<?php

namespace App\Services\Events;

use App\Models\QrCode;
use App\Models\QrEventRegistration;
use App\Models\UserWalletTransaction;
use App\Services\Billing\PaystackService;
use App\Services\Billing\SmsService;
use App\Services\Billing\WalletService;
use Illuminate\Support\Str;
use RuntimeException;

class EventRegistrationService
{
    /** Platform fee on paid ticket sales. */
    public const PLATFORM_FEE_RATE_TICKETING = 0.15;

    /** Reduced platform fee on contribution / donation funds. */
    public const PLATFORM_FEE_RATE_CONTRIBUTIONS = 0.09;

    public function __construct(
        private PaystackService $paystack,
        private WalletService $wallet,
        private SmsService $sms,
    ) {}

    /**
     * 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.');
        }

        // Capacity guard (0 = unlimited) — ticketing only.
        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);

        $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,
        ]);

        // Free ticket — done.
        if ($amountMinor === 0) {
            $this->notifyConfirmed($registration->fresh('qrCode'));

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

        // Paid ticket — start Paystack.
        $reference = 'QREP-' . strtoupper(Str::random(16));
        $registration->update(['payment_reference' => $reference]);

        $paystackData = $this->paystack->initializeTransaction([
            'email'        => $email,
            'amount'       => $amountMinor,
            'currency'     => $registration->currency,
            'reference'    => $reference,
            'callback_url' => route('qr.public.event.callback', ['shortCode' => $qrCode->short_code]),
            'metadata'     => [
                'registration_id' => $registration->id,
                'qr_code_id'      => $qrCode->id,
                'merchant_id'     => $qrCode->user_id,
                'attendee_name'   => $registration->attendee_name,
                'attendee_email'  => $email,
            ],
        ]);

        return [
            'registration' => $registration,
            'paid'         => true,
            'checkout_url' => 'https://checkout.paystack.com/' . $paystackData['access_code'],
        ];
    }

    public function complete(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'
            ? self::PLATFORM_FEE_RATE_CONTRIBUTIONS
            : self::PLATFORM_FEE_RATE_TICKETING;

        $paidAmount = round(($data['amount'] ?? 0) / 100, 2);
        $platformFee = round($paidAmount * $feeRate, 2);
        $organizerAmount = round($paidAmount - $platformFee, 2);

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

        $this->wallet->credit(
            $registration->organizer,
            $organizerAmount,
            UserWalletTransaction::SOURCE_SERVICE_TRANSFER,
            $reference,
            sprintf(
                '%s — %s (%s)',
                ($registration->qrCode->content()['mode'] ?? 'ticketing') === 'contributions' ? 'Event contribution' : 'Event ticket',
                $registration->qrCode->label,
                $registration->tier_name
            ),
            [
                'source'          => 'qr_event',
                'registration_id' => $registration->id,
                'qr_code_id'      => $registration->qr_code_id,
                'platform_fee_ghs' => $platformFee,
            ]
        );

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

        return $registration;
    }

    private function notifyConfirmed(QrEventRegistration $registration): void
    {
        if (! $registration->attendee_phone) {
            return;
        }

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

        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
            );
        }

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

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

        return $code;
    }
}