require 'rdf/isomorphic'
require 'linkeddata'
require 'active_support'
require 'rails_config'
require 'krikri/ldp'
require 'krikri/search_index'

require 'dpla/map'
require 'rdf/marmotta'
require 'oai/client'
require 'rest-client'
require 'edtf'
require 'text'
require 'csv'

require 'resque'

module Krikri
  ##
  # Krikri provides metadata aggregation and enhancement services.
  class Engine < ::Rails::Engine
    isolate_namespace Krikri

    def configure_blacklight!
      return unless File.exist?(Blacklight.solr_file)
      krikri_solr = Krikri::Settings.solr
      Blacklight.solr_config = Blacklight.solr_config.merge(krikri_solr) unless
        krikri_solr.nil?
    end

    # Autoload various classes and modules in lib
    config.autoload_paths += Dir["#{config.root}/lib/**/"]

    config.generators do |g|
      g.test_framework :rspec, :fixture => false
      g.fixture_replacement :factory_girl, :dir => 'spec/factories'
      g.assets false
      g.helper false
    end

    initializer 'settings' do
      conf_path = root.join('config')
      setting_files = [conf_path.join('settings.yml'),
                       conf_path.join('settings', "#{Rails.env}.yml"),
                       conf_path.join('environments', "#{Rails.env}.yml"),
                       conf_path.join('settings.local.yml'),
                       conf_path.join('settings', "#{Rails.env}.local.yml"),
                       conf_path.join('environments', "#{Rails.env}.local.yml")
                      ].map(&:to_s)

      settings_const = Kernel.const_get(RailsConfig.const_name)

      source_paths = settings_const.add_source!('nil')[0..-2].map(&:path)
      source_paths = setting_files + source_paths

      RailsConfig.load_and_set_settings(source_paths)
      Krikri::Settings = Kernel.const_get(RailsConfig.const_name)
    end

    initializer :append_migrations do |app|
      unless app.root.to_s == root.to_s
        config.paths['db/migrate'].expanded.each do |exp_path|
          app.config.paths['db/migrate'] << exp_path
        end
      end
    end

    initializer :register_harvesters do
      Krikri::Harvester::Registry
        .register(:oai, Krikri::Harvesters::OAIHarvester)
      Krikri::Harvester::Registry
        .register(:couchdb, Krikri::Harvesters::CouchdbHarvester)

    end

    initializer :rdf_repository do
      Krikri::Repository =
        RDF::Marmotta.new(Krikri::Settings['marmotta']['base'])
    end

    initializer :blacklight_settings do
      configure_blacklight!
    end

    initializer :aggregation do
      DPLA::MAP::Aggregation.class_eval do
        include Krikri::MapCrosswalk
        include Krikri::LDP::RdfSource
        configure :base_uri => Krikri::Settings['marmotta']['item_container']

        def mint_id!(seed = nil)
          set_subject!(mint_id_fragment(seed))
          update_source_resource_subject
        end

        ##
        # Forceably update the subject for the dpla:SourceResource to use a
        # fragment URI. This is necessary because of an issue in
        # ActiveTriples.
        #
        # @see https://github.com/ActiveTriples/ActiveTriples/issues/107
        def update_source_resource_subject
          unless sourceResource.empty?
            sr = get_values(RDF::EDM::aggregatedCHO).first
            orig = sourceResource_ids.first
            # Q: should we have a check like `orig.node?` here?
            sr.set_subject!(rdf_subject / '#sourceResource')
            sr.persist!
            update([self, RDF::EDM::aggregatedCHO, sr])
            delete([orig, nil, nil])
          end
        end

        ##
        # Get the persisted original record for this Aggregation.
        # @return [Krikri::OriginalRecord, nil]
        #
        # An Exception will be raised if:
        #   the original record id is invalid.
        #   the original record has not been persisted to Marmotta.
        #   there is a connection problem with  Marmotta.
        def original_record
          Krikri::OriginalRecord.load(originalRecord.first.rdf_subject
            .to_s)
        end

        private

        def local_name_from_original_record
          return nil if originalRecord.empty?
          raise "#{self} has more than one OriginalRecord, cannot source a " \
          "definitive identifier." unless originalRecord.length == 1
          originalRecord.first.rdf_subject.path.split('/').last.split('.').first
        end

        def mint_id_fragment(seed = nil)
          return seed if seed
          return SecureRandom.hex if
            originalRecord.empty? || originalRecord.first.node?
          local_name_from_original_record
        end
      end
    end

    ##
    # Allow the methods in Krikri::ApplicatoinHelper to be accessible by the
    # host application.
    initializer 'krikri.helpers' do |app|
      ActionView::Base.send :include, Krikri::ApplicationHelper
    end
  end
end