<?php
/**
 * Which marketplace category each WooCommerce category goes to. Pure PHP.
 *
 * @package Tidelist
 */

namespace Tidelist\Mapping;

/**
 * WooCommerce category to marketplace category map (for one account).
 */
final class CategoryMap {

	/**
	 * WooCommerce category ID => marketplace category ID.
	 *
	 * @var array<int, int>
	 */
	private $map = array();

	/**
	 * Constructor.
	 *
	 * @param array $map WooCommerce category ID => marketplace category ID.
	 */
	public function __construct( array $map = array() ) {
		foreach ( $map as $wc => $remote ) {
			if ( (int) $wc > 0 && (int) $remote > 0 ) {
				$this->map[ (int) $wc ] = (int) $remote;
			}
		}
	}

	/**
	 * The map of one channel (or account) out of the stored setting (key => map).
	 *
	 * @param array      $setting Stored setting.
	 * @param int|string $key     Channel ID, or an account ID.
	 */
	public static function from_setting( array $setting, $key = 0 ): self {
		return new self( (array) ( $setting[ $key ] ?? $setting[ (string) $key ] ?? array() ) );
	}

	/**
	 * The stored setting with this map for one channel (or account).
	 *
	 * @param array      $setting Stored setting.
	 * @param int|string $key     Channel ID, or an account ID.
	 */
	public function to_setting( array $setting, $key = 0 ): array {
		$setting[ $key ] = $this->map;
		return $setting;
	}

	/**
	 * Maps a WooCommerce category (0 as marketplace category removes the mapping).
	 *
	 * @param int $wc_id  WooCommerce category ID.
	 * @param int $remote_id marketplace category ID.
	 */
	public function set( int $wc_id, int $remote_id ): void {
		if ( $remote_id > 0 && $wc_id > 0 ) {
			$this->map[ $wc_id ] = $remote_id;
		} else {
			unset( $this->map[ $wc_id ] );
		}
	}

	/**
	 * The marketplace category this WooCommerce category is mapped to directly.
	 *
	 * @param int $wc_id WooCommerce category ID.
	 */
	public function get( int $wc_id ): ?int {
		return $this->map[ $wc_id ] ?? null;
	}

	/**
	 * All mappings.
	 *
	 * @return array<int, int>
	 */
	public function all(): array {
		return $this->map;
	}

	/**
	 * The marketplace category for a product: the closest mapped category among its categories, looking at each
	 * category and then its parents. A direct mapping beats an inherited one. Among equally close ones the most specific
	 * shop category (the one deepest in the tree) wins, so "Men's jackets" beats a general "Jackets" the product is also
	 * in; any remaining tie goes to the lowest category ID.
	 *
	 * @param int[]    $product_category_ids WooCommerce category IDs of the product.
	 * @param callable $ancestors            callable( int $id ): int[] parents, nearest first.
	 * @return int|null marketplace category ID, or null when nothing is mapped ("not mapped").
	 */
	public function resolve( array $product_category_ids, callable $ancestors ): ?int {
		$all = $this->candidates( $product_category_ids, $ancestors );
		return $all ? $all[0] : null;
	}

	/**
	 * Every marketplace category the product's shop categories lead to, best first (the first one is what resolve()
	 * returns). More than one means the product sits in shop categories that are mapped to different marketplace
	 * categories, so the choice is a guess the owner may want to check.
	 *
	 * @param int[]    $product_category_ids WooCommerce category IDs of the product.
	 * @param callable $ancestors            callable( int $id ): int[] parents, nearest first.
	 * @return int[] Distinct marketplace category IDs.
	 */
	public function candidates( array $product_category_ids, callable $ancestors ): array {
		$found = array();
		foreach ( $product_category_ids as $start ) {
			$start   = (int) $start;
			$parents = array_map( 'intval', (array) call_user_func( $ancestors, $start ) );
			$chain   = array_merge( array( $start ), $parents );
			foreach ( $chain as $distance => $id ) {
				if ( isset( $this->map[ $id ] ) ) {
					// Closest first, then deepest start category, then lowest ID.
					$found[] = array( $distance, -count( $parents ), $start, $this->map[ $id ] );
					break;
				}
			}
		}
		sort( $found );
		return array_values( array_unique( array_column( $found, 3 ) ) );
	}
}