<?php
/**
 * Lists and labels for the pickers in the campaign guide: products, categories, tags and attribute
 * values. An empty search lists everything a page at a time, so the shop can browse instead of
 * having to remember names. Labels are unique, so the app can show them for stored IDs.
 *
 * @package CNWS\Coupons
 */

namespace CNWS\Coupons\Admin;

defined( 'ABSPATH' ) || exit;

final class Lookup {

	public const PAGE_SIZE = 30;

	/**
	 * @param string $search Name or SKU; empty lists all products by name.
	 * @param int    $page   Page, from 1.
	 * @return array{items: array, more: bool}
	 */
	public static function products( string $search, int $page = 1 ): array {
		if ( ! class_exists( '\WC_Data_Store' ) || ! function_exists( 'wc_get_products' ) ) {
			return self::page( array(), false );
		}

		$offset = ( max( 1, $page ) - 1 ) * self::PAGE_SIZE;

		if ( '' === $search ) {
			$ids = wc_get_products(
				array(
					'status'  => array( 'publish', 'private', 'draft' ),
					'type'    => array_keys( wc_get_product_types() ),
					'orderby' => 'title',
					'order'   => 'ASC',
					'limit'   => self::PAGE_SIZE + 1,
					'offset'  => $offset,
					'return'  => 'ids',
				)
			);
		} else {
			$store = \WC_Data_Store::load( 'product' );
			$ids   = array_slice( (array) $store->search_products( $search, '', true, false, $offset + self::PAGE_SIZE + 1 ), $offset );
		}

		$ids   = array_values( array_filter( array_map( 'intval', (array) $ids ) ) );
		$more  = count( $ids ) > self::PAGE_SIZE;
		$items = array();

		foreach ( array_slice( $ids, 0, self::PAGE_SIZE ) as $id ) {
			$product = wc_get_product( $id );

			if ( $product ) {
				$items[] = array(
					'id'    => $id,
					'label' => self::product_label( $product ),
					'meta'  => self::product_meta( $product ),
				);
			}
		}

		return self::page( $items, $more );
	}

	/**
	 * @param int[] $ids Product IDs.
	 * @return array<int, string> ID => "Name (#ID)".
	 */
	public static function product_labels( array $ids ): array {
		$labels = array();

		foreach ( $ids as $id ) {
			$product = wc_get_product( $id );

			if ( $product ) {
				$labels[ $id ] = self::product_label( $product );
			}
		}

		return $labels;
	}

	/**
	 * @param string $taxonomy product_cat or product_tag.
	 * @param string $search   Name; empty lists all by name.
	 * @param int    $page     Page, from 1.
	 * @return array{items: array, more: bool}
	 */
	public static function terms( string $taxonomy, string $search, int $page = 1 ): array {
		$terms = get_terms(
			array(
				'taxonomy'   => $taxonomy,
				'hide_empty' => false,
				'search'     => $search,
				'orderby'    => 'name',
				'number'     => self::PAGE_SIZE + 1,
				'offset'     => ( max( 1, $page ) - 1 ) * self::PAGE_SIZE,
			)
		);
		$terms = is_array( $terms ) ? $terms : array();
		$items = array();

		foreach ( array_slice( $terms, 0, self::PAGE_SIZE ) as $term ) {
			$items[] = self::term_item( $term, false );
		}

		return self::page( $items, count( $terms ) > self::PAGE_SIZE );
	}

	/**
	 * Values of every global attribute, e.g. "Colour: Red". Searching for an attribute's name lists
	 * all its values.
	 *
	 * @param string $search Value or attribute name; empty lists all.
	 * @param int    $page   Page, from 1.
	 * @return array{items: array, more: bool}
	 */
	public static function attribute_terms( string $search, int $page = 1 ): array {
		if ( ! function_exists( 'wc_get_attribute_taxonomies' ) ) {
			return self::page( array(), false );
		}

		$offset = ( max( 1, $page ) - 1 ) * self::PAGE_SIZE;
		$wanted = $offset + self::PAGE_SIZE + 1;
		$found  = array();

		foreach ( wc_get_attribute_taxonomies() as $attribute ) {
			$by_name = '' !== $search && false !== stripos( (string) $attribute->attribute_label, $search );
			$terms   = get_terms(
				array(
					'taxonomy'   => wc_attribute_taxonomy_name( $attribute->attribute_name ),
					'hide_empty' => false,
					'search'     => $by_name ? '' : $search,
					'orderby'    => 'name',
					'number'     => $wanted - count( $found ),
				)
			);

			foreach ( is_array( $terms ) ? $terms : array() as $term ) {
				$found[] = $term;
			}

			if ( count( $found ) >= $wanted ) {
				break;
			}
		}

		$items = array();

		foreach ( array_slice( $found, $offset, self::PAGE_SIZE ) as $term ) {
			$items[] = self::term_item( $term, true );
		}

		return self::page( $items, count( $found ) > $offset + self::PAGE_SIZE );
	}

	/**
	 * @param int[] $ids       Term IDs.
	 * @param bool  $attribute Prefix the attribute name, e.g. "Colour: Red".
	 * @return array<int, string>
	 */
	public static function term_labels( array $ids, bool $attribute = false ): array {
		if ( ! $ids ) {
			return array();
		}

		$terms  = get_terms(
			array(
				'include'    => $ids,
				'hide_empty' => false,
			)
		);
		$labels = array();

		foreach ( is_array( $terms ) ? $terms : array() as $term ) {
			$labels[ (int) $term->term_id ] = self::term_label( $term, $attribute );
		}

		return $labels;
	}

	/**
	 * @param \WP_Term $term      Term.
	 * @param bool     $attribute Prefix the attribute name.
	 */
	private static function term_item( \WP_Term $term, bool $attribute ): array {
		return array(
			'id'    => (int) $term->term_id,
			'label' => self::term_label( $term, $attribute ),
			/* translators: %d: number of products. */
			'meta'  => sprintf( _n( '%d product', '%d products', (int) $term->count, 'webstyle-coupons' ), (int) $term->count ),
		);
	}

	/**
	 * @param \WP_Term $term      Term.
	 * @param bool     $attribute Prefix the attribute name.
	 */
	private static function term_label( \WP_Term $term, bool $attribute ): string {
		$name = html_entity_decode( $term->name, ENT_QUOTES );

		if ( $attribute && function_exists( 'wc_attribute_label' ) ) {
			return wc_attribute_label( $term->taxonomy ) . ': ' . $name;
		}

		// Two categories can share a name in different branches; the parent tells them apart.
		if ( $term->parent ) {
			$parent = get_term( $term->parent, $term->taxonomy );

			if ( $parent instanceof \WP_Term ) {
				return html_entity_decode( $parent->name, ENT_QUOTES ) . ' › ' . $name;
			}
		}

		return $name;
	}

	/**
	 * @param \WC_Product $product Product.
	 */
	private static function product_label( $product ): string {
		return sprintf( '%s (#%d)', wp_strip_all_tags( html_entity_decode( $product->get_name(), ENT_QUOTES ) ), $product->get_id() );
	}

	/**
	 * SKU and price, so products with similar names can be told apart.
	 *
	 * @param \WC_Product $product Product.
	 */
	private static function product_meta( $product ): string {
		$parts = array();

		if ( $product->get_sku() ) {
			/* translators: %s: product SKU. */
			$parts[] = sprintf( __( 'SKU %s', 'webstyle-coupons' ), $product->get_sku() );
		}

		$price = $product->get_price_html();

		if ( '' !== $price ) {
			$parts[] = trim( html_entity_decode( wp_strip_all_tags( $price ), ENT_QUOTES ) );
		}

		return implode( ' · ', $parts );
	}

	/**
	 * @param array $items Items.
	 * @param bool  $more  More pages exist.
	 * @return array{items: array, more: bool}
	 */
	private static function page( array $items, bool $more ): array {
		return array(
			'items' => $items,
			'more'  => $more,
		);
	}
}