<?php
/**
 * Loads the bundled German and Spanish translations.
 *
 * The admin screens follow the language each user picked in their WordPress profile: any German
 * variant (de_DE, de_DE_formal, de_AT, de_CH ...) gets German, any Spanish variant gets Spanish,
 * everything else stays English. Visitors on the front end get the site language the same way.
 *
 * @package ForensixDigital
 */

declare(strict_types=1);

namespace ForensixDigital\Core;

defined( 'ABSPATH' ) || exit;

/**
 * Translation loader for Forensix Digital and its add-ons.
 */
final class I18n {

	/**
	 * Languages shipped with the plugins, by language code.
	 *
	 * @var array<string, string>
	 */
	public const LOCALES = array(
		'de' => 'de_DE',
		'es' => 'es_ES',
	);

	/**
	 * Text domains and their languages folders.
	 *
	 * @var array<string, string>
	 */
	private static array $domains = array();

	/**
	 * Whether the hooks are in place.
	 *
	 * @var bool
	 */
	private static bool $hooked = false;

	/**
	 * Registers a text domain whose translations live in the given folder.
	 *
	 * @param string $domain Text domain.
	 * @param string $path   Absolute path of the languages folder.
	 */
	public static function add( string $domain, string $path ): void {
		self::$domains[ $domain ] = untrailingslashit( $path );
		if ( ! self::$hooked ) {
			self::$hooked = true;
			add_filter( 'plugin_locale', array( self::class, 'filter_locale' ), 10, 2 );
			add_filter( 'load_script_translation_file', array( self::class, 'filter_script_file' ), 10, 3 );
			add_action( 'init', array( self::class, 'load' ), 0 );
		}
		if ( did_action( 'init' ) ) {
			self::load_domain( $domain );
		}
	}

	/**
	 * Maps a WordPress locale to one of the shipped languages, or returns it unchanged.
	 *
	 * @param string $locale Locale such as de_DE_formal or es_MX.
	 */
	public static function map( string $locale ): string {
		$language = strtolower( substr( $locale, 0, 2 ) );
		return self::LOCALES[ $language ] ?? $locale;
	}

	/**
	 * Uses the shipped language for our own text domains.
	 *
	 * @param string $locale Locale WordPress picked.
	 * @param string $domain Text domain being loaded.
	 */
	public static function filter_locale( $locale, $domain ): string {
		$locale = (string) $locale;
		return isset( self::$domains[ (string) $domain ] ) ? self::map( $locale ) : $locale;
	}

	/**
	 * Points script translations of our domains at the shipped language file.
	 *
	 * @param string|false $file   Translation file WordPress looks for.
	 * @param string       $handle Script handle.
	 * @param string       $domain Text domain.
	 * @return string|false
	 */
	public static function filter_script_file( $file, $handle, $domain ) {
		if ( ! is_string( $file ) || ! isset( self::$domains[ (string) $domain ] ) ) {
			return $file;
		}
		$locale = determine_locale();
		$mapped = self::map( $locale );
		if ( $mapped === $locale ) {
			return $file;
		}
		return str_replace( '-' . $locale . '-', '-' . $mapped . '-', $file );
	}

	/**
	 * Loads all registered text domains. Hooked to init, priority 0.
	 */
	public static function load(): void {
		foreach ( array_keys( self::$domains ) as $domain ) {
			self::load_domain( $domain );
		}
	}

	/**
	 * Loads one text domain from its languages folder.
	 *
	 * @param string $domain Text domain.
	 */
	private static function load_domain( string $domain ): void {
		$locale = self::map( determine_locale() );
		if ( ! in_array( $locale, self::LOCALES, true ) ) {
			return;
		}
		$file = self::$domains[ $domain ] . '/' . $domain . '-' . $locale . '.mo';
		if ( is_readable( $file ) ) {
			load_textdomain( $domain, $file, $locale );
		}
	}

	/**
	 * Path of the folder that holds a domain's script translations.
	 *
	 * @param string $domain Text domain.
	 */
	public static function path( string $domain ): string {
		return self::$domains[ $domain ] ?? '';
	}
}