import.php

<?php

if (php_sapi_name() == 'cli') {
    $pairingHash = $argv[1];
    define('IGNORE_LTI', true);
}

require_once 'common.inc.php';

use smtech\ReflexiveCanvasLTI\LTI\ToolProvider;
use Battis\Educoder\Pest_Unauthorized;
use Battis\Educoder\Pest_ClientError;
use Battis\BootstrapSmarty\NotificationMessage;

/*
 * TODO: it would be nice to be able to cleanly remove a synched calendar
 */
/*
 * TODO: it would be nice to be able unschedule a scheduled sync without
 * removing the calendar
 */
/*
 * TODO: how about something to extirpate non-synced data (could be done right
 * now by brute force -- once overwrite is implemented -- by marking all of the
 * cached events as invalid and then importing the calendar and overwriting,
 * but that's a little icky)
 */
/*
 * TODO: right now, if a user changes a synced event in Canvas, it will never
 * get "corrected" back to the ICS feed... we could cache the Canvas events as
 * well as the ICS feed and do a periodic (much less frequent, given the speed
 * of looking everything up in the API) check and re-sync modified events too
 */

/*
 * pretend we have the interactive parameters if we were passed a pairing hash
 * by sync.php
 */
if (!empty($pairingHash)) {
    $calendars = $toolbox->mysql_query("SELECT * FROM `calendars` WHERE `id` = '$pairingHash'");
    $calendar = $calendars->fetch_assoc();
    $_REQUEST['cal'] = $calendar['ics_url'];
    $_REQUEST['canvas_url'] = $calendar['canvas_url'];
}

/* do we have the vital information (an ICS feed and a URL to a canvas object)? */
if (empty($_REQUEST['canvas_url'])) {
    $_REQUEST['canvas_url'] =
        $toolbox->config('TOOL_CANVAS_API')['url'] .
        '/courses/' . $_SESSION[ToolProvider::class]['canvas']['course_id'];
}
if (isset($_REQUEST['cal']) && isset($_REQUEST['canvas_url'])) {
    if ($canvasContext = $toolbox->getCanvasContext($_REQUEST['canvas_url'])) {
        /* check ICS feed to be sure it exists */
        if ($toolbox->urlExists($_REQUEST['cal'])) {
            /* look up the canvas object -- mostly to make sure that it exists! */
            $canvasObject = false;
            try {
                $canvasObject = $toolbox->api_get($canvasContext['verification_url']);
            } catch (Exception $e) {
                $toolbox->postMessage(
                    "Error accessing Canvas object",
                    $canvasContext['verification_url'],
                    NotificationMessage::DANGER
                );
            }
            if ($canvasObject) {
                /*
                 * calculate the unique pairing ID of this ICS feed and canvas
                 * object, if we don't already have one
                 */
                if (empty($pairingHash)) {
                    $pairingHash = $toolbox->getPairingHash($_REQUEST['cal'], $canvasContext['canonical_url']);
                }

                /*
                 * lock this calendar from other processes
                 */
                if ($toolbox->lock($pairingHash)) {
                    $log = Log::singleton('file', __DIR__ . "/logs/$pairingHash.log");
                    $toolbox->postMessage('Sync started', $toolbox->getSyncTimestamp(), NotificationMessage::INFO);

                    /* tell users that it's started and to cool their jets */
                    if (php_sapi_name() != 'cli') {
                        $toolbox->smarty_assign(
                            'calendarPreviewUrl',
                            $toolbox->config('TOOL_CANVAS_API')['url'] .
                            "/calendar?include_contexts={$canvasContext['context']}_{$canvasObject['id']}"
                        );
                        $toolbox->smarty_display('import-started.tpl');
                    }

                    /* parse the ICS feed */
                    $ics = new vcalendar(
                        array(
                            'unique_id' => $toolbox->config('TOOL_ID'),
                            'url' => $_REQUEST['cal']
                        )
                    );
                    $ics->parse();

                    /* log this pairing in the database cache, if it doesn't already exist */
                    $calendarCacheResponse = $toolbox->mysql_query("
                        SELECT *
                            FROM `calendars`
                            WHERE
                                `id` = '$pairingHash'
                    ");
                    $calendarCache = $calendarCacheResponse->fetch_assoc();

                    /* if the calendar is already cached, just update the sync timestamp */
                    if ($calendarCache) {
                        $toolbox->mysql_query("
                            UPDATE `calendars`
                                SET
                                    `synced` = '" . $toolbox->getSyncTimestamp() . "'
                                WHERE
                                    `id` = '$pairingHash'
                        ");
                    } else {
                        $toolbox->mysql_query("
                            INSERT INTO `calendars`
                                (
                                    `id`,
                                    `name`,
                                    `ics_url`,
                                    `canvas_url`,
                                    `synced`,
                                    `enable_regexp_filter`,
                                    `include_regexp`,
                                    `exclude_regexp`
                                )
                                VALUES (
                                    '$pairingHash',
                                    '" . $toolbox->getMySQL()->escape_string($ics->getProperty('X-WR-CALNAME')[1]) . "',
                                    '{$_REQUEST['cal']}',
                                    '{$canvasContext['canonical_url']}',
                                    '" . $toolbox->getSyncTimestamp() . "',
                                    '" . ($_REQUEST['enable_regexp_filter'] == VALUE_ENABLE_REGEXP_FILTER) . "',
                                    " . ($_REQUEST['enable_regexp_filter'] == VALUE_ENABLE_REGEXP_FILTER ?
                                        "'" . $toolbox->getMySQL()->escape_string($_REQUEST['include_regexp']) . "'" : 'NULL'
                                    ) . ",
                                    " . ($_REQUEST['enable_regexp_filter'] == VALUE_ENABLE_REGEXP_FILTER ?
                                        "'" . $toolbox->getMySQL()->escape_string($_REQUEST['exclude_regexp']) . "'" : 'NULL'
                                    ) . "
                                )
                        ");
                    }

                    /* refresh calendar information from cache database */
                    $calendarCacheResponse = $toolbox->mysql_query("
                        SELECT *
                            FROM `calendars`
                            WHERE
                                `id` = '$pairingHash'
                    ");
                    $calendarCache = $calendarCacheResponse->fetch_assoc();

                    /*
                     * walk through $master_array and update the Canvas calendar to
                     * match the ICS feed, caching changes in the database */
                    /*
                     * TODO: would it be worth the performance improvement to just
                     * process things from today's date forward? (i.e. ignore old
                     * items, even if they've changed...)
                     */
                    /*
                     * TODO: the best window for syncing would be the term of the
                     * course in question, right?
                     */
                    /*
                     * TODO: Arbitrarily selecting events in for a year on either
                     * side of today's date, probably a better system?
                     */
                    foreach ($ics->selectComponents(
                        date('Y') - 1, // startYear
                        date('m'), // startMonth
                        date('d'), // startDay
                        date('Y') + 1, // endYEar
                        date('m'), // endMonth
                        date('d'), // endDay
                        'vevent', // cType
                        false, // flat
                        true, // any
                        true // split
                    ) as $year) {
                        foreach ($year as $month => $days) {
                            foreach ($days as $day => $events) {
                                foreach ($events as $i => $event) {
                                    /* does this event already exist in Canvas? */
                                    $eventHash = $toolbox->getEventHash($event);

                                    /* if the event should be included... */
                                    if ($toolbox->filterEvent($event, $calendarCache)) {
                                        /* have we cached this event already? */
                                        $eventCacheResponse = $toolbox->mysql_query("
                                            SELECT *
                                                FROM `events`
                                                WHERE
                                                    `calendar` = '{$calendarCache['id']}' AND
                                                    `event_hash` = '$eventHash'
                                        ");


                                        /* if we already have the event cached in its current form, just update
                                           the timestamp */
                                        $eventCache = $eventCacheResponse->fetch_assoc();
                                        if ($eventCache) {
                                            $toolbox->mysql_query("
                                                UPDATE `events`
                                                    SET
                                                        `synced` = '" . $toolbox->getSyncTimestamp() . "'
                                                    WHERE
                                                        `id` = '{$eventCache['id']}'
                                            ");

                                        /* otherwise, add this new event and cache it */
                                        } else {
                                            /* multi-day event instance start times need to be changed to _this_ date */
                                            $start = new DateTime(
                                                iCalUtilityFunctions::_date2strdate($event->getProperty('DTSTART'))
                                            );
                                            $end = new DateTime(
                                                iCalUtilityFunctions::_date2strdate($event->getProperty('DTEND'))
                                            );
                                            if ($event->getProperty('X-RECURRENCE')) {
                                                $start = new DateTime($event->getProperty('X-CURRENT-DTSTART')[1]);
                                                $end = new DateTime($event->getProperty('X-CURRENT-DTEND')[1]);
                                            }
                                            $start->setTimeZone(new DateTimeZone(LOCAL_TIMEZONE));
                                            $end->setTimeZone(new DateTimeZone(LOCAL_TIMEZONE));

                                            try {
                                                $calendarEvent = $toolbox->api_post(
                                                    "/calendar_events",
                                                    array(
                                                        'calendar_event[context_code]' => "{$canvasContext['context']}_{$canvasObject['id']}",
                                                        'calendar_event[title]' => preg_replace('%^([^\]]+)(\s*\[[^\]]+\]\s*)+$%', '\\1', strip_tags($event->getProperty('SUMMARY'))),
                                                        'calendar_event[description]' => \Michelf\Markdown::defaultTransform(str_replace('\n', "\n\n", $event->getProperty('DESCRIPTION', 1))),
                                                        'calendar_event[start_at]' => $start->format(CANVAS_TIMESTAMP_FORMAT),
                                                        'calendar_event[end_at]' => $end->format(CANVAS_TIMESTAMP_FORMAT),
                                                        'calendar_event[location_name]' => $event->getProperty('LOCATION')
                                                    )
                                                );
                                                $toolbox->mysql_query("
                                                    INSERT INTO `events`
                                                        (
                                                            `calendar`,
                                                            `calendar_event[id]`,
                                                            `event_hash`,
                                                            `synced`
                                                        )
                                                        VALUES (
                                                            '{$calendarCache['id']}',
                                                            '{$calendarEvent['id']}',
                                                            '$eventHash',
                                                            '" . $toolbox->getSyncTimestamp() . "'
                                                        )
                                                ");
                                            } catch (Exception $e) {
                                                $toolbox->postMessage(
                                                    'Error creating calendar event',
                                                    $eventHash,
                                                    NotificationMessage::ERROR
                                                );
                                            }
                                        }
                                    }
                                }
                            }
                        }
                    }

                    /* clean out previously synced events that are no longer correct */
                    $deletedEventsResponse = $toolbox->mysql_query("
                        SELECT * FROM `events`
                            WHERE
                                `calendar` = '{$calendarCache['id']}' AND
                                `synced` != '" . $toolbox->getSyncTimestamp() . "'
                    ");
                    while ($deletedEventCache = $deletedEventsResponse->fetch_assoc()) {
                        try {
                            $deletedEvent = $toolbox->api_delete(
                                "calendar_events/{$deletedEventCache['calendar_event[id]']}",
                                array(
                                    'cancel_reason' => $toolbox->getSyncTimestamp(),
                                    'as_user_id' => ($canvasContext['context'] == 'user' ? $canvasObject['id'] : '') // TODO: this feels skeevy -- like the empty string will break
                                )
                            );
                        } catch (Pest_Unauthorized $e) {
                            /* if the event has been deleted in Canvas, we'll get an error when
                               we try to delete it a second time. We still need to delete it from
                               our cache database, however */
                            $toolbox->postMessage(
                                'Cache out-of-sync',
                                "calendar_event[{$deletedEventCache['calendar_event[id]']}] no longer exists and will be purged from cache.",
                                NotificationMessage::INFO
                            );
                        } catch (Pest_ClientError $e) {
                            $toolbox->postMessage(
                                'API Client Error',
                                '<pre>' . print_r(array(
                                    'Status' => $PEST->lastStatus(),
                                    'Error' => $PEST->lastBody(),
                                    'Verb' => $verb,
                                    'URL' => $url,
                                    'Data' => $data
                                ), false) . '</pre>',
                                NotificationMessage::ERROR
                            );
                            if (php_sapi_name() != 'cli') {
                                $toolbox->smarty_display('page.tpl');
                            }
                            exit;
                        }
                        $toolbox->mysql_query("
                            DELETE FROM `events`
                                WHERE
                                    `id` = '{$deletedEventCache['id']}'
                        ");
                    }

                    /* if this was a scheduled import (i.e. a sync), update that schedule */
                    if (isset($_REQUEST['schedule'])) {
                        $toolbox->mysql_query("
                            UPDATE `schedules`
                                SET
                                    `synced` = '" . $toolbox->getSyncTimestamp() . "'
                                WHERE
                                    `id` = '{$_REQUEST['schedule']}'
                        ");
                    }
                    /* are we setting up a regular synchronization? */
                    if (isset($_REQUEST['sync']) && $_REQUEST['sync'] != SCHEDULE_ONCE) {
                        // FIXME CRON SYNC SETUP GOES HERE

                        /* add to the cache database schedule, replacing any schedules for this
                           calendar that are already there */
                        $schedulesResponse = $toolbox->mysql_query("
                            SELECT *
                                FROM `schedules`
                                WHERE
                                    `calendar` = '{$calendarCache['id']}'
                        ");

                        if ($schedule = $schedulesResponse->fetch_assoc()) {
                            /* only need to worry if the cached schedule is different from the
                               new one we just set */
                            if ($shellArguments[INDEX_SCHEDULE] != $schedule['schedule']) {
                                /* was this the last schedule to require this trigger? */
                                $schedulesResponse = $toolbox->mysql_query("
                                    SELECT *
                                        FROM `schedules`
                                        WHERE
                                            `calendar` != '{$calendarCache['id']}' AND
                                            `schedule` == '{$schedule['schedule']}'
                                ");
                                /* we're the last one, delete it from crontab */
                                if ($schedulesResponse->num_rows == 0) {
                                    $crontabs = preg_replace("%^.*{$schedule['schedule']}.*" . PHP_EOL . '%', '', shell_exec('crontab -l'));
                                    $filename = md5($toolbox->getSyncTimestamp()) . '.txt';
                                    file_put_contents("/tmp/$filename", $crontabs);
                                    shell_exec("crontab /tmp/$filename");
                                    $toolbox->postMessage('Unused schedule', "removed schedule '{$schedule['schedule']}' from crontab", NotificationMessage::INFO);
                                }

                                $toolbox->mysql_query("
                                    UPDATE `schedules`
                                        SET
                                            `schedule` = '" . $shellArguments[INDEX_SCHEDULE] . "',
                                            `synced` = '" . $toolbox->getSyncTimestamp() . "'
                                        WHERE
                                            `calendar` = '{$calendarCache['id']}'
                                ");
                            }
                        } else {
                            $toolbox->mysql_query("
                                INSERT INTO `schedules`
                                    (
                                        `calendar`,
                                        `schedule`,
                                        `synced`
                                    )
                                    VALUES (
                                        '{$calendarCache['id']}',
                                        '" . $_REQUEST['sync'] . "',
                                        '" . $toolbox->getSyncTimestamp() . "'
                                    )
                            ");
                        }
                    }

                    /* if we're ovewriting data (for example, if this is a recurring sync, we
                       need to remove the events that were _not_ synced this in this round */
                    if (isset($_REQUEST['overwrite']) && $_REQUEST['overwrite'] == VALUE_OVERWRITE_CANVAS_CALENDAR) {
                        // TODO: actually deal with this
                    }

                    // TODO: deal with messaging based on context

                    $toolbox->postMessage('Finished sync', $toolbox->getSyncTimestamp(), NotificationMessage::INFO);
                    $toolbox->unlock($pairingHash);
                    exit;
                }
            } else {
                $toolbox->postMessage(
                    'Canvas Object  Not Found',
                    'The object whose URL you submitted could not be found.<pre>' . print_r(array(
                        'Canvas URL' => $_REQUEST['canvas_url'],
                        'Canvas Context' => $canvasContext,
                        'Canvas Object' => $canvasObject
                    ), false) . '</pre>',
                    NotificationMessage::ERROR
                );
            }
        } else {
            $toolbox->postMessage(
                'ICS feed  Not Found',
                'The calendar whose URL you submitted could not be found.<pre>' . $_REQUEST['cal'] . '</pre>',
                NotificationMessage::ERROR
            );
        }
    } else {
        $toolbox->postMessage(
            'Invalid Canvas URL',
            'The Canvas URL you submitted could not be parsed.<pre>' . $_REQUEST['canvas_url'] . '</pre>',
            NotificationMessage::ERROR
        );
        if (php_sapi_name() != 'cli') {
            $toolbox->smarty_display('page.tpl');
        }
        exit;
    }
} else {
    if (php_sapi_name() != 'cli') {
        $toolbox->smarty_display('import.tpl');
    }
}