module RSpec
  module Mocks
    module AnyInstance
      # Given a class `TheClass`, `TheClass.any_instance` returns a `Recorder`,
      # which records stubs and message expectations for later playback on
      # instances of `TheClass`.
      #
      # Further constraints are stored in instances of [Chain](Chain).
      #
      # @see AnyInstance
      # @see Chain
      class Recorder
        # @private
        attr_reader :message_chains, :stubs, :klass

        def initialize(klass)
          @message_chains = MessageChains.new
          @stubs = Hash.new { |hash, key| hash[key] = [] }
          @observed_methods = []
          @played_methods = {}
          @backed_up_method_owner = {}
          @klass = klass
          @expectation_set = false

          return unless RSpec::Mocks.configuration.verify_partial_doubles?
          RSpec::Mocks.configuration.verifying_double_callbacks.each do |block|
            block.call(ObjectReference.for(klass))
          end
        end

        # Initializes the recording a stub to be played back against any
        # instance of this object that invokes the submitted method.
        #
        # @see Methods#stub
        def stub(method_name, &block)
          observe!(method_name)
          message_chains.add(method_name, StubChain.new(self, method_name, &block))
        end

        # Initializes the recording a stub chain to be played back against any
        # instance of this object that invokes the method matching the first
        # argument.
        #
        # @see Methods#stub_chain
        def stub_chain(*method_names_and_optional_return_values, &block)
          normalize_chain(*method_names_and_optional_return_values) do |method_name, args|
            observe!(method_name)
            message_chains.add(method_name, StubChainChain.new(self, *args, &block))
          end
        end

        # @private
        def expect_chain(*method_names_and_optional_return_values, &block)
          @expectation_set = true
          normalize_chain(*method_names_and_optional_return_values) do |method_name, args|
            observe!(method_name)
            message_chains.add(method_name, ExpectChainChain.new(self, *args, &block))
          end
        end

        # Initializes the recording a message expectation to be played back
        # against any instance of this object that invokes the submitted
        # method.
        #
        # @see Methods#should_receive
        def should_receive(method_name, &block)
          @expectation_set = true
          observe!(method_name)
          message_chains.add(method_name, PositiveExpectationChain.new(self, method_name, &block))
        end

        # The opposite of `should_receive`
        #
        # @see Methods#should_not_receive
        def should_not_receive(method_name, &block)
          should_receive(method_name, &block).never
        end

        # Removes any previously recorded stubs, stub_chains or message
        # expectations that use `method_name`.
        #
        # @see Methods#unstub
        def unstub(method_name)
          unless @observed_methods.include?(method_name.to_sym)
            AnyInstance.error_generator.raise_method_not_stubbed_error(method_name)
          end
          message_chains.remove_stub_chains_for!(method_name)
          stubs[method_name].clear
          stop_observing!(method_name) unless message_chains.has_expectation?(method_name)
        end

        # @api private
        #
        # Used internally to verify that message expectations have been
        # fulfilled.
        def verify
          return unless @expectation_set
          return if message_chains.all_expectations_fulfilled?

          AnyInstance.error_generator.raise_second_instance_received_message_error(message_chains.unfulfilled_expectations)
        end

        # @private
        def stop_all_observation!
          @observed_methods.each { |method_name| restore_method!(method_name) }
        end

        # @private
        def playback!(instance, method_name)
          RSpec::Mocks.space.ensure_registered(instance)
          message_chains.playback!(instance, method_name)
          @played_methods[method_name] = instance
          received_expected_message!(method_name) if message_chains.has_expectation?(method_name)
        end

        # @private
        def instance_that_received(method_name)
          @played_methods[method_name]
        end

        # @private
        def build_alias_method_name(method_name)
          "__#{method_name}_without_any_instance__"
        end

        # @private
        def already_observing?(method_name)
          @observed_methods.include?(method_name) || super_class_observing?(method_name)
        end

        # @private
        def notify_received_message(_object, message, args, _blk)
          has_expectation = false

          message_chains.each_unfulfilled_expectation_matching(message, *args) do |expectation|
            has_expectation = true
            expectation.expectation_fulfilled!
          end

          return unless has_expectation

          restore_method!(message)
          mark_invoked!(message)
        end

      protected

        def stop_observing!(method_name)
          restore_method!(method_name)
          @observed_methods.delete(method_name)
          super_class_observers_for(method_name).each do |ancestor|
            ::RSpec::Mocks.space.
              any_instance_recorder_for(ancestor).stop_observing!(method_name)
          end
        end

      private

        def ancestor_is_an_observer?(method_name)
          lambda do |ancestor|
            unless ancestor == @klass
              ::RSpec::Mocks.space.
                any_instance_recorder_for(ancestor).already_observing?(method_name)
            end
          end
        end

        def super_class_observers_for(method_name)
          @klass.ancestors.select(&ancestor_is_an_observer?(method_name))
        end

        def super_class_observing?(method_name)
          @klass.ancestors.any?(&ancestor_is_an_observer?(method_name))
        end

        def normalize_chain(*args)
          args.shift.to_s.split('.').map { |s| s.to_sym }.reverse.each { |a| args.unshift a }
          yield args.first, args
        end

        def received_expected_message!(method_name)
          message_chains.received_expected_message!(method_name)
          restore_method!(method_name)
          mark_invoked!(method_name)
        end

        def restore_method!(method_name)
          if public_protected_or_private_method_defined?(build_alias_method_name(method_name))
            restore_original_method!(method_name)
          else
            remove_dummy_method!(method_name)
          end
        end

        def restore_original_method!(method_name)
          return unless @klass.instance_method(method_name).owner == @klass

          alias_method_name = build_alias_method_name(method_name)
          @klass.class_exec(@backed_up_method_owner) do |backed_up_method_owner|
            remove_method method_name

            # A @klass can have methods implemented (see Method#owner) in @klass
            # or inherited from a superclass. In ruby 2.2 and earlier, we can copy
            # a method regardless of the 'owner' and restore it to @klass after
            # because a call to 'super' from @klass's copied method would end up
            # calling the original class's superclass's method.
            #
            # With the commit below, available starting in 2.3.0, ruby changed
            # this behavior and a call to 'super' from the method copied to @klass
            # will call @klass's superclass method, which is the original
            # implementer of this method!  This leads to very strange errors
            # if @klass's copied method calls 'super', since it would end up
            # calling itself, the original method implemented in @klass's
            # superclass.
            #
            # For ruby 2.3 and above, we need to only restore methods that
            # @klass originally owned.
            #
            # https://github.com/ruby/ruby/commit/c8854d2ca4be9ee6946e6d17b0e17d9ef130ee81
            if RUBY_VERSION < "2.3" || backed_up_method_owner[method_name.to_sym] == self
              alias_method method_name, alias_method_name
            end
            remove_method alias_method_name
          end
        end

        def remove_dummy_method!(method_name)
          @klass.class_exec do
            remove_method method_name
          end
        end

        def backup_method!(method_name)
          return unless public_protected_or_private_method_defined?(method_name)

          alias_method_name = build_alias_method_name(method_name)
          @backed_up_method_owner[method_name.to_sym] ||= @klass.instance_method(method_name).owner
          @klass.class_exec do
            alias_method alias_method_name, method_name
          end
        end

        def public_protected_or_private_method_defined?(method_name)
          MethodReference.method_defined_at_any_visibility?(@klass, method_name)
        end

        def observe!(method_name)
          allow_no_prepended_module_definition_of(method_name)

          if RSpec::Mocks.configuration.verify_partial_doubles? && !Mocks.configuration.temporarily_suppress_partial_double_verification
            unless public_protected_or_private_method_defined?(method_name)
              AnyInstance.error_generator.raise_does_not_implement_error(@klass, method_name)
            end
          end

          stop_observing!(method_name) if already_observing?(method_name)
          @observed_methods << method_name
          backup_method!(method_name)
          recorder = self
          @klass.__send__(:define_method, method_name) do |*args, &blk|
            recorder.playback!(self, method_name)
            __send__(method_name, *args, &blk)
          end
          @klass.__send__(:ruby2_keywords, method_name) if @klass.respond_to?(:ruby2_keywords, true)
        end

        def mark_invoked!(method_name)
          backup_method!(method_name)
          recorder = self
          @klass.__send__(:define_method, method_name) do |*_args, &_blk|
            invoked_instance = recorder.instance_that_received(method_name)
            inspect = "#<#{self.class}:#{object_id} #{instance_variables.map { |name| "#{name}=#{instance_variable_get name}" }.join(', ')}>"
            AnyInstance.error_generator.raise_message_already_received_by_other_instance_error(
              method_name, inspect, invoked_instance
            )
          end
        end

        if Support::RubyFeatures.module_prepends_supported?
          def allow_no_prepended_module_definition_of(method_name)
            prepended_modules = RSpec::Mocks::Proxy.prepended_modules_of(@klass)
            problem_mod = prepended_modules.find { |mod| mod.method_defined?(method_name) }
            return unless problem_mod

            AnyInstance.error_generator.raise_not_supported_with_prepend_error(method_name, problem_mod)
          end
        else
          def allow_no_prepended_module_definition_of(_method_name)
            # nothing to do; prepends aren't supported on this version of ruby
          end
        end
      end
    end
  end
end