discourse/migrations/lib/importer/executor.rb

# frozen_string_literal: true

module Migrations::Importer
  class Executor
    def initialize(config, options)
      @intermediate_db = ::Migrations::Database.connect(config[:intermediate_db])
      @discourse_db = DiscourseDB.new
      @shared_data = SharedData.new(@discourse_db)

      attach_mappings_db(config[:mappings_db], options[:reset])
      attach_uploads_db(config[:uploads_db])
    end

    def start
      runtime =
        ::Migrations::DateHelper.track_time do
          execute_steps
        ensure
          cleanup
        end

      puts I18n.t("importer.done", runtime: ::Migrations::DateHelper.human_readable_time(runtime))
    end

    private

    def attach_mappings_db(db_path, reset)
      ::Migrations::Database.reset!(db_path) if reset
      migrate_and_attach(db_path, ::Migrations::Database::MAPPINGS_DB_SCHEMA_PATH, "mapped")
    end

    def attach_uploads_db(db_path)
      migrate_and_attach(db_path, ::Migrations::Database::UPLOADS_DB_SCHEMA_PATH, "files")
    end

    def migrate_and_attach(db_path, schema_path, alias_name)
      ::Migrations::Database.migrate(db_path, migrations_path: schema_path)
      @intermediate_db.execute("ATTACH DATABASE ? AS #{alias_name}", db_path)
    end

    def step_classes
      steps_module = ::Migrations::Importer::Steps
      classes =
        steps_module
          .constants
          .map { |c| steps_module.const_get(c) }
          .select { |klass| klass.is_a?(Class) && klass < ::Migrations::Importer::Step }
      TopologicalSorter.sort(classes)
    end

    def execute_steps
      max = step_classes.size

      step_classes
        .each
        .with_index(1) do |step_class, index|
          puts "#{step_class.title} [#{index}/#{max}]"
          step = step_class.new(@intermediate_db, @discourse_db, @shared_data)
          step.execute
          puts ""
        end
    end

    def cleanup
      @intermediate_db.close
      @discourse_db.close
    end
  end
end