# Licensed to Elasticsearch B.V. under one or more contributor
# license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright
# ownership. Elasticsearch B.V. licenses this file to you under
# the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.

module Elasticsearch
  module Model
    module Adapter
      # An adapter for Mongoid-based models
      #
      # @see http://mongoid.org
      #
      module Mongoid
        Adapter.register(
          self,
          lambda do |klass|
            !!defined?(::Mongoid::Document) &&
              klass.respond_to?(:ancestors) &&
              klass.ancestors.include?(::Mongoid::Document)
          end
        )

        module Records
          # Return a `Mongoid::Criteria` instance
          #
          def records
            criteria = klass.where(:id.in => ids)

            criteria.instance_exec(response.response['hits']['hits']) do |hits|
              define_singleton_method :to_a do
                self.entries.sort_by { |e| hits.index { |hit| hit['_id'].to_s == e.id.to_s } }
              end
            end

            criteria
          end

          # Intercept call to sorting methods, so we can ignore the order from Elasticsearch
          #
          %w| asc desc order_by |.each do |name|
            define_method name do |*args|
              criteria = records.__send__ name, *args
              criteria.instance_exec do
                define_singleton_method(:to_a) { self.entries }
              end

              criteria
            end
          end
        end

        module Callbacks
          # Handle index updates (creating, updating or deleting documents)
          # when the model changes, by hooking into the lifecycle
          #
          # @see http://mongoid.org/en/mongoid/docs/callbacks.html
          #
          def self.included(base)
            base.after_create  { |document| document.__elasticsearch__.index_document  }
            base.after_update  { |document| document.__elasticsearch__.update_document }
            base.after_destroy { |document| document.__elasticsearch__.delete_document }
          end
        end

        module Importing
          # Fetch batches of records from the database
          #
          # @see https://github.com/mongoid/mongoid/issues/1334
          # @see https://github.com/karmi/retire/pull/724
          #
          def __find_in_batches(options={}, &block)
            batch_size = options[:batch_size] || 1_000
            query = options[:query]
            named_scope = options[:scope]
            preprocess = options[:preprocess]

            scope = all
            scope = scope.send(named_scope) if named_scope
            scope = query.is_a?(Proc) ? scope.class_exec(&query) : scope.where(query) if query
            scope.no_timeout.each_slice(batch_size) do |items|
              yield (preprocess ? self.__send__(preprocess, items) : items)
            end
          end

          def __transform
            lambda { |a| { index: { _id: a.id.to_s, data: a.as_indexed_json } } }
          end
        end
      end
    end
  end
end