trpc-optimistic-updates.ts

export function optimisticallyUpdateArray<Data>(
  condition: (data: Data) => boolean,
  replacement: Data | ((data: Data) => Data),
) {
  return (data: Data[] | undefined) => {
    if (!data) return data
    const index = data.findIndex(condition)
    if (index === -1) return data
    const newData = [...data]
    newData.splice(
      index,
      1,
      typeof replacement === 'function'
        ? // @ts-ignore
          replacement(data[index])
        : replacement,
    )
    return newData
  }
}

export function optimisticallyUpdateObject<Data>(
  condition: (data: Data) => boolean,
  replacement: Data | ((data: Data) => Data),
) {
  return (data: Data | undefined) => {
    if (!data) return data
    if (!condition(data)) return data
    return typeof replacement === 'function'
      ? // @ts-ignore
        replacement(data)
      : replacement
  }
}