# Copyright (C) 2014-2015 MongoDB, Inc.
#
# Licensed 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 Mongo
  module Protocol

    # MongoDB Wire protocol Update message.
    #
    # This is a client request message that is sent to the server in order
    # to update documents matching the provided query.
    #
    # The default is to update a single document. In order to update many at
    # a time users should set the +:multi_update+ flag for the update.
    #
    # If an upsert (update or insert) is desired, users can set the +:upsert+
    # flag in order to indicate they would like to insert the merged selector
    # and update if no document matching the update query currently exists.
    #
    # @api semipublic
    class Update < Message

      # Creates a new Update message
      #
      # @example Update single document
      #   Update.new('xgen', 'users', {:name => 'Tyler'}, {:name => 'Bob'})
      #
      # @example Perform a multi update
      #   Update.new('xgen', 'users',
      #     {:age => 20}, {:age => 21}, :flags => [:multi_update])
      #
      # @example Perform an upsert
      #   Update.new('xgen', 'users', {:name => 'Tyler'}, :flags => [:upsert])
      #
      # @param database [String, Symbol]  The database to update.
      # @param collection [String, Symbol] The collection to update.
      # @param selector [Hash] The update selector.
      # @param update [Hash] The update to perform.
      # @param options [Hash] The additional query options.
      #
      # @option options :flags [Array] The flags for the update message.
      #
      #   Supported flags: +:upsert+, +:multi_update+
      def initialize(database, collection, selector, update, options = {})
        @namespace   = "#{database}.#{collection}"
        @selector    = selector
        @update      = update
        @flags       = options[:flags] || []
      end

      # The log message for an update operation.
      #
      # @example Get the log message.
      #   update.log_message
      #
      # @return [ String ] The log message
      #
      # @since 2.0.0
      def log_message
        fields = []
        fields << ["%s |", "UPDATE"]
        fields << ["namespace=%s", namespace]
        fields << ["selector=%s", selector.inspect]
        fields << ["udpdate=%s", update.inspect]
        fields << ["flags=%s", flags.inspect]
        f, v = fields.transpose
        f.join(" ") % v
      end

      private

      # The operation code required to specify an Update message.
      # @return [Fixnum] the operation code.
      def op_code
        2001
      end

      # Available flags for an Update message.
      FLAGS = [:upsert, :multi_update]

      # Field representing Zero encoded as an Int32.
      field :zero, Zero

      # @!attribute
      # @return [String] The namespace for this Update message.
      field :namespace, CString

      # @!attribute
      # @return [Array<Symbol>] The flags for this Update message.
      field :flags, BitVector.new(FLAGS)

      # @!attribute
      # @return [Hash] The selector for this Update message.
      field :selector, Document

      # @!attribute
      # @return [Hash] The update for this Delete message.
      field :update, Document
    end
  end
end