# Copyright 2017 Google LLC
#
# 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
#
#     https://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 "google/gax"
require "pathname"

module Google
  module Cloud
    module Spanner
      module Admin
        # rubocop:disable LineLength

        ##
        # # Ruby Client for Cloud Spanner Instance Admin API ([Alpha](https://github.com/GoogleCloudPlatform/google-cloud-ruby#versioning))
        #
        # [Cloud Spanner Instance Admin API][Product Documentation]:
        #
        # - [Product Documentation][]
        #
        # ## Quick Start
        # In order to use this library, you first need to go through the following
        # steps:
        #
        # 1. [Select or create a Cloud Platform project.](https://console.cloud.google.com/project)
        # 2. [Enable billing for your project.](https://cloud.google.com/billing/docs/how-to/modify-project#enable_billing_for_a_project)
        # 3. [Enable the Cloud Spanner Instance Admin API.](https://console.cloud.google.com/apis/api/spanner-admin-instance)
        # 4. [Setup Authentication.](https://googlecloudplatform.github.io/google-cloud-ruby/#/docs/google-cloud/master/guides/authentication)
        #
        # ### Next Steps
        # - Read the [Cloud Spanner Instance Admin API Product documentation][Product Documentation]
        #   to learn more about the product and see How-to Guides.
        # - View this [repository's main README](https://github.com/GoogleCloudPlatform/google-cloud-ruby/blob/master/README.md)
        #   to see the full list of Cloud APIs that we cover.
        #
        # [Product Documentation]: https://cloud.google.com/spanner-admin-instance
        #
        #
        module Instance
          # rubocop:enable LineLength

          FILE_DIR = File.realdirpath(Pathname.new(__FILE__).join("..").join("instance"))

          AVAILABLE_VERSIONS = Dir["#{FILE_DIR}/*"]
            .select { |file| File.directory?(file) }
            .select { |dir| Google::Gax::VERSION_MATCHER.match(File.basename(dir)) }
            .select { |dir| File.exist?(dir + ".rb") }
            .map { |dir| File.basename(dir) }

          ##
          # Cloud Spanner Instance Admin API
          #
          # The Cloud Spanner Instance Admin API can be used to create, delete,
          # modify and list instances. Instances are dedicated Cloud Spanner serving
          # and storage resources to be used by Cloud Spanner databases.
          #
          # Each instance has a "configuration", which dictates where the
          # serving resources for the Cloud Spanner instance are located (e.g.,
          # US-central, Europe). Configurations are created by Google based on
          # resource availability.
          #
          # Cloud Spanner billing is based on the instances that exist and their
          # sizes. After an instance exists, there are no additional
          # per-database or per-operation charges for use of the instance
          # (though there may be additional network bandwidth charges).
          # Instances offer isolation: problems with databases in one instance
          # will not affect other instances. However, within an instance
          # databases can affect each other. For example, if one database in an
          # instance receives a lot of requests and consumes most of the
          # instance resources, fewer resources are available for other
          # databases in that instance, and their performance may suffer.
          #
          # @param version [Symbol, String]
          #   The major version of the service to be used. By default :v1
          #   is used.
          # @overload new(version:, credentials:, scopes:, client_config:, timeout:)
          #   @param credentials [Google::Auth::Credentials, String, Hash, GRPC::Core::Channel, GRPC::Core::ChannelCredentials, Proc]
          #     Provides the means for authenticating requests made by the client. This parameter can
          #     be many types.
          #     A `Google::Auth::Credentials` uses a the properties of its represented keyfile for
          #     authenticating requests made by this client.
          #     A `String` will be treated as the path to the keyfile to be used for the construction of
          #     credentials for this client.
          #     A `Hash` will be treated as the contents of a keyfile to be used for the construction of
          #     credentials for this client.
          #     A `GRPC::Core::Channel` will be used to make calls through.
          #     A `GRPC::Core::ChannelCredentials` for the setting up the RPC client. The channel credentials
          #     should already be composed with a `GRPC::Core::CallCredentials` object.
          #     A `Proc` will be used as an updater_proc for the Grpc channel. The proc transforms the
          #     metadata for requests, generally, to give OAuth credentials.
          #   @param scopes [Array<String>]
          #     The OAuth scopes for this service. This parameter is ignored if
          #     an updater_proc is supplied.
          #   @param client_config [Hash]
          #     A Hash for call options for each method. See
          #     Google::Gax#construct_settings for the structure of
          #     this data. Falls back to the default config if not specified
          #     or the specified config is missing data points.
          #   @param timeout [Numeric]
          #     The default timeout, in seconds, for calls made through this client.
          def self.new(*args, version: :v1, **kwargs)
            unless AVAILABLE_VERSIONS.include?(version.to_s.downcase)
              raise "The version: #{version} is not available. The available versions " \
                "are: [#{AVAILABLE_VERSIONS.join(", ")}]"
            end

            require "#{FILE_DIR}/#{version.to_s.downcase}"
            version_module = Google::Cloud::Spanner::Admin::Instance
              .constants
              .select {|sym| sym.to_s.downcase == version.to_s.downcase}
              .first
            Google::Cloud::Spanner::Admin::Instance.const_get(version_module).new(*args, **kwargs)
          end
        end
      end
    end
  end
end