# Copyright 2015 Google Inc. All rights reserved.
#
# 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 Gcloud
  module Dns
    class Zone
      ##
      # # DNS Zone Transaction
      #
      # This object is used by {Zone#update} when passed a block. These methods
      # are used to update the records that are sent to the Google Cloud DNS
      # API.
      #
      # @example
      #   require "gcloud"
      #
      #   gcloud = Gcloud.new
      #   dns = gcloud.dns
      #   zone = dns.zone "example-com"
      #   zone.update do |tx|
      #     tx.add     "example.com.", "A",  86400, "1.2.3.4"
      #     tx.remove  "example.com.", "TXT"
      #     tx.replace "example.com.", "MX", 86400, ["10 mail1.example.com.",
      #                                              "20 mail2.example.com."]
      #     tx.modify "www.example.com.", "CNAME" do |cname|
      #       cname.ttl = 86400 # only change the TTL
      #     end
      #   end
      #
      class Transaction
        # @private
        attr_reader :additions, :deletions

        ##
        # @private Creates a new transaction.
        def initialize zone
          @zone = zone
          @additions = []
          @deletions = []
        end

        ##
        # Adds a record to the Zone.
        #
        # @param [String] name The owner of the record. For example:
        #   `example.com.`.
        # @param [String] type The identifier of a [supported record
        #   type](https://cloud.google.com/dns/what-is-cloud-dns).
        #   For example: `A`, `AAAA`, `CNAME`, `MX`, or `TXT`.
        # @param [Integer] ttl The number of seconds that the record can be
        #   cached by resolvers.
        # @param [String, Array<String>] data The resource record data, as
        #   determined by `type` and defined in
        #   [RFC 1035 (section 5)](http://tools.ietf.org/html/rfc1035#section-5)
        #   and [RFC 1034 (section
        #   3.6.1)](http://tools.ietf.org/html/rfc1034#section-3.6.1). For
        #   example: `192.0.2.1` or `example.com.`.
        #
        # @example
        #   require "gcloud"
        #
        #   gcloud = Gcloud.new
        #   dns = gcloud.dns
        #   zone = dns.zone "example-com"
        #   zone.update do |tx|
        #     tx.add     "example.com.", "A",  86400, "1.2.3.4"
        #   end
        #
        def add name, type, ttl, data
          @additions += Array(@zone.record(name, type, ttl, data))
        end

        ##
        # Removes records from the Zone. The records are looked up before they
        # are removed.
        #
        # @param [String] name The owner of the record. For example:
        #   `example.com.`.
        # @param [String] type The identifier of a [supported record
        #   type](https://cloud.google.com/dns/what-is-cloud-dns).
        #   For example: `A`, `AAAA`, `CNAME`, `MX`, or `TXT`.
        #
        # @example
        #   require "gcloud"
        #
        #   gcloud = Gcloud.new
        #   dns = gcloud.dns
        #   zone = dns.zone "example-com"
        #   zone.update do |tx|
        #     tx.remove  "example.com.", "TXT"
        #   end
        #
        def remove name, type
          @deletions += @zone.records(name, type).all
        end

        ##
        # Replaces existing records on the Zone. Records matching the `name` and
        # `type` are replaced.
        #
        # @param [String] name The owner of the record. For example:
        #   `example.com.`.
        # @param [String] type The identifier of a [supported record
        #   type](https://cloud.google.com/dns/what-is-cloud-dns).
        #   For example: `A`, `AAAA`, `CNAME`, `MX`, or `TXT`.
        # @param [Integer] ttl The number of seconds that the record can be
        #   cached by resolvers.
        # @param [String, Array<String>] data The resource record data, as
        #   determined by `type` and defined in
        #   [RFC 1035 (section 5)](http://tools.ietf.org/html/rfc1035#section-5)
        #   and [RFC 1034 (section
        #   3.6.1)](http://tools.ietf.org/html/rfc1034#section-3.6.1). For
        #   example: `192.0.2.1` or `example.com.`.
        #
        # @example
        #   require "gcloud"
        #
        #   gcloud = Gcloud.new
        #   dns = gcloud.dns
        #   zone = dns.zone "example-com"
        #   zone.update do |tx|
        #     tx.replace "example.com.", "MX", 86400, ["10 mail1.example.com.",
        #                                              "20 mail2.example.com."]
        #   end
        #
        def replace name, type, ttl, data
          remove name, type
          add name, type, ttl, data
        end

        ##
        # Modifies records on the Zone. Records matching the `name` and `type`
        # are yielded to the block where they can be modified.
        #
        # @param [String] name The owner of the record. For example:
        #   `example.com.`.
        # @param [String] type The identifier of a [supported record
        #   type](https://cloud.google.com/dns/what-is-cloud-dns).
        #   For example: `A`, `AAAA`, `CNAME`, `MX`, or `TXT`.
        # @yield [record] a block yielding each matching record
        # @yieldparam [Record] record the record to be modified
        #
        # @example
        #   require "gcloud"
        #
        #   gcloud = Gcloud.new
        #   dns = gcloud.dns
        #   zone.update do |tx|
        #     tx.modify "www.example.com.", "CNAME" do |cname|
        #       cname.ttl = 86400 # only change the TTL
        #     end
        #   end
        #
        def modify name, type
          existing = @zone.records(name, type).all.to_a
          updated = existing.map(&:dup)
          updated.each { |r| yield r }
          @additions += updated
          @deletions += existing
        end
      end
    end
  end
end