defmodule HyperLLM.Provider.Anthropic.OpenAICompatibility do
  @moduledoc """
  This module is used to convert OpenAI requests to Anthropic requests and vice versa.
  """
  import HyperLLM.Provider

  def attach(%Req.Request{} = request, _options \\ []) do
    request
    |> Req.Request.prepend_request_steps(openai_request: &from_openai_request/1)
    |> Req.Request.append_response_steps(openai_response: &to_openai_response/1)
  end

  def from_openai_request(request) do
    case request.url do
      %URI{path: "/v1/messages"} ->
        build_anthropic_request(request)

      url ->
        dbg(url)
        request
    end
  end

  defp build_anthropic_request(%{options: %{json: json}} = request) do
    json =
      json
      |> cast(:stop_sequences)
      |> cast(:metadata)

    Map.update!(request, :options, fn options ->
      %{options | json: json}
    end)
  end

  defp build_anthropic_request(request), do: request

  defp cast(data, :stop_sequences) do
    rename_key(data, :stop, :stop_sequences, fn stop_sequences ->
      if is_list(stop_sequences) do
        stop_sequences
      else
        [stop_sequences]
      end
    end)
  end

  defp cast(%{user_id: user_id} = json, :metadata) when not is_nil(user_id) do
    json
    |> Map.put_new(:metadata, %{})
    |> Map.put(:metadata, %{user_id: user_id})
    |> Map.delete(:user_id)
  end

  defp cast(data, _), do: data

  defp to_openai_response({%{url: %URI{path: "/v1/messages"}} = request, response}) do
    dbg(request)

    # when the headers of the requestion are  "content-type" => ["text/event-stream; charset=utf-8"] use the streaming responses
    if Map.get(response.headers, "content-type") == ["text/event-stream; charset=utf-8"] do
      to_openai_chat_completion_streaming_response({request, response})
    else
      to_openai_chat_completion_response({request, response})
    end
  end

  defp to_openai_response({request, response}) do
    {request, response}
  end

  def to_openai_chat_completion_streaming_response({request, response}) do
    {request, response}
  end

  def to_openai_chat_completion_response({request, response}) do
    usage = Map.get(response.body, "usage", %{})
    content = hd(response.body["content"])

    response =
      response
      |> Map.put(:body, %{
        "id" => response.body["id"],
        "created" => DateTime.utc_now() |> DateTime.to_unix(),
        "model" => request.options.json.model,
        "object" => "chat.completion",
        "service_tier" => "default",
        "system_fingerprint" => nil,
        "choices" => [
          %{
            "index" => 0,
            "message" => %{
              "role" => "assistant",
              "content" => content["text"]
            },
            "logprobs" => nil,
            "finish_reason" => response.body["stop_reason"]
          }
        ],
        "usage" => %{
          "prompt_tokens" => Map.get(usage, "input_tokens", 0),
          "completion_tokens" => Map.get(usage, "output_tokens", 0),
          "total_tokens" => Map.get(usage, "input_tokens", 0) + Map.get(usage, "output_tokens", 0)
        }
      })

    {request, response}
  end
end