In testing the claim form we concluded that we cannot edit the same

claim record on the check page when creating a claim.

Issues were found when the user would click the back buttons to go back
to the check page after completing half their changes. The changes they
did were being saved. Even if they backed off from doing them.

To solve this issue and many others, we are implementing a revision
system on the claim.

Creating a revision every time a user wants to edit a claim from the
check page. If they back off half way through their changes we revert
back to the last valid claim revision.

This implementation will increase the audit records and possibly pollute
some of them with `system changes` i.e. changes to `previous_revision_id`
or `next_revision_id` which the user doesn't care about.

For the draft claim

This should fix the issue where a support user edits a draft claim and
with every edit, the draft claim is updated for everyone.

This will only `update` the draft claim when the support user actually
clicks `Update claim`.

They way this works is by using the `internal_draft` status. A generated
revision starts with `internal_draft` as its status and is changed to
draft when the support user finishes editing the draft claim. The
previous revision is then set to `internal_draft`, to not show more than
1 claim per reference.

app/assets/stylesheets/application.scss

@@ -11,3 +11,4 @@ $govuk-assets-path: "";
 @import "filter-form";
 @import "app-related-aside";
 @import "lists";
+@import "buttons";

app/assets/stylesheets/buttons.scss

@@ -0,0 +1,12 @@
+button.govuk-link {
+  all: unset;
+}
+
+button.govuk-link {
+    font-family: "GDS Transport", arial, sans-serif;
+    -webkit-font-smoothing: antialiased;
+    -moz-osx-font-smoothing: grayscale;
+    text-decoration: underline;
+    text-decoration-thickness: max(1px, .0625rem);
+    text-underline-offset: 0.1578em;
+}

app/controllers/claims/schools/claims/mentor_trainings_controller.rb

@@ -3,6 +3,17 @@ class Claims::Schools::Claims::MentorTrainingsController < Claims::ApplicationCo
   before_action :authorize_claim
   helper_method :mentor_training_form
 
+  def create_revision
+    revision = Claims::Claim::CreateRevision.call(claim: @claim)
+    mentor_training = revision.mentor_trainings.find_by(mentor_id: params.require(:id))
+
+    redirect_to edit_claims_school_claim_mentor_training_path(
+      @school,
+      revision,
+      mentor_training,
+    )
+  end
+
   def edit; end
 
   def update

app/controllers/claims/schools/claims/mentors_controller.rb

@@ -24,6 +24,11 @@ def create
     end
   end
 
+  def create_revision
+    revision = Claims::Claim::CreateRevision.call(claim: @claim)
+    redirect_to edit_claims_school_claim_mentors_path(@school, revision)
+  end
+
   def edit; end
 
   def update

app/controllers/claims/schools/claims_controller.rb

@@ -2,8 +2,9 @@ class Claims::Schools::ClaimsController < Claims::ApplicationController
   include Claims::BelongsToSchool
 
   before_action :has_school_accepted_grant_conditions?
-  before_action :set_claim, only: %i[show check confirmation submit edit update rejected]
+  before_action :set_claim, only: %i[show check confirmation submit edit update rejected create_revision]
   before_action :authorize_claim
+  before_action :get_valid_revision, only: :check
 
   helper_method :claim_provider_form
 
@@ -21,6 +22,11 @@ def create
     end
   end
 
+  def create_revision
+    revision = Claims::Claim::CreateRevision.call(claim: @claim)
+    redirect_to edit_claims_school_claim_path(@school, revision)
+  end
+
   def show; end
 
   def check
@@ -88,4 +94,10 @@ def claim_id
   def authorize_claim
     authorize @claim || Claims::Claim
   end
+
+  def get_valid_revision
+    revision = @claim.get_valid_revision
+
+    redirect_to check_claims_school_claim_path(@school, revision) if revision != @claim
+  end
 end

app/controllers/claims/support/schools/claims/mentor_trainings_controller.rb

@@ -3,6 +3,17 @@ class Claims::Support::Schools::Claims::MentorTrainingsController < Claims::Appl
   before_action :authorize_claim
   helper_method :mentor_training_form
 
+  def create_revision
+    revision = Claims::Claim::CreateRevision.call(claim: @claim)
+    mentor_training = revision.mentor_trainings.find_by(mentor_id: params.require(:id))
+
+    redirect_to edit_claims_support_school_claim_mentor_training_path(
+      @school,
+      revision,
+      mentor_training,
+    )
+  end
+
   def edit; end
 
   def update

app/controllers/claims/support/schools/claims/mentors_controller.rb

@@ -20,6 +20,11 @@ def create
     end
   end
 
+  def create_revision
+    revision = Claims::Claim::CreateRevision.call(claim: @claim)
+    redirect_to edit_claims_support_school_claim_mentors_path(@school, revision)
+  end
+
   def edit; end
 
   def update

app/controllers/claims/support/schools/claims_controller.rb

@@ -1,8 +1,10 @@
 class Claims::Support::Schools::ClaimsController < Claims::Support::ApplicationController
   include Claims::BelongsToSchool
 
-  before_action :set_claim, only: %i[check draft show edit update remove destroy rejected]
+  before_action :set_claim, only: %i[check draft show edit update remove destroy rejected create_revision]
   before_action :authorize_claim
+  before_action :get_valid_revision, only: :check
+
   helper_method :claim_provider_form
 
   def index
@@ -29,6 +31,11 @@ def create
     end
   end
 
+  def create_revision
+    revision = Claims::Claim::CreateRevision.call(claim: @claim)
+    redirect_to edit_claims_support_school_claim_path(@school, revision)
+  end
+
   def check
     last_mentor_training = @claim.mentor_trainings.order_by_mentor_full_name.last
 
@@ -56,8 +63,14 @@ def update
   def draft
     return redirect_to rejected_claims_support_school_claim_path unless @claim.valid_mentor_training_hours?
 
-    success_message = @claim.draft? ? t(".update_success") : t(".add_success")
-    Claims::Claim::CreateDraft.call(claim: @claim)
+    claim_was_draft = @claim.was_draft?
+    success_message = claim_was_draft ? t(".update_success") : t(".add_success")
+
+    if claim_was_draft
+      Claims::Claim::UpdateDraft.call(claim: @claim)
+    else
+      Claims::Claim::CreateDraft.call(claim: @claim)
+    end
 
     redirect_to claims_support_school_claims_path(@school), flash: { success: success_message }
   end
@@ -96,4 +109,10 @@ def claim_provider_form
   def authorize_claim
     authorize @claim || Claims::Claim
   end
+
+  def get_valid_revision
+    revision = @claim.get_valid_revision
+
+    redirect_to check_claims_support_school_claim_path(@school, revision) if revision != @claim
+  end
 end

app/forms/claims/claim/mentor_training_form.rb

@@ -43,7 +43,7 @@ def persist
 
   def back_path
     if mentor_trainings.index(mentor_training).zero?
-      edit_claims_school_claim_mentor_path(school, claim, mentor_training.mentor_id)
+      edit_claims_school_claim_mentors_path(school, claim)
     else
       edit_claims_school_claim_mentor_training_path(school, claim, previous_mentor_training)
     end

app/forms/claims/support/claim/mentor_training_form.rb

@@ -1,7 +1,7 @@
 class Claims::Support::Claim::MentorTrainingForm < Claims::Claim::MentorTrainingForm
   def back_path
     if mentor_trainings.index(mentor_training).zero?
-      edit_claims_support_school_claim_mentor_path(school, claim, mentor_training.mentor_id)
+      edit_claims_support_school_claim_mentors_path(school, claim)
     else
       edit_claims_support_school_claim_mentor_training_path(school, claim, previous_mentor_training)
     end

app/models/claims/claim.rb

@@ -2,26 +2,28 @@
 #
 # Table name: claims
 #
-#  id                :uuid             not null, primary key
-#  created_by_type   :string
-#  reference         :string
-#  status            :enum
-#  submitted_at      :datetime
-#  submitted_by_type :string
-#  created_at        :datetime         not null
-#  updated_at        :datetime         not null
-#  created_by_id     :uuid
-#  provider_id       :uuid
-#  school_id         :uuid             not null
-#  submitted_by_id   :uuid
+#  id                   :uuid             not null, primary key
+#  created_by_type      :string
+#  reference            :string
+#  status               :enum
+#  submitted_at         :datetime
+#  submitted_by_type    :string
+#  created_at           :datetime         not null
+#  updated_at           :datetime         not null
+#  created_by_id        :uuid
+#  previous_revision_id :uuid
+#  provider_id          :uuid
+#  school_id            :uuid             not null
+#  submitted_by_id      :uuid
 #
 # Indexes
 #
-#  index_claims_on_created_by    (created_by_type,created_by_id)
-#  index_claims_on_provider_id   (provider_id)
-#  index_claims_on_reference     (reference) UNIQUE
-#  index_claims_on_school_id     (school_id)
-#  index_claims_on_submitted_by  (submitted_by_type,submitted_by_id)
+#  index_claims_on_created_by            (created_by_type,created_by_id)
+#  index_claims_on_previous_revision_id  (previous_revision_id)
+#  index_claims_on_provider_id           (provider_id)
+#  index_claims_on_reference             (reference)
+#  index_claims_on_school_id             (school_id)
+#  index_claims_on_submitted_by          (submitted_by_type,submitted_by_id)
 #
 # Foreign Keys
 #
@@ -41,8 +43,15 @@ class Claims::Claim < ApplicationRecord
   has_many :mentor_trainings, dependent: :destroy
   has_many :mentors, through: :mentor_trainings
 
+  belongs_to :previous_revision, class_name: "Claims::Claim", optional: true
+
   validates :status, presence: true
-  validates :reference, uniqueness: { case_sensitive: false }, allow_nil: true
+  validates(
+    :reference,
+    uniqueness: { case_sensitive: false },
+    allow_nil: true,
+    unless: :has_revision?,
+  )
 
   ACTIVE_STATUSES = %i[draft submitted].freeze
 
@@ -58,10 +67,11 @@ class Claims::Claim < ApplicationRecord
   delegate :full_name, to: :submitted_by, prefix: true, allow_nil: true
 
   def valid_mentor_training_hours?
-    mentor_trainings_without_current_claim = Claims::MentorTraining.joins(:claim).merge(Claims::Claim.active).where(
-      mentor_id: mentor_trainings.select(:mentor_id),
-      provider_id:,
-    ).where.not(claim_id: id)
+    mentor_trainings_without_current_claim = Claims::MentorTraining.joins(:claim)
+      .merge(Claims::Claim.active).where(
+        mentor_id: mentor_trainings.select(:mentor_id),
+        provider_id:,
+      ).where.not(claim_id: [id, previous_revision_id])
     grouped_trainings = [*mentor_trainings, *mentor_trainings_without_current_claim].group_by { [_1.mentor_id, _1.provider_id] }
 
     grouped_trainings.transform_values { _1.sum(&:hours_completed) }.values.all? { _1 <= MAXIMUM_CLAIMABLE_HOURS }
@@ -78,4 +88,28 @@ def amount
   def active?
     ACTIVE_STATUSES.include?(status.to_sym)
   end
+
+  def ready_to_be_checked?
+    mentors.present? && mentor_trainings.without_hours.blank?
+  end
+
+  def get_valid_revision
+    Claims::Claim::RemoveEmptyMentorTrainingHours.call(claim: self)
+
+    mentor_trainings.present? ? self : previous_revision
+  end
+
+  def was_draft?
+    claim_record = self
+    claim_record = claim_record.previous_revision while claim_record.present? && !claim_record.draft?
+
+    claim_record.nil? ? false : claim_record.draft?
+  end
+
+  private
+
+  def has_revision?
+    previous_revision_id.present? ||
+      id.present? && Claims::Claim.find_by(previous_revision_id: id).present?
+  end
 end

app/policies/claims/claim_policy.rb

@@ -7,6 +7,10 @@ def update?
     edit?
   end
 
+  def create_revision?
+    edit?
+  end
+
   def submit?
     !user.support_user? && !record.submitted?
   end

app/services/claims/claim/create_revision.rb

@@ -0,0 +1,26 @@
+class Claims::Claim::CreateRevision
+  include ServicePattern
+
+  def initialize(claim:)
+    @claim = claim
+  end
+
+  def call
+    revision_record = deep_dup
+    revision_record.save!
+
+    revision_record
+  end
+
+  private
+
+  attr_reader :claim
+
+  def deep_dup
+    dup_record = claim.dup
+    dup_record.mentor_trainings = claim.mentor_trainings.map(&:dup)
+    dup_record.previous_revision_id = claim.id
+    dup_record.status = :internal_draft
+    dup_record
+  end
+end

app/services/claims/claim/update_draft.rb

@@ -0,0 +1,28 @@
+class Claims::Claim::UpdateDraft < Claims::Claim::CreateDraft
+  include ServicePattern
+
+  def call
+    ActiveRecord::Base.transaction do
+      updated_claim.save!
+      update_previous_revisions_to_internal_draft
+    end
+  end
+
+  private
+
+  def update_previous_revisions_to_internal_draft
+    claim_record = updated_claim.previous_revision
+
+    while claim_record.present?
+      claim_record.update!(status: :internal_draft) if claim_record.draft?
+      claim_record = claim_record.previous_revision
+    end
+  end
+
+  def updated_claim
+    @updated_claim ||= begin
+      claim.status = :draft
+      claim
+    end
+  end
+end

app/services/claims/mentor/calculate_remaining_mentor_training_hours_for_provider.rb

@@ -11,7 +11,7 @@ def initialize(mentor:, provider:, claim: nil, mentor_training: nil)
 
   def call
     MAXIMUM_CLAIMABLE_HOURS_PER_PROVIDER -
-      Claims::Mentor::CalculateTotalMentorTrainingHoursForProvider.call(mentor:, provider:) +
+      Claims::Mentor::CalculateTotalMentorTrainingHoursForProvider.call(mentor:, provider:, claim: mentor_training&.claim) +
       current_mentor_training_hours
   end
 

app/services/claims/mentor/calculate_total_mentor_training_hours_for_provider.rb

@@ -1,16 +1,17 @@
 class Claims::Mentor::CalculateTotalMentorTrainingHoursForProvider
   include ServicePattern
 
-  def initialize(mentor:, provider:)
+  def initialize(mentor:, provider:, claim: nil)
     @mentor = mentor
     @provider = provider
+    @claim = claim
   end
 
   def call
-    mentor.mentor_trainings.joins(:claim).merge(Claims::Claim.active).where(provider:).sum(:hours_completed)
+    mentor.mentor_trainings.joins(:claim).merge(Claims::Claim.active).where(provider:).where.not(claim_id: claim&.previous_revision_id).sum(:hours_completed)
   end
 
   private
 
-  attr_reader :mentor, :provider
+  attr_reader :mentor, :provider, :claim
 end