add first pass at error handling for filter dates

this does not include case where one or more of
the values is blank, or where the 'to' date is
before the 'from' date.

if there are errors, we do the rest of the filters
without the erroring ones, so as to return
something helpful.

lib/engines/content_block_manager/app/components/content_block_manager/content_block/document/index/date_filter_component.html.erb

@@ -4,6 +4,7 @@
   prefix: "last_updated_from",
   date_heading: "From",
   date_only: true,
+  error_items: helpers.errors_for(@errors, "last_updated_from"),
   year: {
     id: "last_updated_from_1i",
     name: "last_updated_from[1i]",
@@ -32,6 +33,7 @@
   prefix: "last_updated_to",
   date_heading: "To",
   date_only: true,
+  error_items: helpers.errors_for(@errors, "last_updated_to"),
   year: {
     id: "last_updated_to_1i",
     name: "last_updated_to[1i]",

lib/engines/content_block_manager/app/components/content_block_manager/content_block/document/index/date_filter_component.rb

@@ -1,5 +1,6 @@
 class ContentBlockManager::ContentBlock::Document::Index::DateFilterComponent < ViewComponent::Base
-  def initialize(filters: nil)
+  def initialize(filters: nil, errors: nil)
     @filters = filters
+    @errors = errors
   end
 end

lib/engines/content_block_manager/app/components/content_block_manager/content_block/document/index/filter_options_component.html.erb

@@ -62,7 +62,7 @@
         },
         content: {
           html: (
-            render(ContentBlockManager::ContentBlock::Document::Index::DateFilterComponent.new(filters: @filters))
+            render(ContentBlockManager::ContentBlock::Document::Index::DateFilterComponent.new(filters: @filters, errors: @errors))
           ),
         },
         expanded: true,

lib/engines/content_block_manager/app/components/content_block_manager/content_block/document/index/filter_options_component.rb

@@ -1,7 +1,8 @@
 class ContentBlockManager::ContentBlock::Document::Index::FilterOptionsComponent < ViewComponent::Base
   include ActionView::Helpers::RecordTagHelper
-  def initialize(filters:)
+  def initialize(filters:, errors: nil)
     @filters = filters
+    @errors = errors
   end
 
 private

lib/engines/content_block_manager/app/controllers/content_block_manager/content_block/documents_controller.rb

@@ -3,7 +3,12 @@ def index
     if params_filters.any?
       session[:content_block_filters] = params_filters
       @filters = params_filters
-      @content_block_documents = ContentBlockManager::ContentBlock::Document::DocumentFilter.new(@filters).paginated_documents
+      filter_result = ContentBlockManager::ContentBlock::Document::DocumentFilter.new(@filters)
+      @content_block_documents = filter_result.paginated_documents
+      unless filter_result.valid?
+        @errors = filter_result.errors
+        @error_summary_errors = @errors.map { |error| { text: error.full_message, href: "##{error.attribute}_3i" } }
+      end
       render :index
     elsif params[:reset_fields].blank? && session_filters.any?
       redirect_to content_block_manager.content_block_manager_root_path(session_filters)

lib/engines/content_block_manager/app/models/content_block_manager/content_block/document/document_filter.rb

@@ -1,15 +1,39 @@
 module ContentBlockManager
   class ContentBlock::Document::DocumentFilter
+    FILTER_ERROR = Data.define(:attribute, :full_message)
+    attr_reader :errors
+
     def initialize(filters = {})
       @filters = filters
+      @errors = []
     end
 
     def paginated_documents
       unpaginated_documents.page(page).per(default_page_size)
     end
 
+    def valid?
+      return @valid if defined?(@valid)
+
+      @valid ||= begin
+        validate_date(:last_updated_from)
+        validate_date(:last_updated_to)
+
+        errors.empty?
+      end
+    end
+
   private
 
+    def validate_date(key)
+      return unless is_date_present?(key)
+
+      date = date_from_filters(key)
+      Time.zone.local(date[:year], date[:month], date[:day])
+    rescue ArgumentError, TypeError, NoMethodError
+      @errors << FILTER_ERROR.new(attribute: key.to_s, full_message: "#{key.to_s.humanize} is not a valid date")
+    end
+
     def page
       @filters[:page].presence || 1
     end
@@ -22,23 +46,25 @@ def is_date_present?(date_key)
       @filters[date_key].present? && @filters[date_key].all? { |_, value| value.present? }
     end
 
+    def date_from_filters(date_key)
+      filter = @filters[date_key]
+      year = filter["1i"].to_i
+      month = filter["2i"].to_i
+      day = filter["3i"].to_i
+      { year:, month:, day: }
+    end
+
     def from_date
       @from_date ||= if is_date_present?(:last_updated_from)
-                       filter = @filters[:last_updated_from]
-                       year = filter["1i"].to_i
-                       month = filter["2i"].to_i
-                       day = filter["3i"].to_i
-                       Time.zone.local(year, month, day)
+                       date = date_from_filters(:last_updated_from)
+                       Time.zone.local(date[:year], date[:month], date[:day])
                      end
     end
 
     def to_date
       @to_date ||= if is_date_present?(:last_updated_to)
-                     filter = @filters[:last_updated_to]
-                     year = filter["1i"].to_i
-                     month = filter["2i"].to_i
-                     day = filter["3i"].to_i
-                     Time.zone.local(year, month, day, 23, 59, 59)
+                     date = date_from_filters(:last_updated_to)
+                     Time.zone.local(date[:year], date[:month], date[:day], 23, 59, 59)
                    end
     end
 
@@ -49,8 +75,8 @@ def unpaginated_documents
       documents = documents.with_keyword(@filters[:keyword]) if @filters[:keyword].present?
       documents = documents.where(block_type: @filters[:block_type]) if @filters[:block_type].present?
       documents = documents.with_lead_organisation(@filters[:lead_organisation]) if @filters[:lead_organisation].present?
-      documents = documents.from_date(from_date) if from_date
-      documents = documents.to_date(to_date) if to_date
+      documents = documents.from_date(from_date) if valid? && from_date
+      documents = documents.to_date(to_date) if valid? && to_date
       documents.order("content_block_editions.updated_at DESC")
     end
   end

lib/engines/content_block_manager/app/views/content_block_manager/content_block/documents/index.html.erb

@@ -1,6 +1,13 @@
 
 <% content_for :title_margin_bottom, 6 %>
 
+<% if @error_summary_errors %>
+  <%= render "govuk_publishing_components/components/error_summary", {
+    title: "There is a problem",
+    items: @error_summary_errors,
+  } %>
+<% end %>
+
 <div class="govuk-grid-row content-block-manager-header">
     <div class="govuk-grid-column-one-half">
       <h1 class="gem-c-title__text govuk-heading-xl">
@@ -29,6 +36,7 @@
     <%= render(
           ContentBlockManager::ContentBlock::Document::Index::FilterOptionsComponent.new(
             filters: @filters,
+            errors: @errors,
             ),
           ) %>
   </div>

lib/engines/content_block_manager/features/search_for_object.feature

@@ -71,6 +71,12 @@ Feature: Search for a content object
     And I click to view results
     And "1" content blocks are returned in total
 
+  Scenario: GDS Editor sees errors when searching by invalid dates
+    When I visit the Content Block Manager home page
+    And I input invalid dates to filter by
+    And I click to view results
+    Then I should see a message that the filter dates are invalid
+
   @javascript
   Scenario: GDS Editor can copy embed code
     When I visit the Content Block Manager home page

lib/engines/content_block_manager/features/step_definitions/content_block_manager_steps.rb

@@ -401,6 +401,11 @@ def should_show_edit_form_for_email_address_content_block(document_title, email_
   assert_text "#{ContentBlockManager::ContentBlock::Edition.human_attribute_name("details_#{field_name}")} is an invalid #{format.titleize}"
 end
 
+Then("I should see a message that the filter dates are invalid") do
+  expect(page).to have_selector("a[href='#last_updated_from_3i']"), text: "Last updated from is not a valid date"
+  expect(page).to have_selector("a[href='#last_updated_to_3i']"), text: "Last updated to is not a valid date"
+end
+
 Then("I should see a permissions error") do
   assert_text "Permissions error"
 end
@@ -595,6 +600,16 @@ def should_show_edit_form_for_email_address_content_block(document_title, email_
   fill_in "last_updated_to_3i", with: date.day
 end
 
+When("I input invalid dates to filter by") do
+  fill_in "last_updated_from_1i", with: "1"
+  fill_in "last_updated_from_2i", with: "34"
+  fill_in "last_updated_from_3i", with: "56"
+
+  fill_in "last_updated_to_1i", with: "1"
+  fill_in "last_updated_to_2i", with: "67"
+  fill_in "last_updated_to_3i", with: "56"
+end
+
 When("I enter an invalid date") do
   fill_in "Year", with: "01"
 end

lib/engines/content_block_manager/test/components/content_block/document/index/date_filter_component_test.rb

@@ -37,4 +37,19 @@ class ContentBlockManager::ContentBlock::Document::Index::DateFilterComponentTes
     assert_selector "input[name='last_updated_to[2i]'][value='4']"
     assert_selector "input[name='last_updated_to[1i]'][value='2026']"
   end
+
+  it "renders errors if there are errors on the date filter" do
+    errors = [
+      ContentBlockManager::ContentBlock::Document::DocumentFilter::FILTER_ERROR.new(
+        attribute: "last_updated_from", full_message: "From date is not in the correct format",
+      ),
+      ContentBlockManager::ContentBlock::Document::DocumentFilter::FILTER_ERROR.new(
+        attribute: "last_updated_to", full_message: "To date is not in the correct format",
+      ),
+    ]
+    render_inline(ContentBlockManager::ContentBlock::Document::Index::DateFilterComponent.new(errors:))
+
+    assert_selector ".govuk-error-message", text: "From date is not in the correct format"
+    assert_selector ".govuk-error-message", text: "To date is not in the correct format"
+  end
 end

lib/engines/content_block_manager/test/components/content_block/document/index/filter_options_component_test.rb

@@ -82,14 +82,21 @@ class ContentBlockManager::ContentBlock::Document::Index::FilterOptionsComponent
     assert_selector "option[selected='selected'][value=2]"
   end
 
-  it "passes filters to Date component" do
+  it "passes filters and errors to Date component" do
     filters = { lead_organisation: "2" }
-    date_component = ContentBlockManager::ContentBlock::Document::Index::DateFilterComponent.new(filters:)
-    ContentBlockManager::ContentBlock::Document::Index::DateFilterComponent.expects(:new).with(filters:).returns(date_component)
+    errors = [
+      ContentBlockManager::ContentBlock::Document::DocumentFilter::FILTER_ERROR.new(
+        attribute: "last_updated_from", full_message: "From date is not in the correct format",
+      ),
+    ]
+    date_component = ContentBlockManager::ContentBlock::Document::Index::DateFilterComponent.new(filters:, errors:)
+    ContentBlockManager::ContentBlock::Document::Index::DateFilterComponent.expects(:new).with(filters:, errors:)
+                                                                           .returns(date_component)
 
     render_inline(
       ContentBlockManager::ContentBlock::Document::Index::FilterOptionsComponent.new(
         filters:,
+        errors:,
       ),
     )