// TODO: only works with NanoHTTPD for now
sclass HttpFromFileSystem {
  File baseDir;
  bool serveDirectoryListings; // default to false
  
  *() {}
  *(File *baseDir) {}
  *(File *baseDir, bool *serveDirectoryListings) {}
  
  O serve(S uri) {
    LS parts = nempties(splitAtSlash(uri));
    
    // process . and ..
    for i over parts:
      if (eq(parts.get(i), ".")) parts.remove(i);
      else if (eq(parts.get(i), ".."))
        if (i == 0) fail(".. leading nowhere: " + uri);
        else {
          parts.remove(i);
          parts.remove(--i);
        }
      
    if (all validFileName(parts)) {
      print(parts);
      fail("Bad path: " + uri);
    }
    
    File f = baseDir;
    if (!isDirectory(baseDir)) print("Base dir not found: " + f2s(f));
    for (S part : parts) {
      f = newFile(f, part);
      if (!fileExists(f))
        fail("Path not found: " + uri);
    }
    if (isDirectory(f))
      ret serveListing(f);
    else
      ret serveFile(f);
  }
  
  O serveFile(File f) {
    ret main serveFile(f, contentTypeForFile(f));
  }
  
  O serveListing(File dir) {
    if (!serveDirectoryListings) fail("Can't serve directory listings");
    ret "Directory listing"
      + ul_htmlEncode(listFileNames(dir));
  }
  
  swappable S contentTypeForFile(File f) {
    ret or2(extensionToMimeType(fileExtension(f)), binaryMimeType());
  }
  
  swappable bool validFileName(S name) { ret isValidFileName(name); }
}