<?php

namespace RoosterLMS\Display;

use RoosterLMS\Data\Db;
use RoosterLMS\Data\SqlPart;
use RoosterLMS\Faq\Faq;
use RoosterLMS\Faq\FaqGroup;
use RoosterLMS\Faq\FaqLinks;
use RoosterLMS\Faq\FaqTarget;

defined( 'ABSPATH' ) || exit;

final class FaqQuery {

	private static array $memo = array();

	public static function for_target( FaqTarget $target, int $id ): array {
		$id  = FaqTarget::SITE === $target ? 0 : $id;
		$key = $target->value . ':' . $id;
		if ( isset( self::$memo[ $key ] ) ) {
			return self::$memo[ $key ];
		}
		global $wpdb;
		$links = Db::table( 'faq_links' );
		$faqs  = Db::table( 'faqs' );
		$sql   = SqlPart::of( '( ' )->add( SqlPart::of(
			'SELECT f.*, l.position AS l_pos, l.kind AS l_kind, l.ref_id AS l_ref FROM %i l JOIN %i f ON f.id = l.ref_id WHERE l.target_type = %d AND l.target_id = %d AND l.kind = %d AND f.state = %d',
			$links,
			$faqs,
			$target->value,
			$id,
			FaqLinks::KIND_FAQ,
			Faq::PUBLISHED
		) )->add( ' ) UNION ALL ( ' )->add( SqlPart::of(
			'SELECT f.*, l.position, l.kind, l.ref_id FROM %i l JOIN %i g ON g.id = l.ref_id AND g.state = %d JOIN %i f ON f.group_id = g.id AND f.state = %d WHERE l.target_type = %d AND l.target_id = %d AND l.kind = %d',
			$links,
			Db::table( 'faq_groups' ),
			FaqGroup::ACTIVE,
			$faqs,
			Faq::PUBLISHED,
			$target->value,
			$id,
			FaqLinks::KIND_GROUP
		) )->add( ' ) ORDER BY l_pos, l_kind, l_ref, position, id' );
		$out  = array();
		$seen = array();
		foreach ( Db::rows( $sql ) as $row ) {
			$faq = Faq::from_row( $row );
			if ( ! isset( $seen[ $faq->id ] ) ) {
				$seen[ $faq->id ] = true;
				$out[]            = $faq;
			}
		}
		self::$memo[ $key ] = $out;
		return $out;
	}

	public static function forget(): void {
		self::$memo = array();
	}
}