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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Class for converting files between different file formats using unoconv.
*
* @package core_files
* @copyright 2017 Damyon Wiese
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core_files;
defined('MOODLE_INTERNAL') || die();
use stored_file;
/**
* Class for converting files between different formats using unoconv.
*
* @package core_files
* @copyright 2017 Damyon Wiese
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class converter {
/**
* Get a list of enabled plugins and classes.
*
* @return array List of enabled plugins
*/
protected function get_enabled_plugins() {
$plugins = \core\plugininfo\fileconverter::get_enabled_plugins();
$pluginclasses = [];
foreach ($plugins as $plugin) {
$pluginclasses[$plugin] = \core\plugininfo\fileconverter::get_classname($plugin);
}
return $pluginclasses;
}
/**
* Return the file_storage API.
*
* This allows for mocking of the file_storage API.
*
* @return \file_storage
*/
protected function get_file_storage() {
return get_file_storage();
}
/**
* Start the conversion for a stored_file into a new format.
*
* @param stored_file $file The file to convert
* @param string $format The desired target file format (file extension)
* @param boolean $forcerefresh If true, the file will be converted every time (not cached).
* @return conversion conversion object
*/
public function start_conversion(stored_file $file, $format, $forcerefresh = false) {
$conversions = conversion::get_conversions_for_file($file, $format);
if ($forcerefresh || count($conversions) > 1) {
while ($conversion = array_shift($conversions)) {
if ($conversion->get('id')) {
$conversion->delete();
}
}
}
if (empty($conversions)) {
$conversion = new conversion(0, (object) [
'sourcefileid' => $file->get_id(),
'targetformat' => $format,
]);
$conversion->create();
} else {
$conversion = array_shift($conversions);
}
if ($conversion->get('status') !== conversion::STATUS_COMPLETE) {
$this->poll_conversion($conversion);
}
return $conversion;
}
/**
* Poll for updates to the supplied conversion.
*
* @param conversion $conversion The conversion in progress
* @return $this
*/
public function poll_conversion(conversion $conversion) {
$format = $conversion->get('targetformat');
$file = $conversion->get_sourcefile();
if ($conversion->get('status') == conversion::STATUS_IN_PROGRESS) {
// The current conversion is in progress.
// Check for updates.
if ($instance = $conversion->get_converter_instance()) {
$instance->poll_conversion_status($conversion);
} else {
// Unable to fetch the converter instance.
// Reset the status back to PENDING so that it may be picked up again.
$conversion->set('status', conversion::STATUS_PENDING);
}
$conversion->update();
}
// Refresh the status.
$status = $conversion->get('status');
if ($status === conversion::STATUS_PENDING || $status === conversion::STATUS_FAILED) {
// The current status is either pending or failed.
// Attempt to pick up a new converter and convert the document.
$from = pathinfo($file->get_filename(), PATHINFO_EXTENSION);
$converters = $this->get_document_converter_classes($from, $format);
$currentconverter = $this->get_next_converter($converters, $conversion->get('converter'));
if (!$currentconverter) {
// No more converters available.
$conversion->set('status', conversion::STATUS_FAILED);
$conversion->update();
return $this;
}
do {
$conversion
->set('converter', $currentconverter)
->set('status', conversion::STATUS_IN_PROGRESS)
->update();
$instance = $conversion->get_converter_instance();
$instance->start_document_conversion($conversion);
$failed = $conversion->get('status') === conversion::STATUS_FAILED;
$currentconverter = $this->get_next_converter($converters, $currentconverter);
} while ($failed && $currentconverter);
$conversion->update();
}
return $this;
}
/**
* Fetch the next converter to try.
*
* @param array $converters The list of converters to try
* @param string|null $currentconverter The converter currently in use
* @return string|false Name of next converter if present
*/
protected function get_next_converter($converters, $currentconverter = null) {
if ($currentconverter) {
$keys = array_keys($converters, $currentconverter);
$key = $keys[0];
if (isset($converters[$key + 1])) {
return $converters[$key + 1];
} else {
return false;
}
} else if (!empty($converters)) {
return $converters[0];
} else {
return false;
}
}
/**
* Fetch the class for the preferred document converter.
*
* @param string $from The source target file (file extension)
* @param string $to The desired target file format (file extension)
* @return string The class for document conversion
*/
protected function get_document_converter_classes($from, $to) {
$classes = [];
$converters = $this->get_enabled_plugins();
foreach ($converters as $plugin => $classname) {
if (!class_exists($classname)) {
continue;
}
if (!$classname::are_requirements_met()) {
continue;
}
if ($classname::supports($from, $to)) {
$classes[] = $classname;
}
}
return $classes;
}
/**
* Check whether document conversion is supported for this file and target format.
*
* @param stored_file $file The file to convert
* @param string $to The desired target file format (file extension)
* @return bool Whether the target type can be converted
*/
public function can_convert_storedfile_to(stored_file $file, $to) {
if ($file->is_directory()) {
// Directories cannot be converted.
return false;
}
if (!$file->get_filesize()) {
// Empty files cannot be converted.
return false;
}
$from = pathinfo($file->get_filename(), PATHINFO_EXTENSION);
if (!$from) {
// No file extension could be found. Unable to determine converter.
return false;
}
return $this->can_convert_format_to($from, $to);
}
/**
* Check whether document conversion is supported for this file and target format.
*
* @param string $from The source target file (file extension)
* @param string $to The desired target file format (file extension)
* @return bool Whether the target type can be converted
*/
public function can_convert_format_to($from, $to) {
return !empty($this->get_document_converter_classes($from, $to));
}
}