Simplify OpenAI api implementation

lib/open_ai/api.ex

@@ -1,85 +1,30 @@
 defmodule OpenAI.API do
-  # Lifted from https://fly.io/phoenix-files/streaming-openai-responses/
-  def gpt_stream(completion, api_key, cb) do
-    fun = fn request, finch_request, finch_name, finch_options ->
-      fun = fn
-        {:status, status}, response ->
-          %{response | status: status}
+  def gpt(completion, api_key) do
+    resp =
+      Req.post!("https://api.openai.com/v1/chat/completions",
+        receive_timeout: 10_000,
+        connect_options: [timeout: 2_500],
+        json: %{
+          model: completion.model,
+          messages: [Map.take(completion, [:content, :role])],
+          response_format: %{type: "json_object"},
+          temperature: completion.temperature
+        },
+        auth: {:bearer, api_key}
+      )
 
-        {:headers, headers}, response ->
-          %{response | headers: headers}
-
-        {:data, data}, response ->
-          body =
-            data
-            |> String.split("data: ")
-            |> Enum.map(fn str ->
-              str
-              |> String.trim()
-              |> decode_body(cb)
-            end)
-            |> Enum.filter(fn d -> d != :ok end)
-
-          old_body = if response.body == "", do: [], else: response.body
-
-          %{response | body: old_body ++ body}
-      end
-
-      case Finch.stream(finch_request, finch_name, Req.Response.new(), fun, finch_options) do
-        {:ok, response} -> {request, response}
-        {:error, exception, _response} -> {request, exception}
-      end
+    if resp.status in 200..299 do
+      content = get_in(resp.body, ["choices", Access.at(0), "message", "content"])
+      {:ok, JSON.decode!(content)}
+    else
+      {:error, resp.body}
     end
-
-    Req.post!("https://api.openai.com/v1/chat/completions",
-      receive_timeout: 1000,
-      connect_options: [
-        timeout: 2500
-      ],
-      json: %{
-        model: completion.model,
-        messages: [Map.take(completion, [:content, :role])],
-        response_format: %{type: "json_object"},
-        stream: true,
-        temperature: completion.temperature
-      },
-      auth: {:bearer, api_key},
-      finch_request: fun
-    )
   end
 
   def chat_stream(messages, instructions, model, temperature, api_key, cb) do
-    fun = fn request, finch_request, finch_name, finch_options ->
-      fun = fn
-        {:status, status}, response ->
-          %{response | status: status}
-
-        {:headers, headers}, response ->
-          %{response | headers: headers}
-
-        {:data, data}, response ->
-          data
-          |> String.split("\n")
-          |> Enum.each(fn line ->
-            line
-            |> String.trim()
-            |> decode_responses_event(cb)
-          end)
-
-          response
-      end
-
-      case Finch.stream(finch_request, finch_name, Req.Response.new(), fun, finch_options) do
-        {:ok, response} -> {request, response}
-        {:error, exception, _response} -> {request, exception}
-      end
-    end
-
     case Req.post("https://api.openai.com/v1/responses",
            receive_timeout: 60_000,
-           connect_options: [
-             timeout: 5_000
-           ],
+           connect_options: [timeout: 5_000],
            json: %{
              model: model,
              instructions: instructions,
@@ -89,16 +34,21 @@ defmodule OpenAI.API do
              temperature: temperature
            },
            auth: {:bearer, api_key},
-           finch_request: fun
+           into: fn {:data, data}, {req, resp} ->
+             buffer = Req.Request.get_private(req, :sse_buffer, "")
+             {events, buffer} = ServerSentEvents.parse(buffer <> data)
+             req = Req.Request.put_private(req, :sse_buffer, buffer)
+
+             for %{data: json} <- events do
+               decode_responses_event(json, cb)
+             end
+
+             {:cont, {req, resp}}
+           end
          ) do
-      {:ok, %{status: status}} when status in 200..299 ->
-        :ok
-
-      {:ok, %{body: body}} ->
-        {:error, "OpenAI API error: #{inspect(body)}"}
-
-      {:error, exception} ->
-        {:error, "Connection error: #{Exception.message(exception)}"}
+      {:ok, %{status: status}} when status in 200..299 -> :ok
+      {:ok, %{body: body}} -> {:error, "OpenAI API error: #{inspect(body)}"}
+      {:error, exception} -> {:error, "Connection error: #{Exception.message(exception)}"}
     end
   end
 
@@ -120,19 +70,10 @@ defmodule OpenAI.API do
     end
   end
 
-  defp decode_body("", _), do: :ok
-  defp decode_body("[DONE]", _), do: :ok
-  defp decode_body(json, cb), do: cb.(JSON.decode!(json))
-
-  defp decode_responses_event("", _cb), do: :ok
-  defp decode_responses_event("event:" <> _rest, _cb), do: :ok
-
-  defp decode_responses_event("data: " <> json, cb) do
+  defp decode_responses_event(json, cb) do
     case JSON.decode!(json) do
       %{"type" => "response.output_text.delta", "delta" => delta} -> cb.(delta)
       _other -> :ok
     end
   end
-
-  defp decode_responses_event(_line, _cb), do: :ok
 end