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   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  namespace mod_data\local\importer;
  18  
  19  use coding_exception;
  20  use core_php_time_limit;
  21  use file_packer;
  22  
  23  /**
  24   * Importer class for importing data and - if needed - files as well from a zip archive.
  25   *
  26   * @package    mod_data
  27   * @copyright  2023 ISB Bayern
  28   * @author     Philipp Memmel
  29   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  30   */
  31  abstract class entries_importer {
  32  
  33      /** @var string The import file path of the file which data should be imported from. */
  34      protected string $importfilepath;
  35  
  36      /** @var string The original name of the import file name including extension of the file which data should be imported from. */
  37      protected string $importfilename;
  38  
  39      /** @var string $importfiletype The file type of the import file. */
  40      protected string $importfiletype;
  41  
  42      /** @var file_packer Zip file packer to extract files from a zip archive. */
  43      private file_packer $packer;
  44  
  45      /** @var bool Tracks state if zip archive has been extracted already. */
  46      private bool $zipfileextracted;
  47  
  48      /** @var string Temporary directory where zip archive is being extracted to. */
  49      private string $extracteddir;
  50  
  51      /**
  52       * Creates an entries_importer object.
  53       *
  54       * This object can be used to import data from data files (like csv) and zip archives both including a data file and files to be
  55       * stored in the course module context.
  56       *
  57       * @param string $importfilepath the complete path of the import file including filename
  58       * @param string $importfilename the import file name as uploaded by the user
  59       * @throws coding_exception if a wrong file type is being used
  60       */
  61      public function __construct(string $importfilepath, string $importfilename) {
  62          $this->importfilepath = $importfilepath;
  63          $this->importfilename = $importfilename;
  64          $this->importfiletype = pathinfo($importfilename, PATHINFO_EXTENSION);
  65          $this->zipfileextracted = false;
  66          if ($this->importfiletype !== $this->get_import_data_file_extension() && $this->importfiletype !== 'zip') {
  67              throw new coding_exception('Only "zip" or "' . $this->get_import_data_file_extension() . '" files are '
  68                  . 'allowed.');
  69          }
  70      }
  71  
  72      /**
  73       * Return the file extension of the import data file which is being used, for example 'csv' for a csv entries_importer.
  74       *
  75       * @return string the file extension of the export data file
  76       */
  77      abstract public function get_import_data_file_extension(): string;
  78  
  79      /**
  80       * Returns the file content of the data file.
  81       *
  82       * Returns the content of the file directly if the entries_importer's file is a data file itself.
  83       *  If the entries_importer's file is a zip archive, the content of the first found data file in the
  84       *  zip archive's root will be returned.
  85       *
  86       * @return false|string the data file content as string; false, if file cannot be found/read
  87       */
  88      public function get_data_file_content(): false|string {
  89          if ($this->importfiletype !== 'zip') {
  90              // We have no zip archive, so the file itself must be the data file.
  91              return file_get_contents($this->importfilepath);
  92          }
  93  
  94          // So we have a zip archive and need to find the right data file in the root of the zip archive.
  95          $this->extract_zip();
  96          $datafilenames = array_filter($this->packer->list_files($this->importfilepath),
  97              fn($file) => pathinfo($file->pathname, PATHINFO_EXTENSION) === $this->get_import_data_file_extension()
  98                  && !str_contains($file->pathname, '/'));
  99          if (empty($datafilenames) || count($datafilenames) > 1) {
 100              return false;
 101          }
 102          return file_get_contents($this->extracteddir . reset($datafilenames)->pathname);
 103      }
 104  
 105      /**
 106       * Returns the file content from a file which has been stored in the zip archive.
 107       *
 108       * @param string $filename
 109       * @param string $zipsubdir
 110       * @return false|string the file content as string, false if the file could not be found/read
 111       */
 112      public function get_file_content_from_zip(string $filename, string $zipsubdir = 'files/'): false|string {
 113          if (empty($filename)) {
 114              // Nothing to return.
 115              return false;
 116          }
 117          // Just to be sure extract if not extracted yet.
 118          $this->extract_zip();
 119          if (!str_ends_with($zipsubdir, '/')) {
 120              $zipsubdir .= '/';
 121          }
 122          $filepathinextractedzip = $this->extracteddir . $zipsubdir . $filename;
 123          return file_exists($filepathinextractedzip) ? file_get_contents($filepathinextractedzip) : false;
 124      }
 125  
 126      /**
 127       * Extracts (if not already done and if we have a zip file to deal with) the zip file to a temporary directory.
 128       *
 129       * @return void
 130       */
 131      private function extract_zip(): void {
 132          if ($this->zipfileextracted || $this->importfiletype !== 'zip') {
 133              return;
 134          }
 135          $this->packer = get_file_packer();
 136          core_php_time_limit::raise(180);
 137          $this->extracteddir = make_request_directory();
 138          if (!str_ends_with($this->extracteddir, '/')) {
 139              $this->extracteddir .= '/';
 140          }
 141          $this->packer->extract_to_pathname($this->importfilepath, $this->extracteddir);
 142          $this->zipfileextracted = true;
 143      }
 144  }