<?php

namespace App\Services\Transfer;

use App\Models\QrCode;
use App\Models\Transfer;
use App\Models\TransferDownloadEvent;
use App\Models\TransferFile;
use App\Models\User;
use App\Services\Qr\QrImageGeneratorService;
use App\Support\Qr\QrStyleDefaults;
use Illuminate\Http\Request;
use Illuminate\Http\UploadedFile;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Hash;
use Illuminate\Support\Facades\Storage;
use Illuminate\Support\Str;
use RuntimeException;

class TransferService
{
    public function __construct(
        private QrImageGeneratorService $imageGenerator,
    ) {}

    /**
     * @param  array<string, mixed>  $data
     * @param  list<UploadedFile>  $files
     */
    public function create(User $user, array $data, array $files): Transfer
    {
        if ($files === []) {
            throw new RuntimeException('Add at least one file to share.');
        }

        $maxFiles = (int) config('transfer.max_files_per_transfer', 20);
        if (count($files) > $maxFiles) {
            throw new RuntimeException("You can upload up to {$maxFiles} files per transfer.");
        }

        $maxBytes = (int) config('transfer.max_file_bytes', 0);
        $billingPeriodDays = (int) config('transfer.billing_period_days', 30);

        return DB::transaction(function () use ($user, $data, $files, $maxBytes, $billingPeriodDays) {
            $passwordHash = null;
            if (! empty($data['password'])) {
                $passwordHash = Hash::make((string) $data['password']);
            }

            $recipientEmail = trim((string) ($data['recipient_email'] ?? ''));

            $transfer = Transfer::create([
                'user_id' => $user->id,
                'title' => trim((string) $data['title']),
                'message' => isset($data['message']) ? trim((string) $data['message']) : null,
                'recipient_email' => $recipientEmail !== '' ? $recipientEmail : null,
                'recipient_email_milestones' => $recipientEmail !== '' ? ['created'] : null,
                'recipient_milestones_sent' => [],
                'owner_milestones_sent' => [],
                'password_hash' => $passwordHash,
                'retention_days' => $billingPeriodDays,
                'status' => Transfer::STATUS_ACTIVE,
            ]);

            $totalBytes = 0;
            foreach ($files as $file) {
                if (! $file instanceof UploadedFile) {
                    continue;
                }

                if ($maxBytes > 0 && $file->getSize() > $maxBytes) {
                    throw new RuntimeException($file->getClientOriginalName().' exceeds the maximum file size.');
                }

                $stored = $this->storeFile($user, $transfer, $file);
                $totalBytes += $stored->size_bytes;
            }

            if ($totalBytes === 0) {
                throw new RuntimeException('No valid files were uploaded.');
            }

            $qrCode = $this->createQrCode($user, $transfer, $data);
            $transfer->update([
                'qr_code_id' => $qrCode->id,
                'storage_bytes' => $totalBytes,
            ]);

            $transfer = $transfer->fresh(['files', 'qrCode']);
            app(TransferBillingService::class)->chargeInitialPeriod($transfer, $user);

            $transfer = $transfer->fresh(['files', 'qrCode']);
            app(TransferRecipientMailService::class)->notifyRecipient($transfer, 'created');

            return $transfer;
        });
    }

    public function recordDownload(Transfer $transfer, ?TransferFile $file, Request $request): void
    {
        TransferDownloadEvent::create([
            'transfer_id' => $transfer->id,
            'transfer_file_id' => $file?->id,
            'downloaded_at' => now(),
            'ip_hash' => $request->ip() ? hash('sha256', $request->ip()) : null,
            'user_agent' => Str::limit((string) $request->userAgent(), 500, ''),
        ]);

        $transfer->increment('downloads_total');
        if ($file) {
            $file->increment('downloads_total');
        }
    }

    public function verifyPassword(Transfer $transfer, ?string $password): bool
    {
        if (! $transfer->isPasswordProtected()) {
            return true;
        }

        return $password !== null && Hash::check($password, $transfer->password_hash);
    }

    private function storeFile(User $user, Transfer $transfer, UploadedFile $file): TransferFile
    {
        return $this->storeFileWithName(
            $user,
            $transfer,
            $file,
            $file->getClientOriginalName() ?: ('file.'.($file->getClientOriginalExtension() ?: 'bin')),
        );
    }

    public function addStorageFile(User $user, Transfer $transfer, UploadedFile $file, string $displayName): TransferFile
    {
        $stored = $this->storeFileWithName($user, $transfer, $file, $displayName);
        $transfer->increment('storage_bytes', $stored->size_bytes);

        return $stored;
    }

    private function storeFileWithName(User $user, Transfer $transfer, UploadedFile $file, string $displayName): TransferFile
    {
        $uuid = Str::uuid()->toString();
        $ext = $file->getClientOriginalExtension() ?: 'bin';
        $path = $user->id.'/transfers/'.$transfer->id.'/'.$uuid.'.'.$ext;

        $file->storeAs('', $path, 'qr');

        return TransferFile::create([
            'transfer_id' => $transfer->id,
            'original_name' => $displayName,
            'disk' => 'qr',
            'path' => $path,
            'mime_type' => $file->getMimeType() ?: 'application/octet-stream',
            'size_bytes' => (int) $file->getSize(),
        ]);
    }

    /**
     * @param  array<string, mixed>  $data
     */
    private function createQrCode(User $user, Transfer $transfer, array $data): QrCode
    {
        $shortCode = $this->generateUniqueShortCode();
        $style = QrStyleDefaults::merge($data['style'] ?? null);

        $qrCode = QrCode::create([
            'user_id' => $user->id,
            'short_code' => $shortCode,
            'type' => QrCode::TYPE_TRANSFER,
            'label' => $transfer->title,
            'payload' => [
                'content' => [
                    'transfer_id' => $transfer->id,
                    'message' => $transfer->message,
                ],
                'style' => $style,
            ],
            'is_active' => true,
            'destination_updated_at' => now(),
        ]);

        $this->imageGenerator->generateAndStore($qrCode);

        return $qrCode;
    }

    private function generateUniqueShortCode(): string
    {
        do {
            $code = Str::lower(Str::random(8));
        } while (QrCode::query()->where('short_code', $code)->exists());

        return $code;
    }

    public function delete(Transfer $transfer): void
    {
        DB::transaction(function () use ($transfer) {
            foreach ($transfer->files as $file) {
                Storage::disk($file->disk)->delete($file->path);
            }

            if ($transfer->qrCode) {
                if ($transfer->qrCode->png_path) {
                    Storage::disk('qr')->delete($transfer->qrCode->png_path);
                }
                if ($transfer->qrCode->svg_path) {
                    Storage::disk('qr')->delete($transfer->qrCode->svg_path);
                }
                $transfer->qrCode->update(['is_active' => false]);
            }

            $transfer->update(['status' => Transfer::STATUS_DELETED]);
        });
    }

    public function deleteFile(TransferFile $file): void
    {
        DB::transaction(function () use ($file) {
            $transfer = $file->transfer()->lockForUpdate()->first();
            Storage::disk($file->disk)->delete($file->path);
            $size = $file->size_bytes;
            $file->delete();

            $transfer->decrement('storage_bytes', $size);

            if ($transfer->files()->count() === 0 && ! $transfer->shouldPersistWhenEmpty()) {
                $this->delete($transfer->fresh(['files', 'qrCode']));
            }
        });
    }

    /** @param  list<TransferFile>  $files */
    public function deleteFiles(array $files): void
    {
        foreach ($files as $file) {
            $this->deleteFile($file);
        }
    }

    /** @param  list<TransferFile>  $files */
    public function moveFiles(Transfer $destination, array $files): void
    {
        if ($files === []) {
            return;
        }

        DB::transaction(function () use ($destination, $files) {
            $destination = Transfer::query()->lockForUpdate()->findOrFail($destination->id);
            $movedBytes = 0;
            $sourceAdjustments = [];

            foreach ($files as $file) {
                if ($file->transfer_id === $destination->id) {
                    continue;
                }

                $sourceId = $file->transfer_id;
                $movedBytes += $file->size_bytes;
                $sourceAdjustments[$sourceId] = ($sourceAdjustments[$sourceId] ?? 0) + $file->size_bytes;
                $file->update(['transfer_id' => $destination->id]);
            }

            foreach ($sourceAdjustments as $sourceId => $bytes) {
                Transfer::query()->whereKey($sourceId)->decrement('storage_bytes', $bytes);
                $source = Transfer::query()->with('files')->find($sourceId);
                if ($source && $source->files->isEmpty() && $source->status !== Transfer::STATUS_DELETED && ! $source->shouldPersistWhenEmpty()) {
                    $this->delete($source->fresh(['files', 'qrCode']));
                }
            }

            if ($movedBytes > 0) {
                $destination->increment('storage_bytes', $movedBytes);
            }
        });
    }
}