func NewDiscoveryRESTMapper()

in restmapper/discovery.go [43:143]
80 lines of code
12 McCabe index (conditional complexity)

func NewDiscoveryRESTMapper(groupResources []*APIGroupResources) meta.RESTMapper {
	unionMapper := meta.MultiRESTMapper{}

	var groupPriority []string
	// /v1 is special.  It should always come first
	resourcePriority := []schema.GroupVersionResource{{Group: "", Version: "v1", Resource: meta.AnyResource}}
	kindPriority := []schema.GroupVersionKind{{Group: "", Version: "v1", Kind: meta.AnyKind}}

	for _, group := range groupResources {
		groupPriority = append(groupPriority, group.Group.Name)

		// Make sure the preferred version comes first
		if len(group.Group.PreferredVersion.Version) != 0 {
			preferred := group.Group.PreferredVersion.Version
			if _, ok := group.VersionedResources[preferred]; ok {
				resourcePriority = append(resourcePriority, schema.GroupVersionResource{
					Group:    group.Group.Name,
					Version:  group.Group.PreferredVersion.Version,
					Resource: meta.AnyResource,
				})

				kindPriority = append(kindPriority, schema.GroupVersionKind{
					Group:   group.Group.Name,
					Version: group.Group.PreferredVersion.Version,
					Kind:    meta.AnyKind,
				})
			}
		}

		for _, discoveryVersion := range group.Group.Versions {
			resources, ok := group.VersionedResources[discoveryVersion.Version]
			if !ok {
				continue
			}

			// Add non-preferred versions after the preferred version, in case there are resources that only exist in those versions
			if discoveryVersion.Version != group.Group.PreferredVersion.Version {
				resourcePriority = append(resourcePriority, schema.GroupVersionResource{
					Group:    group.Group.Name,
					Version:  discoveryVersion.Version,
					Resource: meta.AnyResource,
				})

				kindPriority = append(kindPriority, schema.GroupVersionKind{
					Group:   group.Group.Name,
					Version: discoveryVersion.Version,
					Kind:    meta.AnyKind,
				})
			}

			gv := schema.GroupVersion{Group: group.Group.Name, Version: discoveryVersion.Version}
			versionMapper := meta.NewDefaultRESTMapper([]schema.GroupVersion{gv})

			for _, resource := range resources {
				scope := meta.RESTScopeNamespace
				if !resource.Namespaced {
					scope = meta.RESTScopeRoot
				}

				// if we have a slash, then this is a subresource and we shouldn't create mappings for those.
				if strings.Contains(resource.Name, "/") {
					continue
				}

				plural := gv.WithResource(resource.Name)
				singular := gv.WithResource(resource.SingularName)
				// this is for legacy resources and servers which don't list singular forms.  For those we must still guess.
				if len(resource.SingularName) == 0 {
					_, singular = meta.UnsafeGuessKindToResource(gv.WithKind(resource.Kind))
				}

				versionMapper.AddSpecific(gv.WithKind(strings.ToLower(resource.Kind)), plural, singular, scope)
				versionMapper.AddSpecific(gv.WithKind(resource.Kind), plural, singular, scope)
				// TODO this is producing unsafe guesses that don't actually work, but it matches previous behavior
				versionMapper.Add(gv.WithKind(resource.Kind+"List"), scope)
			}
			// TODO why is this type not in discovery (at least for "v1")
			versionMapper.Add(gv.WithKind("List"), meta.RESTScopeRoot)
			unionMapper = append(unionMapper, versionMapper)
		}
	}

	for _, group := range groupPriority {
		resourcePriority = append(resourcePriority, schema.GroupVersionResource{
			Group:    group,
			Version:  meta.AnyVersion,
			Resource: meta.AnyResource,
		})
		kindPriority = append(kindPriority, schema.GroupVersionKind{
			Group:   group,
			Version: meta.AnyVersion,
			Kind:    meta.AnyKind,
		})
	}

	return meta.PriorityRESTMapper{
		Delegate:         unionMapper,
		ResourcePriority: resourcePriority,
		KindPriority:     kindPriority,
	}
}