<?php
/**
 * Component language override on top of the standard WordPress translation loading.
 *
 * WordPress loads community translation packs on demand (no load_plugin_textdomain(), discouraged since 4.6);
 * strings a pack does not translate are filled from the bundled catalog in the site's language.
 * A module whose display language differs from the site language is translated from the bundled table instead,
 * so one site can show a Chinese module on an English page without switching the whole request locale.
 *
 * @package ActiKidz_Local_Activities
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit; }
/** Scoped component translations independent of installed core packs. */
final class AKLA_Translations {
	/** Plugin text domain. */
	const DOMAIN = 'actikidz-local-activities';

	/** Bundled catalog locale for each component language. */
	const CATALOGS = array(
		'zh'    => 'zh_CN',
		'zh-TW' => 'zh_TW',
		'fr'    => 'fr_CA',
	);

	/**
	 * Active component language.
	 *
	 * @var string|null
	 */
	private static $language = null;
	/**
	 * Site language while a component language is active (null: unsupported or no component language).
	 *
	 * @var string|null
	 */
	private static $site = null;
	/**
	 * Bundled translations by English source text (plurals: singular and plural joined by NUL).
	 *
	 * @var array|null
	 */
	private static $index = null;
	/**
	 * Set a component language and return its previous value.
	 *
	 * @param mixed $language Language.
	 *
	 * @return mixed Result or rendered output as documented by the caller.
	 */
	public static function language( $language ) {
		$previous       = self::$language;
		self::$language = $language;
		self::$site     = null === $language ? null : self::site_language();
		return $previous;
	}

	/**
	 * Map a WordPress locale to a component language.
	 *
	 * @param string $locale WordPress locale such as zh_HK or fr_CA.
	 * @return string|null en, zh, zh-TW or fr; null for other languages.
	 */
	public static function locale_language( $locale ) {
		$locale = (string) $locale;
		if ( in_array( $locale, array( 'zh_CN', 'zh_SG' ), true ) ) {
			return 'zh';
		}
		if ( in_array( $locale, array( 'zh_TW', 'zh_HK' ), true ) ) {
			return 'zh-TW';
		}
		if ( 'fr' === $locale || str_starts_with( $locale, 'fr_' ) ) {
			return 'fr';
		}
		if ( 'en' === $locale || str_starts_with( $locale, 'en_' ) ) {
			return 'en';
		}
		return null;
	}

	/**
	 * Language WordPress is currently translating into.
	 *
	 * @return string|null Component language of determine_locale(), or null when unsupported.
	 */
	public static function site_language() {
		return self::locale_language( determine_locale() );
	}

	/**
	 * Whether a component language is the one WordPress already translates into.
	 *
	 * @param string $language Component language.
	 * @return bool True when site translations (and $wp_locale names) are already in that language.
	 */
	public static function matches_site( $language ) {
		$site = null !== self::$language && $language === self::$language ? self::$site : self::site_language();
		return $language === $site;
	}

	/**
	 * Component language that must override WordPress translations, if any.
	 *
	 * @return string|null Language, or null when WordPress translations already match.
	 */
	private static function override_language() {
		return null !== self::$language && self::$language !== self::$site ? self::$language : null;
	}

	/**
	 * Translate a module string when its language differs from the site language.
	 *
	 * @param mixed $translation Translation WordPress loaded (community pack), or the English text.
	 * @param mixed $text        English source text.
	 *
	 * @return mixed Translation in the component language.
	 */
	public static function translate( $translation, $text ) {
		$language = self::override_language();
		if ( null === $language ) {
			// Same language as the site: a community translation wins; only untranslated text uses the bundled catalog.
			if ( $translation !== $text ) {
				return $translation; }
			$language = self::site_language();
			if ( null === $language || 'en' === $language ) {
				return $translation; }
		}
		if ( 'en' === $language ) {
			return $text; }
		$value = self::index()[ $text ][ $language ] ?? '';
		// Untranslated strings fall back to English rather than to the (different) site language.
		return is_string( $value ) && '' !== $value ? $value : $text;
	}

	/**
	 * Translate a counted module string when its language differs from the site language.
	 *
	 * @param mixed $translation Translation WordPress selected.
	 * @param mixed $single      English singular.
	 * @param mixed $plural      English plural.
	 * @param mixed $number      Count.
	 * @return mixed Translation in the component language.
	 */
	public static function translate_plural( $translation, $single, $plural, $number ) {
		$language = self::override_language();
		if ( null === $language ) {
			// Same language as the site: a community translation wins; only untranslated text uses the bundled catalog.
			if ( $translation !== $single && $translation !== $plural ) {
				return $translation;
			}
			$language = self::site_language();
			if ( null === $language || 'en' === $language ) {
				return $translation;
			}
		}
		$many  = 1 !== (int) $number;
		$value = 'en' === $language ? '' : ( self::index()[ $single . "\0" . $plural ][ $language ] ?? '' );
		if ( is_array( $value ) && 2 === count( $value ) && '' !== $value[0] && '' !== $value[1] ) {
			// French (the only two-form bundled language): singular for 0 and 1.
			return (int) $number > 1 ? $value[1] : $value[0];
		}
		if ( is_string( $value ) && '' !== $value ) {
			return $value; // Chinese has one form.
		}
		return $many ? $plural : $single;
	}

	/**
	 * Bundled translations indexed by source text, built once per request.
	 *
	 * @return array Map of English text (plural: singular NUL plural) to array( zh, zh-TW, fr ).
	 */
	private static function index() {
		if ( null === self::$index ) {
			$rows        = wp_json_file_decode( AKLA_DIR . 'languages/translations.json', array( 'associative' => true ) );
			self::$index = array();
			foreach ( is_array( $rows ) ? $rows : array() as $row ) {
				if ( ! is_array( $row ) || ! isset( $row[0] ) ) {
					continue;
				}
				$key                 = is_array( $row[0] ) ? implode( "\0", $row[0] ) : (string) $row[0];
				self::$index[ $key ] = array(
					'zh'    => $row[1] ?? '',
					'zh-TW' => $row[2] ?? '',
					'fr'    => $row[3] ?? '',
				);
			}
		}
		return self::$index;
	}

	/**
	 * Bundled catalog locale for a site locale without its own file (zh_HK → zh_TW, zh_SG → zh_CN, fr_FR → fr_CA).
	 *
	 * @param string $locale WordPress locale.
	 * @return string|null Bundled locale, or null.
	 */
	private static function bundled_locale( $locale ) {
		$language = self::locale_language( $locale );
		return null === $language || 'en' === $language ? null : self::CATALOGS[ $language ];
	}

	/**
	 * Use the closest bundled catalog when the site locale has none (filter: load_textdomain_mofile).
	 *
	 * @param mixed $mofile Catalog path WordPress is about to load.
	 * @param mixed $domain Text domain.
	 * @return mixed Catalog path.
	 */
	public static function mofile( $mofile, $domain ) {
		if ( self::DOMAIN !== $domain || ! is_string( $mofile ) || is_readable( $mofile ) ) {
			return $mofile;
		}
		$locale  = determine_locale();
		$bundled = self::bundled_locale( $locale );
		if ( null === $bundled || $bundled === $locale ) {
			return $mofile;
		}
		$candidate = AKLA_DIR . 'languages/' . self::DOMAIN . '-' . $bundled . '.mo';
		return is_readable( $candidate ) ? $candidate : $mofile;
	}

	/**
	 * Use the closest bundled script catalog when the site locale has none (filter: load_script_translation_file).
	 *
	 * @param mixed $file   JSON catalog path.
	 * @param mixed $handle Script handle.
	 * @param mixed $domain Text domain.
	 * @return mixed JSON catalog path.
	 */
	public static function script_file( $file, $handle, $domain ) {
		if ( self::DOMAIN !== $domain || ! is_string( $file ) || is_readable( $file ) ) {
			return $file;
		}
		$locale  = determine_locale();
		$bundled = self::bundled_locale( $locale );
		$prefix  = self::DOMAIN . '-' . $locale . '-';
		$name    = basename( $file );
		if ( null === $bundled || $bundled === $locale || ! str_starts_with( $name, $prefix ) ) {
			return $file;
		}
		$candidate = AKLA_DIR . 'languages/' . self::DOMAIN . '-' . $bundled . '-' . substr( $name, strlen( $prefix ) );
		return is_readable( $candidate ) ? $candidate : $file;
	}

	/**
	 * Translate an existing catalog code; preserve unknown values without guessing.
	 *
	 * @param string $code Source code, retained separately as the submitted value.
	 * @return string Plain label; callers must escape for their output context.
	 */
	public static function price_unit( $code ) {
		$labels = array(
			'DROP_IN'  => __( 'Single class', 'actikidz-local-activities' ),
			'PACKAGE'  => __( 'Class package', 'actikidz-local-activities' ),
			'MONTHLY'  => __( 'Monthly membership', 'actikidz-local-activities' ),
			'SEMESTER' => __( 'Semester program', 'actikidz-local-activities' ),
			'ANNUAL'   => __( 'Annual membership', 'actikidz-local-activities' ),
			'VARIES'   => __( 'Varies by schedule', 'actikidz-local-activities' ),
		);
		return $labels[ $code ] ?? $code;
	}
}