<?php

/**
 * The ics import/export engine.
 *
 * @author     Time.ly Network Inc.
 * @since      2.0
 *
 * @package    AI1EC
 * @subpackage AI1EC.Import-export
 */
class Ai1ec_Ics_Import_Export_Engine
	extends Ai1ec_Base
	implements Ai1ec_Import_Export_Engine {

	/**
	 * @var Ai1ec_Taxonomy
	 */
	protected $_taxonomy_model = null;

	/**
	 * Recurrence rule class. Contains filter method.
	 *
	 * @var Ai1ec_Recurrence_Rule
	 */
	protected $_rule_filter = null;

	/* (non-PHPdoc)
	 * @see Ai1ec_Import_Export_Engine::import()
	 */
	public function import( array $arguments ) {
		$cal = $this->_registry->get( 'vcalendar' );
		if ( $cal->parse( $arguments['source'] ) ) {
			try {
				$result = $this->add_vcalendar_events_to_db(
					$cal,
					$arguments
				);
			} catch ( Ai1ec_Parse_Exception $exception ) {
				throw new Ai1ec_Parse_Exception(
					'Processing "' . $arguments['source'] .
					'" triggered error: ' . $exception->getMessage()
				);
			}
			return $result;
		}
		throw new Ai1ec_Parse_Exception( 'The passed string is not a valid ics feed' );
	}

	/* (non-PHPdoc)
	 * @see Ai1ec_Import_Export_Engine::export()
	 */
	public function export( array $arguments, array $params = array() ) {
		$c = new vcalendar();
		$c->setProperty( 'calscale', 'GREGORIAN' );
		$c->setProperty( 'method', 'PUBLISH' );
		// if no post id are specified do not export those properties
		// as they would create a new calendar in outlook.
		// a user reported this in AIOEC-982 and said this would fix it
		if( true === $arguments['do_not_export_as_calendar'] ) {
			$c->setProperty( 'X-WR-CALNAME', get_bloginfo( 'name' ) );
			$c->setProperty( 'X-WR-CALDESC', get_bloginfo( 'description' ) );
		}
		$c->setProperty( 'X-FROM-URL', home_url() );
		// Timezone setup
		$tz = $this->_registry->get( 'date.timezone' )->get_default_timezone();
		if ( $tz ) {
			$c->setProperty( 'X-WR-TIMEZONE', $tz );
			$tz_xprops = array( 'X-LIC-LOCATION' => $tz );
			iCalUtilityFunctions::createTimezone( $c, $tz, $tz_xprops );
		}

		$this->_taxonomy_model = $this->_registry->get( 'model.taxonomy' );
		$post_ids = array();
		foreach ( $arguments['events'] as $event ) {
			$post_ids[] = $event->get( 'post_id' );
		}
		$this->_taxonomy_model->prepare_meta_for_ics( $post_ids );
		$this->_registry->get( 'controller.content-filter' )
			->clear_the_content_filters();
		foreach ( $arguments['events'] as $event ) {
			$c = $this->_insert_event_in_calendar(
				$event,
				$c,
				true,
				$params
			);
		}
		$this->_registry->get( 'controller.content-filter' )
			->restore_the_content_filters();
		$str = ltrim( $c->createCalendar() );
		return $str;
	}

	/**
	 * Check if date-time specification has no (empty) time component.
	 *
	 * @param array $datetime Datetime array returned by iCalcreator.
	 *
	 * @return bool Timelessness.
	 */
	protected function _is_timeless( array $datetime ) {
		$timeless = true;
		foreach ( array( 'hour', 'min', 'sec' ) as $field ) {
			$timeless &= (
					isset( $datetime[$field] ) &&
					0 != $datetime[$field]
			)
			? false
			: true;
		}
		return $timeless;
	}

	/**
	 * Process vcalendar instance - add events to database.
	 *
	 * @param vcalendar $v    Calendar to retrieve data from.
	 * @param array     $args Arbitrary arguments map.
	 *
	 * @throws Ai1ec_Parse_Exception
	 *
	 * @internal param stdClass $feed           Instance of feed (see Ai1ecIcs plugin).
	 * @internal param string   $comment_status WP comment status: 'open' or 'closed'.
	 * @internal param int      $do_show_map    Map display status (DB boolean: 0 or 1).
	 *
	 * @return int Count of events added to database.
	 */
	public function add_vcalendar_events_to_db(
		vcalendar $v,
		array $args
	) {
		$forced_timezone = null;
		$feed            = isset( $args['feed'] ) ? $args['feed'] : null;
		$comment_status  = isset( $args['comment_status'] ) ? $args['comment_status'] : 'open';
		$do_show_map     = isset( $args['do_show_map'] ) ? $args['do_show_map'] : 0;
		$count           = 0;
		$events_in_db    = isset( $args['events_in_db'] ) ? $args['events_in_db'] : 0;
		$v->sort();
		// Reverse the sort order, so that RECURRENCE-IDs are listed before the
		// defining recurrence events, and therefore take precedence during
		// caching.
		$v->components = array_reverse( $v->components );

		// TODO: select only VEVENT components that occur after, say, 1 month ago.
		// Maybe use $v->selectComponents(), which takes into account recurrence

		// Fetch default timezone in case individual properties don't define it
		$tz             = $v->getComponent( 'vtimezone' );
		$local_timezone = $this->_registry->get( 'date.timezone' )->get_default_timezone();
		$timezone       = $local_timezone;
		if ( ! empty( $tz ) ) {
			$timezone = $tz->getProperty( 'TZID' );
		}

		$feed_name     = $v->getProperty( 'X-WR-CALNAME' );
		$x_wr_timezone = $v->getProperty( 'X-WR-TIMEZONE' );
		if (
			isset( $x_wr_timezone[1] ) &&
			is_array( $x_wr_timezone )
		) {
			$forced_timezone = (string)$x_wr_timezone[1];
			$timezone        = $forced_timezone;
		}

		$messages        = array();
		if ( empty( $forced_timezone ) ) {
			$forced_timezone = $local_timezone;
		}
		$current_timestamp = $this->_registry->get( 'date.time' )->format_to_gmt();
		// initialize empty custom exclusions structure
		$exclusions        = array();
		// go over each event
		while ( $e = $v->getComponent( 'vevent' ) ) {

			// Event data array.
			$data = array();
			// =====================
			// = Start & end times =
			// =====================
			$start = $e->getProperty( 'dtstart', 1, true );
			$end   = $e->getProperty( 'dtend',   1, true );
			// For cases where a "VEVENT" calendar component
			// specifies a "DTSTART" property with a DATE value type but none
			// of "DTEND" nor "DURATION" property, the event duration is taken to
			// be one day.  For cases where a "VEVENT" calendar component
			// specifies a "DTSTART" property with a DATE-TIME value type but no
			// "DTEND" property, the event ends on the same calendar date and
			// time of day specified by the "DTSTART" property.
			if ( empty( $end ) )  {
				// #1 if duration is present, assign it to end time
				$end = $e->getProperty( 'duration', 1, true, true );
				if ( empty( $end ) ) {
					// #2 if only DATE value is set for start, set duration to 1 day
					if ( ! isset( $start['value']['hour'] ) ) {
						$end = array(
							'value' => array(
								'year'  => $start['value']['year'],
								'month' => $start['value']['month'],
								'day'   => $start['value']['day'] + 1,
								'hour'  => 0,
								'min'   => 0,
								'sec'   => 0,
							),
						);
						if ( isset( $start['value']['tz'] ) ) {
							$end['value']['tz'] = $start['value']['tz'];
						}
					} else {
						// #3 set end date to start time
						$end = $start;
					}
				}
			}
			$categories = $e->getProperty( "CATEGORIES", false, true );
			$imported_cat = array( Ai1ec_Event_Taxonomy::CATEGORIES => array() );
			// If the user chose to preserve taxonomies during import, add categories.
			if( $categories && $feed->keep_tags_categories ) {
				$imported_cat = $this->add_categories_and_tags(
						$categories['value'],
						$imported_cat,
						false,
						true
				);
			}
			$feed_categories = $feed->feed_category;
			if( ! empty( $feed_categories ) ) {
				$imported_cat = $this->add_categories_and_tags(
						$feed_categories,
						$imported_cat,
						false,
						false
				);
			}
			$tags = $e->getProperty( "X-TAGS", false, true );
			$imported_tags = array( Ai1ec_Event_Taxonomy::TAGS => array() );
			// If the user chose to preserve taxonomies during import, add tags.
			if( $tags && $feed->keep_tags_categories ) {
				$imported_tags = $this->add_categories_and_tags(
						$tags[1]['value'],
						$imported_tags,
						true,
						true
				);
			}
			$feed_tags = $feed->feed_tags;
			if( ! empty( $feed_tags ) ) {
				$imported_tags = $this->add_categories_and_tags(
						$feed_tags,
						$imported_tags,
						true,
						true
				);
			}
			// Event is all-day if no time components are defined
			$allday = $this->_is_timeless( $start['value'] ) &&
				$this->_is_timeless( $end['value'] );
			// Also check the proprietary MS all-day field.
			$ms_allday = $e->getProperty( 'X-MICROSOFT-CDO-ALLDAYEVENT' );
			if ( ! empty( $ms_allday ) && $ms_allday[1] == 'TRUE' ) {
				$allday = true;
			}
			$event_timezone = $timezone;
			if ( $allday ) {
				$event_timezone = $local_timezone;
			}
			$start = $this->_time_array_to_datetime(
				$start,
				$event_timezone,
				$feed->import_timezone ? $forced_timezone : null
			);
			$end   = $this->_time_array_to_datetime(
				$end,
				$event_timezone,
				$feed->import_timezone ? $forced_timezone : null
			);
			if ( false === $start || false === $end ) {
				throw new Ai1ec_Parse_Exception(
					'Failed to parse one or more dates given timezone "' .
					var_export( $event_timezone, true ) . '"'
				);
				continue;
			}

			// If all-day, and start and end times are equal, then this event has
			// invalid end time (happens sometimes with poorly implemented iCalendar
			// exports, such as in The Event Calendar), so set end time to 1 day
			// after start time.
			if ( $allday && $start->format() === $end->format() ) {
				$end->adjust_day( +1 );
			}

			$data += compact( 'start', 'end', 'allday' );

			// =======================================
			// = Recurrence rules & recurrence dates =
			// =======================================
			if ( $rrule = $e->createRrule() ) {
				$rrule = explode( ':', $rrule );
				$rrule = trim( end( $rrule ) );
			}

			if ( $exrule = $e->createExrule() ) {
				$exrule = explode( ':', $exrule );
				$exrule = trim( end( $exrule ) );
			}

			if ( $rdate = $e->createRdate() ) {
				$rdate = explode( ':', $rdate );
				$rdate = trim( end( $rdate ) );
			}

			// ===================
			// = Exception dates =
			// ===================
			$exdate = '';
			if ( $exdates = $e->createExdate() ){
				// We may have two formats:
				// one exdate with many dates ot more EXDATE rules
				$exdates      = explode( 'EXDATE', $exdates );
				$def_timezone = $this->_get_import_timezone( $event_timezone );
				foreach ( $exdates as $exd ) {
					if ( empty( $exd ) ) {
						continue;
					}
					$exploded       = explode( ':', $exd );
					$excpt_timezone = $def_timezone;
					$excpt_date     = null;
					foreach ( $exploded as $particle ) {
						if ( ';TZID=' === substr( $particle, 0, 6 ) ) {
							$excpt_timezone = substr( $particle, 6 );
						} else {
							$excpt_date = trim( $particle );
						}
					}
					$exploded       = explode( ',', $excpt_date );
					foreach ( $exploded as $particle ) {
						// Google sends YYYYMMDD for all-day excluded events
						if (
							$allday &&
							8 === strlen( $particle )
						) {
							$particle    .= 'T000000Z';
							$excpt_timezone = 'UTC';
						}
						$ex_dt = $this->_registry->get(
							'date.time',
							$particle,
							$excpt_timezone
						);
						if ( $ex_dt ) {
							if ( isset( $exdate{0} ) ) {
								$exdate .= ',';
							}
							$exdate .= $ex_dt->format( 'Ymd\THis', $excpt_timezone );
						}
					}
				}
			}
			// Add custom exclusions if there any
			$recurrence_id = $e->getProperty( 'recurrence-id' );
			if (
				false === $recurrence_id &&
				! empty( $exclusions[$e->getProperty( 'uid' )] )
			) {
				if ( isset( $exdate{0} ) ) {
					$exdate .= ',';
				}
				$exdate .= implode( ',', $exclusions[$e->getProperty( 'uid' )] );
			}
			// ========================
			// = Latitude & longitude =
			// ========================
			$latitude = $longitude = NULL;
			$geo_tag  = $e->getProperty( 'geo' );
			if ( is_array( $geo_tag ) ) {
				if (
					isset( $geo_tag['latitude'] ) &&
					isset( $geo_tag['longitude'] )
				) {
					$latitude  = (float)$geo_tag['latitude'];
					$longitude = (float)$geo_tag['longitude'];
				}
			} else if ( ! empty( $geo_tag ) && false !== strpos( $geo_tag, ';' ) ) {
				list( $latitude, $longitude ) = explode( ';', $geo_tag, 2 );
				$latitude  = (float)$latitude;
				$longitude = (float)$longitude;
			}
			unset( $geo_tag );
			if ( NULL !== $latitude ) {
				$data += compact( 'latitude', 'longitude' );
				// Check the input coordinates checkbox, otherwise lat/long data
				// is not present on the edit event page
				$data['show_coordinates'] = 1;
			}
			// ===================
			// = Venue & address =
			// ===================
			$address = $venue = '';
			$location = $e->getProperty( 'location' );
			$matches = array();
			// This regexp matches a venue / address in the format
			// "venue @ address" or "venue - address".
			preg_match( '/\s*(.*\S)\s+[\-@]\s+(.*)\s*/', $location, $matches );
			// if there is no match, it's not a combined venue + address
			if ( empty( $matches ) ) {
				// temporary fix for Mac ICS import. Se AIOEC-2187
				// and https://github.com/iCalcreator/iCalcreator/issues/13
				$location = str_replace( '\n', "\n", $location );
				// if there is a comma, probably it's an address
				if ( false === strpos( $location, ',' ) ) {
					$venue = $location;
				} else {
					$address = $location;
				}
			} else {
				$venue = isset( $matches[1] ) ? $matches[1] : '';
				$address = isset( $matches[2] ) ? $matches[2] : '';
			}

			// =====================================================
			// = Set show map status based on presence of location =
			// =====================================================
			$event_do_show_map = $do_show_map;
			if (
				1 === $do_show_map &&
				NULL === $latitude &&
				empty( $address )
			) {
				$event_do_show_map = 0;
			}
				
			// ==================
			// = Cost & tickets =
			// ==================
			$cost       = $e->getProperty( 'X-COST' );
			$cost       = $cost ? $cost[1] : '';
			$ticket_url = $e->getProperty( 'X-TICKETS-URL' );
			$ticket_url = $ticket_url ? $ticket_url[1] : '';

			// ===============================
			// = Contact name, phone, e-mail =
			// ===============================
			$organizer = $e->getProperty( 'organizer' );
			if (
				'MAILTO:' === substr( $organizer, 0, 7 ) &&
				false === strpos( $organizer, '@' )
			) {
				$organizer = substr( $organizer, 7 );
			}
			$contact = $e->getProperty( 'contact' );
			$elements = explode( ';', $contact, 4 );

			foreach ( $elements as $el ) {
				$el = trim( $el );
				// Detect e-mail address.
				if ( false !== strpos( $el, '@' ) ) {
					$data['contact_email'] = $el;
				}
				// Detect URL.
				elseif ( false !== strpos( $el, '://' ) ) {
					$data['contact_url']   = $el;
				}
				// Detect phone number.
				elseif ( preg_match( '/\d/', $el ) ) {
					$data['contact_phone'] = $el;
				}
				// Default to name.
				else {
					$data['contact_name']  = $el;
				}
			}
			if ( ! isset( $data['contact_name'] ) || ! $data['contact_name'] ) {
				// If no contact name, default to organizer property.
				$data['contact_name']    = $organizer;
			}

			$description = stripslashes(
							str_replace(
								'\n',
								"\n",
								$e->getProperty( 'description' )
							));
			
			$description = $this->_remove_ticket_url( $description );				

			// Store yet-unsaved values to the $data array.
			$data += array(
				'recurrence_rules'  => $rrule,
				'exception_rules'   => $exrule,
				'recurrence_dates'  => $rdate,
				'exception_dates'   => $exdate,
				'venue'             => $venue,
				'address'           => $address,
				'cost'              => $cost,
				'ticket_url'        => $ticket_url,
				'show_map'          => $event_do_show_map,
				'ical_feed_url'     => $feed->feed_url,
				'ical_source_url'   => $e->getProperty( 'url' ),
				'ical_organizer'    => $organizer,
				'ical_contact'      => $contact,
				'ical_uid'          => $this->_get_ical_uid( $e ),
				'categories'        => array_keys( $imported_cat[Ai1ec_Event_Taxonomy::CATEGORIES] ),
				'tags'              => array_keys( $imported_tags[Ai1ec_Event_Taxonomy::TAGS] ),
				'feed'              => $feed,
				'post'              => array(
					'post_status'       => 'publish',
					'comment_status'    => $comment_status,
					'post_type'         => AI1EC_POST_TYPE,
					'post_author'       => 1,
					'post_title'        => $e->getProperty( 'summary' ),
					'post_content'      => $description
				)
			);
			// register any custom exclusions for given event
			$exclusions = $this->_add_recurring_events_exclusions(
				$e,
				$exclusions,
				$start
			);

			// Create event object.
			$data  = apply_filters(
				'ai1ec_pre_init_event_from_feed',
				$data,
				$e,
				$feed
			);

			$event = $this->_registry->get( 'model.event', $data );		

			// Instant Event
			$is_instant = $e->getProperty( 'X-INSTANT-EVENT' );
			if ( $is_instant ) {
				$event->set_no_end_time();
			}

			$recurrence = $event->get( 'recurrence_rules' );
			$search = $this->_registry->get( 'model.search' );
			// first let's check by UID
			$matching_event_id = $search
				->get_matching_event_by_uid_and_url(
					$event->get( 'ical_uid' ),
					$event->get( 'ical_feed_url' )
				);
			// if no result, perform the legacy check.
			if ( null === $matching_event_id ) {
				$matching_event_id = $search
					->get_matching_event_id(
						$event->get( 'ical_uid' ),
						$event->get( 'ical_feed_url' ),
						$event->get( 'start' ),
						! empty( $recurrence )
					);
			}
			if ( null === $matching_event_id ) {
				
				// =================================================
				// = Event was not found, so store it and the post =
				// =================================================
				$event->save();
				$count++;
			} else {				
				// ======================================================
				// = Event was found, let's store the new event details =
				// ======================================================

				// Update the post
				$post               = get_post( $matching_event_id );

				if ( null !== $post ) {
					$post->post_title   = $event->get( 'post' )->post_title;
					$post->post_content = $event->get( 'post' )->post_content;
					wp_update_post( $post );

					// Update the event
					$event->set( 'post_id', $matching_event_id );
					$event->set( 'post',    $post );
					$event->save( true );
					$count++;
				}
			}
			do_action( 'ai1ec_ics_event_saved', $event, $feed );

			// import not standard taxonomies.
			unset( $imported_cat[Ai1ec_Event_Taxonomy::CATEGORIES] );
			foreach ( $imported_cat as $tax_name => $ids ) {
				wp_set_post_terms( $event->get( 'post_id' ), array_keys( $ids ), $tax_name );
			}

			unset( $imported_tags[Ai1ec_Event_Taxonomy::TAGS] );
			foreach ( $imported_tags as $tax_name => $ids ) {
				wp_set_post_terms( $event->get( 'post_id' ), array_keys( $ids ), $tax_name );
			}

			unset( $events_in_db[$event->get( 'post_id' )] );
		} //close while iteration

		return array(
			'count'            => $count,
			'events_to_delete' => $events_in_db,
			'messages'         => $messages,
			'name'             => $feed_name,
		);
	}

	/**
	 * Parse importable feed timezone to sensible value.
	 *
	 * @param string $def_timezone Timezone value from feed.
	 *
	 * @return string Valid timezone name to use.
	 */
	protected function _get_import_timezone( $def_timezone ) {
		$parser   = $this->_registry->get( 'date.timezone' );
		$timezone = $parser->get_name( $def_timezone );
		if ( false === $timezone ) {
			return 'sys.default';
		}
		return $timezone;
	}

	/**
	 * time_array_to_timestamp function
	 *
	 * Converts time array to time string.
	 * Passed array: Array( 'year', 'month', 'day', ['hour', 'min', 'sec', ['tz']] )
	 * Return int: UNIX timestamp in GMT
	 *
	 * @param array       $time            iCalcreator time property array
	 *                                     (*full* format expected)
	 * @param string      $def_timezone    Default time zone in case not defined
	 *                                     in $time
	 * @param null|string $forced_timezone Timezone to use instead of UTC.
	 *
	 * @return int UNIX timestamp
	 **/
	protected function _time_array_to_datetime(
		array $time,
		$def_timezone,
		$forced_timezone = null
	) {
		$timezone = '';
		if ( isset( $time['params']['TZID'] ) ) {
			$timezone = $time['params']['TZID'];
		} elseif (
				isset( $time['value']['tz'] ) &&
				'Z' === $time['value']['tz']
		) {
			$timezone = 'UTC';
		}
		if ( empty( $timezone ) ) {
			$timezone = $def_timezone;
		}

		$date_time = $this->_registry->get( 'date.time' );

		if ( ! empty( $timezone ) ) {
			$parser   = $this->_registry->get( 'date.timezone' );
			$timezone = $parser->get_name( $timezone );
			if ( false === $timezone ) {
				return false;
			}
			$date_time->set_timezone( $timezone );
		}

		if ( ! isset( $time['value']['hour'] ) ) {
			$time['value']['hour'] = $time['value']['min'] =
				$time['value']['sec'] = 0;
		}

		$date_time->set_date(
			$time['value']['year'],
			$time['value']['month'],
			$time['value']['day']
		)->set_time(
			$time['value']['hour'],
			$time['value']['min'],
			$time['value']['sec']
		);
		if (
			'UTC' === $timezone &&
			null !== $forced_timezone
		) {
			$date_time->set_timezone( $forced_timezone );
		}
		return $date_time;
	}

	/**
	 * Convert an event from a feed into a new Ai1ec_Event object and add it to
	 * the calendar.
	 *
	 * @param Ai1ec_Event $event    Event object.
	 * @param vcalendar   $calendar Calendar object.
	 * @param bool        $export   States whether events are created for export.
	 * @param array       $params   Additional parameters for export.
	 *
	 * @return void
	 */
	protected function _insert_event_in_calendar(
			Ai1ec_Event $event,
			vcalendar $calendar,
			$export = false,
			array $params = array()
	) {

		$tz  = $this->_registry->get( 'date.timezone' )
			->get_default_timezone();

		$e   = & $calendar->newComponent( 'vevent' );
		$uid = '';
		if ( $event->get( 'ical_uid' ) ) {
			$uid = addcslashes( $event->get( 'ical_uid' ), "\\;,\n" );
		} else {
			$uid = $event->get_uid();
			$event->set( 'ical_uid', $uid );
			$event->save( true );
		}
		$e->setProperty( 'uid', $this->_sanitize_value( $uid ) );
		$e->setProperty(
			'url',
			get_permalink( $event->get( 'post_id' ) )
		);

		// =========================
		// = Summary & description =
		// =========================
		$e->setProperty(
			'summary',
			$this->_sanitize_value(
				html_entity_decode(
					apply_filters( 'the_title', $event->get( 'post' )->post_title ),
					ENT_QUOTES,
					'UTF-8'
				)
			)
		);

		$content = apply_filters(
			'ai1ec_the_content',
			apply_filters(
				'the_content',
				$event->get( 'post' )->post_content
			)
		);

		//Adding Ticket URL to the Description field
		if ( $event->get( 'ticket_url' ) ) {					
			$url     = $event->get( 'ticket_url' );
			$content = $this->_remove_ticket_url( $content );	
			$content = $content
		             . '<p>' . __( 'Tickets: ', AI1EC_PLUGIN_NAME )
		             . '<a class="ai1ec-ticket-url-exported" href="'
		             . $url . '">' . $url
		             . '</a>.</p>'; 
		}

		$content = str_replace(']]>', ']]&gt;', $content);
		$content = html_entity_decode( $content, ENT_QUOTES, 'UTF-8' );

		// Prepend featured image if available.
		$size = null;
		$avatar = $this->_registry->get( 'view.event.avatar' );
		$matches = $avatar->get_image_from_content( $content );
		// if no img is already present - add thumbnail
		if ( empty( $matches ) ) {
			if ( $img_url = $avatar->get_post_thumbnail_url( $event, $size ) ) {
				$content = '<div class="ai1ec-event-avatar alignleft timely"><img src="' .
					esc_attr( $img_url ) . '" width="' . $size[0] . '" height="' .
					$size[1] . '" /></div>' . $content;
			}
		}

		if ( isset( $params['no_html'] ) && $params['no_html'] ) {
			$e->setProperty(
				'description',
				$this->_sanitize_value(
					strip_tags( strip_shortcodes( $content ) )
				)
			);
			if ( ! empty( $content ) ) {
				$html_content = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">\n' .
					'<HTML>\n<HEAD>\n<TITLE></TITLE>\n</HEAD>\n<BODY>' . $content .
					'</BODY></HTML>';
				$e->setProperty(
					'X-ALT-DESC',
					$this->_sanitize_value( $html_content ),
					array(
						'FMTTYPE' => 'text/html',
					)
				);
				unset( $html_content );
			}
		} else {
			$e->setProperty( 'description', $this->_sanitize_value( $content ) );
		}
		$revision = (int)current(
			array_keys(
				wp_get_post_revisions( $event->get( 'post_id' ) )
			)
		);
		$e->setProperty( 'sequence', $revision );

		// =====================
		// = Start & end times =
		// =====================
		$dtstartstring = '';
		$dtstart = $dtend = array();
		if ( $event->is_allday() ) {
			$dtstart['VALUE'] = $dtend['VALUE'] = 'DATE';
			// For exporting all day events, don't set a timezone
			if ( $tz && ! $export ) {
				$dtstart['TZID'] = $dtend['TZID'] = $tz;
			}

			// For exportin' all day events, only set the date not the time
			if ( $export ) {
				$e->setProperty(
					'dtstart',
					$this->_sanitize_value(
						$event->get( 'start' )->format( 'Ymd' )
					),
					$dtstart
				);
				$e->setProperty(
					'dtend',
					$this->_sanitize_value(
						$event->get( 'end' )->format( 'Ymd' )
					),
					$dtend
				);
			} else {
				$e->setProperty(
					'dtstart',
					$this->_sanitize_value(
						$event->get( 'start' )->format( "Ymd\T" )
					),
					$dtstart
				);
				$e->setProperty(
					'dtend',
					$this->_sanitize_value(
						$event->get( 'end' )->format( "Ymd\T" )
					),
					$dtend
				);
			}
		} else {
			if ( $tz ) {
				$dtstart['TZID'] = $dtend['TZID'] = $tz;
			}
			// This is used later.
			$dtstartstring = $event->get( 'start' )->format( "Ymd\THis" );
			$e->setProperty(
				'dtstart',
				$this->_sanitize_value( $dtstartstring ),
				$dtstart
			);

			if ( false === (bool)$event->get( 'instant_event' ) ) {
				$e->setProperty(
					'dtend',
					$this->_sanitize_value(
						$event->get( 'end' )->format( "Ymd\THis" )
					),
					$dtend
				);
			}
		}

		// ========================
		// = Latitude & longitude =
		// ========================
		if (
			floatval( $event->get( 'latitude' ) ) ||
			floatval( $event->get( 'longitude' ) )
		) {
			$e->setProperty(
				'geo',
				$event->get( 'latitude' ),
				$event->get( 'longitude' )
			);
		}

		// ===================
		// = Venue & address =
		// ===================
		if ( $event->get( 'venue' ) || $event->get( 'address' ) ) {
			$location = array(
				$event->get( 'venue' ),
				$event->get( 'address' )
			);
			$location = array_filter( $location );
			$location = implode( ' @ ', $location );
			$e->setProperty( 'location', $this->_sanitize_value( $location ) );
		}

		$categories = array();
		$language   = get_bloginfo( 'language' );

		foreach (
			$this->_taxonomy_model->get_post_categories(
				$event->get( 'post_id' )
			)
			as $cat
		) {
			$categories[] = $cat->name;
		}
		$e->setProperty(
			'categories',
			implode( ',', $categories ),
			array( "LANGUAGE" => $language )
		);
		$tags = array();
		foreach (
			$this->_taxonomy_model->get_post_tags( $event->get( 'post_id' ) )
			as $tag
		) {
			$tags[] = $tag->name;
		}
		if( ! empty( $tags) ) {
			$e->setProperty(
				'X-TAGS',
				implode( ',', $tags ),
				array( "LANGUAGE" => $language )
			);
		}
		// ==================
		// = Cost & tickets =
		// ==================
		if ( $event->get( 'cost' ) ) {
			$e->setProperty(
				'X-COST',
				$this->_sanitize_value( $event->get( 'cost' ) )
			);
		}
		if ( $event->get( 'ticket_url' ) ) {
			$e->setProperty(
				'X-TICKETS-URL',
				$this->_sanitize_value(
					$event->get( 'ticket_url' )
				)
			);
		}
		// =================
		// = Instant Event =
		// =================
		if ( $event->is_instant() ) {
			$e->setProperty(
				'X-INSTANT-EVENT',
				$this->_sanitize_value( $event->is_instant() )
			);
		}

		// ====================================
		// = Contact name, phone, e-mail, URL =
		// ====================================
		$contact = array(
			$event->get( 'contact_name' ),
			$event->get( 'contact_phone' ),
			$event->get( 'contact_email' ),
			$event->get( 'contact_url' ),
		);
		$contact = array_filter( $contact );
		$contact = implode( '; ', $contact );
		$e->setProperty( 'contact', $this->_sanitize_value( $contact ) );

		// ====================
		// = Recurrence rules =
		// ====================
		$rrule = array();
		$recurrence = $event->get( 'recurrence_rules' );
		$recurrence = $this->_filter_rule( $recurrence );
		if ( ! empty( $recurrence ) ) {
			$rules = array();
			foreach ( explode( ';', $recurrence ) as $v) {
				if ( strpos( $v, '=' ) === false ) {
					continue;
				}

				list( $k, $v ) = explode( '=', $v );
				$k = strtoupper( $k );
				// If $v is a comma-separated list, turn it into array for iCalcreator
				switch ( $k ) {
					case 'BYSECOND':
					case 'BYMINUTE':
					case 'BYHOUR':
					case 'BYDAY':
					case 'BYMONTHDAY':
					case 'BYYEARDAY':
					case 'BYWEEKNO':
					case 'BYMONTH':
					case 'BYSETPOS':
						$exploded = explode( ',', $v );
						break;
					default:
						$exploded = $v;
						break;
				}
				// iCalcreator requires a more complex array structure for BYDAY...
				if ( $k == 'BYDAY' ) {
					$v = array();
					foreach ( $exploded as $day ) {
						$v[] = array( 'DAY' => $day );
					}
				} else {
					$v = $exploded;
				}
				$rrule[ $k ] = $v;
			}
		}

		// ===================
		// = Exception rules =
		// ===================
		$exceptions = $event->get( 'exception_rules' );
		$exceptions = $this->_filter_rule( $exceptions );
		$exrule = array();
		if ( ! empty( $exceptions ) ) {
			$rules = array();

			foreach ( explode( ';', $exceptions ) as $v) {
				if ( strpos( $v, '=' ) === false ) {
					continue;
				}

				list($k, $v) = explode( '=', $v );
				$k = strtoupper( $k );
				// If $v is a comma-separated list, turn it into array for iCalcreator
				switch ( $k ) {
					case 'BYSECOND':
					case 'BYMINUTE':
					case 'BYHOUR':
					case 'BYDAY':
					case 'BYMONTHDAY':
					case 'BYYEARDAY':
					case 'BYWEEKNO':
					case 'BYMONTH':
					case 'BYSETPOS':
						$exploded = explode( ',', $v );
						break;
					default:
						$exploded = $v;
						break;
				}
				// iCalcreator requires a more complex array structure for BYDAY...
				if ( $k == 'BYDAY' ) {
					$v = array();
					foreach ( $exploded as $day ) {
						$v[] = array( 'DAY' => $day );
					}
				} else {
					$v = $exploded;
				}
				$exrule[ $k ] = $v;
			}
		}

		// add rrule to exported calendar
		if ( ! empty( $rrule ) && ! isset( $rrule['RDATE'] ) ) {
			$e->setProperty( 'rrule', $this->_sanitize_value( $rrule ) );
		}
		// add exrule to exported calendar
		if ( ! empty( $exrule ) && ! isset( $exrule['EXDATE'] ) ) {
			$e->setProperty( 'exrule', $this->_sanitize_value( $exrule ) );
		}

		// ===================
		// = Exception dates =
		// ===================
		// For all day events that use a date as DTSTART, date must be supplied
		// For other other events which use DATETIME, we must use that as well
		// We must also match the exact starting time
		$recurrence_dates = $event->get( 'recurrence_dates' );
		$recurrence_dates = $this->_filter_rule( $recurrence_dates );
		if ( ! empty( $recurrence_dates ) ) {
			$params    = array(
				'VALUE' => 'DATE-TIME',
				'TZID'  => $tz,
			);
			$dt_suffix = $event->get( 'start' )->format( '\THis' );
			foreach (
				explode( ',', $recurrence_dates )
				as $exdate
			) {
				// date-time string in EXDATES is formatted as 'Ymd\THis\Z', that
				// means - in UTC timezone, thus we use `format_to_gmt` here.
				$exdate = $this->_registry->get( 'date.time', $exdate )
					->format_to_gmt( 'Ymd' );
				$e->setProperty(
					'rdate',
					array( $exdate . $dt_suffix ),
					$params
				);
			}
		}
		$exception_dates = $event->get( 'exception_dates' );
		$exception_dates = $this->_filter_rule( $exception_dates );
		if ( ! empty( $exception_dates ) ) {
			$params    = array(
				'VALUE' => 'DATE-TIME',
				'TZID'  => $tz,
			);
			$dt_suffix = $event->get( 'start' )->format( '\THis' );
			foreach (
				explode( ',', $exception_dates )
				as $exdate
			) {
				// date-time string in EXDATES is formatted as 'Ymd\THis\Z', that
				// means - in UTC timezone, thus we use `format_to_gmt` here.
				$exdate = $this->_registry->get( 'date.time', $exdate )
					->format_to_gmt( 'Ymd' );
				$e->setProperty(
					'exdate',
					array( $exdate . $dt_suffix ),
					$params
				);
			}
		}
		return $calendar;
	}

	/**
	 * _sanitize_value method
	 *
	 * Convert value, so it be safe to use on ICS feed. Used before passing to
	 * iCalcreator methods, for rendering.
	 *
	 * @param string $value Text to be sanitized
	 *
	 * @return string Safe value, for use in HTML
	 */
	protected function _sanitize_value( $value ) {
		if ( ! is_scalar( $value ) ) {
			return $value;
		}
		$safe_eol = "\n";
		$value    = strtr(
				trim( $value ),
				array(
					"\r\n" => $safe_eol,
					"\r"   => $safe_eol,
					"\n"   => $safe_eol,
				)
		);
		$value = addcslashes( $value, '\\' );
		return $value;
	}

	/**
	 * Takes a comma-separated list of tags or categories.
	 * If they exist, reuses
	 * the existing ones. If not, creates them.
	 *
	 * The $imported_terms array uses keys to store values rather than values to
	 * speed up lookups (using isset() insted of in_array()).
	 *
	 * @param string  $terms
	 * @param array   $imported_terms
	 * @param boolean $is_tag
	 * @param boolean $use_name
	 *
	 * @return array
	 */
	public function add_categories_and_tags(
		$terms,
		array $imported_terms,
		$is_tag,
		$use_name
	) {
		$taxonomy       = $is_tag ? 'events_tags' : 'events_categories';
		$categories     = explode( ',', $terms );
		$event_taxonomy = $this->_registry->get( 'model.event.taxonomy' );

		foreach ( $categories as $cat_name ) {
			$cat_name = trim( $cat_name );
			if ( empty( $cat_name ) ) {
				continue;
			}
			$term = $event_taxonomy->initiate_term( $cat_name, $taxonomy, ! $use_name );
			if ( false !== $term ) {
				if ( ! isset( $imported_terms[$term['taxonomy']] ) ) {
					$imported_terms[$term['taxonomy']] = array();
				}
				$imported_terms[$term['taxonomy']][$term['term_id']] = true;
			}
		}
		return $imported_terms;
	}

	/**
	 * Returns modified ical uid for google recurring edited events.
	 *
	 * @param vevent $e Vevent object.
	 *
	 * @return string ICAL uid.
	 */
	protected function _get_ical_uid( $e ) {
		$ical_uid      = $e->getProperty( 'uid' );
		$recurrence_id = $e->getProperty( 'recurrence-id' );
		if ( false !== $recurrence_id ) {
			$ical_uid = implode( '', array_values( $recurrence_id ) ) . '-' .
				$ical_uid;
		}

		return $ical_uid;
	}

	/**
	 * Returns modified exclusions structure for given event.
	 *
	 * @param vcalendar       $e          Vcalendar event object.
	 * @param array           $exclusions Exclusions.
	 * @param Ai1ec_Date_Time $start Date time object.
	 *
	 * @return array Modified exclusions structure.
	 */
	protected function _add_recurring_events_exclusions( $e, $exclusions, $start ) {
		$recurrence_id = $e->getProperty( 'recurrence-id' );
		if (
			false === $recurrence_id ||
			! isset( $recurrence_id['year'] ) ||
			! isset( $recurrence_id['month'] ) ||
			! isset( $recurrence_id['day'] )
		) {
			return $exclusions;
		}
		$year = $month = $day = $hour = $min = $sec = null;
		extract( $recurrence_id, EXTR_IF_EXISTS );
		$timezone = '';
		$exdate   = sprintf( '%04d%02d%02d', $year, $month, $day );
		if (
			null === $hour ||
			null === $min ||
			null === $sec
		) {
			$hour = $min = $sec = '00';
			$timezone = 'Z';
		}
		$exdate .= sprintf(
			'T%02d%02d%02d%s',
			$hour,
			$min,
			$sec,
			$timezone
		);
		$exclusions[$e->getProperty( 'uid' )][] = $exdate;
		return $exclusions;
	}

	/**
	 * Filter recurrence / exclusion rule or dates. Avoid throwing exception for old, malformed values.
	 *
	 * @param string $rule Rule or dates value.
	 *
	 * @return string Fixed rule or dates value.
	 */
	protected function _filter_rule( $rule ) {
		if ( null === $this->_rule_filter ) {
			$this->_rule_filter = $this->_registry->get( 'recurrence.rule' );
		}
		return $this->_rule_filter->filter_rule( $rule );
	}

	/**
	 * Remove the Ticket URL that maybe exists inside the field Description of the Event
	 */
	protected function _remove_ticket_url( $description ) {
		return preg_replace( '/<p>[^<>]+<a[^<>]+class=[\'"]?ai1ec-ticket-url-exported[\'"]?[^<>]+>.[^<>]+<\/a>[\.\s]*<\/p>/'
				, ''
				, $description );
	}

}