Refactor organisation name change logic to ensure visibility and uniqueness of change dates

app/controllers/organisation_name_changes_controller.rb

@@ -10,13 +10,13 @@ class OrganisationNameChangesController < ApplicationController
       notice_message = @organisation_name_change.immediate_change ? "Name change saved successfully." : "Name change scheduled for #{@organisation_name_change.formatted_change_date}."
       redirect_to organisation_path(@organisation), notice: notice_message
     else
-      render template: "organisations/change_name", status: :unprocessable_entity
+      render :new, status: :unprocessable_entity
     end
   end
 
   def change_name
     @organisation_name_change = OrganisationNameChange.new
-    render "organisations/change_name", layout: "application"
+    render :new, layout: "application"
   end
 
 private

app/models/organisation.rb

@@ -73,7 +73,7 @@ class Organisation < ApplicationRecord
   end
 
   def name(date: Time.zone.now)
-    name_change = organisation_name_changes.find { |change| change.includes_date?(date) }
+    name_change = organisation_name_changes.visible.find { |change| change.includes_date?(date) }
     name_change&.name || read_attribute(:name)
   end
 
@@ -105,8 +105,8 @@ class Organisation < ApplicationRecord
   end
 
   def fetch_name_changes_with_dates
-    organisation_name_changes.order(:change_date).map.with_index do |change, index|
-      next_change = organisation_name_changes.order(:change_date)[index + 1]
+    organisation_name_changes.visible.order(:change_date).map.with_index do |change, index|
+      next_change = organisation_name_changes.visible.order(:change_date)[index + 1]
       {
         name: change.name,
         start_date: change.change_date,

app/models/organisation_name_change.rb

@@ -7,6 +7,7 @@ class OrganisationNameChange < ApplicationRecord
   validates :change_date, presence: true, unless: -> { immediate_change }
   validate :change_date_must_be_after_last_change_date
   validate :name_must_be_different_from_current
+  validate :change_date_must_be_unique_for_organisation
 
   attr_accessor :immediate_change
 
@@ -45,18 +46,31 @@ class OrganisationNameChange < ApplicationRecord
 private
 
   def set_change_date_if_immediate
-    self.change_date = Time.zone.now if immediate_change
+    self.change_date = Time.zone.now if immediate_change == true
   end
 
   def change_date_must_be_after_last_change_date
     return if change_date.blank?
 
-    last_change_date = organisation.organisation_name_changes.where("change_date < ?", change_date).order(change_date: :desc).first&.change_date
+    last_change_date = organisation.organisation_name_changes
+                                   .visible
+                                   .where("change_date < ?", change_date)
+                                   .order(change_date: :desc)
+                                   .first&.change_date
+
     if last_change_date && change_date <= last_change_date
       errors.add(:change_date, "Start date must be after the last change date (#{last_change_date}).")
     end
   end
 
+  def change_date_must_be_unique_for_organisation
+    return if change_date.blank?
+
+    if organisation.organisation_name_changes.visible.select(&:persisted?).any? { |record| record.change_date.to_date == change_date.to_date }
+      errors.add(:change_date, "Start date cannot be the same as a previous change date for this organisation.")
+    end
+  end
+
   def name_must_be_different_from_current
     return if name.blank? || change_date.blank?