<?php

namespace Events;

require_once __DIR__.'/../vendor/autoload.php';

use Carbon\Carbon;
use ICal\ICal;

/**
 * Events Plugin iCalendar Class
 *
 * The Events iCalendar Class provides variables and functions to read one or
 * more ics file(s) and creates a page for each event found. The created
 * events are parsed by the plugin in the usual way.
 *
 * Based on the already existing calendarProcessor.php by Kaleb Heitzman.
 *
 * @package    Events
 * @author     Michael <pikim@web.de>
 * @copyright  2019 Michael
 * @license    https://opensource.org/licenses/MIT MIT
 * @version    1.1.0
 * @link       https://github.com/pikim/grav-plugin-events
 * @since      1.1.0 Initial Release
 */
class iCalendarProcessor
{
    /**
     * @var  plugin config
     * @since  1.1.0  Initial Release
     */
    protected $config;

    /**
     * @var  Grav locator
     * @since  1.1.0  Initial Release
     */
    protected $loc;

    /**
     * iCalendar Class Construct
     *
     * Setup a pointer to plugin config and Grav locator.
     *
     * @since  1.1.0  Initial Release
     * @return void
     */
    public function __construct()
    {
        // get a grav instance
        $grav = \Grav\Common\Grav::instance();

        $this->config = $grav['config']->get('plugins.events');
        $this->loc = $grav['locator']->base;
    }

    /**
     * Process iCalendar file(s)
     *
     * Parses the given ics file(s), sorts them and creates the output folder(s)
     * with the parsed event(s).
     *
     * @param[in] mode, 0 to add new events only;
     *                  1 to recreate all events after
     *                  deleting the whole folder first
     *
     * @since  1.1.0  Initial Release
     * @return void
     */
    public function process( $mode )
    {
        // if path to icalendar folder isn't set, set it to a default
        if ( ! key_exists('icalendar_folder', $this->config) ) {
            $this->config['icalendar_folder'] = "/ical";
        }

        // generate path
        $ical_path = $this->loc . '/user/pages' . $this->config['icalendar_folder'];

        // eventually clear/delete the folder first
        if ( is_dir($ical_path) && $mode != 0 ) {
            $this->rmdir_recursive($ical_path);
        }

        // recreate desired folder
        if ( ! is_dir($ical_path) ) {
            mkdir($ical_path, 0755, true);
        }

        // if icalendars isn't set, set it to a default
        if ( ! key_exists('icalendars', $this->config) ) {
            $this->config['icalendars'] = "";
        }

        // get the single iCalendar file(s) as array
        $ical_files = explode("\n", $this->config['icalendars']);

        // open and parse iCalendar file(s)
        $ical = new ICal(
            $ical_files,
            array(
                'defaultSpan'                 => 2,     // Default value
                'defaultTimeZone'             => 'UTC',
                'defaultWeekStart'            => 'MO',  // Default value
                'disableCharacterReplacement' => false, // Default value
                'filterDaysAfter'             => null,  // Default value
                'filterDaysBefore'            => null,  // Default value
                'skipRecurrence'              => false, // Default value
            )
        );

        // get events sorted by date
        $events = $ical->sortEventsWithOrder($ical->events());

        // create an array to hold the filepaths
        // this helps to handle recurrences while creating the pages
        $files = array();

        // create a page from each event
        foreach ( $events as $event ) {
            $this->create_page($ical_path, $event, $files);
        }
    }

    /**
     * Delete folder(s) and file(s)
     *
     * Recursively deletes a folder with all subfolder(s) and file(s).
     *
     * @since  1.1.0  Initial Release
     * @return void
     */
    private function rmdir_recursive( $dir )
    {
        foreach ( scandir($dir) as $file ) {
            if ( '.' === $file || '..' === $file )
                continue;

            if ( is_dir("$dir/$file") ) {
                $this->rmdir_recursive("$dir/$file");
            }
            else {
                unlink("$dir/$file");
            }
        }

        rmdir($dir);
    }

    /**
     * Creates a new page for a given event.
     *
     * Parses a given event and creates the accoring folder and event.md file.
     *
     * Currently ignores rrules as the used ics-parser doesn't support them
     * correctly. Instead, it prefixes each event folder with the month and day
     * of the according event.
     *
     * @since  1.1.0  Initial Release
     * @return void
     */
    private function create_page( $ical_path, $event, &$files )
    {
        $file_name = '/event.md';

        // get the event information
        $uid = $event->uid;
        $summary = $event->summary;
        $location = $event->location;
        $description = $event->description;
        $last_modified = strtotime($event->last_modified);
        if ( isset($event->recurrence_id) ) {
            $recurrence_id = strtotime($event->recurrence_id);
        }
        $start = strtotime($event->dtstart);
        $end = strtotime($event->dtend);

        // split if element exists
        $categories = array();
        if ( isset($event->categories) ) {
            $categories = explode(',', $event->categories);
        }

        // split if element exists
        $rrule = array();
        if ( isset($event->rrule) ) {
            $rrule = explode(';', $event->rrule);
        }

        // create path to destination folder
        $year = date('Y', $start);
        $moda = date('md', $start); // recurrences don't work atm, prefix the path with month & day
        $slug = strtolower($summary);

        // remove special characters from slug
        $search = array(" ", "&amp;", "ä", "ö", "ü", "ß");
        $replace = array("-", "-", "ae", "oe", "ue", "ss");
        $slug = str_replace($search, $replace, $slug);
        $slug = preg_replace('/[^\da-z\-]/i', '-', $slug);
        $slug = preg_replace('/-+/', '-', $slug);
        $slug = rtrim(ltrim($slug, '-'), '-');

        // create path
//        $path = $ical_path . '/' . $year . '/' . $slug;
        $path = $ical_path . '/' . $year . '/' . $moda . '_' . $slug;

        // create desired folders
        if ( ! is_dir($path) ) {
            mkdir($path, 0755, true);
        }

        // append file name to path
        $file = $path . $file_name;

        // if a file with this name already exists
        if ( is_file($file) ) {
            $file_time = filemtime($file);

            // get uid of existing file
            $lines = file($file);
            $file_uid = $lines[1];
            $file_uid = str_replace("uid: '", "", $file_uid);
            $file_uid = rtrim($file_uid, "'".PHP_EOL);

            if ( $file_time === $last_modified
              && $file_uid === $uid ) {
                // leave if file exists and hasn't changed
                return;
            }

            // handle events with the same slug => two events have the same title
//             if ( $file_uid !== $uid ) {
                // create token and append it to the slug
                $token = substr(md5($uid . date('d-m-Y H:i', $start)), 0, 6);
                $path = str_replace($slug, $slug . '-' . $token, $path);

                // create folder and new filename
                if ( ! is_dir($path) ) {
                    mkdir($path, 0755, true);
                }

                $file = $path . $file_name;
//             }
        }

        // append file to the list of files
        $files[$start . '__' . $uid] = $file;

        // handle recurrences
//        if ( isset($recurrence_id) ) {
//        }

        // write new page:
        // https://discourse.getgrav.org/t/creating-pages-dynamically-from-plugin/20223/3

        // double ' to make it work as title
        $title = str_replace("'", "''", $summary);

        // prepare file content
        $content  = "---".PHP_EOL;
        $content .= "uid: '{$uid}'".PHP_EOL;
        $content .= "title: '{$title}'".PHP_EOL;
//        $content .= "subtitle: '" . date('d-m-Y H:i', $start) . "'".PHP_EOL;

        if ( is_array($categories) ) {
            $content .= "taxonomy:".PHP_EOL;
            $content .= "    category:".PHP_EOL;
            foreach ( $categories as $category ) {
                $content .= "        - {$category}".PHP_EOL;
            }
        }

        $content .= "event:".PHP_EOL;
        $content .= "    start: '" . date('d-m-Y H:i', $start) . "'".PHP_EOL;
        $content .= "    end: '" . date('d-m-Y H:i', $end) . "'".PHP_EOL;

/*        if ( is_array($rrule) ) {
            foreach ( $rrule as $rule ) {
                $rule = explode('=', $rule);

                switch ( $rule[0] ) {
                    case "FREQ":
                        $freq = "    freq: " . strtolower($rule[1]) .PHP_EOL;
                        break;

                    case "BYDAY":
                        // replace iCal days with plugin days
                        $search = array("MO", "TU", "WE", "TH", "FR", "SA", "SU");
                        $replace = array("M", "T", "W", "R", "F", "S", "U");
                        $days = str_replace($search, $replace, $rule[1]);

                        // remove commas
                        $days = str_replace(',', '', $days);
                        $repeat = "    repeat: {$days}".PHP_EOL;

                        // daily does not work with repeat so delete it
                        if ( strpos($freq, "daily") !== false ) {
                            $freq = "";
                        }
                        break;
/*
                    // currently unsupported iCal rrules
                    case "BYWEEKNO":
                        break;

                    case "BYMONTH":
                        break;

                    case "BYMONTHDAY":
                        break;

                    case "BYYEARDAY":
                        break;

                    case "BYSETPOS":
                        break;

                    case "COUNT":
                        break;

                    case "INTERVAL":
                        break;

                    case "WKST":
                        break;
* /
                    case "UNTIL":
                        $time = strtotime($rule[1]);
                        $until = "    until: '" . date('d-m-Y', $time) . "'".PHP_EOL;
                        break;
                }
            }

            $content .= $repeat;
            $content .= $freq;
            $content .= $until;
        }*/

        if ( isset($location) && $location !== "" ) {
            $content .= "    location: '{$location}'".PHP_EOL;
        }

        $content .= "---".PHP_EOL;
        $content .= "".PHP_EOL;
        $content .= "{$description}".PHP_EOL;

        // write content to file
        $fp = fopen($file, 'w');
        fwrite($fp, $content);
        fclose($fp);

        // set modification time
        touch($file, $last_modified);
        touch($path, $last_modified);
    }
}