chore: GPT Reply suggestion & summarize endpoints (#7011)

Adds additional endpoints for OpenAI integration which will allow
- Reply Suggestions
- Summarization

ref: #6436
fixes: https://linear.app/chatwoot/issue/CW-1596/backend-for-generating-conversation-summary

lib/integrations/openai/processor_service.rb

@@ -1,25 +1,98 @@
 class Integrations::Openai::ProcessorService
+  # 3.5 support 4,096 tokens
+  # 1 token is approx 4 characters
+  # 4,096 * 4 = 16,384 characters, sticking to 15,000 to be safe
+  TOKEN_LIMIT = 15_000
+  API_URL = 'https://api.openai.com/v1/chat/completions'.freeze
+  GPT_MODEL = 'gpt-3.5-turbo'.freeze
+
+  ALLOWED_EVENT_NAMES = %w[rephrase summarize reply_suggestion].freeze
+
   pattr_initialize [:hook!, :event!]
 
   def perform
-    rephrase_message if event['name'] == 'rephrase'
+    event_name = event['name']
+    return nil unless valid_event_name?(event_name)
+
+    send("#{event_name}_message")
   end
 
   private
 
-  def rephrase_body(tone, message)
+  def valid_event_name?(event_name)
+    ALLOWED_EVENT_NAMES.include?(event_name)
+  end
+
+  def rephrase_body
     {
-      model: 'gpt-3.5-turbo',
+      model: GPT_MODEL,
       messages: [
-        { role: 'system', content: "You are a helpful support agent. Please rephrase the following response to a more #{tone} tone." },
-        { role: 'user', content: message }
+        { role: 'system',
+          content: "You are a helpful support agent. Please rephrase the following response to a more #{event['data']['tone']} tone." },
+        { role: 'user', content: event['data']['content'] }
       ]
     }.to_json
   end
 
+  def conversation_messages(in_array_format: false)
+    conversation = hook.account.conversations.find_by(display_id: event['data']['conversation_display_id'])
+    messages = in_array_format ? [] : ''
+    character_count = 0
+
+    conversation.messages.chat.reorder('id desc').each do |message|
+      character_count += message.content.length
+      break if character_count > TOKEN_LIMIT
+
+      formatted_message = format_message(message, in_array_format)
+      messages.prepend(formatted_message)
+    end
+    messages
+  end
+
+  def format_message(message, in_array_format)
+    in_array_format ? format_message_in_array(message) : format_message_in_string(message)
+  end
+
+  def format_message_in_array(message)
+    { role: (message.incoming? ? 'user' : 'assistant'), content: message.content }
+  end
+
+  def format_message_in_string(message)
+    sender_type = message.incoming? ? 'Customer' : 'Agent'
+    "#{sender_type} #{message.sender&.name} : #{message.content}\n"
+  end
+
+  def summarize_body
+    {
+      model: GPT_MODEL,
+      messages: [
+        { role: 'system',
+          content: 'Please summarize the key points from the following conversation between support agents and ' \
+                   'customer as bullet points for the next support agent looking into the conversation' },
+        { role: 'user', content: conversation_messages }
+      ]
+    }.to_json
+  end
+
+  def reply_suggestion_body
+    {
+      model: GPT_MODEL,
+      messages: [
+        { role: 'system', content: 'Please suggest a reply to the following conversation between support agents and customer' }
+      ].concat(conversation_messages(in_array_format: true))
+    }.to_json
+  end
+
+  def reply_suggestion_message
+    make_api_call(reply_suggestion_body)
+  end
+
+  def summarize_message
+    make_api_call(summarize_body)
+  end
+
   def rephrase_message
-    response = make_api_call(rephrase_body(event['data']['tone'], event['data']['content']))
-    JSON.parse(response)['choices'].first['message']['content']
+    make_api_call(rephrase_body)
   end
 
   def make_api_call(body)
@@ -28,12 +101,7 @@ class Integrations::Openai::ProcessorService
       'Authorization' => "Bearer #{hook.settings['api_key']}"
     }
 
-    response = HTTParty.post(
-      'https://api.openai.com/v1/chat/completions',
-      headers: headers,
-      body: body
-    )
-
-    response.body
+    response = HTTParty.post(API_URL, headers: headers, body: body)
+    JSON.parse(response.body)['choices'].first['message']['content']
   end
 end