<?php

declare(strict_types=1);

namespace ProCalendarWP\Events;

use ProCalendarWP\Contracts\Module;

final class NextDate implements Module
{
    public function register(): void
    {
        add_action('init', function (): void {
            foreach (['pcwp_event', 'pcwp_series'] as $type) {
                register_post_meta($type, '_pcwp_next_start_utc', ['type' => 'string', 'single' => true, 'show_in_rest' => true, 'auth_callback' => '__return_false']);
            }
            if (! wp_next_scheduled('pcwp_refresh_next_dates')) {
                wp_schedule_event(time() + HOUR_IN_SECONDS, 'hourly', 'pcwp_refresh_next_dates');
            }
            $cursor = (int) get_option('pcwp_next_dates_cursor', 0);
            if (get_option('pcwp_next_dates_version') !== '1' && ! wp_next_scheduled('pcwp_backfill_next_dates', [$cursor])) {
                wp_schedule_single_event(time() + 10, 'pcwp_backfill_next_dates', [$cursor]);
            }
        });
        add_action('pcwp_refresh_next_dates', [$this, 'refresh']);
        add_action('pcwp_series_propagation_end', [$this, 'refresh']);
        add_action('pcwp_occurrence_synced', [$this, 'event']);
        add_action('pcwp_backfill_next_dates', [$this, 'backfill']);
        add_action('pcwp_refresh_series_dates', [$this, 'seriesBatch']);
        add_action('pcwp_refresh_event_dates', [$this, 'eventBatch']);
    }

    public function backfill(int $after = 0): void
    {
        global $wpdb;
        $ids = $wpdb->get_col($wpdb->prepare("SELECT ID FROM {$wpdb->posts} WHERE post_type='pcwp_event' AND ID>%d ORDER BY ID LIMIT 50", $after));
        foreach ($ids as $id) {
            $this->event((int) $id);
        }
        if (count($ids) === 50) {
            update_option('pcwp_next_dates_cursor', (int) end($ids), false);
            wp_schedule_single_event(time() + 10, 'pcwp_backfill_next_dates', [(int) end($ids)]);
        } else {
            $this->refresh();
            update_option('pcwp_next_dates_version', '1', false);
            delete_option('pcwp_next_dates_cursor');
        }
    }

    public function event(int $id): void
    {
        $event = (new WpEventRepository())->find($id);
        if ($event === null || get_post_status($id) !== 'publish' || in_array($event->status, ['canceled', 'postponed'], true)) {
            delete_post_meta($id, '_pcwp_next_start_utc');
            return;
        }
        try {
            $times = ($event->schedule['type'] ?? '') === 'daily' ? array_column(DailySchedule::intervals($event->schedule, $event->timezone), 'time') : [new EventTime($event->startLocal, $event->endLocal, $event->timezone)];
        } catch (\InvalidArgumentException) {
            delete_post_meta($id, '_pcwp_next_start_utc');
            return;
        }
        foreach ($times as $time) {
            if ($time->endUtc()->getTimestamp() >= time()) {
                update_post_meta($id, '_pcwp_next_start_utc', $time->startUtc()->format('Y-m-d H:i:s'));
                return;
            }
        }
        delete_post_meta($id, '_pcwp_next_start_utc');
    }

    public function refresh(int $seriesId = 0): void
    {
        if ($seriesId === 0) {
            $this->seriesBatch();
            $this->eventBatch();
            return;
        }
        global $wpdb;
        $seriesIds = [$seriesId];
        foreach ($seriesIds as $id) {
            $next = $wpdb->get_var($wpdb->prepare("SELECT MIN(o.start_utc) FROM {$wpdb->prefix}pcwp_occurrences o INNER JOIN {$wpdb->posts} p ON p.ID=o.event_id WHERE o.series_id=%d AND o.end_utc>=UTC_TIMESTAMP() AND p.post_status='publish' AND o.event_status NOT IN ('canceled','postponed')", $id));
            if ($next) {
                update_post_meta((int) $id, '_pcwp_next_start_utc', $next);
            } else {
                delete_post_meta((int) $id, '_pcwp_next_start_utc');
            }
        }
    }

    public function seriesBatch(int $after = 0): void
    {
        global $wpdb;
        $ids = $wpdb->get_col($wpdb->prepare("SELECT ID FROM {$wpdb->posts} WHERE post_type='pcwp_series' AND ID>%d ORDER BY ID LIMIT 50", $after));
        foreach ($ids as $id) {
            $this->refresh((int) $id);
        }
        if (count($ids) === 50) {
            wp_schedule_single_event(time() + 10, 'pcwp_refresh_series_dates', [(int) end($ids)]);
        }
    }

    public function eventBatch(int $after = 0): void
    {
        global $wpdb;
        $ids = $wpdb->get_col($wpdb->prepare("SELECT DISTINCT pm.post_id FROM {$wpdb->postmeta} pm INNER JOIN {$wpdb->posts} p ON p.ID=pm.post_id WHERE p.post_type='pcwp_event' AND pm.meta_key='_pcwp_next_start_utc' AND pm.meta_value<UTC_TIMESTAMP() AND pm.post_id>%d ORDER BY pm.post_id LIMIT 50", $after));
        foreach ($ids as $id) {
            $this->event((int) $id);
        }
        if (count($ids) === 50) {
            wp_schedule_single_event(time() + 10, 'pcwp_refresh_event_dates', [(int) end($ids)]);
        }
    }
}