Implement Detector, Category, DetectorCategory

** Why are these changes being introduced:

Our chosen architecture calls for a set of models that will comprise a
sort of "knowledge graph", which TACOS will consult during the
categorization process. This includes classes for Category, Detector,
and a linking DetectorCategory class. The Detector and DetectorCategory
classes will each define a confidence value.

** Relevant ticket(s):

* https://mitlibraries.atlassian.net/browse/tco-82

** How does this address that need:

This defines those classes. The migration includes the creation of the
needed records for each class: Three category records, six detectors,
and five records which link between them.

There are currently no detectors which map to two of the categories,
although we have talked about those being needed. Additionally, one
detector, SuggestedResource, is unique in that specific records will
count toward each category - so it isn't appropriate to have a link
record which uniformly connects to only one category.

** Document any side effects to this change:

We previously had a Detector model file, but it was set as a Module in
order to provide a namespace for its subclasses. This has been updated
to be just a class, which impacts the dashboard and test files. Also,
there was a method to define a table name prefix, which has been moved
from the Detector file to the subclass files.

app/dashboards/detector/suggested_resource_dashboard.rb

@@ -2,7 +2,7 @@
 
 require 'administrate/base_dashboard'
 
-module Detector
+class Detector
   class SuggestedResourceDashboard < Administrate::BaseDashboard
     # ATTRIBUTE_TYPES
     # a hash that describes the type of each of the model's fields.

app/models/category.rb

@@ -0,0 +1,4 @@
+class Category < ApplicationRecord
+  has_many :detector_categories
+  has_many :detectors, through: :detector_categories
+end

app/models/detector.rb

@@ -2,8 +2,7 @@
 
 # Detectors are classes that implement various algorithms that allow us to identify patterns
 # within search terms.
-module Detector
-  def self.table_name_prefix
-    'detector_'
-  end
+class Detector < ApplicationRecord
+  has_many :detector_categories
+  has_many :categories, through: :detector_categories
 end

app/models/detector/journal.rb

@@ -10,12 +10,16 @@
 #  created_at      :datetime         not null
 #  updated_at      :datetime         not null
 #
-module Detector
+class Detector
   # Detector::Journal stores information about academic journals loaded from external sources to allow us to check our
   # incoming Terms against these information
   class Journal < ApplicationRecord
     before_save :downcase_fields!
 
+    def self.table_name_prefix
+      'detector_'
+    end
+
     # Identify journals in which the incoming phrase matches a Journal.name exactly
     #
     # @note We always store the Journal.name downcased, so we should also always downcase the phrase

app/models/detector/standard_identifiers.rb

@@ -1,11 +1,15 @@
 # frozen_string_literal: true
 
-module Detector
+class Detector
   # Detector::StandardIdentifiers detects the identifiers DOI, ISBN, ISSN, PMID.
   # See /docs/reference/pattern_detection_and_enhancement.md for details.
   class StandardIdentifiers
     attr_reader :identifiers
 
+    def self.table_name_prefix
+      'detector_'
+    end
+
     def initialize(term)
       @identifiers = {}
       term_pattern_checker(term)

app/models/detector/suggested_resource.rb

@@ -15,13 +15,17 @@
 
 require 'stringex/core_ext'
 
-module Detector
+class Detector
   # Detector::SuggestedResource stores custom hints that we want to send to the
   # user in response to specific strings. For example, a search for "web of
   # science" should be met with our custom login link to Web of Science via MIT.
   class SuggestedResource < ApplicationRecord
     before_save :update_fingerprint
 
+    def self.table_name_prefix
+      'detector_'
+    end
+
     # This exists for the before_save lifecycle hook to call the calculate_fingerprint method, to ensure that these
     # records always have a correctly-calculated fingerprint. It has no arguments and returns nothing.
     def update_fingerprint

app/models/detector_category.rb

@@ -0,0 +1,4 @@
+class DetectorCategory < ApplicationRecord
+  belongs_to :category
+  belongs_to :detector
+end

db/migrate/20240909183413_create_categories.rb

@@ -0,0 +1,42 @@
+class CreateCategories < ActiveRecord::Migration[7.1]
+  def change
+    create_table :detectors do |t|
+      t.string :name
+      t.float :confidence
+
+      t.timestamps
+    end
+
+    create_table :categories do |t|
+      t.string :name
+      t.text :description
+
+      t.timestamps
+    end
+
+    create_table :detector_categories do |t|
+      t.belongs_to :detector, null: false, foreign_key: true
+      t.belongs_to :category, null: false, foreign_key: true
+      t.float :confidence
+
+      t.timestamps
+    end
+
+    Detector.create(name: 'DOI', confidence: 0.95)
+    Detector.create(name: 'ISBN', confidence: 0.8)
+    Detector.create(name: 'ISSN', confidence: 0.6)
+    Detector.create(name: 'PMID', confidence: 0.95)
+    Detector.create(name: 'Journal', confidence: 0.2)
+    Detector.create(name: 'SuggestedResource', confidence: 0.95)
+
+    Category.create(name: 'Informational', description: 'A type of search where the user is looking for broad information, rather than an individual item. Also known as "open-ended" or "topical".')
+    Category.create(name: 'Navigational', description: 'A type of search where the user has a location in mind, and wants to go there. In library discovery, this should mean a URL that will not be in the searched index.')
+    Category.create(name: 'Transactional', description: 'A type of search where the user has an item in mind, and wants to get that item. Also known as "known-item".')
+
+    DetectorCategory.create(detector: Detector.find_by(name: 'DOI'), category: Category.find_by(name: 'Transactional'), confidence: 0.95)
+    DetectorCategory.create(detector: Detector.find_by(name: 'ISBN'), category: Category.find_by(name: 'Transactional'), confidence: 0.95)
+    DetectorCategory.create(detector: Detector.find_by(name: 'ISSN'), category: Category.find_by(name: 'Transactional'), confidence: 0.95)
+    DetectorCategory.create(detector: Detector.find_by(name: 'PMID'), category: Category.find_by(name: 'Transactional'), confidence: 0.95)
+    DetectorCategory.create(detector: Detector.find_by(name: 'Journal'), category: Category.find_by(name: 'Transactional'), confidence: 0.5)
+  end
+end

test/models/detector/journal_test.rb

@@ -12,7 +12,7 @@
 #
 require 'test_helper'
 
-module Detector
+class Detector
   class JournalTest < ActiveSupport::TestCase
     test 'exact term match on journal name' do
       expected = detector_journals('the_new_england_journal_of_medicine')
@@ -57,4 +57,4 @@ class JournalTest < ActiveSupport::TestCase
       assert_equal(mixed_case.downcase, actual.name)
     end
   end
-end
+end

test/models/detector/standard_identifiers_test.rb

@@ -2,7 +2,7 @@
 
 require 'test_helper'
 
-module Detector
+class Detector
   class StandardIdentifiersTest < ActiveSupport::TestCase
     test 'ISBN detected in a string' do
       actual = Detector::StandardIdentifiers.new('test 978-3-16-148410-0 test').identifiers
@@ -191,4 +191,4 @@ class StandardIdentifiersTest < ActiveSupport::TestCase
       end
     end
   end
-end
+end

test/models/detector/suggested_resource_test.rb

@@ -14,7 +14,7 @@
 #
 require 'test_helper'
 
-module Detector
+class Detector
   class SuggestedResourceTest < ActiveSupport::TestCase
     test 'fingerprints are generated automatically' do
       resource = {