<?php
require_once ('html-components.php');
require_once ('vendor/autoload.php');

use ICal\ICal;

date_default_timezone_set("Europe/Berlin");

/**
 * Returns the name of a month
 * 
 * @param int $month Month index, 1 to 12
 * 
 * @return string Month name
 * @return string Blank string if invalid month was given
 */
function getLocalizedMonthName ($month) {
    if (! $month || $month > 12 || $month < 1) return "";

    return [
        "Januar",
        "Februar",
        "März",
        "April",
        "Mai",
        "Juni",
        "Juli",
        "August",
        "September",
        "Oktober",
        "November",
        "Dezember"
    ][$month - 1];
}

/**
 * Returns the short name of a day of week
 * 
 * @param int $day_of_week DoW index, 1 to 7
 * 
 * @return string Day of week name
 * @return string Blank string if invalid DoW was given
 */
function getLocalizedShortDayName ($day_of_week) {
    if ($day_of_week < 1 || $day_of_week > 7) return "";

    return [
        "Mo.",
        "Di.",
        "Mi.",
        "Do.",
        "Fr.",
        "Sa.",
        "So."
    ][$day_of_week - 1];
}

/**
 * Tests if a given date is today
 * 
 * @param DateTime $date DateTime object to compare against
 * 
 * @return true  when the DateTime object is today
 * @return false when the DateTime object is not today
 */
function isDateTimeToday ($date) {
    return $date -> format ("Y-m-d") == date ("Y-m-d");
}

/**
 * Tests if a given date is within the current month
 * 
 * @param DateTime $date  DateTime object to compare against
 * @param int      $month Month to check against (defaults to current month)
 * 
 * @return true  when the DateTime object is within the current month
 * @return false when the DateTime object is not within the current month
 */
function isDateTimeWithinMonth ($date, $month = null) {
    $compareDate = new DateTime ();
    if ($month != null) $compareDate = new DateTime ("this year $month/01");

    return $date -> format ("Y-m") == $compareDate -> format ("Y-m");
}

/**
 * Tests if a given date is during the weekend
 * 
 * @param DateTime $date DateTime object to test
 * 
 * @return true  when the DateTime object is a weekend day
 * @return false when the DateTime object is a week day
 */
function isDateTimeDuringWeekend ($date) {
    return intval ($date -> format ("N")) > 5;
}

/**
 * Fetches an ICal object from an ICS URL
 * 
 * @param string $url ICS URL to fetch from
 * 
 * @return ICal ICal object
 */
function getCalendar ($url) {
    try {
        $ical = new ICal (false, array(
            'defaultSpan'                 => 2,     // Default value
            'defaultTimeZone'             => 'Europe/Berlin',
            'defaultWeekStart'            => 'MO',  // Default value
            'disableCharacterReplacement' => false, // Default value
            'filterDaysAfter'             => null,  // Default value
            'filterDaysBefore'            => null
        ));
        
        $ical -> initUrl(
            $url,
            $username = null,
            $password = null,
            $userAgent = null
        );
    } catch (Exception $e) {
        showError( "ICal error: " . $e -> getMessage() );
        return $ical;
    }

    return $ical;
}

/**
 * Returns all events from an iCal object
 * 
 * @param ICal $ical ICal object
 * 
 * @return array Array of event objects
 * @return false False on failure
 */
function getEvents ($ical) {
    if (! $ical) return false;

    return $ical -> sortEventsWithOrder (
        $ical -> events ()
    );
}

/**
 * Returns all events from an ICal object for a specific day
 * 
 * @param ICal $ical  ICal object
 * @param int  $day   Day
 * @param int  $month Month (defaults to current month)
 * @param int  $year  Year (default to current year)
 * 
 * @return array Array of event objects
 * @return false False on failure
 */
function getEventsForDay ($ical, $day, $month = null, $year = null) {
    if (! $ical) return false;

    $date_format = "Y-m-d h:i:s";

    return $ical -> sortEventsWithOrder (
        $ical -> eventsFromRange (
            date ($date_format, mktime (0, 0, 0, $month, $day, $year)),
            date ($date_format, mktime (23, 59, 59, $month, $day, $year)),
        )
    );
}

/**
 * Wrapper for getEventsForDay.
 * Returns all events from an ICal object for a specific date
 * 
 * @param ICal     $ical ICal object
 * @param DateTime $date DateTime object
 * 
 * @return array Array of event objects
 * @return false False on failure
 */
function getEventsForDate ($ical, $date) {
    return getEventsForDay (
        $ical,
        intval($date -> format ("d")),
        intval($date -> format ("m")),
        intval($date -> format ("Y"))
    );
}

/**
 * Get events from ICal object limited by a start date
 * and amount to days forward from the start date
 * 
 * @param ICal     $ical      ICal object
 * @param DateTime $startDate Date to start from
 * @param int      $days      Amount of days to get
 */
function getEventsFromRange ($ical, $startDate, $days) {
    if (! $ical) return false;

    return $ical -> sortEventsWithOrder (
        $ical -> getEventsFromRange (
            $startDate -> format ("Y-m-d H:i:s"),
            $startDate -> modify ("+ {$days} days") -> format ("Y-m-d H:i:s")
        )
    );
}