Add streaming chat

app/models/chat.rb

@@ -20,4 +20,42 @@ class Chat < ApplicationRecord
       )
     end
   end
+
+  def generate_next_ai_response
+    if messages.conversation.ordered.last&.role == "assistant"
+      Rails.logger.info("Skipping response because last message was an assistant message")
+      return
+    end
+
+    openai.chat(
+      parameters: {
+        model: "gpt-4o-mini",
+        stream: streamer,
+        n: 1,
+        messages: messages.conversation.order(:created_at).map do |message|
+          {
+            role: message.role,
+            content: message.content
+          }
+        end
+      }
+    )
+  end
+
+  private
+    def openai
+      OpenAI::Client.new(access_token: ENV["OPENAI_ACCESS_TOKEN"])
+    end
+
+    def streamer
+      message = messages.create!(
+        role: "assistant",
+        content: ""
+      )
+
+      proc do |chunk, _bytesize|
+        new_content = chunk.dig("choices", 0, "delta", "content")
+        message.update(content: message.content + new_content) if new_content
+      end
+    end
 end