<?php
declare(strict_types=1);
namespace KTXM\ServiceWopi\Preview;

use Imagick;
use KTXC\Context\TenantContextInterface;
use KTXF\Preview\MimeType;
use KTXF\Preview\PreviewGenerationException;
use KTXF\Preview\PreviewRequest;
use KTXF\Preview\PreviewResult;
use KTXF\Preview\PreviewSource;
use KTXF\Preview\Provider\PreviewProviderInterface;
use KTXF\Resource\BinaryResource;
use KTXF\Resource\Provider\ProviderInterface;
use KTXM\ProviderPreviewImageMagick\Provider as ImageProvider;
use KTXM\ServiceWopi\Host\WopiService;
use Throwable;

final class Provider implements PreviewProviderInterface
{
    public function __construct(
        private readonly TenantContextInterface $tenant,
        private readonly WopiService $wopi,
        private readonly ConversionClient $client,
        private readonly ImageProvider $images,
    ) {}

    public function type(): string { return ProviderInterface::TYPE_PREVIEW; }
    public function identifier(): string { return 'wopi'; }
    public function label(): string { return 'WOPI Office'; }
    public function description(): string { return 'Generates first-page previews using the configured office server'; }
    public function icon(): string { return 'file-document'; }
    public function priority(): int { return 100; }

    public function supports(string $sourceMimeType, PreviewRequest $request): bool
    {
        try {
            if (!class_exists(Imagick::class)
                || !in_array(MimeType::normalize($sourceMimeType), WopiService::FORMATS, true)
                || !$this->images->supports('image/png', $request)) {
                return false;
            }
            $this->wopi->configuration($this->tenant->requireIdentifier());
            return true;
        } catch (Throwable) {
            return false;
        }
    }

    public function generate(PreviewSource $source, PreviewRequest $request): PreviewResult
    {
        if (!$this->supports($source->mimeType, $request)) {
            throw new PreviewGenerationException('WOPI does not support the requested preview conversion');
        }
        $config = $this->wopi->configuration($this->tenant->requireIdentifier());
        $limit = min($request->maxSourceSize, $config->maxBytes);
        if ($source->size !== null && $source->size > $limit) {
            throw new PreviewGenerationException('Preview source exceeds the configured size limit');
        }
        $content = '';
        foreach ($source->open()->stream() as $chunk) {
            if (!is_string($chunk) || strlen($content) + strlen($chunk) > $limit) {
                throw new PreviewGenerationException('Invalid or oversized preview source');
            }
            $content .= $chunk;
        }
        if ($content === '') { throw new PreviewGenerationException('Preview source is empty'); }

        $pdf = $this->client->pdf($config->office, $content, array_search($source->mimeType, WopiService::FORMATS, true), $source->mimeType);
        $file = tmpfile();
        if ($file === false) { throw new PreviewGenerationException('Cannot create preview temporary file'); }
        $image = new Imagick();
        try {
            if (fwrite($file, $pdf) !== strlen($pdf)) {
                throw new PreviewGenerationException('Cannot write preview temporary file');
            }
            $image->setResolution(96, 96);
            $image->readImage('pdf:' . stream_get_meta_data($file)['uri'] . '[0]');
            $image->setImageFormat('png');
            $png = $image->getImageBlob();
            return $this->images->generate(new PreviewSource(
                $source->sourceType, $source->identity, $source->signature, 'image/png', strlen($png),
                static fn () => new BinaryResource('page.png', 'image/png', (static function () use ($png): \Generator { yield $png; })()),
            ), new PreviewRequest($request->maxWidth, $request->maxHeight, $request->preferredMimeType, $request->quality, ConversionClient::MAX_RESPONSE_BYTES));
        } catch (Throwable $error) {
            throw new PreviewGenerationException('Could not render the office preview', previous: $error);
        } finally {
            $image->clear();
            fclose($file);
        }
    }
}