<?php

namespace App\Services\Billing;

use App\Enums\CreditTransactionType;
use App\Enums\SinglePurchaseStatus;
use App\Models\CreditTopup;
use App\Models\User;
use Illuminate\Support\Facades\DB;

/**
 * Wallet-Aufladung über Credit-Pakete (Stripe). Der Kauf wird als Pending-
 * CreditTopup angelegt und nach Zahlungseingang (Webhook) der Wallet
 * gutgeschrieben — idempotent über die `credited_at`-Marke.
 */
class CreditTopupService
{
    public function __construct(private readonly CreditWalletService $wallet) {}

    /**
     * Verfügbare Credit-Pakete aus der Config.
     *
     * @return list<array{key: string, price_cents: int, credits: int}>
     */
    public function packs(): array
    {
        return array_values(config('credits.packs', []));
    }

    /**
     * @return array{key: string, price_cents: int, credits: int}|null
     */
    public function findPack(string $key): ?array
    {
        foreach ($this->packs() as $pack) {
            if ($pack['key'] === $key) {
                return $pack;
            }
        }

        return null;
    }

    /**
     * Legt einen Pending-Topup für ein Paket an (vor dem Stripe-Checkout).
     */
    public function startTopup(User $user, string $packKey): CreditTopup
    {
        $pack = $this->findPack($packKey);

        if (! $pack) {
            throw new \InvalidArgumentException("Unbekanntes Credit-Paket: {$packKey}.");
        }

        return $user->creditTopups()->create([
            'pack_key' => $pack['key'],
            'credits' => $pack['credits'],
            'price_cents' => $pack['price_cents'],
            'currency' => config('billing.default_currency'),
            'status' => SinglePurchaseStatus::Pending,
        ]);
    }

    /**
     * Schreibt einen bezahlten Topup der Wallet gut. Idempotent: bereits
     * gutgeschriebene Topups (credited_at gesetzt) werden übersprungen.
     */
    public function fulfill(CreditTopup $topup, ?string $sessionId = null, ?string $paymentIntentId = null): void
    {
        if ($topup->credited_at !== null) {
            return;
        }

        DB::transaction(function () use ($topup, $sessionId, $paymentIntentId): void {
            $topup->update([
                'status' => SinglePurchaseStatus::Paid,
                'paid_at' => $topup->paid_at ?? now(),
                'credited_at' => now(),
                'stripe_checkout_session_id' => $sessionId ?? $topup->stripe_checkout_session_id,
                'stripe_payment_intent_id' => $paymentIntentId ?? $topup->stripe_payment_intent_id,
            ]);

            $this->wallet->credit(
                $topup->user,
                $topup->credits,
                CreditTransactionType::Topup,
                "Credit-Paket {$topup->pack_key}",
                $topup,
            );
        });
    }
}