defmodule MvWeb.MemberLive.Index.Cookie do
  @moduledoc """
  Shared cookie-header parsing for the member-overview persistence chain.

  Both `MvWeb.MemberLive.Index.ViewSettings` and
  `MvWeb.MemberLive.Index.FieldSelection` read their persisted value from the
  raw request `Cookie:` header on the disconnected mount, so the parsing lives
  here once.
  """

  @doc """
  Parses a raw `Cookie:` request-header string into a `%{name => value}` map,
  URL-decoding each value. A valueless entry (`"key"`) maps to `""`; malformed
  segments are skipped.
  """
  @spec parse_header(String.t()) :: %{String.t() => String.t()}
  def parse_header(cookie_header) when is_binary(cookie_header) do
    cookie_header
    |> String.split(";")
    |> Enum.map(&String.trim/1)
    |> Enum.map(&String.split(&1, "=", parts: 2))
    |> Enum.reduce(%{}, fn
      [key, value], acc -> Map.put(acc, key, URI.decode(value))
      [key], acc -> Map.put(acc, key, "")
      _, acc -> acc
    end)
  end
end