Hack to query separate SOLR instance for text-extraction

lib/hydra/derivatives/processors/full_text.rb

@@ -0,0 +1,80 @@
+# frozen_string_literal: true
+
+# rubocop:disable Metrics/AbcSize
+module Hydra::Derivatives::Processors
+  # Extract the full text from the content using Solr's extract handler
+  class FullText < Processor
+    # Run the full text extraction and save the result
+    # @return [TrueClass,FalseClass] was the process successful.
+    def process
+      output_file_service.call(extract, directives)
+    end
+
+    private
+
+    ##
+    # Extract full text from the content using Solr's extract handler.
+    # This will extract text from the file
+    #
+    # @return [String] The extracted text
+    def extract
+      JSON.parse(fetch)[''].rstrip
+    end
+
+    # send the request to the extract service and return the response if it was successful.
+    # TODO: this pulls the whole file into memory. We should stream it from Fedora instead
+    # @return [String] the result of calling the extract service
+    def fetch
+      resp = http_request
+      raise "Solr Extract service was unsuccessful. '#{uri}' returned code #{resp.code} for #{source_path}\n#{resp.body}" unless resp.code == '200'
+
+      file_content.rewind if file_content.respond_to?(:rewind)
+      resp.body.force_encoding(resp.type_params['charset']) if resp.type_params['charset']
+      resp.body
+    end
+
+    # Send the request to the extract service
+    # @return [Net::HttpResponse] the result of calling the extract service
+    def http_request
+      Net::HTTP.start(uri.host, uri.port, use_ssl: check_for_ssl) do |http|
+        req = Net::HTTP::Post.new(uri.request_uri, request_headers)
+        req.basic_auth uri.user, uri.password unless uri.password.nil?
+        req.body = file_content
+        http.request req
+      end
+    end
+
+    def file_content
+      @file_content ||= File.open(source_path).read
+    end
+
+    # @return [Hash] the request headers to send to the Solr extract service
+    def request_headers
+      { Faraday::Request::UrlEncoded::CONTENT_TYPE => mime_type.to_s,
+        Faraday::Adapter::CONTENT_LENGTH => original_size.to_s }
+    end
+
+    def mime_type
+      Hydra::Derivatives::MimeTypeService.mime_type(source_path)
+    end
+
+    def original_size
+      File.size(source_path)
+    end
+
+    # @returns [URI] path to the extract service
+    def uri
+      @uri ||= connection_url + 'update/extract?extractOnly=true&wt=json&extractFormat=text'
+    end
+
+    def check_for_ssl
+      uri.scheme == 'https'
+    end
+
+    # @returns [URI] path to the solr collection
+    def connection_url
+      URI.parse(ENV.fetch('SOLR_EXTRACT_URL', 'localhost') + '/')
+    end
+  end
+end
+# rubocop:enable Metrics/AbcSize