module RSpec
  module Core
    # Wrapper for an instance of a subclass of {ExampleGroup}. An instance of
    # `RSpec::Core::Example` is returned by example definition methods
    # such as {ExampleGroup.it it} and is yielded to the {ExampleGroup.it it},
    # {Hooks#before before}, {Hooks#after after}, {Hooks#around around},
    # {MemoizedHelpers::ClassMethods#let let} and
    # {MemoizedHelpers::ClassMethods#subject subject} blocks.
    #
    # This allows us to provide rich metadata about each individual
    # example without adding tons of methods directly to the ExampleGroup
    # that users may inadvertantly redefine.
    #
    # Useful for configuring logging and/or taking some action based
    # on the state of an example's metadata.
    #
    # @example
    #
    #     RSpec.configure do |config|
    #       config.before do |example|
    #         log example.description
    #       end
    #
    #       config.after do |example|
    #         log example.description
    #       end
    #
    #       config.around do |example|
    #         log example.description
    #         example.run
    #       end
    #     end
    #
    #     shared_examples "auditable" do
    #       it "does something" do
    #         log "#{example.full_description}: #{auditable.inspect}"
    #         auditable.should do_something
    #       end
    #     end
    #
    # @see ExampleGroup
    # @note Example blocks are evaluated in the context of an instance
    #   of an `ExampleGroup`, not in the context of an instance of `Example`.
    class Example
      # @private
      #
      # Used to define methods that delegate to this example's metadata
      def self.delegate_to_metadata(key)
        define_method(key) { @metadata[key] }
      end

      # @return [ExecutionResult] represents the result of running this example.
      delegate_to_metadata :execution_result
      # @return [String] the relative path to the file where this example was defined.
      delegate_to_metadata :file_path
      # @return [String] the full description (including the docstrings of
      #   all parent example groups).
      delegate_to_metadata :full_description
      # @return [String] the exact source location of this example in a form
      #   like `./path/to/spec.rb:17`
      delegate_to_metadata :location
      # @return [Boolean] flag that indicates that the example is not expected to pass.
      #   It will be run and will either have a pending result (if a failure occurs)
      #   or a failed result (if no failure occurs).
      delegate_to_metadata :pending
      # @return [Boolean] flag that will cause the example to not run.
      #   The {ExecutionResult} status will be `:pending`.
      delegate_to_metadata :skip

      # Returns the string submitted to `example` or its aliases (e.g.
      # `specify`, `it`, etc).  If no string is submitted (e.g. `it { is_expected.to
      # do_something }`) it returns the message generated by the matcher if
      # there is one, otherwise returns a message including the location of the
      # example.
      def description
        description = metadata[:description].to_s.empty? ?
          "example at #{location}" :
          metadata[:description]
        RSpec.configuration.format_docstrings_block.call(description)
      end

      # @attr_reader
      #
      # Returns the first exception raised in the context of running this
      # example (nil if no exception is raised)
      attr_reader :exception

      # @attr_reader
      #
      # Returns the metadata object associated with this example.
      attr_reader :metadata

      # @attr_reader
      # @private
      #
      # Returns the example_group_instance that provides the context for
      # running this example.
      attr_reader :example_group_instance

      # @attr
      # @private
      attr_accessor :clock

      # Creates a new instance of Example.
      # @param example_group_class [Class] the subclass of ExampleGroup in which this Example is declared
      # @param description [String] the String passed to the `it` method (or alias)
      # @param user_metadata [Hash] additional args passed to `it` to be used as metadata
      # @param example_block [Proc] the block of code that represents the example
      # @api private
      def initialize(example_group_class, description, user_metadata, example_block=nil)
        @example_group_class = example_group_class
        @example_block       = example_block

        @metadata = Metadata::ExampleHash.create(
          @example_group_class.metadata, user_metadata, description, example_block
        )

        @example_group_instance = @exception = nil
        @clock = RSpec::Core::Time
      end

      # Returns the example group class that provides the context for running
      # this example.
      def example_group
        @example_group_class
      end

      alias_method :pending?, :pending
      alias_method :skipped?, :skip

      # @api private
      # instance_execs the block passed to the constructor in the context of
      # the instance of {ExampleGroup}.
      # @param example_group_instance the instance of an ExampleGroup subclass
      def run(example_group_instance, reporter)
        @example_group_instance = example_group_instance
        RSpec.current_example = self

        start(reporter)

        begin
          if skipped?
            Pending.mark_pending! self, skip
          elsif !RSpec.configuration.dry_run?
            with_around_example_hooks do
              begin
                run_before_example
                @example_group_instance.instance_exec(self, &@example_block)

                if pending?
                  Pending.mark_fixed! self

                  raise Pending::PendingExampleFixedError,
                    'Expected example to fail since it is pending, but it passed.',
                    [location]
                end
              rescue Pending::SkipDeclaredInExample
                # no-op, required metadata has already been set by the `skip`
                # method.
              rescue Exception => e
                set_exception(e)
              ensure
                run_after_example
              end
            end
          end
        rescue Exception => e
          set_exception(e)
        ensure
          @example_group_instance.instance_variables.each do |ivar|
            @example_group_instance.instance_variable_set(ivar, nil)
          end
          @example_group_instance = nil
        end

        finish(reporter)
      ensure
        RSpec.current_example = nil
      end

      # Wraps both a `Proc` and an {Example} for use in {Hooks#around
      # around} hooks. In around hooks we need to yield this special
      # kind of object (rather than the raw {Example}) because when
      # there are multiple `around` hooks we have to wrap them recursively.
      #
      # @example
      #
      #     RSpec.configure do |c|
      #       c.around do |ex| # Procsy which wraps the example
      #         if ex.metadata[:key] == :some_value && some_global_condition
      #           raise "some message"
      #         end
      #         ex.run         # run delegates to ex.call
      #       end
      #     end
      #
      # @note This class also exposes the instance methods of {Example},
      #   proxying them through to the wrapped {Example} instance.
      class Procsy
        # The {Example} instance.
        attr_reader :example

        Example.public_instance_methods(false).each do |name|
          unless name.to_sym == :run
            define_method(name) { |*a, &b| @example.__send__(name, *a, &b) }
          end
        end

        Proc.public_instance_methods(false).each do |name|
          define_method(name) { |*a, &b| @proc.__send__(name, *a, &b) }
        end
        alias run call

        def initialize(example, &block)
          @example = example
          @proc    = block
        end

        # @private
        def wrap(&block)
          self.class.new(example, &block)
        end
      end

      # @private
      def any_apply?(filters)
        MetadataFilter.any_apply?(filters, metadata)
      end

      # @private
      def all_apply?(filters)
        MetadataFilter.all_apply?(filters, metadata) || @example_group_class.all_apply?(filters)
      end

      # @private
      def around_example_hooks
        @around_example_hooks ||= example_group.hooks.around_example_hooks_for(self)
      end

      # @private
      #
      # Used internally to set an exception in an after hook, which
      # captures the exception but doesn't raise it.
      def set_exception(exception, context=nil)
        if pending? && !(Pending::PendingExampleFixedError === exception)
          execution_result.pending_exception = exception
        else
          if @exception
            # An error has already been set; we don't want to override it,
            # but we also don't want silence the error, so let's print it.
            msg = <<-EOS

  An error occurred #{context}
    #{exception.class}: #{exception.message}
    occurred at #{exception.backtrace.first}

            EOS
            RSpec.configuration.reporter.message(msg)
          end

          @exception ||= exception
        end
      end

      # @private
      #
      # Used internally to set an exception and fail without actually executing
      # the example when an exception is raised in before(:context).
      def fail_with_exception(reporter, exception)
        start(reporter)
        set_exception(exception)
        finish(reporter)
      end

      # @private
      #
      # Used internally to skip without actually executing the example when
      # skip is used in before(:context)
      def skip_with_exception(reporter, exception)
        start(reporter)
        Pending.mark_skipped! self, exception.argument
        finish(reporter)
      end

      # @private
      def instance_exec_with_rescue(context, &block)
        @example_group_instance.instance_exec(self, &block)
      rescue Exception => e
        set_exception(e, context)
      end

      # @private
      def instance_exec(*args, &block)
        @example_group_instance.instance_exec(*args, &block)
      end

    private

      def with_around_example_hooks(&block)
        if around_example_hooks.empty?
          yield
        else
          @example_group_class.hooks.run(:around, :example, self, Procsy.new(self, &block))
        end
      rescue Exception => e
        set_exception(e, "in an `around(:example)` hook")
      end

      def start(reporter)
        reporter.example_started(self)
        execution_result.started_at = clock.now
      end

      def finish(reporter)
        pending_message = execution_result.pending_message

        if @exception
          record_finished :failed
          execution_result.exception = @exception
          reporter.example_failed self
          false
        elsif pending_message
          record_finished :pending
          execution_result.pending_message = pending_message
          reporter.example_pending self
          true
        else
          record_finished :passed
          reporter.example_passed self
          true
        end
      end

      def record_finished(status)
        execution_result.record_finished(status, clock.now)
      end

      def run_before_example
        @example_group_instance.setup_mocks_for_rspec
        @example_group_class.hooks.run(:before, :example, self)
      end

      def run_after_example
        @example_group_class.hooks.run(:after, :example, self)
        verify_mocks
        assign_generated_description if RSpec.configuration.expecting_with_rspec?
      rescue Exception => e
        set_exception(e, "in an `after(:example)` hook")
      ensure
        @example_group_instance.teardown_mocks_for_rspec
      end

      def verify_mocks
        @example_group_instance.verify_mocks_for_rspec if mocks_need_verification?
      rescue Exception => e
        if pending?
          execution_result.pending_fixed = false
          @exception = nil
        else
          set_exception(e)
        end
      end

      def mocks_need_verification?
        exception.nil? || execution_result.pending_fixed?
      end

      def assign_generated_description
        if metadata[:description].empty? && (description = RSpec::Matchers.generated_description)
          metadata[:description] = description
          metadata[:full_description] << description
        end
      rescue Exception => e
        set_exception(e, "while assigning the example description")
      ensure
        RSpec::Matchers.clear_generated_description
      end

      def skip_message
        if String === skip
          skip
        else
          Pending::NO_REASON_GIVEN
        end
      end

      # Represents the result of executing an example.
      # Behaves like a hash for backwards compatibility.
      class ExecutionResult
        include HashImitatable

        # @return [Symbol] `:passed`, `:failed` or `:pending`.
        attr_accessor :status

        # @return [Exception, nil] The failure, if there was one.
        attr_accessor :exception

        # @return [Time] When the example started.
        attr_accessor :started_at

        # @return [Time] When the example finished.
        attr_accessor :finished_at

        # @return [Float] How long the example took in seconds.
        attr_accessor :run_time

        # @return [String, nil] The reason the example was pending,
        #   or nil if the example was not pending.
        attr_accessor :pending_message

        # @return [Exception, nil] The exception triggered while
        #   executing the pending example. If no exception was triggered
        #   it would no longer get a status of `:pending` unless it was
        #   tagged with `:skip`.
        attr_accessor :pending_exception

        # @return [Boolean] For examples tagged with `:pending`,
        #   this indicates whether or not it now passes.
        attr_accessor :pending_fixed

        alias pending_fixed? pending_fixed

        # @api private
        # Records the finished status of the example.
        def record_finished(status, finished_at)
          self.status      = status
          self.finished_at = finished_at
          self.run_time    = (finished_at - started_at).to_f
        end

      private

        # For backwards compatibility we present `status` as a string
        # when presenting the legacy hash interface.
        def hash_for_delegation
          super.tap do |hash|
            hash[:status] &&= status.to_s
          end
        end

        def set_value(name, value)
          value &&= value.to_sym if name == :status
          super(name, value)
        end

        def get_value(name)
          if name == :status
            status.to_s if status
          else
            super
          end
        end

        def issue_deprecation(method_name, *args)
          RSpec.deprecate("Treating `metadata[:execution_result]` as a hash",
                          :replacement => "the attributes methods to access the data")
        end
      end
    end

    # @private
    # Provides an execution context for before/after :suite hooks.
    class SuiteHookContext < Example
      def initialize
        super(AnonymousExampleGroup, "", {})
      end

      # To ensure we don't silence errors...
      def set_exception(exception, context=nil)
        raise exception
      end
    end
  end
end