<?php

declare( strict_types=1 );

namespace AcezSeo\Support;

if ( ! defined( 'ABSPATH' ) )
{
	exit;
}

/**
 * Detects active multilingual plugins (WPML, Polylang, TranslatePress) and
 * resolves language information for schema.org's `inLanguage` property.
 * Mirrors the SeoPluginDetector approach: detection by the plugins' own
 * runtime markers, extensible via filter.
 */
final class MultilingualPluginDetector
{
	public static function detect(): ?string
	{
		$known = array(
			'WPML'           => static fn(): bool => class_exists( 'SitePress' ) || defined( 'ICL_SITEPRESS_VERSION' ),
			'Polylang'       => static fn(): bool => function_exists( 'pll_current_language' ),
			'TranslatePress' => static fn(): bool => class_exists( 'TRP_Translate_Press' ) || defined( 'TRP_PLUGIN_VERSION' ),
		);

		/**
		 * Filters the list of "plugin name => detection callback" pairs used
		 * to detect active multilingual plugins.
		 *
		 * @param array<string, callable(): bool> $known
		 */
		$known = (array) apply_filters( 'acez_seo_known_multilingual_plugins', $known );

		foreach ( $known as $name => $check )
		{
			if ( is_callable( $check ) && $check() )
			{
				return (string) $name;
			}
		}

		return null;
	}

	public static function is_active(): bool
	{
		return null !== self::detect();
	}

	/**
	 * BCP 47 language tag (e.g. "pl-PL") for a specific post — asks the
	 * multilingual plugin for the post's own language (a translation is a
	 * separate WP_Post with its own language), falling back to the site locale.
	 */
	public static function post_language( \WP_Post $post ): string
	{
		if ( function_exists( 'pll_get_post_language' ) )
		{
			$locale = (string) pll_get_post_language( $post->ID, 'locale' );

			if ( '' !== $locale )
			{
				return self::to_bcp47( $locale );
			}
		}

		if ( class_exists( 'SitePress' ) || defined( 'ICL_SITEPRESS_VERSION' ) )
		{
			$details = apply_filters( 'wpml_post_language_details', null, $post->ID ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- this hook name belongs to WP core or another plugin (WPML/core sitemaps) being invoked/filtered, not one of ours — must stay unprefixed to match their API.

			if ( is_array( $details ) && '' !== (string) ( $details['locale'] ?? '' ) )
			{
				return self::to_bcp47( (string) $details['locale'] );
			}
		}

		return self::to_bcp47( (string) get_locale() );
	}

	/**
	 * Locales configured in the multilingual plugin (for the per-language
	 * overrides UI). Empty when none is active or the list can't be read.
	 *
	 * @return string[] e.g. ['pl_PL', 'en_US']
	 */
	public static function languages(): array
	{
		if ( function_exists( 'pll_languages_list' ) )
		{
			return array_map( 'strval', (array) pll_languages_list( array( 'fields' => 'locale' ) ) );
		}

		if ( class_exists( 'SitePress' ) || defined( 'ICL_SITEPRESS_VERSION' ) )
		{
			$languages = apply_filters( 'wpml_active_languages', null ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- this hook name belongs to WP core or another plugin (WPML/core sitemaps) being invoked/filtered, not one of ours — must stay unprefixed to match their API.
			$locales   = array();

			foreach ( (array) $languages as $language )
			{
				$locale = (string) ( $language['default_locale'] ?? '' );

				if ( '' !== $locale )
				{
					$locales[] = $locale;
				}
			}

			return $locales;
		}

		return array();
	}

	/**
	 * Current request's language as a locale string (e.g. "pl_PL") — used as
	 * the key for per-language setting overrides.
	 */
	public static function current_locale(): string
	{
		if ( function_exists( 'pll_current_language' ) )
		{
			$locale = (string) pll_current_language( 'locale' );

			if ( '' !== $locale )
			{
				return $locale;
			}
		}

		return (string) get_locale();
	}

	/**
	 * Current request's language in BCP 47 form (e.g. "pl-PL") — the
	 * `inLanguage` value for graphs that have no WP_Post to ask
	 * post_language() about (taxonomy archives, the blog index).
	 */
	public static function current_language(): string
	{
		return self::to_bcp47( self::current_locale() );
	}

	/**
	 * The SOURCE (original) post of a translation, resolved through the
	 * multilingual plugin's own documented API (M35 — researched, not
	 * guessed): Polylang = the translation in the DEFAULT language
	 * (pll_get_post_translations + pll_default_language), WPML = the element
	 * flagged "original" in the post's translation group
	 * (wpml_element_trid + wpml_get_element_translations). Null when no
	 * plugin is active, the post IS the original, or it has no source.
	 */
	public static function translation_source( \WP_Post $post ): ?\WP_Post
	{
		if ( function_exists( 'pll_get_post_translations' ) && function_exists( 'pll_default_language' ) )
		{
			$translations = (array) pll_get_post_translations( $post->ID );
			$default_slug = (string) pll_default_language( 'slug' );
			$source_id    = (int) ( $translations[ $default_slug ] ?? 0 );

			if ( $source_id > 0 && $source_id !== $post->ID )
			{
				$source = get_post( $source_id );

				return $source instanceof \WP_Post ? $source : null;
			}

			return null;
		}

		if ( class_exists( 'SitePress' ) || defined( 'ICL_SITEPRESS_VERSION' ) )
		{
			$element_type = 'post_' . $post->post_type;
			$trid         = apply_filters( 'wpml_element_trid', null, $post->ID, $element_type ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- this hook name belongs to WP core or another plugin (WPML/core sitemaps) being invoked/filtered, not one of ours — must stay unprefixed to match their API.

			if ( empty( $trid ) )
			{
				return null;
			}

			$translations = apply_filters( 'wpml_get_element_translations', null, $trid, $element_type ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- this hook name belongs to WP core or another plugin (WPML/core sitemaps) being invoked/filtered, not one of ours — must stay unprefixed to match their API.

			foreach ( (array) $translations as $translation )
			{
				if ( ! is_object( $translation ) )
				{
					continue;
				}

				$element_id = (int) ( $translation->element_id ?? 0 );

				if ( '1' === (string) ( $translation->original ?? '' ) && $element_id > 0 && $element_id !== $post->ID )
				{
					$source = get_post( $element_id );

					return $source instanceof \WP_Post ? $source : null;
				}
			}
		}

		return null;
	}

	/**
	 * All language versions of this post, INCLUDING itself (M56 — hreflang
	 * sitemap tags). Same underlying plugin APIs as `translation_source()`,
	 * but the full sibling set instead of just the default-language member.
	 *
	 * @return array<string, string> BCP 47 language tag => absolute URL
	 */
	public static function translations( \WP_Post $post ): array
	{
		if ( function_exists( 'pll_get_post_translations' ) )
		{
			$map = array();

			foreach ( (array) pll_get_post_translations( $post->ID ) as $translated_id )
			{
				$translated_id = (int) $translated_id;

				if ( $translated_id <= 0 )
				{
					continue;
				}

				$translated_post = get_post( $translated_id );

				if ( ! $translated_post instanceof \WP_Post )
				{
					continue;
				}

				$permalink = get_permalink( $translated_post );

				if ( is_string( $permalink ) )
				{
					$map[ self::post_language( $translated_post ) ] = $permalink;
				}
			}

			return $map;
		}

		if ( class_exists( 'SitePress' ) || defined( 'ICL_SITEPRESS_VERSION' ) )
		{
			$element_type = 'post_' . $post->post_type;
			$trid         = apply_filters( 'wpml_element_trid', null, $post->ID, $element_type ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- this hook name belongs to WP core or another plugin (WPML/core sitemaps) being invoked/filtered, not one of ours — must stay unprefixed to match their API.

			if ( empty( $trid ) )
			{
				return array();
			}

			$translations = apply_filters( 'wpml_get_element_translations', null, $trid, $element_type ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- this hook name belongs to WP core or another plugin (WPML/core sitemaps) being invoked/filtered, not one of ours — must stay unprefixed to match their API.
			$map          = array();

			foreach ( (array) $translations as $translation )
			{
				if ( ! is_object( $translation ) )
				{
					continue;
				}

				$element_id = (int) ( $translation->element_id ?? 0 );

				if ( $element_id <= 0 )
				{
					continue;
				}

				$translated_post = get_post( $element_id );

				if ( ! $translated_post instanceof \WP_Post )
				{
					continue;
				}

				$permalink = get_permalink( $translated_post );
				$lang      = (string) ( $translation->language_code ?? '' );

				if ( is_string( $permalink ) && '' !== $lang )
				{
					$map[ $lang ] = $permalink;
				}
			}

			return $map;
		}

		return array();
	}

	private static function to_bcp47( string $locale ): string
	{
		return str_replace( '_', '-', $locale );
	}
}