Display basic tabs in consents index page

This queries the list of patient_sessions and splits them into the
respective categories that match the tabs in the design.

app/controllers/consents_controller.rb

@@ -1,7 +1,16 @@
 class ConsentsController < ApplicationController
   before_action :set_session
+  before_action :set_patient_sessions, only: %i[index]
 
   def index
+    methods = %i[consent_given? consent_refused? consent_conflicts? no_consent?]
+
+    @tabs =
+      @patient_sessions.group_by do |patient_session|
+        methods.find { |m| patient_session.send(m) }
+      end
+
+    methods.each { |m| @tabs[m] ||= [] }
   end
 
   private
@@ -12,4 +21,12 @@ def set_session
         params.fetch(:session_id) { params.fetch(:id) }
       )
   end
+
+  def set_patient_sessions
+    @patient_sessions =
+      @session
+        .patient_sessions
+        .includes(patient: :consents)
+        .order("patients.first_name", "patients.last_name")
+  end
 end

app/models/concerns/patient_session_state_machine_concern.rb

@@ -104,6 +104,12 @@ def consent_refused?
       consents.any?(&:response_refused?)
     end
 
+    def consent_conflicts?
+      return false if no_consent?
+
+      consents.any?(&:response_given?) && consents.any?(&:response_refused?)
+    end
+
     def no_consent?
       consents.empty?
     end

app/views/consents/index.html.erb

@@ -7,3 +7,25 @@
 <% end %>
 
 <%= h1 "Check consent responses", class: "govuk-heading-l" %>
+
+<%= govuk_tabs title: "Vaccinations", classes: 'nhsuk-tabs' do |c|
+  c.with_tab(label: "Consent given (#{ @tabs[:consent_given?].size })",
+             classes: 'nhsuk-tabs__panel') do
+    @tabs[:consent_given?].size.to_s
+  end
+
+  c.with_tab(label: "Consent refused (#{ @tabs[:consent_refused?].size })",
+             classes: 'nhsuk-tabs__panel') do
+    @tabs[:consent_refused?].size.to_s
+  end
+
+  c.with_tab(label: "Consent conflicts (#{ @tabs[:consent_conflicts?].size })",
+             classes: 'nhsuk-tabs__panel') do
+    @tabs[:consent_conflicts?].size.to_s
+  end
+
+  c.with_tab(label: "No response (#{ @tabs[:no_consent?].size })",
+             classes: 'nhsuk-tabs__panel') do
+    @tabs[:no_consent?].size.to_s
+  end
+end %>