feat: Ability to improve drafts in the editor using GPT integration (#6957)

ref: https://github.com/chatwoot/chatwoot/issues/6436
fixes: https://linear.app/chatwoot/issue/CW-1552/ability-to-rephrase-text-in-the-editor-using-gpt-integration

---------

Co-authored-by: Sojan <sojan@pepalo.com>
Co-authored-by: Nithin David Thomas <1277421+nithindavid@users.noreply.github.com>

spec/lib/integrations/openai/processor_service_spec.rb

@@ -0,0 +1,51 @@
+require 'rails_helper'
+
+RSpec.describe Integrations::Openai::ProcessorService do
+  subject { described_class.new(hook: hook, event: event) }
+
+  let(:hook) { create(:integrations_hook, :openai) }
+  let(:expected_headers) { { 'Authorization' => "Bearer #{hook.settings['api_key']}" } }
+  let(:openai_response) do
+    {
+      'choices' => [
+        {
+          'message' => {
+            'content' => 'This is a rephrased test message.'
+          }
+        }
+      ]
+    }.to_json
+  end
+
+  describe '#perform' do
+    context 'when event name is rephrase' do
+      let(:event) { { 'name' => 'rephrase', 'data' => { 'tone' => 'friendly', 'content' => 'This is a test message' } } }
+
+      it 'returns the rephrased message using the tone in data' do
+        request_body = {
+          'model' => 'gpt-3.5-turbo',
+          'messages' => [
+            { '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
+
+        stub_request(:post, 'https://api.openai.com/v1/chat/completions')
+          .with(body: request_body, headers: expected_headers)
+          .to_return(status: 200, body: openai_response, headers: {})
+
+        result = subject.perform
+        expect(result).to eq('This is a rephrased test message.')
+      end
+    end
+
+    context 'when event name is not rephrase' do
+      let(:event) { { 'name' => 'unknown', 'data' => {} } }
+
+      it 'returns nil' do
+        expect(subject.perform).to be_nil
+      end
+    end
+  end
+end