# frozen_string_literal: true

# Copyright 2021 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
#
#     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 "shellwords"
require "English"

module Google
  module Serverless
    class Exec
      ##
      # A collection of utility functions and classes for interacting with an
      # installation of the gcloud SDK.
      #
      module Gcloud
        ##
        # Base class for gcloud related errors.
        #
        class Error < ::StandardError
        end

        ##
        # Exception raised when the gcloud binary could not be found.
        #
        class BinaryNotFound < Gcloud::Error
          def initialize
            super "GCloud binary not found in path"
          end
        end

        ##
        # Exception raised when the project gcloud config is not set.
        #
        class ProjectNotSet < Gcloud::Error
          def initialize
            super "GCloud project configuration not set"
          end
        end

        ##
        # Exception raised when gcloud auth has not been completed.
        #
        class GcloudNotAuthenticated < Gcloud::Error
          def initialize
            super "GCloud not authenticated"
          end
        end

        ##
        # Exception raised when gcloud fails and returns an error.
        #
        class GcloudFailed < Gcloud::Error
          def initialize code
            super "GCloud failed with result code #{code}"
          end
        end

        class << self
          ##
          # @private
          # Returns the path to the gcloud binary, or nil if the binary could
          # not be found.
          #
          # @return [String,nil] Path to the gcloud binary.
          #
          def binary_path
            unless defined? @binary_path
              @binary_path =
                if ::Gem.win_platform?
                  `where gcloud` == "" ? nil : "gcloud"
                else
                  path = `which gcloud`.strip
                  path.empty? ? nil : path
                end
            end
            @binary_path
          end

          ##
          # @private
          # Returns the path to the gcloud binary. Raises BinaryNotFound if the
          # binary could not be found.
          #
          # @return [String] Path to the gcloud binary.
          # @raise [BinaryNotFound] The gcloud binary is not present.
          #
          def binary_path!
            value = binary_path
            raise BinaryNotFound unless value
            value
          end

          ##
          # @private
          # Returns the ID of the current project, or nil if no project has
          # been set.
          #
          # @return [String,nil] ID of the current project.
          #
          def current_project
            unless defined? @current_project
              params = [
                "config", "list", "core/project", "--format=value(core.project)"
              ]
              @current_project = execute params, capture: true
              @current_project = nil if @current_project.empty?
            end
            @current_project
          end

          ##
          # @private
          # Returns the ID of the current project. Raises ProjectNotSet if no
          # project has been set in the gcloud configuration.
          #
          # @return [String] ID of the current project.
          # @raise [ProjectNotSet] The project config has not been set.
          #
          def current_project!
            value = current_project
            raise ProjectNotSet if value.empty?
            value
          end

          ##
          # @private
          # Verifies that all gcloud related dependencies are satisfied.
          # Specifically, verifies that the gcloud binary is installed and
          # authenticated, and a project has been set.
          #
          # @raise [BinaryNotFound] The gcloud binary is not present.
          # @raise [ProjectNotSet] The project config has not been set.
          # @raise [GcloudNotAuthenticated] Gcloud has not been authenticated.
          #
          def verify!
            binary_path!
            current_project!
            auths = execute ["auth", "list", "--format=value(account)"],
                            capture: true
            raise GcloudNotAuthenticated if auths.empty?
          end

          ##
          # @private
          # Execute a given gcloud command in a subshell.
          #
          # @param args [Array<String>] The gcloud args.
          # @param echo [boolean] Whether to echo the command to the terminal.
          #     Defaults to false.
          # @param capture [boolean] If true, return the output. If false, return
          #     a boolean indicating success or failure. Defaults to false.
          # @param assert [boolean] If true, raise GcloudFailed on failure.
          #     Defaults to true.
          # @return [String,Integer] Either the output or the success status,
          #     depending on the value of the `capture` parameter.
          #
          def execute args, echo: false, capture: false, assert: true
            cmd_array = [binary_path!] + args
            cmd =
              if ::Gem.win_platform?
                cmd_array.join " "
              else
                ::Shellwords.join cmd_array
              end
            puts cmd if echo
            result = capture ? `#{cmd}` : system(cmd)
            code = $CHILD_STATUS.exitstatus
            raise GcloudFailed, code if assert && code != 0
            result
          end

          ##
          # @private
          # Execute a given gcloud command in a subshell, and return the output
          # as a string.
          #
          # @param args [Array<String>] The gcloud args.
          # @return [String] The command output.
          #
          def capture args
            execute args, capture: true
          end
        end
      end
    end
  end
end