<?php

namespace BookStack\Exports;

use BookStack\Exceptions\PdfExportException;

use Dompdf\Dompdf;

use FontLib\Font;

use Illuminate\Support\Str;

use Knp\Snappy\Pdf as SnappyPdf;

use Symfony\Component\Process\Exception\ProcessTimedOutException;

use Symfony\Component\Process\Process;

class PdfGenerator

{

const ENGINE_DOMPDF = 'dompdf';

const ENGINE_WKHTML = 'wkhtml';

const ENGINE_COMMAND = 'command';

/**

* Generate PDF content from the given HTML content.

* @throws PdfExportException

*/

public function fromHtml(string $html): string

{

return match ($this->getActiveEngine()) {

self::ENGINE_COMMAND => $this->renderUsingCommand($html),

self::ENGINE_WKHTML => $this->renderUsingWkhtml($html),

default => $this->renderUsingDomPdf($html)

};

}

/**

* Get the currently active PDF engine.

* Returns the value of an `ENGINE_` const on this class.

*/

public function getActiveEngine(): string

{

if (config('exports.pdf_command')) {

return self::ENGINE_COMMAND;

}

if ($this->getWkhtmlBinaryPath() && config('app.allow_untrusted_server_fetching') === true) {

return self::ENGINE_WKHTML;

}

return self::ENGINE_DOMPDF;

}

protected function getWkhtmlBinaryPath(): string

{

$wkhtmlBinaryPath = config('exports.snappy.pdf_binary');

if (file_exists(base_path('wkhtmltopdf'))) {

$wkhtmlBinaryPath = base_path('wkhtmltopdf');

}

return $wkhtmlBinaryPath ?: '';

}

protected function renderUsingDomPdf(string $html): string

{

$options = config('exports.dompdf');

$domPdf = new Dompdf($options);

$domPdf->setBasePath(base_path('public'));

$fontMetrics = $domPdf->getFontMetrics();

$userFontfamilies = $this->getUserDomPdfFontFamilies();

foreach ($userFontfamilies as $fontFamily => $fonts) {

try {

$fontMetrics->setFontFamily($fontFamily, $fonts);

} catch (\Exception $exception) {

$expectedPath = storage_path('fonts/dompdf');

throw new PdfExportException("Failed to create required font data in {$expectedPath}, Ensure all content in this location is writable by the web server");

}

}

$domPdf->loadHTML($this->convertEntities($html));

$domPdf->render();

return (string) $domPdf->output();

}

/**

* @return array<string, array<string, string>>

*/

protected function getUserDomPdfFontFamilies(): array

{

$fontStore = storage_path('fonts/dompdf');

if (!is_dir($fontStore)) {

return [];

}

$fontFamilies = [];

$fontFiles = glob($fontStore . DIRECTORY_SEPARATOR . '*.ttf');

foreach ($fontFiles as $fontFile) {

$fontFileName = basename($fontFile, '.ttf');

$expectedUfm = $fontStore . DIRECTORY_SEPARATOR . $fontFileName . '.ufm';

if (!file_exists($expectedUfm)) {

$font = Font::load($fontFile);

$font->parse();

try {

$font->saveAdobeFontMetrics($expectedUfm);

} catch (\Exception $exception) {

throw new PdfExportException("Failed to create required font data at $expectedUfm, Ensure this location is writable by the web server");

}

}

$nameParts = explode('-', $fontFileName);

if (count($nameParts) === 1 || $nameParts[1] === 'Regular') {

$nameParts[1] = 'Normal';

}

$family = trim(strtolower(preg_replace('/([A-Z])/', ' $1', $nameParts[0])));

$variation = Str::snake($nameParts[1]);

if (!isset($fontFamilies[$family])) {

$fontFamilies[$family] = [];

}

$fontFamilies[$family][$variation] = $fontStore . DIRECTORY_SEPARATOR . $fontFileName;

}

return $fontFamilies;

}

/**

* @throws PdfExportException

*/

protected function renderUsingCommand(string $html): string

{

$command = config('exports.pdf_command');

$inputHtml = tempnam(sys_get_temp_dir(), 'bs-pdfgen-html-');

$outputPdf = tempnam(sys_get_temp_dir(), 'bs-pdfgen-output-');

$replacementsByPlaceholder = [

'{input_html_path}' => $inputHtml,

'{output_pdf_path}' => $outputPdf,

];

foreach ($replacementsByPlaceholder as $placeholder => $replacement) {

$command = str_replace($placeholder, escapeshellarg($replacement), $command);

}

file_put_contents($inputHtml, $html);

$timeout = intval(config('exports.pdf_command_timeout'));

$process = Process::fromShellCommandline($command);

$process->setTimeout($timeout);

$cleanup = function () use ($inputHtml, $outputPdf) {

foreach ([$inputHtml, $outputPdf] as $file) {

if (file_exists($file)) {

unlink($file);

}

}

};

try {

$process->run();

} catch (ProcessTimedOutException $e) {

$cleanup();

throw new PdfExportException("PDF Export via command failed due to timeout at {$timeout} second(s)");

}

if (!$process->isSuccessful()) {

$cleanup();

throw new PdfExportException("PDF Export via command failed with exit code {$process->getExitCode()}, stdout: {$process->getOutput()}, stderr: {$process->getErrorOutput()}");

}

$pdfContents = file_get_contents($outputPdf);

$cleanup();

if ($pdfContents === false) {

throw new PdfExportException("PDF Export via command failed, unable to read PDF output file");

} else if (empty($pdfContents)) {

throw new PdfExportException("PDF Export via command failed, PDF output file is empty");

}

return $pdfContents;

}

protected function renderUsingWkhtml(string $html): string

{

$snappy = new SnappyPdf($this->getWkhtmlBinaryPath());

$options = config('exports.snappy.options');

return $snappy->getOutputFromHtml($html, $options);

}

/**

* Taken from https://github.com/barryvdh/laravel-dompdf/blob/v2.1.1/src/PDF.php

* Copyright (c) 2021 barryvdh, MIT License

* https://github.com/barryvdh/laravel-dompdf/blob/v2.1.1/LICENSE

*/

protected function convertEntities(string $subject): string

{

$entities = [

'€' => '&euro;',

'£' => '&pound;',

];

foreach ($entities as $search => $replace) {

$subject = str_replace($search, $replace, $subject);

}

return $subject;

}

}