fileExists method

Future<File?> fileExists(
  1. String filename, {
  2. int? size,
  3. String? url,
  4. bool temporary = false,
})

Returns a File with the provided filename and size, if any exist in the downloadsDirectory.

If size is null, then an attempt to get the size from the given url will be performed.

Implementation

Future<File?> fileExists(
  String filename, {
  int? size,
  String? url,
  bool temporary = false,
}) async {
  if ((size != null || url != null) && !PlatformUtils.isWeb) {
    if (size == null) {
      final Headers headers = (await (await dio).head(url!)).headers;
      final List<String>? contentLength = headers['content-length'];

      if (contentLength != null) {
        size = int.parse((contentLength)[0]);
      }
    }

    final Directory directory = temporary
        ? await temporaryDirectory
        : await downloadsDirectory;
    String name = p.basenameWithoutExtension(filename);
    String ext = p.extension(filename);
    File file = File('${directory.path}/$filename');

    // TODO: Compare hashes instead of sizes.
    for (int i = 1; await file.exists() && await file.length() != size; ++i) {
      file = File('${directory.path}/$name ($i)$ext');
    }

    if (await file.exists()) {
      return file;
    }
  }

  return null;
}