ACD-573: Add schema and sample for the new application detail endpoint

Add new service to validate the response from the CP endpoint (for now court_application_details/all_fields.json) against the schema.

app/controllers/api/internal/v2/court_applications_controller.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+module Api
+  module Internal
+    module V2
+      class CourtApplicationsController < ApplicationController
+        def show
+          # TODO: this will be the new application details endpoint
+          raise NotImplementedError
+        end
+      end
+    end
+  end
+end

app/services/schema_validator.rb

@@ -0,0 +1,43 @@
+require "json-schema"
+require "uri"
+
+class SchemaValidator < ApplicationService
+  def initialize(schema:, json_response:)
+    @schema = schema
+    @json_response = json_response
+
+    load_schema_references
+  end
+
+  def call
+    JSON::Validator.validate!(@schema, @json_response)
+  rescue JSON::Schema::ValidationError => e
+    Rails.logger.error("JSON Schema Validation Error: #{e.message}")
+    false
+  end
+
+private
+
+  def load_schema_references
+    refs = [{
+              filename: "lib/schemas/global/apiCourtsDefinitions.json",
+              url: "http://justice.gov.uk/core/courts/external/apiCourtsDefinitions.json",
+            },
+            {
+              filename: "lib/schemas/global/apiJudicialResult.json",
+              url: "http://justice.gov.uk/core/courts/external/apiJudicialResult.json",
+            },
+            {
+              filename: "lib/schemas/global/apiDelegatedPowers.json",
+              url: "http://justice.gov.uk/core/courts/external/apiDelegatedPowers.json",
+            }]
+
+    refs.each do |ref|
+      json_schema = JSON::Schema.new(
+        JSON.parse(File.open(Rails.root.join(ref[:filename]).to_s).read),
+        Addressable::URI.parse(ref[:url]),
+      )
+      JSON::Validator.add_schema(json_schema)
+    end
+  end
+end

config/routes.rb

@@ -27,6 +27,7 @@
       end
 
       api_version(module: "V2", path: { value: "v2" }) do
+        resources :court_applications, only: [:show]
         resources :prosecution_cases, only: [:index], param: :reference do
           resources :defendants, only: %i[show]
         end