<?php

namespace Appwrite\Platform\Tasks;

use Appwrite\Utopia\Queue\Connections;
use Swoole\Timer;
use Utopia\CLI\Console;
use Utopia\Database\DateTime;
use Utopia\Database\Document;
use Utopia\Database\Exception;
use Utopia\Database\Query;
use Utopia\Platform\Action;
use Utopia\System\System;

abstract class ScheduleBase extends Action
{
    protected const UPDATE_TIMER = 10; //seconds
    protected const ENQUEUE_TIMER = 60; //seconds

    protected array $schedules = [];
    protected Connections $connections;

    abstract public static function getName(): string;

    abstract public static function getSupportedResource(): string;

    abstract protected function enqueueResources(
        array $pools,
        callable $getConsoleDB
    );

    public function __construct()
    {
        $this->connections = new Connections();
        $type = static::getSupportedResource();

        $this
            ->desc("Execute {$type}s scheduled in Appwrite")
            ->inject('pools')
            ->inject('getConsoleDB')
            ->inject('getProjectDB')
            ->callback(fn (array $pools, callable $getConsoleDB, callable $getProjectDB) => $this->action($pools, $getConsoleDB, $getProjectDB));
    }

    /**
     * 1. Load all documents from 'schedules' collection to create local copy
     * 2. Create timer that sync all changes from 'schedules' collection to local copy. Only reading changes thanks to 'resourceUpdatedAt' attribute
     * 3. Create timer that prepares coroutines for soon-to-execute schedules. When it's ready, coroutine sleeps until exact time before sending request to worker.
     */
    public function action(array $pools, callable $getConsoleDB, callable $getProjectDB): void
    {
        Console::title(\ucfirst(static::getSupportedResource()) . ' scheduler V1');
        Console::success(APP_NAME . ' ' . \ucfirst(static::getSupportedResource()) . ' scheduler v1 has started');

        [$_, $_, $dbForConsole] = $getConsoleDB();
        /**
         * Extract only necessary attributes to lower memory used.
         *
         * @return  array
         * @throws Exception
         * @var Document $schedule
         */
        $getSchedule = function (Document $schedule) use ($dbForConsole, $getProjectDB): array {
            $project = $dbForConsole->getDocument('projects', $schedule->getAttribute('projectId'));

            $collectionId = match ($schedule->getAttribute('resourceType')) {
                'function' => 'functions',
                'message' => 'messages',
                'execution' => 'executions'
            };

            $resource = $getProjectDB($project)->getDocument(
                $collectionId,
                $schedule->getAttribute('resourceId')
            );

            return [
                '$internalId' => $schedule->getInternalId(),
                '$id' => $schedule->getId(),
                'resourceId' => $schedule->getAttribute('resourceId'),
                'schedule' => $schedule->getAttribute('schedule'),
                'active' => $schedule->getAttribute('active'),
                'resourceUpdatedAt' => $schedule->getAttribute('resourceUpdatedAt'),
                'project' => $project, // TODO: @Meldiron Send only ID to worker to reduce memory usage here
                'resource' => $resource, // TODO: @Meldiron Send only ID to worker to reduce memory usage here
            ];
        };

        $lastSyncUpdate = DateTime::now();

        $limit = 10_000;
        $sum = $limit;
        $total = 0;
        $loadStart = \microtime(true);
        $latestDocument = null;

        while ($sum === $limit) {
            $paginationQueries = [Query::limit($limit)];

            if ($latestDocument) {
                $paginationQueries[] = Query::cursorAfter($latestDocument);
            }

            $results = $dbForConsole->find('schedules', \array_merge($paginationQueries, [
                Query::equal('region', [System::getEnv('_APP_REGION', 'default')]),
                Query::equal('resourceType', [static::getSupportedResource()]),
                Query::equal('active', [true]),
            ]));

            $sum = \count($results);
            $total = $total + $sum;

            foreach ($results as $document) {
                try {
                    $this->schedules[$document->getInternalId()] = $getSchedule($document);
                } catch (\Throwable $th) {
                    $collectionId = match ($document->getAttribute('resourceType')) {
                        'function' => 'functions',
                        'message' => 'messages',
                        'execution' => 'executions'
                    };

                    Console::error("Failed to load schedule for project {$document['projectId']} {$collectionId} {$document['resourceId']}");
                    Console::error($th->getMessage());
                }
            }

            $latestDocument = \end($results);
        }


        Console::success("{$total} resources were loaded in " . (\microtime(true) - $loadStart) . " seconds");

        Console::success("Starting timers at " . DateTime::now());


        Timer::tick(static::UPDATE_TIMER * 1000, function () use ($getConsoleDB, &$lastSyncUpdate, $getSchedule, $pools) {
            [$connection,$pool, $dbForConsole] = $getConsoleDB();
            $connections = new Connections();
            $connections->add($connection, $pool);

            $time = DateTime::now();
            $timerStart = \microtime(true);

            $limit = 1000;
            $sum = $limit;
            $total = 0;
            $latestDocument = null;

            Console::log("Sync tick: Running at $time");

            while ($sum === $limit) {
                $paginationQueries = [Query::limit($limit)];

                if ($latestDocument) {
                    $paginationQueries[] = Query::cursorAfter($latestDocument);
                }

                $results = $dbForConsole->find('schedules', \array_merge($paginationQueries, [
                    Query::equal('region', [System::getEnv('_APP_REGION', 'default')]),
                    Query::equal('resourceType', [static::getSupportedResource()]),
                    Query::greaterThanEqual('resourceUpdatedAt', $lastSyncUpdate),
                ]));

                $sum = count($results);
                $total = $total + $sum;

                foreach ($results as $document) {
                    $localDocument = $this->schedules[$document->getInternalId()] ?? null;

                    // Check if resource has been updated since last sync
                    $org = $localDocument !== null ? \strtotime($localDocument['resourceUpdatedAt']) : null;
                    $new = \strtotime($document['resourceUpdatedAt']);

                    if (!$document['active']) {
                        Console::info("Removing: {$document['resourceId']}");
                        unset($this->schedules[$document->getInternalId()]);
                    } elseif ($new !== $org) {
                        Console::info("Updating: {$document['resourceId']}");
                        $this->schedules[$document->getInternalId()] = $getSchedule($document);
                    }
                }

                $latestDocument = \end($results);
            }

            $lastSyncUpdate = $time;
            $timerEnd = \microtime(true);

            $connections->reclaim();
            Console::log("Sync tick: {$total} schedules were updated in " . ($timerEnd - $timerStart) . " seconds");
        });

        Timer::tick(
            static::ENQUEUE_TIMER * 1000,
            fn () => $this->enqueueResources($pools, $getConsoleDB)
        );

        $this->enqueueResources($pools, $getConsoleDB);
    }
}