feat: Enable Capacity Config UI (#5164)

- Enables Capacity Config in UI
- Rewrite auto assignment Logic to consider only online agents

fixes: #4990

spec/services/auto_assignment/agent_assignment_service_spec.rb

@@ -0,0 +1,38 @@
+require 'rails_helper'
+
+RSpec.describe AutoAssignment::AgentAssignmentService do
+  let!(:account) { create(:account) }
+  let!(:inbox) { create(:inbox, account: account, enable_auto_assignment: false) }
+  let!(:inbox_members) { create_list(:inbox_member, 5, inbox: inbox) }
+  let!(:conversation) { create(:conversation, inbox: inbox, account: account) }
+  let!(:online_users) do
+    {
+      inbox_members[0].user_id.to_s => 'busy',
+      inbox_members[1].user_id.to_s => 'busy',
+      inbox_members[2].user_id.to_s => 'busy',
+      inbox_members[3].user_id.to_s => 'online',
+      inbox_members[4].user_id.to_s => 'online'
+    }
+  end
+
+  before do
+    allow(::OnlineStatusTracker).to receive(:get_available_users).and_return(online_users)
+  end
+
+  describe '#perform' do
+    it 'will assign an online agent to the conversation' do
+      expect(conversation.reload.assignee).to be_nil
+      described_class.new(conversation: conversation, allowed_agent_ids: inbox_members.map(&:user_id).map(&:to_s)).perform
+      expect(conversation.reload.assignee).not_to be_nil
+    end
+  end
+
+  describe '#find_assignee' do
+    it 'will return an online agent from the allowed agent ids in roud robin' do
+      expect(described_class.new(conversation: conversation,
+                                 allowed_agent_ids: inbox_members.map(&:user_id).map(&:to_s)).find_assignee).to eq(inbox_members[3].user)
+      expect(described_class.new(conversation: conversation,
+                                 allowed_agent_ids: inbox_members.map(&:user_id).map(&:to_s)).find_assignee).to eq(inbox_members[4].user)
+    end
+  end
+end