<?php

declare(strict_types=1);

namespace EKSRelay\Core;

/**
 * Maps WPML language codes to ISO 4217 currency codes.
 *
 * Used to resolve the correct shop currency based on the detected language
 * of the customer's message. Handles fallback to EUR for currencies that are
 * not configured in the shop's multicurrency plugin.
 *
 * Supported currencies are read from the STORE_CURRENCIES env variable
 * (comma-separated ISO 4217 codes). Default matches the shop configuration.
 */
final class StoreLocales
{
    /**
     * WPML language code → natural ISO 4217 currency code.
     * Based on the official currency of the country/region for each language.
     */
    private const CURRENCY_MAP = [
        'aed'   => 'AED',  // Arabic (UAE) → UAE Dirham
        'be'    => 'BYN',  // Belarusian → Belarusian ruble (not in shop → fallback)
        'bg'    => 'BGN',  // Bulgarian → Bulgarian lev
        'hr'    => 'EUR',  // Croatian → Euro (adopted 2023)
        'cs'    => 'CZK',  // Czech → Czech koruna
        'da'    => 'DKK',  // Danish → Danish krone
        'nl'    => 'EUR',  // Dutch → Euro
        'en'    => 'EUR',  // English → Euro (default for EU context)
        'et'    => 'EUR',  // Estonian → Euro
        'fi'    => 'EUR',  // Finnish → Euro
        'fr'    => 'EUR',  // French → Euro
        'de'    => 'EUR',  // German → Euro
        'el'    => 'EUR',  // Greek → Euro
        'hu'    => 'HUF',  // Hungarian → Hungarian forint
        'it'    => 'EUR',  // Italian → Euro
        'lv'    => 'EUR',  // Latvian → Euro
        'lt'    => 'EUR',  // Lithuanian → Euro
        'no'    => 'NOK',  // Norwegian → Norwegian krone
        'pl'    => 'PLN',  // Polish → Polish złoty
        'pt-pt' => 'EUR',  // Portuguese (Portugal) → Euro
        'ro'    => 'RON',  // Romanian → Romanian leu
        'sk'    => 'EUR',  // Slovak → Euro
        'sl'    => 'EUR',  // Slovenian → Euro
        'es'    => 'EUR',  // Spanish → Euro
        'sv'    => 'SEK',  // Swedish → Swedish krona
        'tr'    => 'TRY',  // Turkish → Turkish lira (not in shop → fallback)
        'uk'    => 'UAH',  // Ukrainian → Ukrainian hryvnia (not in shop → fallback)
    ];

    /** Fallback currency used when the natural currency is not supported. */
    public const FALLBACK_CURRENCY = 'EUR';

    /**
     * Default list of currencies configured in the shop's multicurrency plugin.
     * Used when STORE_CURRENCIES env variable is not set.
     * Keep in sync with WooCommerce multicurrency configuration.
     */
    private const DEFAULT_SUPPORTED = 'PLN,EUR,AED,CZK,HUF,DKK,SEK,NOK,RON,BGN,GBP';

    /**
     * Resolve a WPML language code to a shop-supported ISO 4217 currency.
     *
     * Returns an array with:
     *   currency         — ISO 4217 code to pass to the WooCommerce API
     *   fallback         — true if we had to fall back from the natural currency
     *   natural_currency — (only when fallback=true) the natural currency for the language
     *   reason           — (only when fallback=true) 'unknown_language' | 'unsupported_currency'
     *
     * @param string|null $language WPML language code (e.g. 'de', 'pl', 'pt-pt')
     */
    public static function resolve(?string $language): array
    {
        if ($language === null || $language === '') {
            return ['currency' => self::FALLBACK_CURRENCY, 'fallback' => false];
        }

        $lang    = strtolower(trim($language));
        $natural = self::CURRENCY_MAP[$lang] ?? null;

        if ($natural === null) {
            return [
                'currency' => self::FALLBACK_CURRENCY,
                'fallback' => true,
                'reason'   => 'unknown_language',
            ];
        }

        if (!in_array($natural, self::supportedCurrencies(), true)) {
            return [
                'currency'         => self::FALLBACK_CURRENCY,
                'fallback'         => true,
                'reason'           => 'unsupported_currency',
                'natural_currency' => $natural,
            ];
        }

        return ['currency' => $natural, 'fallback' => false];
    }

    /**
     * Check whether a currency code is supported by the shop's multicurrency configuration.
     *
     * @param string $currency ISO 4217 code (comparison is case-insensitive)
     */
    public static function isSupported(string $currency): bool
    {
        return in_array(strtoupper($currency), self::supportedCurrencies(), true);
    }

    /**
     * @return string[]
     */
    private static function supportedCurrencies(): array
    {
        $raw = Env::get('STORE_CURRENCIES', self::DEFAULT_SUPPORTED);
        return array_values(array_filter(array_map('trim', explode(',', strtoupper($raw)))));
    }
}