views module.
 *
 * @return array
 *   Array with fieldname, type, and table.
 *
 * @see date_views_date_views_fields()
 */
function _date_ical_get_summary_fields($base = 'node') {
  // Make sure $base is never empty.
  if (empty($base)) {
    $base = 'node';
  }

  $cid = 'date_ical_summary_fields_' . $base;
  cache_clear_all($cid, 'cache_views');

  // Iterate over all the fields that Views knows about.
  $all_fields = date_views_views_fetch_fields($base, 'field');
  $fields = array();
  foreach ($all_fields as $alias => $val) {
    $name = $alias;
    $tmp = explode('.', $name);
    $field_name = $tmp[1];
    $table_name = $tmp[0];

    // Skip unsupported field types and fields that weren't defined through
    // the Field module.
    $info = field_info_field($field_name);
    $supported_summary_fields = array(
      'text',
      'text_long',
      'text_with_summary',
      'node_reference',
      'taxonomy_term_reference',
    );
    if (!$info || !in_array($info['type'], $supported_summary_fields)) {
      continue;
    }

    // Build an array of the field info that we'll need.
    $alias = str_replace('.', '_', $alias);
    $fields['name'][$name] = array(
      'label' => "{$val['group']}: {$val['title']} ($field_name)",
      'table_name' => $table_name,
      'field_name' => $field_name,
      'type' => $info['type'],
    );

    // These are here only to make this $field array conform to the same format
    // as the one returned by _date_views_fields(). They're probably not needed,
    // but I thought that consistency would be a good idea.
    $fields['name'][$name]['real_field_name'] = $field_name;
    $fields['alias'][$alias] = $fields['name'][$name];
  }

  cache_set($cid, $fields, 'cache_views');
  return $fields;
}

/**
 * Convert an rrule array to the iCalcreator format.
 *
 * iCalcreator expects the BYDAY element to be an array like this:
 * (array) ( [([plus] ordwk / minus ordwk)], "DAY" => weekday )
 *
 * But the way that the Date API gives it to us is like this:
 * (array) ( [([plus] ordwk / minus ordwk)]weekday )
 */
function _date_ical_convert_rrule_for_icalcreator($rrule) {
  $new_rrule = array();
  foreach ($rrule as $key => $value) {
    if (strtoupper($key) == 'DATA') {
      // iCalcreator doesn't expect the 'DATA' key that the Date API gives us.
      continue;
    }
    if (strtoupper($key) == 'UNTIL') {
      // iCalcreator expects the 'timestamp' to be array key for UNTIL.
      $value['timestamp'] = strtotime($value['datetime']);
    }
    if (strtoupper($key) == 'BYDAY') {
      $new_byday = array();
      foreach ($value as $day) {
        // Fortunately, the weekday values are always 2 characters.
        $weekday = substr($day, -2);
        $ordwk = substr($day, 0, -2);
        $new_byday[] = array($ordwk, 'DAY' => $weekday);
      }
      $value = $new_byday;
    }
    $new_rrule[$key] = $value;
  }
  return $new_rrule;
}