<?php

namespace App\Services\Events;

use App\Models\QrCode;
use App\Models\QrEventRegistration;
use App\Services\Billing\BillingClient;
use App\Services\Billing\PaystackService;
use App\Services\Billing\SmsService;
use App\Services\Events\EventEmailService;
use App\Services\Meet\EventMeetAccessService;
use App\Services\Pay\PayClient;
use App\Support\LadillLink;
use Illuminate\Support\Str;
use RuntimeException;

class EventRegistrationService
{
    public function __construct(
        private PayClient $pay,
        private PaystackService $paystack,
        private BillingClient $billing,
        private SmsService $sms,
        private EventEmailService $email,
        private EventMeetAccessService $meetAccess,
    ) {}

    /**
     * Register an attendee. Free tiers confirm instantly; paid tiers return a
     * Paystack checkout URL and stay pending until payment completes.
     *
     * @param  array<string, mixed>  $data
     * @return array{registration: QrEventRegistration, paid: bool, checkout_url: ?string}
     */
    public function register(QrCode $qrCode, array $data): array
    {
        $content = $qrCode->content();

        $mode = ($content['mode'] ?? 'ticketing') === 'contributions' ? 'contributions' : 'ticketing';

        if (empty($content['registration_open'])) {
            throw new RuntimeException($mode === 'contributions'
                ? 'Contributions for this event are closed.'
                : 'Registration for this event is closed.');
        }

        $tierName = trim((string) ($data['tier'] ?? ''));
        $tier = null;
        if ($mode === 'contributions') {
            if (! in_array($tierName, $content['contribution_categories'] ?? [], true)) {
                throw new RuntimeException('Select a valid contribution category.');
            }
        } else {
            $tier = collect($content['tiers'] ?? [])->firstWhere('name', $tierName);
            if (! $tier) {
                throw new RuntimeException('Select a valid ticket type.');
            }
        }

        $name = trim((string) ($data['attendee_name'] ?? ''));
        if ($name === '') {
            throw new RuntimeException('Enter your full name.');
        }
        $email = trim((string) ($data['attendee_email'] ?? ''));
        if ($email === '' || ! str_contains($email, '@')) {
            throw new RuntimeException('Enter a valid email address.');
        }

        if ($mode === 'ticketing') {
            $capacity = (int) ($tier['capacity'] ?? 0);
            if ($capacity > 0) {
                $taken = QrEventRegistration::query()
                    ->where('qr_code_id', $qrCode->id)
                    ->where('tier_name', $tierName)
                    ->where('status', QrEventRegistration::STATUS_CONFIRMED)
                    ->count();
                if ($taken >= $capacity) {
                    throw new RuntimeException('Sorry, "'.$tierName.'" is sold out.');
                }
            }
        }

        $badgeFields = [];
        foreach ($content['badge_fields'] ?? [] as $label) {
            $value = trim((string) (($data['badge_fields'] ?? [])[$label] ?? ''));
            if ($value !== '') {
                $badgeFields[$label] = mb_substr($value, 0, 120);
            }
        }

        if ($mode === 'contributions') {
            $priceGhs = round((float) ($data['amount'] ?? 0), 2);
            if ($priceGhs <= 0) {
                throw new RuntimeException('Enter a contribution amount.');
            }
        } else {
            $priceGhs = round((float) ($tier['price'] ?? 0), 2);
        }
        $amountMinor = (int) round($priceGhs * 100);

        $meetReturn = trim((string) ($data['meet_return'] ?? ''));
        $metadata = $meetReturn !== '' ? ['meet_return' => $meetReturn] : null;

        $registration = QrEventRegistration::create([
            'qr_code_id' => $qrCode->id,
            'user_id' => $qrCode->user_id,
            'reference' => 'QRE-'.strtoupper(Str::random(16)),
            'badge_code' => $this->uniqueBadgeCode(),
            'tier_name' => $tierName,
            'amount_minor' => $amountMinor,
            'currency' => $content['currency'] ?? 'GHS',
            'attendee_name' => mb_substr($name, 0, 120),
            'attendee_email' => $email,
            'attendee_phone' => trim((string) ($data['attendee_phone'] ?? '')) ?: null,
            'badge_fields' => $badgeFields ?: null,
            'status' => $amountMinor > 0 ? QrEventRegistration::STATUS_PENDING : QrEventRegistration::STATUS_CONFIRMED,
            'metadata' => $metadata,
        ]);

        if ($amountMinor === 0) {
            $this->notifyConfirmed($registration->fresh('qrCode'));

            return ['registration' => $registration, 'paid' => false, 'checkout_url' => null];
        }

        $qrCode->loadMissing('user');
        $feeTier = $mode === 'contributions' ? 'donations' : 'sales';
        $lineName = $mode === 'contributions'
            ? sprintf('%s — %s', $content['name'] ?? $qrCode->label, $tierName)
            : sprintf('%s ticket — %s', $content['name'] ?? $qrCode->label, $tierName);

        $payOrder = $this->pay->createCheckout([
            'merchant' => $qrCode->user->public_id,
            'fee_tier' => $feeTier,
            'source_service' => 'events',
            'source_ref' => (string) $qrCode->id,
            'callback_url' => LadillLink::path($qrCode->short_code, 'register/callback'),
            'customer_name' => $registration->attendee_name,
            'customer_email' => $email,
            'customer_phone' => $registration->attendee_phone,
            'line_items' => [
                [
                    'name' => $lineName,
                    'unit_price_minor' => $amountMinor,
                    'quantity' => 1,
                ],
            ],
            'metadata' => [
                'registration_id' => $registration->id,
                'registration_reference' => $registration->reference,
                'qr_code_id' => $qrCode->id,
                'mode' => $mode,
            ],
        ]);

        $registration->update([
            'pay_order_id' => $payOrder['id'] ?? null,
            'payment_reference' => $payOrder['reference'],
        ]);

        $checkoutUrl = (string) ($payOrder['checkout_url'] ?? '');
        if ($checkoutUrl === '') {
            throw new RuntimeException('Could not start checkout. Please try again.');
        }

        return [
            'registration' => $registration->fresh(),
            'paid' => true,
            'checkout_url' => $checkoutUrl,
        ];
    }

    public function complete(string $reference): QrEventRegistration
    {
        if (str_starts_with($reference, 'LP-')) {
            return $this->completeLadillPay($reference);
        }

        return $this->completeLegacy($reference);
    }

    private function completeLadillPay(string $reference): QrEventRegistration
    {
        $registration = QrEventRegistration::where('payment_reference', $reference)
            ->where('status', QrEventRegistration::STATUS_PENDING)
            ->firstOrFail();

        $payOrder = $this->pay->verify($reference);
        $platformFeeGhs = ((int) ($payOrder['platform_fee_minor'] ?? 0)) / 100;

        $registration->update([
            'status' => QrEventRegistration::STATUS_CONFIRMED,
            'paid_at' => now(),
            'pay_order_id' => $payOrder['id'] ?? $registration->pay_order_id,
            'metadata' => array_merge((array) $registration->metadata, [
                'ladill_pay' => $payOrder,
                'platform_fee_ghs' => $platformFeeGhs,
            ]),
        ]);

        $this->notifyConfirmed($registration->fresh('qrCode'));

        return $registration;
    }

    /** Legacy QREP-* references before Ladill Pay migration. */
    private function completeLegacy(string $reference): QrEventRegistration
    {
        $registration = QrEventRegistration::where('payment_reference', $reference)
            ->where('status', QrEventRegistration::STATUS_PENDING)
            ->firstOrFail();

        $data = $this->paystack->verifyTransaction($reference);

        if (($data['status'] ?? '') !== 'success') {
            $registration->update(['status' => QrEventRegistration::STATUS_FAILED]);
            throw new RuntimeException('Payment was not successful.');
        }

        $feeRate = ($registration->qrCode?->content()['mode'] ?? 'ticketing') === 'contributions' ? 0.035 : 0.055;
        $paidAmount = round(($data['amount'] ?? 0) / 100, 2);
        $platformFee = round($paidAmount * $feeRate, 2);

        $organizerAmountMinor = (int) round(($paidAmount - $platformFee) * 100);

        $registration->update([
            'status' => QrEventRegistration::STATUS_CONFIRMED,
            'paid_at' => now(),
            'metadata' => array_merge((array) $registration->metadata, [
                'paystack' => $data,
                'platform_fee_ghs' => $platformFee,
                'legacy' => true,
            ]),
        ]);

        $mode = ($registration->qrCode->content()['mode'] ?? 'ticketing') === 'contributions' ? 'contributions' : 'ticketing';
        $this->billing->credit(
            $registration->organizer->public_id,
            $organizerAmountMinor,
            'events',
            'pay',
            $reference,
            $registration->id,
            sprintf(
                '%s — %s (%s)',
                $mode === 'contributions' ? 'Event contribution' : 'Event ticket',
                $registration->qrCode->label,
                $registration->tier_name
            ),
        );

        $this->notifyConfirmed($registration->fresh('qrCode'));

        return $registration;
    }

    private function notifyConfirmed(QrEventRegistration $registration): void
    {
        $registration->loadMissing('qrCode.user');

        $ownerPublicId = (string) $registration->qrCode?->user?->public_id;
        if ($ownerPublicId === '') {
            return;
        }

        $content = $registration->qrCode?->content() ?? [];
        $eventName = $content['name'] ?? $registration->qrCode?->label ?? config('app.name');
        $firstName = explode(' ', $registration->attendee_name)[0];
        $joinUrl = $this->nextVirtualJoinUrl($content);

        if ($registration->attendee_email) {
            $this->email->sendRegistrationConfirmation(
                $ownerPublicId,
                $registration->attendee_email,
                $eventName,
                $registration->badge_code,
                $joinUrl !== '' ? $joinUrl : null,
                $registration->attendee_name,
                $registration->qrCode?->user?->email,
                $registration->qrCode?->user?->name,
            );
        }

        if ($registration->attendee_phone) {
            if (($content['mode'] ?? 'ticketing') === 'contributions') {
                $message = sprintf(
                    'Hi %s, thank you for your %s of %s %s to %s. Ref: %s',
                    $firstName,
                    $registration->tier_name,
                    $registration->currency,
                    number_format($registration->amountCedis(), 2),
                    $eventName,
                    $registration->badge_code
                );
            } else {
                $message = sprintf(
                    'Hi %s, you are registered for %s (%s). Badge code: %s',
                    $firstName,
                    $eventName,
                    $registration->tier_name,
                    $registration->badge_code
                );
            }

            if ($joinUrl !== '') {
                $message .= ' Join: '.$joinUrl;
            }

            $this->sms->send(
                $ownerPublicId,
                $registration->attendee_phone,
                $message,
            );
        }

        $this->meetAccess->syncRegistration($registration->fresh());
    }

    /** @param  array<string, mixed>  $content */
    private function nextVirtualJoinUrl(array $content): string
    {
        $format = (string) ($content['format'] ?? 'in_person');
        if (! in_array($format, ['virtual', 'hybrid'], true)) {
            return '';
        }

        foreach ((array) ($content['virtual_sessions'] ?? []) as $session) {
            if (! is_array($session)) {
                continue;
            }

            $joinUrl = trim((string) ($session['join_url'] ?? ''));
            if ($joinUrl !== '') {
                return $joinUrl;
            }
        }

        return '';
    }

    private function uniqueBadgeCode(): string
    {
        do {
            $code = strtoupper(Str::random(8));
        } while (QrEventRegistration::where('badge_code', $code)->exists());

        return $code;
    }
}