defmodule LoomEx.LLM.SSEParser do
  @spec new() :: binary()
  def new, do: ""

  @spec parse(binary(), binary()) :: {binary(), [map()]}
  def parse(buffer, chunk) do
    data = buffer <> chunk
    parts = String.split(data, "\n\n")
    {remaining, complete} = List.pop_at(parts, -1)

    events =
      complete
      |> Enum.flat_map(fn segment ->
        segment
        |> String.split("\n")
        |> Enum.flat_map(fn line ->
          case String.trim_leading(line) do
            "data: [DONE]" ->
              []

            "data: " <> json ->
              case Jason.decode(json) do
                {:ok, decoded} -> [decoded]
                _ -> []
              end

            _ ->
              []
          end
        end)
      end)

    {remaining || "", events}
  end
end