defmodule Kadena.Types.Signer do
  @moduledoc """
  `Signer` struct definition.
  """

  alias Kadena.Types.{Base16String, Cap}

  @behaviour Kadena.Types.Spec

  @type pub_key :: Base16String.t()
  @type scheme :: :ed25519 | nil
  @type addr :: Base16String.t() | nil
  @type clist :: list(Cap.t()) | nil
  @type value :: pub_key() | scheme() | addr() | clist()
  @type str :: String.t()
  @type validation :: {:ok, value()} | {:error, Keyword.t()}

  @type t :: %__MODULE__{
          pub_key: pub_key(),
          scheme: scheme(),
          addr: addr(),
          clist: clist()
        }

  defstruct [:pub_key, :scheme, :addr, :clist]

  @impl true
  def new(args) do
    pub_key = Keyword.get(args, :pub_key)
    scheme = Keyword.get(args, :scheme)
    addr = Keyword.get(args, :addr)
    clist = Keyword.get(args, :clist)

    with {:ok, pub_key} <- validate_pub_key(pub_key),
         {:ok, scheme} <- validate_scheme(scheme),
         {:ok, addr} <- validate_addr(addr),
         {:ok, clist} <- validate_clist(clist) do
      %__MODULE__{pub_key: pub_key, scheme: scheme, addr: addr, clist: clist}
    end
  end

  @spec validate_pub_key(pub_key :: str()) :: validation()
  defp validate_pub_key(pub_key) when is_binary(pub_key), do: {:ok, Base16String.new(pub_key)}
  defp validate_pub_key(_pub_key), do: {:error, [pub_key: :invalid]}

  @spec validate_scheme(scheme :: scheme()) :: validation()
  defp validate_scheme(nil), do: {:ok, nil}
  defp validate_scheme(:ed25519), do: {:ok, :ed25519}
  defp validate_scheme(_code), do: {:error, [scheme: :invalid]}

  @spec validate_addr(addr :: str() | nil) :: validation()
  defp validate_addr(nil), do: {:ok, nil}
  defp validate_addr(addr) when is_binary(addr), do: {:ok, Base16String.new(addr)}
  defp validate_addr(_addr), do: {:error, [addr: :invalid]}

  @spec validate_clist(clist :: clist()) :: validation()
  defp validate_clist(nil), do: {:ok, nil}
  defp validate_clist([%Cap{} | _tail] = clist), do: {:ok, clist}
  defp validate_clist(_clist), do: {:error, [clist: :not_a_caps_list]}
end