<?php

declare( strict_types=1 );

namespace Senti\Subscription;

use Senti\Shared\WordPress\FoundationUpgrader;
use Senti\Shared\WordPress\Identifiers;
use SentiVendor\WPDesk\Init\Binding\Hookable;
use wpdb;

/**
 * Dispatches queued email notifications in batches via scheduled actions.
 */
final class NotificationWorker implements Hookable {

	private const ACTION       = 'senti_process_notifications';
	private const FALLBACK     = 'senti_notification_fallback';
	private const LIMIT        = 20;
	private const MAX_ATTEMPTS = 3;

	public function __construct(
		private wpdb $wpdb,
		private Mailer $mailer,
		private SubscriptionService $subscriptions
	) {}

	public function hooks(): void {
		add_action( self::ACTION, [ $this, 'process' ] );
		add_action( self::FALLBACK, [ $this, 'process' ] );
		add_action( 'init', [ $this, 'schedule' ] );
	}

	/**
	 * @internal
	 */
	public function schedule(): void {
		if ( get_option( FoundationUpgrader::OPTION ) === false ) {
			return;
		}

		if ( ! wp_next_scheduled( self::FALLBACK ) ) {
			wp_schedule_event( time() + HOUR_IN_SECONDS, 'hourly', self::FALLBACK );
		}
		$this->schedule_next_pending( "{$this->wpdb->prefix}senti_notifications" );
	}

	public static function deactivate(): void {
		wp_clear_scheduled_hook( self::ACTION );
		wp_clear_scheduled_hook( self::FALLBACK );
	}

	/**
	 * @internal
	 */
	public function process(): void {
		$table = "{$this->wpdb->prefix}senti_notifications";
		$this->reclaim_stale( $table );
		$query = $this->wpdb->prepare( 'SELECT notification.id, notification.subscription_id, notification.event_type, notification.subject_id, notification.attempt_count, subscription.email FROM %i notification INNER JOIN %i subscription ON subscription.id = notification.subscription_id WHERE notification.state = %s AND notification.scheduled_gmt <= UTC_TIMESTAMP() AND subscription.state = %s ORDER BY notification.id LIMIT %d', $table, $this->wpdb->prefix . 'senti_subscriptions', 'pending', 'active', self::LIMIT );
		// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- $query is prepared immediately above.
		$rows = is_string( $query ) ? $this->wpdb->get_results( $query ) ?: [] : [];

		foreach ( $rows as $row ) {
			$claimed_at = current_time( 'mysql', true );
			if ( $this->wpdb->update(
				$table,
				[
					'state'         => 'sending',
					'scheduled_gmt' => $claimed_at,
				],
				[
					'id'    => (int) $row->id,
					'state' => 'pending',
				],
				[ '%s' ],
				[ '%d', '%s' ]
			) !== 1 ) {
				continue;
			}

			$permalink = get_permalink( (int) $row->subject_id ) ?: home_url( '/' );
			$unsub_url = $this->subscriptions->unsubscribe_url( (int) $row->subscription_id, (string) $row->email );
			$title     = get_the_title( (int) $row->subject_id );
			$site_name = wp_specialchars_decode( get_bloginfo( 'name' ), ENT_QUOTES );

			if ( (string) $row->event_type === 'feedback_status' ) {
				$status_terms = wp_get_object_terms( (int) $row->subject_id, Identifiers::TAXONOMY_FEEDBACK_STATUS, [ 'fields' => 'names' ] );
				$status_name  = ! is_wp_error( $status_terms ) && $status_terms !== [] ? (string) $status_terms[0] : __( 'Updated', 'senti-feedback' );
				$subject      = sprintf(
					/* translators: 1: Site name. 2: Feedback title. */
					__( '[%1$s] Feedback status update: %2$s', 'senti-feedback' ),
					$site_name,
					$title
				);
				$message = sprintf(
					/* translators: 1: Feedback title. 2: New status. 3: Feedback URL. 4: Unsubscribe URL. */
					__( "An update has been made to a request you are following:\n\nTitle: %1\$s\nStatus: %2\$s\n\nView details: %3\$s\n\n---\nUnsubscribe: %4\$s", 'senti-feedback' ),
					$title,
					$status_name,
					$permalink,
					$unsub_url
				);
			} else {
				$subject = sprintf(
					/* translators: 1: Site name. 2: Release title. */
					__( '[%1$s] New product release: %2$s', 'senti-feedback' ),
					$site_name,
					$title
				);
				$message = sprintf(
					/* translators: 1: Release title. 2: Release URL. 3: Unsubscribe URL. */
					__( "A new product release has been published:\n\n%1\$s\n\nView update: %2\$s\n\n---\nUnsubscribe: %3\$s", 'senti-feedback' ),
					$title,
					$permalink,
					$unsub_url
				);
			}

			$sent = $this->mailer->send( (string) $row->email, $subject, $message );
			if ( $sent ) {
				$this->wpdb->update(
					$table,
					[
						'state'      => 'sent',
						'sent_gmt'   => current_time( 'mysql', true ),
						'last_error' => null,
					],
					[ 'id' => (int) $row->id ],
					[ '%s', '%s' ],
					[ '%d' ]
				);
				continue;
			}

			$attempts = (int) $row->attempt_count + 1;
			$state    = $attempts >= self::MAX_ATTEMPTS ? 'failed' : 'pending';
			$delay    = min( (int) ( 5 * ( 2 ** ( $attempts - 1 ) ) ), 30 ) * MINUTE_IN_SECONDS;
			$this->wpdb->update(
				$table,
				[
					'state'                 => $state,
					'attempt_count'         => $attempts,
					'scheduled_gmt'         => gmdate( 'Y-m-d H:i:s', time() + $delay ),
					'last_error'            => 'wp_mail failed',
				],
				[ 'id' => (int) $row->id ],
				[ '%s', '%d', '%s', '%s' ],
				[ '%d' ]
			);
		}

		$this->schedule_next_pending( $table );
	}

	private function reclaim_stale( string $table ): void {
		$cutoff = gmdate( 'Y-m-d H:i:s', time() - 15 * MINUTE_IN_SECONDS );
		$query  = $this->wpdb->prepare( 'UPDATE %i SET state = CASE WHEN attempt_count + 1 >= %d THEN %s ELSE %s END, attempt_count = attempt_count + 1, scheduled_gmt = %s, last_error = %s WHERE state = %s AND scheduled_gmt < %s', $table, self::MAX_ATTEMPTS, 'failed', 'pending', gmdate( 'Y-m-d H:i:s', time() + 5 * MINUTE_IN_SECONDS ), 'delivery worker timed out', 'sending', $cutoff );

		if ( is_string( $query ) ) {
			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- $query is prepared immediately above.
			$this->wpdb->query( $query );
		}
	}

	private function schedule_next_pending( string $table ): void {
		$query = $this->wpdb->prepare( 'SELECT MIN(scheduled_gmt) FROM %i WHERE state = %s', $table, 'pending' );
		// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- $query is prepared immediately above.
		$next = is_string( $query ) ? $this->wpdb->get_var( $query ) : null;
		if ( ! is_string( $next ) || $next === '' ) {
			return;
		}
		$timestamp = max( time() + MINUTE_IN_SECONDS, strtotime( $next . ' UTC' ) ?: time() + MINUTE_IN_SECONDS );
		$scheduled = wp_next_scheduled( self::ACTION );
		if ( $scheduled !== false && $scheduled <= $timestamp ) {
			return;
		}
		wp_clear_scheduled_hook( self::ACTION );
		wp_schedule_single_event( $timestamp, self::ACTION );
	}
}