<?php

namespace App\Dav;

use App\Member\Member;
use App\User;
use Sabre\CalDAV\Backend\AbstractBackend;
use Sabre\DAV\PropPatch;
use Sabre\VObject\Component\VCard;

/**
 * @template M as array{lastmodified: int, etag: string, uri: string, id: int, size: int}
 */
class CalendarBackend extends AbstractBackend
{
    /**
     * Returns a list of calendars for a principal.
     *
     * Every project is an array with the following keys:
     *  * id, a unique id that will be used by other functions to modify the
     *    calendar. This can be the same as the uri or a database key.
     *  * uri, which is the basename of the uri with which the calendar is
     *    accessed.
     *  * principaluri. The owner of the calendar. Almost always the same as
     *    principalUri passed to this method.
     *
     * Furthermore it can contain webdav properties in clark notation. A very
     * common one is '{DAV:}displayname'.
     *
     * Many clients also require:
     * {urn:ietf:params:xml:ns:caldav}supported-calendar-component-set
     * For this property, you can just return an instance of
     * Sabre\CalDAV\Property\SupportedCalendarComponentSet.
     *
     * If you return {http://sabredav.org/ns}read-only and set the value to 1,
     * ACL will automatically be put in read-only mode.
     *
     * @param string $principalUri
     *
     * @return array<int, array<string, mixed>>
     */
    public function getCalendarsForUser($principalUri)
    {
        if (1 !== preg_match('/^principals\/(.*)$/', $principalUri, $matches)) {
            return [];
        }

        User::where('email', $matches[1])->firstOrFail();

        return [
            [
                'id' => 'birthdays',
                'principaluri' => $principalUri,
                'uri' => 'birthdays',
                '{DAV:}displayname' => 'Geburtstage',
            ],
        ];
    }

    /**
     * Creates a new calendar for a principal.
     *
     * If the creation was a success, an id must be returned that can be used to
     * reference this calendar in other methods, such as updateCalendar.
     *
     * The id can be any type, including ints, strings, objects or array.
     *
     * @param string $principalUri
     * @param string $calendarUri
     * @param array<string, mixed> $properties
     *
     * @return mixed
     */
    public function createCalendar($principalUri, $calendarUri, array $properties)
    {
    }

    /**
     * Updates properties for a calendar.
     *
     * The list of mutations is stored in a Sabre\DAV\PropPatch object.
     * To do the actual updates, you must tell this object which properties
     * you're going to process with the handle() method.
     *
     * Calling the handle method is like telling the PropPatch object "I
     * promise I can handle updating this property".
     *
     * Read the PropPatch documentation for more info and examples.
     *
     * @param mixed $calendarId
     * @return void
     */
    public function updateCalendar($calendarId, \Sabre\DAV\PropPatch $propPatch)
    {
    }

    /**
     * Delete a calendar and all its objects.
     *
     * @param mixed $calendarId
     * @return void
     */
    public function deleteCalendar($calendarId)
    {
    }

    /**
     * Returns all calendar objects within a calendar.
     *
     * Every item contains an array with the following keys:
     *   * calendardata - The iCalendar-compatible calendar data
     *   * uri - a unique key which will be used to construct the uri. This can
     *     be any arbitrary string, but making sure it ends with '.ics' is a
     *     good idea. This is only the basename, or filename, not the full
     *     path.
     *   * lastmodified - a timestamp of the last modification time
     *   * etag - An arbitrary string, surrounded by double-quotes. (e.g.:
     *   '"abcdef"')
     *   * size - The size of the calendar objects, in bytes.
     *   * component - optional, a string containing the type of object, such
     *     as 'vevent' or 'vtodo'. If specified, this will be used to populate
     *     the Content-Type header.
     *
     * Note that the etag is optional, but it's highly encouraged to return for
     * speed reasons.
     *
     * The calendardata is also optional. If it's not returned
     * 'getCalendarObject' will be called later, which *is* expected to return
     * calendardata.
     *
     * If neither etag or size are specified, the calendardata will be
     * used/fetched to determine these numbers. If both are specified the
     * amount of times this is needed is reduced by a great degree.
     *
     * @param mixed $calendarId
     *
     * @return array
     * @return void
     */
    public function getCalendarObjects($calendarId)
    {
        return Member::whereNotNull('birthday')->get()->map(fn ($member) => $this->calendarObjectMeta($member))->toArray();
    }

    private function calendarObjectMeta(Member $member): array
    {
        return [
            'calendardata' => $member->toCalendarObject()->serialize(),
            'uri' => $member->slug . '.ics',
            'lastmodified' => $member->updated_at->timestamp,
            'etag' => '"' . $member->etag . '"',
            'size' => strlen($member->toCalendarObject()->serialize()),
            'component' => 'vevent',
        ];
    }

    /**
     * Returns information from a single calendar object, based on it's object
     * uri.
     *
     * The object uri is only the basename, or filename and not a full path.
     *
     * The returned array must have the same keys as getCalendarObjects. The
     * 'calendardata' object is required here though, while it's not required
     * for getCalendarObjects.
     *
     * This method must return null if the object did not exist.
     *
     * @param mixed  $calendarId
     * @param string $objectUri
     *
     * @return array|null
     */
    public function getCalendarObject($calendarId, $objectUri)
    {
        $member = Member::where('slug', str($objectUri)->replace('.ics', ''))->first();

        if (!$member || !$member->toCalendarObject()) {
            return null;
        }

        return [
            ...$this->calendarObjectMeta($member),
            'calendardata' => $member->toCalendarObject()->serialize(),
        ];
    }

    /**
     * Returns a list of calendar objects.
     *
     * This method should work identical to getCalendarObject, but instead
     * return all the calendar objects in the list as an array.
     *
     * If the backend supports this, it may allow for some speed-ups.
     *
     * @param mixed $calendarId
     *
     * @return array
     */
    public function getMultipleCalendarObjects($calendarId, array $uris)
    {
        return Member::whereNotNull('birthday')->get()->map(fn ($member) => $this->getCalendarObject($calendarId, $member->slug . '.ics'))->toArray();
    }

    /**
     * Creates a new calendar object.
     *
     * The object uri is only the basename, or filename and not a full path.
     *
     * It is possible to return an etag from this function, which will be used
     * in the response to this PUT request. Note that the ETag must be
     * surrounded by double-quotes.
     *
     * However, you should only really return this ETag if you don't mangle the
     * calendar-data. If the result of a subsequent GET to this object is not
     * the exact same as this request body, you should omit the ETag.
     *
     * @param mixed  $calendarId
     * @param string $objectUri
     * @param string $calendarData
     *
     * @return string|null
     */
    public function createCalendarObject($calendarId, $objectUri, $calendarData)
    {
    }

    /**
     * Updates an existing calendarobject, based on it's uri.
     *
     * The object uri is only the basename, or filename and not a full path.
     *
     * It is possible return an etag from this function, which will be used in
     * the response to this PUT request. Note that the ETag must be surrounded
     * by double-quotes.
     *
     * However, you should only really return this ETag if you don't mangle the
     * calendar-data. If the result of a subsequent GET to this object is not
     * the exact same as this request body, you should omit the ETag.
     *
     * @param mixed  $calendarId
     * @param string $objectUri
     * @param string $calendarData
     *
     * @return string|null
     */
    public function updateCalendarObject($calendarId, $objectUri, $calendarData)
    {
    }

    /**
     * Deletes an existing calendar object.
     *
     * The object uri is only the basename, or filename and not a full path.
     *
     * @param mixed  $calendarId
     * @param string $objectUri
     */
    public function deleteCalendarObject($calendarId, $objectUri)
    {
    }

    /**
     * Performs a calendar-query on the contents of this calendar.
     *
     * The calendar-query is defined in RFC4791 : CalDAV. Using the
     * calendar-query it is possible for a client to request a specific set of
     * object, based on contents of iCalendar properties, date-ranges and
     * iCalendar component types (VTODO, VEVENT).
     *
     * This method should just return a list of (relative) urls that match this
     * query.
     *
     * The list of filters are specified as an array. The exact array is
     * documented by Sabre\CalDAV\CalendarQueryParser.
     *
     * Note that it is extremely likely that getCalendarObject for every path
     * returned from this method will be called almost immediately after. You
     * may want to anticipate this to speed up these requests.
     *
     * This method provides a default implementation, which parses *all* the
     * iCalendar objects in the specified calendar.
     *
     * This default may well be good enough for personal use, and calendars
     * that aren't very large. But if you anticipate high usage, big calendars
     * or high loads, you are strongly adviced to optimize certain paths.
     *
     * The best way to do so is override this method and to optimize
     * specifically for 'common filters'.
     *
     * Requests that are extremely common are:
     *   * requests for just VEVENTS
     *   * requests for just VTODO
     *   * requests with a time-range-filter on either VEVENT or VTODO.
     *
     * ..and combinations of these requests. It may not be worth it to try to
     * handle every possible situation and just rely on the (relatively
     * easy to use) CalendarQueryValidator to handle the rest.
     *
     * Note that especially time-range-filters may be difficult to parse. A
     * time-range filter specified on a VEVENT must for instance also handle
     * recurrence rules correctly.
     * A good example of how to interprete all these filters can also simply
     * be found in Sabre\CalDAV\CalendarQueryFilter. This class is as correct
     * as possible, so it gives you a good idea on what type of stuff you need
     * to think of.
     *
     * @param mixed $calendarId
     *
     * @return array
     */
    public function calendarQuery($calendarId, array $filters)
    {
    }

    /**
     * Searches through all of a users calendars and calendar objects to find
     * an object with a specific UID.
     *
     * This method should return the path to this object, relative to the
     * calendar home, so this path usually only contains two parts:
     *
     * calendarpath/objectpath.ics
     *
     * If the uid is not found, return null.
     *
     * This method should only consider * objects that the principal owns, so
     * any calendars owned by other principals that also appear in this
     * collection should be ignored.
     *
     * @param string $principalUri
     * @param string $uid
     *
     * @return string|null
     */
    public function getCalendarObjectByUID($principalUri, $uid)
    {
    }
}