<?php

namespace App\Services\Runware;

use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;

/**
 * Keeps a live-ish USD->EUR rate cached for BudgetGuard to convert Runware's
 * USD costs against the EUR monthly cap. Refreshed daily by the scheduler
 * (see routes/console.php); falls back to a static configured rate if no
 * live fetch has ever succeeded, so the cap never stops enforcing.
 */
class CurrencyRateService
{
    protected const CACHE_KEY = 'runware:usd_eur_rate';

    // Refresh runs daily; keep the cached value alive well past that so a
    // single failed fetch doesn't drop back to the fallback rate.
    protected const CACHE_TTL_SECONDS = 60 * 60 * 30;

    public function usdToEur(): float
    {
        return Cache::get(self::CACHE_KEY) ?? (float) config('runware.usd_eur_fallback_rate');
    }

    public function refresh(): ?float
    {
        try {
            $response = Http::timeout(10)->get('https://api.frankfurter.app/latest', [
                'from' => 'USD',
                'to' => 'EUR',
            ]);

            $rate = $response->json('rates.EUR');

            if (! $response->successful() || ! is_numeric($rate)) {
                throw new \RuntimeException('Unexpected FX response: '.$response->body());
            }

            Cache::put(self::CACHE_KEY, (float) $rate, self::CACHE_TTL_SECONDS);

            return (float) $rate;
        } catch (\Throwable $e) {
            Log::warning('Failed to refresh USD/EUR rate, keeping previous cached/fallback value.', [
                'exception' => $e->getMessage(),
            ]);

            return null;
        }
    }
}