# frozen_string_literal: true

module Users
  class DestroyService
    DestroyError = Class.new(StandardError)

    attr_accessor :current_user

    def initialize(current_user)
      @current_user = current_user
    end

    # Synchronously destroys +user+
    #
    # The operation will fail if the user is the sole owner of any groups. To
    # force the groups to be destroyed, pass `delete_solo_owned_groups: true` in
    # +options+.
    #
    # The user's contributions will be migrated to a global ghost user. To
    # force the contributions to be destroyed, pass `hard_delete: true` in
    # +options+.
    #
    # `hard_delete: true` implies `delete_solo_owned_groups: true`.  To perform
    # a hard deletion without destroying solo-owned groups, pass
    # `delete_solo_owned_groups: false, hard_delete: true` in +options+.
    def execute(user, options = {})
      delete_solo_owned_groups = options.fetch(:delete_solo_owned_groups, options[:hard_delete])

      unless Ability.allowed?(current_user, :destroy_user, user) || options[:skip_authorization]
        raise Gitlab::Access::AccessDeniedError, "#{current_user} tried to destroy user #{user}!"
      end

      if !delete_solo_owned_groups && user.solo_owned_groups.present?
        user.errors.add(:base, 'You must transfer ownership or delete groups before you can remove user')
        return user
      end

      # Calling all before/after_destroy hooks for the user because
      # there is no dependent: destroy in the relationship. And the removal
      # is done by a foreign_key. Otherwise they won't be called
      user.members.find_each { |member| member.run_callbacks(:destroy) }

      user.solo_owned_groups.each do |group|
        Groups::DestroyService.new(group, current_user).execute
      end

      namespace = user.namespace
      namespace.prepare_for_destroy

      user.personal_projects.each do |project|
        success = ::Projects::DestroyService.new(project, current_user).execute
        raise DestroyError, "Project #{project.id} can't be deleted" unless success
      end

      yield(user) if block_given?

      MigrateToGhostUserService.new(user).execute(hard_delete: options[:hard_delete])

      response = Snippets::BulkDestroyService.new(current_user, user.snippets).execute(options)
      raise DestroyError, response.message if response.error?

      # Rails attempts to load all related records into memory before
      # destroying: https://github.com/rails/rails/issues/22510
      # This ensures we delete records in batches.
      user.destroy_dependent_associations_in_batches(exclude: [:snippets])
      user.nullify_dependent_associations_in_batches

      # Destroy the namespace after destroying the user since certain methods may depend on the namespace existing
      user_data = user.destroy
      namespace.destroy

      user_data
    end
  end
end

Users::DestroyService.prepend_mod_with('Users::DestroyService')
