# frozen_string_literal: true

class MigrationService
  attr_reader :archive_path, :new_user_name
  delegate :errors, :warnings, to: :archive_validator

  def initialize(archive_path, new_user_name)
    @archive_path = archive_path
    @new_user_name = new_user_name
  end

  def validate
    archive_validator.validate
    raise ArchiveValidationFailed, errors.join("\n") if errors.any?
    raise MigrationAlreadyExists if AccountMigration.where(old_person: old_person).any?
  end

  def perform!
    find_or_create_user
    import_archive
    run_migration
  end

  # when old person can't be resolved we still import data but we don't create&perform AccountMigration instance
  def only_import?
    old_person.nil?
  end

  private

  def find_or_create_user
    archive_importer.user = User.find_by(username: new_user_name)
    archive_importer.create_user(username: new_user_name, password: SecureRandom.hex) if archive_importer.user.nil?
  end

  def import_archive
    archive_importer.import
  end

  def run_migration
    account_migration.save
    account_migration.perform!
  end

  def account_migration
    @account_migration ||= AccountMigration.new(
      old_person:             old_person,
      new_person:             archive_importer.user.person,
      old_private_key:        archive_importer.serialized_private_key,
      old_person_diaspora_id: archive_importer.archive_author_diaspora_id
    )
  end

  def old_person
    @old_person ||= Person.by_account_identifier(archive_validator.archive_author_diaspora_id)
  end

  def archive_importer
    @archive_importer ||= ArchiveImporter.new(archive_validator.archive_hash)
  end

  def archive_validator
    @archive_validator ||= ArchiveValidator.new(archive_file)
  end

  def archive_file
    # TODO: archive is likely to be a .json.gz file
    File.new(archive_path, "r")
  end

  class ArchiveValidationFailed < RuntimeError
  end

  class MigrationAlreadyExists < RuntimeError
  end
end