# frozen_string_literal: true

module Nanoc
  module Int
    class Compiler
      module Phases
        # Provides functionality for suspending and resuming item rep compilation (using fibers).
        class Resume < Abstract
          include Nanoc::Core::ContractsSupport

          DONE = Object.new

          contract Nanoc::Core::ItemRep, C::KeywordArgs[is_outdated: C::Bool], C::Func[C::None => C::Any] => C::Any
          def run(rep, is_outdated:)
            fiber = fiber_for(rep, is_outdated: is_outdated) { yield }
            while fiber.alive?
              res = fiber.resume

              case res
              when Nanoc::Int::Errors::UnmetDependency
                Nanoc::Core::NotificationCenter.post(:compilation_suspended, rep, res.rep, res.snapshot_name)
                raise(res)
              when Proc
                fiber.resume(res.call)
              when DONE # rubocop:disable Lint/EmptyWhen
                # ignore
              else
                raise Nanoc::Int::Errors::InternalInconsistency.new(
                  "Fiber yielded object of unexpected type #{res.class}",
                )
              end
            end
          end

          private

          contract Nanoc::Core::ItemRep, C::KeywordArgs[is_outdated: C::Bool], C::Func[C::None => C::Any] => Fiber
          def fiber_for(rep, is_outdated:) # rubocop:disable Lint/UnusedMethodArgument
            @fibers ||= {}

            @fibers[rep] ||=
              Fiber.new do
                yield
                @fibers.delete(rep)
                DONE
              end

            @fibers[rep]
          end
        end
      end
    end
  end
end