services.rb

# frozen_string_literal: true

# Cloud Foundry Java Buildpack
# Copyright 2013-2020 the original author or authors.
#
# 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.

require 'java_buildpack/component'

module JavaBuildpack
  module Component

    # An abstraction encapsulating the +VCAP_SERVICES+ of an application.
    #
    # A new instance of this type should be created once for the application.
    class Services < Array

      def initialize(raw)
        concat raw.values.flatten
      end

      # Compares the name, label, and tags of each service to the given +filter+.  The method returns the first service
      # that the +filter+ matches.  If no service matches, returns +nil+.
      #
      # @param [Regexp, String] filter a +RegExp+ or +String+ to match against the name, label, and tags of the services
      # @param [String] required_credentials an optional list of keys or groups of keys, where at least one key from the
      #                                      group, must exist in the credentials payload of the candidate service
      # @return [Hash, nil] the first service that +filter+ matches.  If no service matches, returns +nil+.
      def find_service(filter, *required_credentials)
        select(&service?(filter))
          .find(&credentials?(required_credentials))
      end

      # Compares the name, label, and tags of each service to the given +filter+. The method returns the first service
      # that +filter+ matches.  If no service matches, returns +nil+.
      #
      # @param [Regexp, String] filter a +RegExp+ or +String+ to match against the name, label, and tags of the services
      # @return [Hash, nil] the first service that +filter+ matches.  If no service matches, returns +nil+.
      def find_volume_service(filter)
        select(&service?(filter))
          .find(&volume_mount?)
      end

      # Compares the name, label, and tags of each service to the given +filter+.  The method returns +true+ if the
      # +filter+ matches exactly one service, +false+ otherwise.
      #
      # @param [Regexp, String] filter a +RegExp+ or +String+ to match against the name, label, and tags of the services
      # @param [String] required_credentials an optional list of keys or groups of keys, where at least one key from the
      #                                      group, must exist in the credentials payload of the candidate service
      # @return [Boolean] +true+ if the +filter+ matches exactly one service with the required credentials, +false+
      #                   otherwise.
      def one_service?(filter, *required_credentials)
        select(&service?(filter))
          .select(&credentials?(required_credentials))
          .one?
      end

      # Compares the name, label, and tags of each service to the given +filter+. The method returns +true+ if the
      # +filter+ matches exactly one volume service, +false+ otherwise.
      #
      # @param [Regexp, String] filter a +RegExp+ or +String+ to match against the name, label, and tags of the services
      # @return [Boolean] +true+ if the +filter+ matches exactly one volume service with the required credentials,
      #                   +false+ otherwise.
      def one_volume_service?(filter)
        select(&service?(filter))
          .select(&volume_mount?)
          .one?
      end

      private

      def credentials?(required_keys)
        lambda do |service|
          credentials = service['credentials']
          return false if credentials.nil?

          required_keys.all? do |k|
            k.is_a?(Array) ? k.any? { |g| credentials.key?(g) } : credentials.key?(k)
          end
        end
      end

      def volume_mount?
        lambda do |service|
          volume_mounts = service['volume_mounts']
          return false if volume_mounts.nil?

          volume_mounts.one?
        end
      end

      def service?(filter)
        filter = Regexp.new(filter) unless filter.is_a?(Regexp)

        lambda do |service|
          service['name'] =~ filter || service['label'] =~ filter || service['tags'].any? { |tag| tag =~ filter }
        end
      end

    end

  end
end