<?php
/* DISPLAY - iCal export
 *
 */

function communievents_escape_ical_text($text) {
    return strtr($text, array(
        "\\" => "\\\\",
        ',' => '\,',
        ';' => '\;',
        "\r\n" => "\\n", // spec says line breaks need to be \n only
        "\n" => "\\n"
    ));
}

// FIXME! this assumes valid utf-8
function communievents_fold_ical_line_helper($text, $index, $maxlength) {
    $length = 0;
    $i = $index;

    while ($i < strlen($text) && $length < $maxlength) {
        $c = ord($text[$i]);
        if ($c < 128) {
            $clen = 1;
        } else if ($c < 224) {
            $clen = 2;
        } else if ($c < 240) {
            $clen = 3;
        } else {
            $clen = 4;
        }

        if ($length + $clen > $maxlength)
            break;

        $i += $clen;
        $length += $clen;
    }

    return substr($text, $index, $length);
}

function communievents_fold_ical_text($text) {
    //XXX: the iCal spec wants the lines to be at most 75 octets,
    // but we must not split UTF-8 because some readers (notably
    // thunderbird) choke on it, even though the RFC says you
    // should handle it gracefully :-(

    if (strlen($text) <= 75) {
        return $text;
    } else {
        $text_arr = array();
        $text_arr[0] = communievents_fold_ical_line_helper($text, 0, 75);
        $i = strlen($text_arr[0]);
        while ($i < strlen($text)) {
            $s = communievents_fold_ical_line_helper($text, $i, 74);
            $i += strlen($s);
            $text_arr[] = $s;
        }

        return join("\r\n ", $text_arr);
    }
}

function communievents_write_ical_line($field, $text) {
    echo communievents_fold_ical_text("$field:" . communievents_escape_ical_text($text)) . "\r\n";
}

function communievents_print_ical_feed() {
    global $wpdb;

    $tz      = new DateTimeZone(CommuniApi::TIMEZONE);
    $tz_utc  = new DateTimeZone('UTC');
    $now_utc = new DateTime('now', $tz_utc);
    $dtstamp = $now_utc->format('Ymd\THis\Z');

    header('Content-Type: text/calendar');
    header('Content-Disposition: attachment; filename="communievents.ics"');

    communievents_write_ical_line('BEGIN', 'VCALENDAR');
    communievents_write_ical_line('VERSION', '2.0');
    communievents_write_ical_line('PRODID', '-//' . get_bloginfo('name') . '//NONSGML Events//EN');
    communievents_write_ical_line('CALSCALE', 'GREGORIAN');
    communievents_write_ical_line('X-WR-TIMEZONE', CommuniApi::TIMEZONE);

    $table_name = $wpdb->prefix . 'communievents_events';

    $list = $wpdb->get_results("SELECT * FROM $table_name WHERE official=1 ORDER BY start");

    if ($list) {
        foreach ($list as $event) {
            $start_dt = new DateTime($event->start, $tz);
            $end_dt = new DateTime($event->end, $tz);

            communievents_write_ical_line('BEGIN', 'VEVENT');

            communievents_write_ical_line('UID', 'communi-event-' . $event->id . '-' . $start_dt->format('U'));
            communievents_write_ical_line('STATUS', 'CONFIRMED');
            communievents_write_ical_line('DTSTAMP', $dtstamp);
            if ($event->allday) {
                communievents_write_ical_line('DTSTART;VALUE=DATE', $start_dt->format('Ymd'));
                if ($end_dt->format('Ymd') != $start_dt->format('Ymd')) {
                    // end is non-inclusive! move it into the next day
                    $end_dt->modify('+1 minute');
                    communievents_write_ical_line('DTEND;VALUE=DATE', $end_dt->format('Ymd'));
                }
            } else {
                communievents_write_ical_line('DTSTART', $start_dt->format('Ymd\THis'));
                if ($event->end != $event->start) {
                    communievents_write_ical_line('DTEND', $end_dt->format('Ymd\THis'));
                }
            }

            communievents_write_ical_line('SUMMARY', $event->title);

            if (!empty($event->description)) {
                communievents_write_ical_line('DESCRIPTION', html_entity_decode(strip_tags($event->description), ENT_QUOTES|ENT_SUBSTITUTE|ENT_HTML5, 'UTF-8'));
                communievents_write_ical_line('X-ALT-DESC;FMTTYPE=text/html', $event->description);
            }

            if (!empty($event->location)) {
                communievents_write_ical_line('LOCATION', $event->location);
            }

            communievents_write_ical_line('URL;VALUE=URI', $event->url);

            communievents_write_ical_line('END', 'VEVENT');
        }
    }

    communievents_write_ical_line('END', 'VCALENDAR');
}

function communievents_setup_ical_feed() {
   add_feed('communievents-ics', 'communievents_print_ical_feed');
   // FIXME: emklahr.de compat HACK
   add_feed('eo-events', 'communievents_print_ical_feed');
}