defmodule ProtoDef.Type.PString do
  use ProtoDef.Type

  alias ProtoDef.Compiler.Preprocess

  defstruct count: nil, count_ident: nil, ident: nil

  def preprocess(args, ctx) do
    %__MODULE__{
      count: Preprocess.process_count(args, ctx),
    }
  end

  def structure(_type, _ctx), do: __MODULE__

  def assign_vars(descr, num, ctx) do
    {count_descr, count_ident, num} =
        ProtoDef.Compiler.AssignIdents.assign_count(descr.count, num, ctx)
    {ident, num} = ProtoDef.Compiler.AssignIdents.make_ident(num, ctx)
    descr = %{ descr |
      count: count_descr,
      count_ident: count_ident,
      ident: ident,
    }
    {descr, ident, num}
  end

  def resolve_references(descr, parents, ctx) do
    count = ProtoDef.Compiler.Resolve.resolve_count(descr.count, parents, ctx)
    %{ descr |
      count: count,
    }
  end

  def decoder_ast(descr, ctx) do
    count_ast = ProtoDef.Compiler.Count.decoder_ast(descr.count, ctx)
    quote do
      with do
        {count, unquote(@data_var)} = unquote(count_ast)
        <<str::binary-size(count), unquote(@data_var)::binary>> = unquote(@data_var)
        {str, unquote(@data_var)}
      end
    end
  end

  def encoder_ast(descr, ctx) do
    count_var = Macro.var(:count, ProtoDef.Type.PString)
    count_encoder = ProtoDef.Compiler.Count.encoder_ast(descr.count, count_var, ctx)
    quote do
      with do
        unquote(count_var) = byte_size(unquote(@input_var))
        count_head = unquote(count_encoder)
        [count_head, unquote(@input_var)]
      end
    end
  end
end