<?php
declare(strict_types=1);

namespace Payments;

/**
 * Findet den Anbieter zu einem payment_methods.module.
 *
 * Konvention: core/payments/providers/<module>/Provider.php mit Klasse
 *   Payments\Providers\<Module in StudlyCase>\Provider
 * Beispiel: module 'paypal_v2' -> Payments\Providers\PaypalV2\Provider
 *
 * Neuer Anbieter = neues Verzeichnis, sonst nichts.
 */
final class Registry
{
    /** @var array<string,ProviderInterface|null> */
    private static array $cache = [];

    public static function has(string $module): bool
    {
        $module = self::clean($module);
        return $module !== '' && \is_file(self::dir($module) . '/Provider.php');
    }

    public static function get(string $module, object $base): ?ProviderInterface
    {
        $module = self::clean($module);
        if ($module === '') {
            return null;
        }
        if (\array_key_exists($module, self::$cache)) {
            return self::$cache[$module];
        }
        $file = self::dir($module) . '/Provider.php';
        if (!\is_file($file)) {
            return self::$cache[$module] = null;
        }
        self::requireCore();
        require_once $file;
        $class = 'Payments\\Providers\\' . self::studly($module) . '\\Provider';
        if (!\class_exists($class)) {
            \error_log('Payments: Provider-Klasse fehlt: ' . $class);
            return self::$cache[$module] = null;
        }
        $p = new $class($base);
        return self::$cache[$module] = ($p instanceof ProviderInterface ? $p : null);
    }

    /** Alle installierten Anbieter (fuer Backend-Liste und Abgleicher). @return list<string> */
    public static function all(): array
    {
        $out = [];
        foreach (\glob(__DIR__ . '/providers/*/Provider.php') ?: [] as $f) {
            $out[] = \basename(\dirname($f));
        }
        \sort($out);
        return $out;
    }

    public static function requireCore(): void
    {
        foreach (['ProviderInterface', 'Result', 'Secrets', 'Log', 'Overview', 'AbstractProvider'] as $c) {
            require_once __DIR__ . '/' . $c . '.php';
        }
    }

    private static function dir(string $module): string
    {
        return __DIR__ . '/providers/' . $module;
    }

    private static function clean(string $module): string
    {
        return \preg_match('/^[a-z0-9_]+$/', $module) ? $module : '';
    }

    private static function studly(string $module): string
    {
        return \str_replace('_', '', \ucwords($module, '_'));
    }
}

// Wer die Registry laedt, bekommt die Kernklassen gleich mit (Secrets, Log, Result ...),
// nicht erst beim ersten Provider. Sonst faellt z.B. der Zahlart-Editor um, der nur
// Secrets braucht.
Registry::requireCore();