<?php

namespace App\Services;

use App\Models\Certificate;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\Storage;
use Illuminate\Support\Str;
use RuntimeException;
use ZipArchive;

class CertificateZipper
{
    /**
     * Build a ZIP archive containing the given certificates' files. When a
     * password is given the entries are AES-256 encrypted with it. Returns
     * the absolute path to the created archive; the caller is responsible
     * for deleting it once sent.
     *
     * @param  Collection<int, Certificate>  $certificates
     */
    public function create(Collection $certificates, ?string $password = null): string
    {
        $archivePath = tempnam(sys_get_temp_dir(), 'certs_').'.zip';

        $zip = new ZipArchive;

        if ($zip->open($archivePath, ZipArchive::CREATE | ZipArchive::OVERWRITE) !== true) {
            throw new RuntimeException('Unable to create ZIP archive.');
        }

        if ($password !== null) {
            $zip->setPassword($password);
        }

        $usedNames = [];

        foreach ($certificates as $certificate) {
            if (blank($certificate->file_path) || ! Storage::disk('local')->exists($certificate->file_path)) {
                continue;
            }

            $entryName = $this->uniqueEntryName($certificate, $usedNames);
            $usedNames[] = $entryName;

            $zip->addFromString($entryName, Storage::disk('local')->get($certificate->file_path));

            if ($password !== null) {
                $zip->setEncryptionName($entryName, ZipArchive::EM_AES_256);
            }
        }

        if ($zip->count() === 0) {
            $zip->close();
            @unlink($archivePath);

            throw new RuntimeException('No files were available to add to the archive.');
        }

        $zip->close();

        return $archivePath;
    }

    /**
     * @param  array<int, string>  $usedNames
     */
    private function uniqueEntryName(Certificate $certificate, array $usedNames): string
    {
        $extension = pathinfo($certificate->file_path, PATHINFO_EXTENSION);
        $base = Str::slug($certificate->title) ?: 'certificate';
        $name = $base.'.'.$extension;
        $counter = 1;

        while (in_array($name, $usedNames, true)) {
            $name = $base.'-'.(++$counter).'.'.$extension;
        }

        return $name;
    }
}