export function addFileWithDedup(state, file, cfg) {
  const originalName = file.name;
  const existing = state.fileMeta.get(originalName);
  let name = originalName;

  if (existing) {
    if (existing.size === file.size) return false;
    const dot = originalName.lastIndexOf('.');
    const base = dot > 0 ? originalName.slice(0, dot) : originalName;
    const extension = dot > 0 ? originalName.slice(dot) : '';
    let suffix = 2;
    while (state.fileMeta.has(`${base}_${suffix}${extension}`)) suffix += 1;
    name = `${base}_${suffix}${extension}`;
  }

  const storedFile = new File([file], name, { lastModified: file.lastModified });
  state.fileMeta.set(name, { size: storedFile.size });
  const includedBytes = state.files.reduce(
    (total, item) => total + (state.overNames.has(item.name) ? 0 : item.size), 0,
  );
  if (storedFile.size > cfg.maxFileBytes
      || includedBytes + storedFile.size > cfg.maxSessionBytes) {
    state.overNames.add(name);
  }
  state.files.push(storedFile);
  return true;
}