<?php
/**
 * Multilingual. The file wpml-config.xml at the root of the plugin does most of the work, for WPML and for Polylang
 * (which reads it): library tabs translatable, product structure copied in every language, tab texts translated,
 * titles of the WooCommerce tabs in string translation. This class maps ids to the language of the page and finds
 * the source of a translation. TranslatePress and Weglot translate the rendered page and need nothing.
 *
 * @package Prodtabs
 */

namespace Prodtabs;

defined( 'ABSPATH' ) || exit;

// phpcs:disable WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- calls to the hooks of WPML.

/**
 * WPML and Polylang helpers.
 */
final class Multilingual {

	/** Context of the titles of the WooCommerce tabs in WPML String Translation, the one of its admin texts. */
	const WPML_CONTEXT = 'admin_texts_prodtabs_settings';

	/** Hooks. */
	public static function init(): void {
		// Safety net when Polylang's reading of wpml-config.xml is turned off (constant PLL_WPML_COMPAT).
		add_filter( 'pll_get_post_types', array( __CLASS__, 'polylang_post_types' ), 10, 2 );
		// After Polylang's own reading of wpml-config.xml (priority 20).
		add_filter( 'pll_copy_post_metas', array( __CLASS__, 'polylang_metas' ), 30, 5 );
		add_action( 'add_option_' . Settings::OPTION, array( __CLASS__, 'register_native_titles' ), 10, 2 );
		add_action( 'update_option_' . Settings::OPTION, array( __CLASS__, 'register_native_titles' ), 10, 2 );
	}

	/**
	 * WPML registers the admin texts of wpml-config.xml only when it reads the file, and only the values already set:
	 * a title given to a WooCommerce tab afterwards would never reach String Translation. The titles are registered
	 * here whenever the settings are saved, under the name WPML gives to admin texts.
	 *
	 * @param mixed $old_or_name Previous value, or the option name when the option is added.
	 * @param mixed $value       New value.
	 */
	public static function register_native_titles( $old_or_name, $value ): void {
		if ( 'wpml' !== self::plugin() || ! is_array( $value ) || empty( $value['natives'] ) || ! is_array( $value['natives'] ) ) {
			return;
		}
		foreach ( Tabs::NATIVE as $key ) {
			$title = isset( $value['natives'][ $key ]['title'] ) ? trim( (string) $value['natives'][ $key ]['title'] ) : '';
			if ( '' !== $title ) {
				do_action( 'wpml_register_single_string', self::WPML_CONTEXT, self::wpml_title_name( $key ), $title );
			}
		}
	}

	/**
	 * Title of a WooCommerce tab in the language of the page, with WPML. WPML translates admin texts on its own only
	 * for those registered when it read wpml-config.xml; the others are asked here.
	 *
	 * @param string $title Title set in the settings.
	 * @param string $key   Native key.
	 */
	public static function native_title( string $title, string $key ): string {
		if ( '' === $title || 'wpml' !== self::plugin() ) {
			return $title;
		}
		return (string) apply_filters( 'wpml_translate_single_string', $title, self::WPML_CONTEXT, self::wpml_title_name( $key ) );
	}

	/**
	 * Name of the title of a WooCommerce tab in WPML String Translation.
	 *
	 * @param string $key Native key.
	 */
	private static function wpml_title_name( string $key ): string {
		return '[' . Settings::OPTION . '][natives][' . $key . ']title';
	}

	/**
	 * Translation plugin in use.
	 *
	 * @return string wpml, polylang, translatepress, weglot or an empty string.
	 */
	public static function plugin(): string {
		if ( defined( 'POLYLANG_VERSION' ) ) {
			return 'polylang';
		}
		if ( defined( 'ICL_SITEPRESS_VERSION' ) ) {
			return 'wpml';
		}
		if ( defined( 'TRP_PLUGIN_VERSION' ) || class_exists( 'TRP_Translate_Press' ) ) {
			return 'translatepress';
		}
		if ( defined( 'WEGLOT_VERSION' ) ) {
			return 'weglot';
		}
		return '';
	}

	/**
	 * Library tabs are translatable with Polylang, like products; not offered in its settings.
	 *
	 * @param string[] $post_types  Post types.
	 * @param bool     $is_settings Whether Polylang builds its settings screen.
	 * @return string[]
	 */
	public static function polylang_post_types( $post_types, $is_settings ) {
		$post_types = (array) $post_types;
		if ( $is_settings ) {
			unset( $post_types[ Library::POST_TYPE ] );
		} else {
			$post_types[ Library::POST_TYPE ] = Library::POST_TYPE;
		}
		return $post_types;
	}

	/**
	 * Metas Polylang copies when a translation is created and keeps synchronized afterwards: the structure, never the
	 * texts. A new translation has no text of its own: until it is translated, it shows the original as not translated
	 * (hidden by the "Tabs not translated yet" setting, counted in the overview), as with WPML. A product without
	 * structure never synchronizes its absence over a translation that has one: Polylang would delete the tabs of every
	 * language.
	 *
	 * @param string[] $keys Meta keys.
	 * @param bool     $sync True for the synchronization, false for the copy at creation.
	 * @param int      $from Post the metas come from.
	 * @param int      $to   Post the metas go to.
	 * @return string[]
	 */
	public static function polylang_metas( $keys, $sync, $from = 0, $to = 0 ) {
		$keys   = (array) $keys;
		$keys[] = Tabs::META_LAYOUT;
		$keys[] = Library::META_SCOPE; // The same products in every language.
		if ( ! $sync ) {
			// Polylang copies the fields to translate of wpml-config.xml at creation: tab texts and shop title stay out.
			$keys = array_diff( $keys, array( Tabs::META_TEXTS, Library::META_SHOP_TITLE ) );
		}
		$keys = array_values( array_unique( $keys ) );
		if ( $sync && $from && $to && ! get_post_meta( (int) $from, Tabs::META_LAYOUT, true ) && get_post_meta( (int) $to, Tabs::META_LAYOUT, true ) ) {
			$keys = array_values( array_diff( $keys, array( Tabs::META_LAYOUT ) ) );
		}
		return $keys;
	}

	/**
	 * Id of the translation of a post in a language (the language of the page by default). When the translation is
	 * missing, the original is used unless the filter prodtabs_untranslated_library_tab returns false.
	 *
	 * @param int         $id        Post id.
	 * @param string      $post_type Post type.
	 * @param string|null $lang      Language code; null for the current language.
	 * @return int 0 when the post must not be shown.
	 */
	public static function translate_post_id( int $id, string $post_type, ?string $lang = null ): int {
		if ( function_exists( 'pll_get_post' ) ) {
			$translated = (int) pll_get_post( $id, null === $lang ? '' : $lang );
		} elseif ( has_filter( 'wpml_object_id' ) ) {
			$translated = (int) apply_filters( 'wpml_object_id', $id, $post_type, false, $lang );
		} else {
			return $id;
		}
		if ( $translated ) {
			return $translated;
		}

		/**
		 * Whether a library tab without a translation in the language of the page shows in its own language.
		 *
		 * @param bool   $show      True unless the "Tabs not translated yet" setting hides them.
		 * @param int    $id        Library tab id.
		 * @param string $post_type Post type.
		 */
		return apply_filters( 'prodtabs_untranslated_library_tab', ! Settings::get( 'hide_untranslated' ), $id, $post_type ) ? $id : 0;
	}

	/**
	 * Id of a post in the language of the page: its translation when there is one, the post itself otherwise.
	 *
	 * @param int    $id        Post id.
	 * @param string $post_type Post type.
	 */
	public static function in_current_language( int $id, string $post_type ): int {
		if ( function_exists( 'pll_get_post' ) ) {
			$translated = (int) pll_get_post( $id );
			return $translated ? $translated : $id;
		}
		if ( has_filter( 'wpml_object_id' ) ) {
			return (int) apply_filters( 'wpml_object_id', $id, $post_type, true );
		}
		return $id;
	}

	/**
	 * Id of the translation of a post in a language, without falling back to the original.
	 *
	 * @param int    $id        Post id.
	 * @param string $post_type Post type.
	 * @param string $lang      Language code.
	 * @return int 0 when there is no translation.
	 */
	public static function translation( int $id, string $post_type, string $lang ): int {
		if ( function_exists( 'pll_get_post' ) ) {
			return (int) pll_get_post( $id, $lang );
		}
		if ( has_filter( 'wpml_object_id' ) ) {
			return (int) apply_filters( 'wpml_object_id', $id, $post_type, false, $lang );
		}
		return 0;
	}

	/**
	 * Original of a group of translations: the post the others were translated from with WPML, the translation in the
	 * default language with Polylang.
	 *
	 * @param int    $id        Post id, in any language of the group.
	 * @param string $post_type Post type.
	 * @return int 0 when unknown.
	 */
	public static function original( int $id, string $post_type ): int {
		if ( function_exists( 'pll_get_post' ) ) {
			$default = (string) pll_default_language();
			return '' !== $default ? (int) pll_get_post( $id, $default ) : 0;
		}
		if ( has_filter( 'wpml_element_trid' ) ) {
			$type = 'post_' . $post_type;
			$trid = apply_filters( 'wpml_element_trid', null, $id, $type );
			foreach ( (array) apply_filters( 'wpml_get_element_translations', null, $trid, $type, false, true ) as $translation ) {
				if ( ! empty( $translation->original ) && isset( $translation->element_id ) ) {
					return (int) $translation->element_id;
				}
			}
		}
		return 0;
	}

	/** Language of the page, empty without a translation plugin that has languages. */
	public static function current_language(): string {
		if ( function_exists( 'pll_current_language' ) ) {
			return (string) pll_current_language();
		}
		if ( has_filter( 'wpml_current_language' ) ) {
			return (string) apply_filters( 'wpml_current_language', null );
		}
		return '';
	}

	/**
	 * Runs a query in every language: Polylang reads 'lang' => '' in the query itself, WPML needs its language switched
	 * to "all" for the time of the query.
	 *
	 * @param callable $query Function that runs the query.
	 * @return mixed What the function returns.
	 */
	public static function all_languages( callable $query ) {
		$wpml    = has_action( 'wpml_switch_language' ) && has_filter( 'wpml_current_language' );
		$current = $wpml ? apply_filters( 'wpml_current_language', null ) : null;
		if ( $wpml ) {
			do_action( 'wpml_switch_language', 'all' );
		}
		try {
			return $query();
		} finally {
			if ( $wpml ) {
				// WPML 5 keeps its switches on a stack, closed by null; earlier versions put back the language given.
				do_action( 'wpml_switch_language', defined( 'ICL_SITEPRESS_VERSION' ) && version_compare( ICL_SITEPRESS_VERSION, '5', '<' ) ? $current : null );
			}
		}
	}

	/**
	 * Ids of a post and of all its translations.
	 *
	 * @param int    $id        Post id.
	 * @param string $post_type Post type.
	 * @return int[]
	 */
	public static function translation_ids( int $id, string $post_type ): array {
		$ids = array( $id );
		if ( function_exists( 'pll_get_post_translations' ) ) {
			$ids = array_merge( $ids, array_values( (array) pll_get_post_translations( $id ) ) );
		} elseif ( has_filter( 'wpml_element_trid' ) ) {
			$type = 'post_' . $post_type;
			$trid = apply_filters( 'wpml_element_trid', null, $id, $type );
			// All statuses: for visitors, WPML leaves out the translations of post types that are not public (shared tabs).
			foreach ( (array) apply_filters( 'wpml_get_element_translations', null, $trid, $type, false, true ) as $translation ) {
				if ( isset( $translation->element_id ) ) {
					$ids[] = (int) $translation->element_id;
				}
			}
		}
		return array_values( array_unique( array_map( 'intval', $ids ) ) );
	}

	/**
	 * Product a translation follows: the original with WPML, the translation in the default language with Polylang.
	 *
	 * @param int $product_id Product id.
	 * @return int 0 when the product is itself the source, or without translation plugin.
	 */
	public static function source_product( int $product_id ): int {
		if ( function_exists( 'pll_get_post_language' ) ) {
			$default = (string) pll_default_language();
			if ( '' === $default || pll_get_post_language( $product_id ) === $default ) {
				return 0;
			}
			return (int) pll_get_post( $product_id, $default );
		}
		$source_lang = self::wpml_source_language( $product_id );
		return '' !== $source_lang ? (int) apply_filters( 'wpml_object_id', $product_id, 'product', false, $source_lang ) : 0;
	}

	/**
	 * Whether the structure of a product's tabs comes from another product and cannot be changed on this one: a WPML
	 * translation copies it from its original. With Polylang the structure is shared and can be changed in any language.
	 *
	 * @param int $product_id Product id.
	 */
	public static function structure_locked( int $product_id ): bool {
		return ! function_exists( 'pll_get_post_language' ) && '' !== self::wpml_source_language( $product_id );
	}

	/**
	 * Language a WPML translation was translated from.
	 *
	 * @param int $product_id Product id.
	 * @return string Empty for an original or without WPML.
	 */
	private static function wpml_source_language( int $product_id ): string {
		if ( ! has_filter( 'wpml_element_language_details' ) ) {
			return '';
		}
		$details = apply_filters(
			'wpml_element_language_details',
			null,
			array(
				'element_id'   => $product_id,
				'element_type' => 'post_product',
			)
		);
		return is_object( $details ) && ! empty( $details->source_language_code ) ? (string) $details->source_language_code : '';
	}

	/**
	 * Languages of the site.
	 *
	 * @return string[] Language codes, empty without WPML or Polylang.
	 */
	public static function languages(): array {
		if ( function_exists( 'pll_languages_list' ) ) {
			return array_map( 'strval', (array) pll_languages_list() );
		}
		if ( has_filter( 'wpml_active_languages' ) ) {
			return array_map( 'strval', array_keys( (array) apply_filters( 'wpml_active_languages', null, array( 'skip_missing' => 0 ) ) ) );
		}
		return array();
	}

	/** Default language of the site, empty without a translation plugin that has languages. */
	public static function default_language(): string {
		if ( function_exists( 'pll_default_language' ) ) {
			return (string) pll_default_language();
		}
		if ( has_filter( 'wpml_default_language' ) ) {
			return (string) apply_filters( 'wpml_default_language', null );
		}
		return '';
	}

	/**
	 * Language of a post.
	 *
	 * @param int $post_id Post id.
	 * @return string Language code, empty when unknown.
	 */
	public static function post_language( int $post_id ): string {
		if ( function_exists( 'pll_get_post_language' ) ) {
			return (string) pll_get_post_language( $post_id );
		}
		if ( has_filter( 'wpml_post_language_details' ) ) {
			$details = apply_filters( 'wpml_post_language_details', null, $post_id );
			return is_array( $details ) && ! empty( $details['language_code'] ) ? (string) $details['language_code'] : '';
		}
		return '';
	}

	/**
	 * Sets the language of a post.
	 *
	 * @param int    $post_id   Post id.
	 * @param string $post_type Post type.
	 * @param string $lang      Language code.
	 */
	public static function set_language( int $post_id, string $post_type, string $lang ): void {
		if ( '' === $lang ) {
			return;
		}
		if ( function_exists( 'pll_set_post_language' ) ) {
			pll_set_post_language( $post_id, $lang );
			return;
		}
		if ( has_action( 'wpml_set_element_language_details' ) ) {
			do_action(
				'wpml_set_element_language_details',
				array(
					'element_id'    => $post_id,
					'element_type'  => 'post_' . $post_type,
					'trid'          => false,
					'language_code' => $lang,
				)
			);
		}
	}

	/**
	 * Links posts as translations of one another.
	 *
	 * @param int[]  $by_lang   Post id by language code; the first one is the original.
	 * @param string $post_type Post type.
	 */
	public static function link_translations( array $by_lang, string $post_type ): void {
		if ( count( $by_lang ) < 2 ) {
			return;
		}
		if ( function_exists( 'pll_save_post_translations' ) ) {
			// Translations already linked are kept: saving a group replaces it, and would unlink the others.
			$merged = array();
			foreach ( $by_lang as $post_id ) {
				$merged += array_map( 'intval', (array) pll_get_post_translations( (int) $post_id ) );
			}
			foreach ( $by_lang as $lang => $post_id ) {
				if ( ! isset( $merged[ $lang ] ) ) {
					$merged[ $lang ] = (int) $post_id;
				}
			}
			pll_save_post_translations( $merged );
			return;
		}
		if ( ! has_filter( 'wpml_element_trid' ) ) {
			return;
		}
		$element_type = 'post_' . $post_type;
		$source_lang  = (string) array_key_first( $by_lang );
		$trid         = apply_filters( 'wpml_element_trid', null, (int) reset( $by_lang ), $element_type );
		foreach ( $by_lang as $lang => $post_id ) {
			if ( (string) $lang === $source_lang ) {
				continue;
			}
			// A post already in another translation group is not moved.
			$own = apply_filters( 'wpml_element_trid', null, (int) $post_id, $element_type );
			if ( $own && $own !== $trid && count( (array) apply_filters( 'wpml_get_element_translations', null, $own, $element_type, false, true ) ) > 1 ) {
				continue;
			}
			do_action(
				'wpml_set_element_language_details',
				array(
					'element_id'           => (int) $post_id,
					'element_type'         => $element_type,
					'trid'                 => $trid,
					'language_code'        => (string) $lang,
					'source_language_code' => $source_lang,
				)
			);
		}
	}
}