ifad/chronomodel

# frozen_string_literal: true

module ActiveRecord
  module Tasks
    class ChronomodelDatabaseTasks < PostgreSQLDatabaseTasks
      CHRONOMODEL_SCHEMAS = [
        ChronoModel::Adapter::TEMPORAL_SCHEMA,
        ChronoModel::Adapter::HISTORY_SCHEMA
      ].freeze

      def structure_dump(*arguments)
        if schema_search_path.present?
          with_chronomodel_schema_search_path { super }
        else
          super
        end

        # The structure.sql includes CREATE SCHEMA statements, but as these are executed
        # when the connection to the database is established, a db:structure:load fails.
        #
        # This code adds the IF NOT EXISTS clause to CREATE SCHEMA statements as long as
        # it is not already present.
        #
        filename = arguments.first
        sql = File.read(filename).gsub(/CREATE SCHEMA (?!IF NOT EXISTS)/, '\&IF NOT EXISTS ')
        File.open(filename, 'w') { |file| file << sql }
      end

      def data_dump(target)
        psql_env

        args = ['-c', '-f', target.to_s]
        args << chronomodel_configuration[:database]

        run_cmd 'pg_dump', args, 'dumping data'
      end

      def data_load(source)
        psql_env

        args = ['-f', source]
        args << chronomodel_configuration[:database]

        run_cmd 'psql', args, 'loading data'
      end

      private

      def chronomodel_configuration
        @chronomodel_configuration ||= @configuration_hash
      end

      # If a schema search path is defined in the configuration file, it will
      # be used by the database tasks class to dump only the specified search
      # path. Here we add also ChronoModel's temporal and history schemas to
      # the search path and yield.
      #
      def with_chronomodel_schema_search_path
        patch_configuration!

        yield
      ensure
        reset_configuration!
      end

      def patch_configuration!
        @original_schema_search_path = schema_search_path

        chronomodel_schema_search_path = "#{schema_search_path},#{CHRONOMODEL_SCHEMAS.join(',')}"

        @configuration_hash = @configuration_hash.dup
        @configuration_hash[:schema_search_path] = chronomodel_schema_search_path
        @configuration_hash.freeze
      end

      def reset_configuration!
        @configuration_hash = @configuration_hash.dup
        @configuration_hash[:schema_search_path] = @original_schema_search_path
        @configuration_hash.freeze
      end

      def schema_search_path
        @schema_search_path ||= chronomodel_configuration[:schema_search_path]
      end
    end
  end
end