<?php
/**
 * Reads products and their variations from WooCommerce.
 *
 * @package LotCost
 */

namespace LotCost;

defined( 'ABSPATH' ) || exit;

/**
 * Describes the pieces of a lot the way the cost engine expects (see CatalogVariant in src/engine/costing.ts):
 * money in hundredths of the shop currency. A piece is a simple product or one variation of a variable product.
 */
final class Catalog {

	const SUPPORTED_TYPES = array( 'simple', 'variable' );

	/**
	 * Price or cost as hundredths of the currency; null when empty.
	 *
	 * @param mixed $amount Amount as WooCommerce hands it over (string or float).
	 */
	public static function to_cents( $amount ): ?int {
		if ( '' === $amount || null === $amount || ! is_numeric( $amount ) ) {
			return null;
		}
		return (int) round( (float) $amount * 100 );
	}

	/**
	 * The cost WooCommerce uses for orders, as hundredths of the currency; null when none is set.
	 *
	 * @param \WC_Product $product Product or variation.
	 */
	private static function store_cost_cents( \WC_Product $product ): ?int {
		if ( ! Cogs::enabled() ) {
			return null;
		}
		$cents = self::to_cents( $product->get_cogs_total_value() );
		return ( null === $cents || $cents <= 0 ) ? null : $cents;
	}

	/**
	 * Units still available, or null when it cannot be told. LotCost reads no order: a piece counts as sold when
	 * it has left the stock. The stock is known when WooCommerce counts it, or when the stock status says "out of stock".
	 *
	 * @param \WC_Product $product Product or variation.
	 */
	private static function available_units( \WC_Product $product ): ?int {
		if ( true === $product->managing_stock() ) {
			$quantity = $product->get_stock_quantity();
			return null === $quantity ? null : max( 0, (int) $quantity );
		}
		return 'outofstock' === $product->get_stock_status() ? 0 : null;
	}

	/**
	 * Describe one piece (a simple product or a variation).
	 *
	 * @param \WC_Product $product       Simple product or variation.
	 * @param string      $product_title Name of the product (the parent's name for a variation).
	 * @return array Same shape as CatalogVariantInfo in src/types.ts.
	 */
	private static function variant_info( \WC_Product $product, string $product_title ): array {
		$is_variation = $product instanceof \WC_Product_Variation;
		$label        = $is_variation ? wc_get_formatted_variation( $product, true, false ) : '';
		return array(
			'id'                => (string) $product->get_id(),
			'productId'         => (string) ( $is_variation ? $product->get_parent_id() : $product->get_id() ),
			'productTitle'      => $product_title,
			'title'             => '' !== $label ? $label : ( $is_variation ? '#' . $product->get_id() : '' ),
			'priceCents'        => self::to_cents( $product->get_price() ),
			'costCents'         => self::store_cost_cents( $product ),
			'inventoryQuantity' => self::available_units( $product ),
		);
	}

	/**
	 * Describe pieces by id. Ids that are not a piece (missing, in the trash, another product type, a variation whose
	 * product is gone) are left out.
	 *
	 * @param array $variant_ids Ids of simple products and variations.
	 * @return array Variant id (string) => description.
	 */
	public function describe_variants( array $variant_ids ): array {
		$ids = array();
		foreach ( $variant_ids as $variant_id ) {
			$id = absint( $variant_id );
			if ( $id > 0 ) {
				$ids[ $id ] = $id;
			}
		}
		if ( ! $ids ) {
			return array();
		}

		// One query warms the caches; anything it does not return is read one by one.
		$loaded = array();
		foreach ( array_chunk( array_values( $ids ), 200 ) as $chunk ) {
			$products = wc_get_products(
				array(
					'include' => $chunk,
					'type'    => array( 'simple', 'variation' ),
					'status'  => array( 'publish', 'draft', 'pending', 'private', 'future' ),
					'limit'   => count( $chunk ),
					'return'  => 'objects',
				)
			);
			foreach ( $products as $product ) {
				$loaded[ $product->get_id() ] = $product;
			}
		}

		$parents = array();
		$info    = array();
		foreach ( $ids as $id ) {
			$product = $loaded[ $id ] ?? wc_get_product( $id );
			if ( ! $product || 'trash' === $product->get_status() ) {
				continue;
			}
			if ( $product instanceof \WC_Product_Variation ) {
				$parent_id = (int) $product->get_parent_id();
				if ( ! isset( $parents[ $parent_id ] ) ) {
					$parent                = wc_get_product( $parent_id );
					$parents[ $parent_id ] = $parent ? $parent : false;
				}
				$parent = $parents[ $parent_id ];
				if ( ! $parent || ! $parent->is_type( 'variable' ) || 'trash' === $parent->get_status() ) {
					continue;
				}
				$info[ (string) $id ] = self::variant_info( $product, $parent->get_name() );
			} elseif ( $product->is_type( 'simple' ) ) {
				$info[ (string) $id ] = self::variant_info( $product, $product->get_name() );
			}
		}
		return $info;
	}

	/**
	 * Find simple and variable products by title for the "add pieces" picker. A variable product comes with its
	 * variations, since each variation is a piece.
	 *
	 * @param string $term  Search text.
	 * @param int    $limit Maximum number of products.
	 * @return array[] Each: id, title, type, variants (descriptions).
	 */
	public function search( string $term, int $limit = 20 ): array {
		$args = array(
			'type'    => self::SUPPORTED_TYPES,
			'status'  => array( 'publish', 'draft', 'pending', 'private' ),
			'limit'   => max( 1, min( 50, $limit ) ),
			'orderby' => 'title',
			'order'   => 'ASC',
			'return'  => 'objects',
		);
		if ( '' !== $term ) {
			$args['s'] = $term;
		}
		$hits = array();
		foreach ( wc_get_products( $args ) as $product ) {
			$variants = array();
			if ( $product->is_type( 'variable' ) ) {
				foreach ( array_slice( $product->get_children(), 0, 100 ) as $child_id ) {
					$variation = wc_get_product( $child_id );
					if ( $variation instanceof \WC_Product_Variation ) {
						$variants[] = self::variant_info( $variation, $product->get_name() );
					}
				}
			} else {
				$variants[] = self::variant_info( $product, $product->get_name() );
			}
			$hits[] = array(
				'id'       => (string) $product->get_id(),
				'title'    => $product->get_name(),
				'type'     => $product->get_type(),
				'variants' => $variants,
			);
		}
		return $hits;
	}
}