<?php

/**
 * @file
 * Provide server side mime type detection.
 */

/**
 * Implements hook_menu().
 */
function mimedetect_menu() {
  $items = array();

  // The admin settings form.
  $items['admin/config/media/mimedetect'] = array(
    'title' => 'Mime type detection',
    'description' => 'Control how the mime type of uploaded files will be determined.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('mimedetect_settings'),
    'access arguments' => array('administer site configuration'),
    'file' => 'mimedetect.admin.inc',
  );

  return $items;
}

/**
 * Detect File Mime Type.
 *
 * @param $file A standard Drupal file object. The uri property is used to
 *   locate the file and if the mime detection fails, the mimetype property is
 *   returned.
 * @return String containing the file's MIME type.
 */
function mimedetect_mime($file) {
  $file = (object)$file;

  // An additional array of mimetypes not included in file_get_mimetype().
  static $additional_mimes = array(
    // Audio types
    'rmi' => 'audio/midi',
    'aidff' => 'audio/x-aiff',
    // Image types
    'cod' => 'image/cis-cod',
    'jfif' => 'image/pipeg',
    'cmx' => 'image/x-cmx',
    // Video types
    'mpa' => 'video/mpeg',
    'mpv2' => 'video/mpeg',
    'asr' => 'video/x-ms-asf',
  );

  $mime = FALSE;
  
  if (variable_get('mimedetect_enable_file_info', FALSE)) {
    $magic_file = variable_get('mimedetect_magic', '');

    // Try to use the fileinfo extension first.
    if (extension_loaded('fileinfo')) {
      static $finfo = FALSE;
      if ($finfo || $finfo = @finfo_open(FILEINFO_MIME, $magic_file)) {
        $mime = finfo_file($finfo, drupal_realpath($file->uri));
      }
    }
  }

  // Try the 'file' binary.
  if ( (!$mime || $mime == 'application/octet-stream')
    && variable_get('mimedetect_enable_file_binary', FALSE)
    && ($filebin = variable_get('mimedetect_file_binary', '/usr/bin/file'))
    && is_executable($filebin))
  {
    // On OSX the -i switch is -I, so if we use the long flags everyone is
    // happy. I checked back to version 3.41 and it still supports the long
    // names but if you run into problems you can use " -bi ".
    $command = $filebin . ' --brief --mime' .
      ( !empty($magic_file)? ' --magic-file=' . escapeshellarg($magic_file) : '' )
       . ' ' . escapeshellarg(drupal_realpath($file->uri));
    $mime = trim(exec($command));
  }

  // with text we often get charset like 'text/plain; charset=us-ascii'
  $mime = explode(';', $mime);
  $mime = trim($mime[0]);

  // ASF derived media formats are hard to detect with magic. They're typically
  // all reported as video/x-ms-asf or application/octet-stream. These aren't
  // really informative about the media type, so we attempt to figure it out by
  // extension. I expect OGG to present similar difficulties in determining how
  // it should be played.
  if (!$mime || $mime == 'application/octet-stream') {
    // Try core's mime mapping first...
    $mime = file_get_mimetype($file->filename);
    // ...and if that doesn't turn up anything try our additional mappings.
    if ($mime == 'application/octet-stream') {
      $mime = file_get_mimetype($file->filename, $additional_mimes);
    }
  }

  return $mime;
}