<?php
/**
 * WooCommerce stock levels.
 *
 * @package Keepwatch
 */

namespace Keepwatch\WooCommerce;

use Keepwatch\Checks\Check;
use Keepwatch\Checks\Result;

defined( 'ABSPATH' ) || exit;

/**
 * Published products that are out of stock or at/below the store's low-stock threshold. Counts only; product names
 * stay on the site (rule 9: no store details leave the site, only totals).
 */
final class StockCheck implements Check {

	/**
	 * {@inheritDoc}
	 */
	public function group(): string {
		return 'woocommerce';
	}

	/**
	 * {@inheritDoc}
	 */
	public function run(): array {
		$counts = $this->counts();
		return null === $counts ? array() : self::evaluate( $counts['out'], $counts['low'] );
	}

	/**
	 * Pure evaluation.
	 *
	 * @param int $out Published products out of stock.
	 * @param int $low Published products in stock at or below the low-stock threshold.
	 * @return Result[]
	 */
	public static function evaluate( int $out, int $low ): array {
		if ( 0 === $out && 0 === $low ) {
			return array( new Result( 'woocommerce.stock', Result::GOOD, __( 'No products are out of stock or running low', 'keepwatch' ) ) );
		}

		if ( $out > 0 ) {
			$label = 0 < $low
				/* translators: 1: products out of stock, 2: products running low */
				? sprintf( __( '%1$d products out of stock, %2$d running low', 'keepwatch' ), $out, $low )
				/* translators: %d: number of products */
				: sprintf( _n( '%d product is out of stock', '%d products are out of stock', $out, 'keepwatch' ), $out );
			$link = admin_url( 'edit.php?post_type=product&stock_status=outofstock' );
		} else {
			/* translators: %d: number of products */
			$label = sprintf( _n( '%d product is running low on stock', '%d products are running low on stock', $low, 'keepwatch' ), $low );
			$link  = admin_url( 'admin.php?page=wc-reports&tab=stock&report=low_in_stock' );
		}

		return array(
			new Result(
				'woocommerce.stock',
				Result::RECOMMENDED,
				$label,
				__( 'Customers cannot buy products that are out of stock. Restock them or hide them from the shop.', 'keepwatch' ),
				$link,
				__( 'View products', 'keepwatch' )
			),
		);
	}

	/**
	 * Out-of-stock and low-stock counts for published products (WooCommerce product lookup table).
	 *
	 * @return array{out: int, low: int}|null
	 */
	private function counts(): ?array {
		global $wpdb;

		$table = $wpdb->prefix . 'wc_product_meta_lookup';
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- read-only counts, cached by the check schedule.
		if ( $table !== $wpdb->get_var( $wpdb->prepare( 'SHOW TABLES LIKE %s', $wpdb->esc_like( $table ) ) ) ) {
			return null;
		}
		$threshold = max( 0, (int) get_option( 'woocommerce_notify_low_stock_amount', 2 ) );

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- see above.
		$row = $wpdb->get_row(
			$wpdb->prepare(
				'SELECT SUM(l.stock_status = %s) AS out_count, SUM(l.stock_status = %s AND l.stock_quantity IS NOT NULL AND l.stock_quantity <= %d) AS low_count
				FROM %i l INNER JOIN %i p ON p.ID = l.product_id WHERE p.post_status = %s AND p.post_type IN (%s, %s)',
				'outofstock',
				'instock',
				$threshold,
				$table,
				$wpdb->posts,
				'publish',
				'product',
				'product_variation'
			),
			ARRAY_A
		);

		return is_array( $row ) ? array(
			'out' => (int) $row['out_count'],
			'low' => (int) $row['low_count'],
		) : null;
	}
}