<?php

namespace App\Actions;

use App\Models\Instance;
use App\Models\Invoice;
use App\Models\Operator;
use App\Models\Subscription;
use App\Models\SubscriptionAddon;
use App\Models\SubscriptionRecord;
use App\Services\Billing\IssueInvoice;
use App\Services\Billing\WithdrawalRight;
use App\Services\Stripe\StripeClient;
use Illuminate\Support\Carbon;
use Illuminate\Support\Facades\Log;
use RuntimeException;
use Throwable;

/**
 * A consumer changes their mind inside fourteen days, and everything that
 * follows from it.
 *
 * One action, because a withdrawal is one event with four consequences and
 * three of them are irreversible. Split across a controller, a command and a
 * page, they would come apart: a service ended with no credit note, a refund
 * sent for a contract still running, a document issued twice by two clicks.
 *
 * In order, and the order is the design:
 *
 *  1. **The right is checked**, by WithdrawalRight and nowhere else. A business
 *     customer is refused here, on the server, whatever the page did or did not
 *     show — every door into this action is the same door.
 *  2. **The withdrawal is claimed**, conditionally, on the contract. Two clicks
 *     in flight write one withdrawal between them; the loser is told it has
 *     already happened rather than sending a second refund.
 *  3. **The paperwork**: the invoice that was issued is CANCELLED by a Storno
 *     with its own number — never edited, never deleted. That is the established
 *     rule for correcting an issued document, and a withdrawal is the clearest
 *     case there is for it.
 *  4. **The money**, which falls out of the paperwork rather than being
 *     computed beside it: the whole of what the cancelled document said. FAGG
 *     §16 would let us keep the pro-rata value of the days the cloud ran, and
 *     the owner has decided not to — a withdrawing consumer gets everything
 *     back. Two sums that must agree cannot disagree if only one of them is
 *     ever calculated, and here there is only the one: the Storno's.
 *  5. **The service ends**, through App\Actions\EndInstanceService and the
 *     `cancellation_scheduled` machinery it already reads — the address comes
 *     down, the DNS record goes, the instance is marked ended. No second way
 *     for an instance to stop being served.
 *
 * ## What happens when the money side fails
 *
 * It is caught, written onto the contract and logged as an error — and the
 * withdrawal still stands. The customer's declaration is what ends the
 * contract; a payment provider being unreachable does not un-declare it, and
 * leaving the service running because a refund timed out would charge them for
 * days they have withdrawn from. `withdrawal_refund_error` is where an operator
 * finds the ones that need a hand.
 */
class WithdrawContract
{
    /** Recorded by the customer themselves, in the portal. */
    public const CHANNEL_PORTAL = 'portal';

    /** Taken by telephone or post and typed in by an operator. */
    public const CHANNEL_OPERATOR = 'operator';

    public function __construct(
        private EndInstanceService $endService,
        private BookAddon $bookAddon,
        private IssueInvoice $invoices,
        private StripeClient $stripe,
        private RecordCommercialEvent $record,
    ) {}

    /**
     * @param  string  $channel  one of the CHANNEL_* constants
     * @param  Operator|null  $by  the operator who took the declaration, when it did not come from the portal
     *
     * @throws RuntimeException with the sentence the customer is shown, when the right does not apply
     */
    public function __invoke(
        Subscription $subscription,
        string $channel = self::CHANNEL_PORTAL,
        ?Operator $by = null,
        ?Carbon $at = null,
    ): Subscription {
        $at ??= now();

        $right = WithdrawalRight::for($subscription);

        if (! $right->open) {
            // The refusal is the customer's own sentence, not a developer's:
            // whatever refuses — the portal, the console, a stale tab — says
            // the same thing, in the same words.
            throw new RuntimeException((string) ($right->refusal ?? __('withdrawal.refusal_expired')));
        }

        // The one atomic gate. Everything below happens exactly once because
        // exactly one caller can turn this column over.
        $claimed = Subscription::query()
            ->whereKey($subscription->getKey())
            ->whereNull('withdrawn_at')
            ->update([
                'withdrawn_at' => $at,
                'withdrawal_channel' => $channel,
                'withdrawal_recorded_by' => $by?->id,
                'updated_at' => now(),
            ]);

        $subscription->refresh();

        if ($claimed === 0) {
            throw new RuntimeException(__('withdrawal.refusal_already'));
        }

        $refunded = $this->settle($subscription, $at);

        $this->endEverything($subscription, $at);

        $this->enterInRegister($subscription, $refunded, $at);

        return $subscription->refresh();
    }

    /**
     * The paperwork and the money.
     *
     * @return int what actually went back to the customer, gross, in cents
     */
    private function settle(Subscription $subscription, Carbon $at): int
    {
        try {
            $original = $this->openingInvoice($subscription);

            // No document was ever issued for this purchase — the company
            // details were incomplete when it was made, or it was a grant. There
            // is nothing to cancel, so the refund is worked out from what was
            // charged instead. Stated here rather than silently skipped: a
            // withdrawal without paperwork is a withdrawal an accountant will
            // ask about.
            if ($original === null) {
                return $this->sendBack($subscription, max(0, $subscription->order?->chargedCents() ?? 0), $at);
            }

            // Taken back in full, with its own gapless number, pointing at the
            // one it cancels. The original keeps its number for ever.
            $storno = $this->invoices->cancelling($original);

            // The refund IS what the cancellation took back — never a second
            // figure computed beside it, which would have to agree with the
            // document and one day would not. The Storno mirrors the original,
            // so this is the whole amount the customer paid.
            return $this->sendBack($subscription, max(0, -(int) $storno->gross_cents), $at);
        } catch (Throwable $e) {
            $this->parkMoneyFailure($subscription, $e);

            return 0;
        }
    }

    /**
     * Put the money back where it came from.
     *
     * Stripe refunds a PAYMENT, not a subscription and not an invoice, so the
     * handle is whatever the checkout reported — a PaymentIntent if there was
     * one, otherwise the invoice that charged the card, resolved through Stripe
     * once. A contract with neither was never paid for through Stripe at all (a
     * grant, a contract opened by hand), and there is nothing to send back.
     */
    private function sendBack(Subscription $subscription, int $grossCents, Carbon $at): int
    {
        $subscription->update(['withdrawal_refund_cents' => $grossCents]);

        if ($grossCents <= 0) {
            return 0;
        }

        $order = $subscription->order;
        $reference = $order?->stripe_payment_intent_id;

        if ($reference === null && $order?->stripe_invoice_id !== null) {
            $reference = $this->stripe->invoicePaymentReference((string) $order->stripe_invoice_id);
        }

        if ($reference === null) {
            throw new RuntimeException(
                'No Stripe payment is recorded for this contract, so the refund has to be sent by hand.'
            );
        }

        $refundId = $this->stripe->refund(
            $reference,
            $grossCents,
            // Keyed on the contract, because a contract is withdrawn from once.
            // A retry after a timeout that in fact went through replays Stripe's
            // first answer rather than sending the money a second time — which
            // is the single most expensive mistake this file could make.
            idempotencyKey: 'clupilot-withdrawal-'.$subscription->uuid,
        );

        $subscription->update([
            'withdrawal_refund_reference' => $refundId,
            'withdrawal_refund_error' => null,
        ]);

        Log::info('Refunded a withdrawal.', [
            'subscription' => $subscription->uuid,
            'refund' => $refundId,
            'gross_cents' => $grossCents,
            'withdrawn_at' => $at->toIso8601String(),
        ]);

        return $grossCents;
    }

    /**
     * A withdrawn contract ends: the modules stop, the address comes down and
     * the contract is closed.
     *
     * Through the machinery that already does this, never beside it. The
     * instance is put into `cancellation_scheduled` with its service ending NOW
     * — which is what a withdrawal means, unlike a cancellation, where the
     * customer keeps the term they paid for — and EndInstanceService is asked
     * the same question it is asked by the nightly sweep.
     *
     * The modules are ended outright rather than at the period end, for the same
     * reason: there is no term left to keep. The customer has withdrawn from the
     * contract the modules hang off, and BookAddon::cancel() takes them off
     * Stripe and out of the register.
     */
    private function endEverything(Subscription $subscription, Carbon $at): void
    {
        foreach (SubscriptionAddon::query()->where('subscription_id', $subscription->id)->active()->get() as $addon) {
            $this->bookAddon->cancel($addon);
        }

        $instance = $this->instanceOf($subscription);

        if ($instance !== null && $instance->status !== 'ended') {
            $instance->update([
                'status' => 'cancellation_scheduled',
                'cancel_requested_at' => $at,
                // Now, not the end of the term. A withdrawal unwinds the
                // contract; there is no paid-up period to run out.
                'service_ends_at' => $at,
            ]);

            ($this->endService)($instance->refresh());
        }

        $subscription->update([
            'status' => 'cancelled',
            'cancelled_at' => $at,
        ]);
    }

    /**
     * The machine this contract pays for.
     *
     * `subscriptions.instance_id` is the link, and it is written when resources
     * are reserved — so a contract withdrawn from before the build got that far
     * has none. The order and then the customer are the fallbacks, in that
     * order, because an order belongs to exactly one purchase and a customer can
     * have more than one instance behind them.
     */
    private function instanceOf(Subscription $subscription): ?Instance
    {
        if ($subscription->instance !== null) {
            return $subscription->instance;
        }

        if ($subscription->order_id !== null) {
            $byOrder = Instance::query()->where('order_id', $subscription->order_id)->latest('id')->first();

            if ($byOrder !== null) {
                return $byOrder;
            }
        }

        return Instance::query()
            ->where('customer_id', $subscription->customer_id)
            ->whereIn('status', ['active', 'provisioning', 'cancellation_scheduled'])
            ->latest('id')
            ->first();
    }

    /**
     * The document issued for the purchase that opened this contract.
     *
     * Cancellations are excluded by construction — one is not an invoice that
     * can be taken back — and so is anything that already has a Storno against
     * it, which IssueInvoice::cancelling() refuses in its own right.
     */
    private function openingInvoice(Subscription $subscription): ?Invoice
    {
        if ($subscription->order_id === null) {
            return null;
        }

        return Invoice::query()
            ->where('order_id', $subscription->order_id)
            ->whereNull('cancels_invoice_id')
            ->orderBy('id')
            ->first();
    }

    /**
     * The refund did not go out. Said on the contract, not only in a log.
     *
     * What this describes is a customer who has withdrawn, whose service has
     * stopped, and who has not had their money back — the one state nobody may
     * discover from a log file three weeks later.
     */
    private function parkMoneyFailure(Subscription $subscription, Throwable $e): void
    {
        Log::error('A withdrawal was declared but the money did not go back.', [
            'subscription' => $subscription->uuid,
            'customer' => $subscription->customer_id,
            'error' => $e->getMessage(),
        ]);

        $subscription->update([
            'withdrawal_refund_error' => mb_substr($e->getMessage(), 0, 250),
        ]);
    }

    /**
     * The entry that says this happened, in the register that cannot be edited.
     *
     * Negative, because it is revenue leaving. The gross is what actually went
     * back, so a withdrawal that could not be refunded records a zero and the
     * `withdrawal_refund_error` beside it says why — rather than claiming money
     * moved that did not.
     */
    private function enterInRegister(Subscription $subscription, int $refundedGross, Carbon $at): void
    {
        ($this->record)(
            event: SubscriptionRecord::EVENT_WITHDRAWAL,
            subscription: $subscription->refresh(),
            netCents: -(int) $subscription->price_cents,
            at: $at,
            extra: ['withdrawal' => [
                'channel' => $subscription->withdrawal_channel,
                // Nothing is charged for them — the refund is the whole amount —
                // but how long the service actually ran is a fact about this
                // contract, and the register is where facts about it are kept.
                'delivered_days' => WithdrawalRight::deliveredDays($subscription, $at),
                'term_days' => WithdrawalRight::termDays($subscription),
                'refunded_gross_cents' => $refundedGross,
            ]],
            chargedGrossCents: -$refundedGross,
            eventKey: 'withdrawal:'.$subscription->uuid,
        );
    }
}