<?php
/**
 * The submission form's product picker.
 *
 * @package Rahkar\WP
 */

declare( strict_types = 1 );

namespace Rahkar\WP\Modules\Testimonials;

use WP_Error;
use WP_REST_Request;
use WP_REST_Response;
use WP_REST_Server;

defined( 'ABSPATH' ) || exit;

/**
 * `GET rahkar/v1/testimonial/products?q=` — products a customer may tag.
 *
 * Logged-in only, like the submission it serves: the form only reaches this
 * step after the OTP login, and an open product search would be a free
 * catalogue scraper.
 *
 * Two modes, set in the module's settings:
 *
 *   all        a title search over published, visible products. Needs two
 *              characters; the answer depends only on the words typed, so it
 *              is cached for ten minutes per phrase and a busy form costs a
 *              query per new phrase, not per keystroke.
 *   purchased  the customer's own paid orders, filtered by what was typed. An
 *              empty query lists them all (up to the cap), so the picker can
 *              show the choices before any typing.
 *
 * Returns only what the picker draws: id, title, a thumbnail URL.
 */
final class ProductSearch {

	/** Results per answer — what fits a dropdown on a phone. */
	private const LIMIT = 8;

	/** Characters before an «all» search runs. */
	private const MIN_CHARS = 2;

	/**
	 * Register the route.
	 *
	 * @internal Hooked callback.
	 */
	public function registerRoute(): void {
		register_rest_route(
			'rahkar/v1',
			'/testimonial/products',
			[
				'methods'             => WP_REST_Server::READABLE,
				'callback'            => [ $this, 'search' ],
				'permission_callback' => static fn(): bool => is_user_logged_in(),
				'args'                => [
					'q' => [
						'type'              => 'string',
						'default'           => '',
						'sanitize_callback' => 'sanitize_text_field',
					],
				],
			]
		);
	}

	/**
	 * Answer one search.
	 *
	 * @param WP_REST_Request $request The request.
	 *
	 * @internal Hooked callback.
	 */
	public function search( WP_REST_Request $request ): WP_REST_Response|WP_Error {
		$mode = FormConfig::get()['product_pick'];
		$q    = trim( (string) $request->get_param( 'q' ) );

		if ( FormConfig::PRODUCT_PURCHASED === $mode ) {
			return rest_ensure_response( $this->purchased( get_current_user_id(), $q ) );
		}

		if ( FormConfig::PRODUCT_ALL === $mode && mb_strlen( $q ) >= self::MIN_CHARS ) {
			return rest_ensure_response( $this->catalogue( $q ) );
		}

		return rest_ensure_response( [] );
	}

	/**
	 * The customer's purchased products whose title contains the query.
	 *
	 * @param int    $userId Customer.
	 * @param string $q      Typed text; empty lists all.
	 *
	 * @return list<array{id:int, title:string, image:string}>
	 */
	private function purchased( int $userId, string $q ): array {
		$out = [];

		foreach ( Purchases::productIds( $userId ) as $id ) {
			$row = $this->row( $id );
			if ( null === $row ) {
				continue;
			}
			if ( '' !== $q && false === mb_stripos( $row['title'], $q ) ) {
				continue;
			}
			$out[] = $row;
			if ( count( $out ) >= self::LIMIT ) {
				break;
			}
		}

		return $out;
	}

	/**
	 * Published, catalogue-visible products matching the query.
	 *
	 * @param string $q Typed text.
	 *
	 * @return list<array{id:int, title:string, image:string}>
	 */
	private function catalogue( string $q ): array {
		$key    = 'rh_tm_ps_' . md5( mb_strtolower( $q ) );
		$cached = get_transient( $key );
		if ( is_array( $cached ) ) {
			return $cached;
		}

		$ids = get_posts(
			[
				'post_type'              => 'product',
				'post_status'            => 'publish',
				's'                      => $q,
				'posts_per_page'         => self::LIMIT * 2,
				'fields'                 => 'ids',
				'no_found_rows'          => true,
				'update_post_term_cache' => false,
			]
		);

		$out = [];
		foreach ( $ids as $id ) {
			$row = $this->row( (int) $id );
			if ( null !== $row ) {
				$out[] = $row;
			}
			if ( count( $out ) >= self::LIMIT ) {
				break;
			}
		}

		set_transient( $key, $out, 10 * MINUTE_IN_SECONDS );

		return $out;
	}

	/**
	 * One picker row, or null for a product that should not be offered.
	 *
	 * Hidden-from-catalogue and unpublished products are left out: a
	 * testimonial tagged to one would show on a page no shopper reaches.
	 *
	 * @param int $id Product ID.
	 *
	 * @return array{id:int, title:string, image:string}|null
	 */
	private function row( int $id ): ?array {
		$product = function_exists( 'wc_get_product' ) ? wc_get_product( $id ) : null;
		if ( ! $product || 'publish' !== $product->get_status() || 'hidden' === $product->get_catalog_visibility() ) {
			return null;
		}

		$image = (string) wp_get_attachment_image_url( (int) $product->get_image_id(), 'thumbnail' );

		return [
			'id'    => $id,
			'title' => wp_strip_all_tags( $product->get_name() ),
			'image' => $image,
		];
	}
}