Allow using cocina json as the data source

This is based on a global feature flag, so we can enable this via shared configs for testing

.rubocop.yml

@@ -24,14 +24,17 @@ Rails:
 Metrics/CyclomaticComplexity:
   Exclude:
     - 'app/models/ability.rb'
+    - 'app/models/cocina_ability.rb'
 
 Metrics/PerceivedComplexity:
   Exclude:
     - 'app/models/ability.rb'
+    - 'app/models/cocina_ability.rb'
 
 Metrics/AbcSize:
   Exclude:
     - 'app/models/ability.rb'
+    - 'app/models/cocina_ability.rb'
     - 'app/controllers/iiif_controller.rb'
 
 Layout/EmptyLinesAroundBlockBody:

.rubocop_todo.yml

@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2023-11-03 20:55:41 UTC using RuboCop version 1.57.2.
+# on 2023-11-08 16:01:02 UTC using RuboCop version 1.57.2.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -28,9 +28,9 @@ Metrics/CyclomaticComplexity:
 # Offense count: 13
 # Configuration parameters: CountComments, CountAsOne, AllowedMethods, AllowedPatterns.
 Metrics/MethodLength:
-  Max: 25
+  Max: 50
 
-# Offense count: 35
+# Offense count: 31
 RSpec/AnyInstance:
   Exclude:
     - 'spec/controllers/media_controller_spec.rb'
@@ -43,7 +43,7 @@ RSpec/AnyInstance:
     - 'spec/requests/iiif_spec.rb'
     - 'spec/requests/media_auth_request_spec.rb'
 
-# Offense count: 89
+# Offense count: 78
 # Configuration parameters: Prefixes, AllowedPatterns.
 # Prefixes: when, with, without
 RSpec/ContextWording:
@@ -80,7 +80,7 @@ RSpec/EmptyLineAfterExampleGroup:
     - 'spec/controllers/legacy_image_service_controller_spec.rb'
     - 'spec/requests/file_auth_request_spec.rb'
 
-# Offense count: 37
+# Offense count: 32
 # This cop supports safe autocorrection (--autocorrect).
 RSpec/EmptyLineAfterFinalLet:
   Exclude:
@@ -159,11 +159,11 @@ RSpec/MessageSpies:
     - 'spec/controllers/file_controller_spec.rb'
     - 'spec/controllers/media_controller_spec.rb'
 
-# Offense count: 67
+# Offense count: 66
 RSpec/MultipleExpectations:
   Max: 12
 
-# Offense count: 81
+# Offense count: 80
 # Configuration parameters: EnforcedStyle, IgnoreSharedExamples.
 # SupportedStyles: always, named_only
 RSpec/NamedSubject:
@@ -183,7 +183,7 @@ RSpec/NamedSubject:
     - 'spec/services/iiif_metadata_service_spec.rb'
     - 'spec/services/media_authentication_json_spec.rb'
 
-# Offense count: 66
+# Offense count: 54
 # Configuration parameters: AllowedGroups.
 RSpec/NestedGroups:
   Max: 6
@@ -217,6 +217,7 @@ RSpec/VerifiedDoubles:
     - 'spec/services/media_authentication_json_spec.rb'
 
 # Offense count: 2
+# This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: EnforcedStyle.
 # SupportedStyles: slashes, arguments
 Rails/FilePath:
@@ -246,7 +247,7 @@ Style/HashAsLastArrayItem:
   Exclude:
     - 'app/controllers/object_controller.rb'
 
-# Offense count: 18
+# Offense count: 13
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: PreferredDelimiters.
 Style/PercentLiteralDelimiters:
@@ -266,17 +267,9 @@ Style/StringConcatenation:
     - 'spec/controllers/object_controller_spec.rb'
     - 'spec/models/stacks_media_token_spec.rb'
 
-# Offense count: 4
+# Offense count: 3
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: MinSize.
 # SupportedStyles: percent, brackets
 Style/SymbolArray:
   EnforcedStyle: brackets
-
-# Offense count: 1
-# This cop supports unsafe autocorrection (--autocorrect-all).
-# Configuration parameters: AllowMethodsWithArguments, AllowedMethods, AllowedPatterns, AllowComments.
-# AllowedMethods: define_method
-Style/SymbolProc:
-  Exclude:
-    - 'app/controllers/webauth_controller.rb'

app/models/cocina_ability.rb

@@ -0,0 +1,119 @@
+# frozen_string_literal: true
+
+##
+# User authentication
+class CocinaAbility
+  include CanCan::Ability
+
+  def initialize(user)
+    # Define abilities for the passed in user here. For example:
+    #
+    user ||= User.new # guest user (not logged in)
+    #   if user.admin?
+    #     can :manage, :all
+    #   else
+    #     can :read, :all
+    #   end
+    #
+    # The first argument to `can` is the action you are giving the user
+    # permission to do.
+    # If you pass :manage it will apply to every action. Other common actions
+    # here are :read, :create, :update and :destroy.
+    #
+    # The second argument is the resource the user can perform the action on.
+    # If you pass :all, it will apply to every resource. Otherwise, pass a Ruby
+    # class of the resource.
+    #
+    # The third argument is an optional hash of conditions to further filter the
+    # objects. For example, here the user can only update published articles.
+    #   can :update, Article, :published => true
+    #
+    # The block argument takes as a parameter an instance of the object for which
+    # permission is being checked. If the block returns true, the user is granted that
+    # ability, otherwise the user is denied that ability. The block is only evaluated
+    # for instances of objects, *not* for classes. If a class is passed to a `can?` or a
+    # `cannot?` that's defined by a block, that check will *always* grant permission.
+    #
+    # See the wiki for details:
+    # https://github.com/CanCanCommunity/cancancan/wiki/Defining-Abilities
+    # https://github.com/CanCanCommunity/cancancan/wiki/Defining-Abilities-with-Blocks
+
+    # NOTE: the below ability definitions which reference StacksFile also implicitly
+    # cover StacksImage and StacksMediaStream, and any other subclasses of StacksFile.
+
+    downloadable_models = [StacksFile, StacksImage]
+    access_models = downloadable_models + [StacksMediaStream]
+
+    can :download, downloadable_models do |f|
+      f.cocina_rights.download == 'world'
+    end
+
+    can [:access], access_models do |f|
+      f.cocina_rights.view == 'world'
+    end
+
+    if user.stanford?
+      can :download, downloadable_models do |f|
+        f.cocina_rights.download == 'stanford'
+      end
+
+      can [:access], access_models do |f|
+        f.cocina_rights.view == 'stanford'
+      end
+    end
+
+    if user.locations.present?
+      can :download, downloadable_models do |f|
+        next unless f.cocina_rights.download == 'location-based'
+
+        user.locations.include?(f.cocina_rights.location)
+      end
+
+      can [:access], access_models do |f|
+        user.locations.any? do |_location|
+          next unless f.cocina_rights.view == 'location-based'
+
+          user.locations.include?(f.cocina_rights.location)
+        end
+      end
+    end
+
+    if user.cdl_tokens.present?
+      # TODO: Actually check if the CDL object is downloadable
+      # can [:download, :read], models do |f|
+      #   ...
+      # end
+
+      can [:access], access_models do |f|
+        next unless f.cocina_rights.controlled_digital_lending?
+
+        user.cdl_tokens.any? { |payload| payload['aud'] == f.id }
+      end
+    end
+
+    cannot :download, RestrictedImage
+
+    # These are called when checking to see if the image response should be served
+    can [:download, :read], Projection do |projection|
+      can?(:download, projection.image)
+    end
+
+    can [:download, :read], Projection do |projection|
+      # Allow access to tile or thumbnail-sized requests for an accessible image
+      (projection.tile? || projection.thumbnail?) && can?(:access, projection.image)
+    end
+
+    can :access, Projection do |projection|
+      can?(:access, projection.image)
+    end
+
+    can :read, Projection do |projection|
+      # Allow access to thumbnail-sized projections of a declared (or implicit) thumbnail for the object;
+      # note that because this is implicit, we do not check rightsMetadata permissions.
+      projection.thumbnail? && projection.object_thumbnail?
+    end
+
+    alias_action :stream, to: :access
+    can :read_metadata, StacksImage
+  end
+end

app/models/cocina_rights.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+# The rights derived from cocina
+class CocinaRights
+  def initialize(file_rights)
+    @file_rights = file_rights
+  end
+
+  def download
+    @file_rights['download']
+  end
+
+  def view
+    @file_rights['view']
+  end
+
+  def controlled_digital_lending?
+    @file_rights['controlledDigitalLending']
+  end
+
+  def location
+    @file_rights['location']
+  end
+end

app/models/purl.rb

@@ -11,7 +11,7 @@ def self.instance
   end
 
   class << self
-    delegate :public_xml, :files, :barcode, to: :instance
+    delegate :public_xml, :public_json, :files, :barcode, to: :instance
   end
 
   # TODO: was etag a valid key?
@@ -26,9 +26,35 @@ def public_xml(druid)
     end
   end
 
-  def files(druid)
+  def public_json(druid)
+    Rails.cache.fetch("purl/#{druid}.json", expires_in: 10.minutes) do
+      benchmark "Fetching public json for #{druid}" do
+        response = Faraday.get(public_json_url(druid))
+        raise Purl::Exception, response.status unless response.success?
+
+        JSON.parse(response.body)
+      end
+    end
+  end
+
+  def files(druid, &block)
     return to_enum(:files, druid) unless block_given?
 
+    Settings.features.cocina ? files_from_json(druid, &block) : files_from_xml(druid, &block)
+  end
+
+  def files_from_json(druid)
+    doc = public_json(druid)
+
+    doc.dig('structural', 'contains').each do |fileset|
+      fileset.dig('structural', 'contains').each do |file|
+        file = StacksFile.new(id: druid, file_name: file['filename'])
+        yield file
+      end
+    end
+  end
+
+  def files_from_xml(druid)
     doc = Nokogiri::XML.parse(public_xml(druid))
 
     doc.xpath('//contentMetadata/resource').each do |resource|
@@ -56,6 +82,10 @@ def public_xml_url(druid)
     Settings.purl.url + "#{druid}.xml"
   end
 
+  def public_json_url(druid)
+    "#{Settings.purl.url}#{druid}.json"
+  end
+
   def logger
     Rails.logger
   end

app/models/stacks_file.rb

@@ -46,5 +46,5 @@ def druid_parts
   def stacks_rights
     @stacks_rights ||= StacksRights.new(id:, file_name:)
   end
-  delegate :rights, to: :stacks_rights
+  delegate :rights, :cocina_rights, to: :stacks_rights
 end

app/models/stacks_image.rb

@@ -62,6 +62,6 @@ def info_service
   def stacks_rights
     @stacks_rights ||= StacksRights.new(id:, file_name:)
   end
-  delegate :rights, :maybe_downloadable?, :object_thumbnail?,
+  delegate :rights, :cocina_rights, :maybe_downloadable?, :object_thumbnail?,
            :stanford_restricted?, :restricted_by_location?, :cdl_restricted?, to: :stacks_rights
 end

app/models/stacks_media_stream.rb

@@ -17,6 +17,7 @@ def file
   def stacks_rights
     @stacks_rights ||= StacksRights.new(id:, file_name:)
   end
-  delegate :rights, :restricted_by_location?, :stanford_restricted?, :embargoed?,
+
+  delegate :rights, :cocina_rights, :restricted_by_location?, :stanford_restricted?, :embargoed?,
            :embargo_release_date, to: :stacks_rights
 end