func parseResources(result *structs.Resources, list *ast.ObjectList) error {
	list = list.Elem()
	if len(list.Items) == 0 {
		return nil
	}
	if len(list.Items) > 1 {
		return fmt.Errorf("only one 'resource' block allowed per task")
	}

	// Get our resource object
	o := list.Items[0]

	// We need this later
	var listVal *ast.ObjectList
	if ot, ok := o.Val.(*ast.ObjectType); ok {
		listVal = ot.List
	} else {
		return fmt.Errorf("resource: should be an object")
	}

	var m map[string]interface{}
	if err := hcl.DecodeObject(&m, o.Val); err != nil {
		return err
	}
	delete(m, "network")

	if err := mapstructure.WeakDecode(m, result); err != nil {
		return err
	}

	// Parse the network resources
	if o := listVal.Filter("network"); len(o.Items) > 0 {
		if len(o.Items) > 1 {
			return fmt.Errorf("only one 'network' resource allowed")
		}

		var r structs.NetworkResource
		var m map[string]interface{}
		if err := hcl.DecodeObject(&m, o.Items[0].Val); err != nil {
			return err
		}
		if err := mapstructure.WeakDecode(m, &r); err != nil {
			return err
		}

		var networkObj *ast.ObjectList
		if ot, ok := o.Items[0].Val.(*ast.ObjectType); ok {
			networkObj = ot.List
		} else {
			return fmt.Errorf("resource: should be an object")
		}
		if err := parsePorts(networkObj, &r); err != nil {
			return err
		}

		result.Networks = []*structs.NetworkResource{&r}
	}

	return nil
}

func parseResources(result *structs.Resources, obj *hclobj.Object) error {
	if obj.Len() > 1 {
		return fmt.Errorf("only one 'resource' block allowed per task")
	}

	for _, o := range obj.Elem(false) {
		var m map[string]interface{}
		if err := hcl.DecodeObject(&m, o); err != nil {
			return err
		}
		delete(m, "network")

		if err := mapstructure.WeakDecode(m, result); err != nil {
			return err
		}

		// Parse the network resources
		if o := o.Get("network", false); o != nil {
			if o.Len() > 1 {
				return fmt.Errorf("only one 'network' resource allowed")
			}

			var r structs.NetworkResource
			var m map[string]interface{}
			if err := hcl.DecodeObject(&m, o); err != nil {
				return err
			}
			if err := mapstructure.WeakDecode(m, &r); err != nil {
				return err
			}

			// Keep track of labels we've already seen so we can ensure there
			// are no collisions when we turn them into environment variables.
			// lowercase:NomalCase so we can get the first for the error message
			seenLabel := map[string]string{}

			for _, label := range r.DynamicPorts {
				if !reDynamicPorts.MatchString(label) {
					return errDynamicPorts
				}
				first, seen := seenLabel[strings.ToLower(label)]
				if seen {
					return fmt.Errorf("Found a port label collision: `%s` overlaps with previous `%s`", label, first)
				} else {
					seenLabel[strings.ToLower(label)] = label
				}

			}

			result.Networks = []*structs.NetworkResource{&r}
		}

	}

	return nil
}

func (s *GenericStack) Select(tg *structs.TaskGroup) (*RankedNode, *structs.Resources) {
	// Reset the max selector and context
	s.maxScore.Reset()
	s.ctx.Reset()
	start := time.Now()

	// Collect the constraints, drivers and resources required by each
	// sub-task to aggregate the TaskGroup totals
	constr := make([]*structs.Constraint, 0, len(tg.Constraints))
	drivers := make(map[string]struct{})
	size := new(structs.Resources)
	constr = append(constr, tg.Constraints...)
	for _, task := range tg.Tasks {
		drivers[task.Driver] = struct{}{}
		constr = append(constr, task.Constraints...)
		size.Add(task.Resources)
	}

	// Update the parameters of iterators
	s.taskGroupDrivers.SetDrivers(drivers)
	s.taskGroupConstraint.SetConstraints(constr)
	s.binPack.SetTasks(tg.Tasks)

	// Find the node with the max score
	option := s.maxScore.Next()

	// Ensure that the task resources were specified
	if option != nil && len(option.TaskResources) != len(tg.Tasks) {
		for _, task := range tg.Tasks {
			option.SetTaskResources(task, task.Resources)
		}
	}

	// Store the compute time
	s.ctx.Metrics().AllocationTime = time.Since(start)
	return option, size
}

func parseResources(result *structs.Resources, list *ast.ObjectList) error {
	list = list.Elem()
	if len(list.Items) == 0 {
		return nil
	}
	if len(list.Items) > 1 {
		return fmt.Errorf("only one 'resource' block allowed per task")
	}

	// Get our resource object
	o := list.Items[0]

	// We need this later
	var listVal *ast.ObjectList
	if ot, ok := o.Val.(*ast.ObjectType); ok {
		listVal = ot.List
	} else {
		return fmt.Errorf("resource: should be an object")
	}

	// Check for invalid keys
	valid := []string{
		"cpu",
		"iops",
		"memory",
		"network",
	}
	if err := checkHCLKeys(listVal, valid); err != nil {
		return multierror.Prefix(err, "resources ->")
	}

	var m map[string]interface{}
	if err := hcl.DecodeObject(&m, o.Val); err != nil {
		return err
	}
	delete(m, "network")

	if err := mapstructure.WeakDecode(m, result); err != nil {
		return err
	}

	// Parse the network resources
	if o := listVal.Filter("network"); len(o.Items) > 0 {
		if len(o.Items) > 1 {
			return fmt.Errorf("only one 'network' resource allowed")
		}

		// Check for invalid keys
		valid := []string{
			"mbits",
			"port",
		}
		if err := checkHCLKeys(o.Items[0].Val, valid); err != nil {
			return multierror.Prefix(err, "resources, network ->")
		}

		var r structs.NetworkResource
		var m map[string]interface{}
		if err := hcl.DecodeObject(&m, o.Items[0].Val); err != nil {
			return err
		}
		if err := mapstructure.WeakDecode(m, &r); err != nil {
			return err
		}

		var networkObj *ast.ObjectList
		if ot, ok := o.Items[0].Val.(*ast.ObjectType); ok {
			networkObj = ot.List
		} else {
			return fmt.Errorf("resource: should be an object")
		}
		if err := parsePorts(networkObj, &r); err != nil {
			return multierror.Prefix(err, "resources, network, ports ->")
		}

		result.Networks = []*structs.NetworkResource{&r}
	}

	// Combine the parsed resources with a default resource block.
	min := structs.DefaultResources()
	min.Merge(result)
	*result = *min
	return nil
}

func (iter *BinPackIterator) Next() *RankedNode {
OUTER:
	for {
		// Get the next potential option
		option := iter.source.Next()
		if option == nil {
			return nil
		}

		// Get the proposed allocations
		proposed, err := option.ProposedAllocs(iter.ctx)
		if err != nil {
			iter.ctx.Logger().Printf(
				"[ERR] sched.binpack: failed to get proposed allocations: %v",
				err)
			continue
		}

		// Index the existing network usage
		netIdx := structs.NewNetworkIndex()
		netIdx.SetNode(option.Node)
		netIdx.AddAllocs(proposed)

		// Assign the resources for each task
		total := new(structs.Resources)
		for _, task := range iter.tasks {
			taskResources := task.Resources.Copy()

			// Check if we need a network resource
			if len(taskResources.Networks) > 0 {
				ask := taskResources.Networks[0]
				offer, err := netIdx.AssignNetwork(ask)
				if offer == nil {
					iter.ctx.Metrics().ExhaustedNode(option.Node,
						fmt.Sprintf("network: %s", err))
					continue OUTER
				}

				// Reserve this to prevent another task from colliding
				netIdx.AddReserved(offer)

				// Update the network ask to the offer
				taskResources.Networks = []*structs.NetworkResource{offer}
			}

			// Store the task resource
			option.SetTaskResources(task, taskResources)

			// Accumulate the total resource requirement
			total.Add(taskResources)
		}

		// Add the resources we are trying to fit
		proposed = append(proposed, &structs.Allocation{Resources: total})

		// Check if these allocations fit, if they do not, simply skip this node
		fit, dim, util, _ := structs.AllocsFit(option.Node, proposed, netIdx)
		if !fit {
			iter.ctx.Metrics().ExhaustedNode(option.Node, dim)
			continue
		}

		// XXX: For now we completely ignore evictions. We should use that flag
		// to determine if its possible to evict other lower priority allocations
		// to make room. This explodes the search space, so it must be done
		// carefully.

		// Score the fit normally otherwise
		fitness := structs.ScoreFit(option.Node, util)
		option.Score += fitness
		iter.ctx.Metrics().ScoreNode(option.Node, "binpack", fitness)
		return option
	}
}

func parseResources(result *structs.Resources, list *ast.ObjectList) error {
	list = list.Elem()
	if len(list.Items) == 0 {
		return nil
	}
	if len(list.Items) > 1 {
		return fmt.Errorf("only one 'resource' block allowed per task")
	}

	// Get our resource object
	o := list.Items[0]

	// We need this later
	var listVal *ast.ObjectList
	if ot, ok := o.Val.(*ast.ObjectType); ok {
		listVal = ot.List
	} else {
		return fmt.Errorf("resource: should be an object")
	}

	var m map[string]interface{}
	if err := hcl.DecodeObject(&m, o.Val); err != nil {
		return err
	}
	delete(m, "network")

	if err := mapstructure.WeakDecode(m, result); err != nil {
		return err
	}

	// Parse the network resources
	if o := listVal.Filter("network"); len(o.Items) > 0 {
		if len(o.Items) > 1 {
			return fmt.Errorf("only one 'network' resource allowed")
		}

		var r structs.NetworkResource
		var m map[string]interface{}
		if err := hcl.DecodeObject(&m, o.Items[0].Val); err != nil {
			return err
		}
		if err := mapstructure.WeakDecode(m, &r); err != nil {
			return err
		}

		// Keep track of labels we've already seen so we can ensure there
		// are no collisions when we turn them into environment variables.
		// lowercase:NomalCase so we can get the first for the error message
		seenLabel := map[string]string{}
		for _, label := range r.DynamicPorts {
			if !reDynamicPorts.MatchString(label) {
				return errDynamicPorts
			}
			first, seen := seenLabel[strings.ToLower(label)]
			if seen {
				return fmt.Errorf("Found a port label collision: `%s` overlaps with previous `%s`", label, first)
			} else {
				seenLabel[strings.ToLower(label)] = label
			}

		}

		result.Networks = []*structs.NetworkResource{&r}
	}

	return nil
}