// tryConvert attempts to convert the given object to the provided versions in order. This function assumes
// the object is in internal version.
func tryConvert(convertor runtime.ObjectConvertor, object runtime.Object, versions ...string) (runtime.Object, error) {
	var last error
	for _, version := range versions {
		if len(version) == 0 {
			return object, nil
		}
		obj, err := convertor.ConvertToVersion(object, version)
		if err != nil {
			last = err
			continue
		}
		return obj, nil
	}
	return nil, last
}

// PatchResource returns a function that will handle a resource patch
// TODO: Eventually PatchResource should just use GuaranteedUpdate and this routine should be a bit cleaner
func PatchResource(r rest.Patcher, scope RequestScope, typer runtime.ObjectTyper, admit admission.Interface, converter runtime.ObjectConvertor) restful.RouteFunction {
	return func(req *restful.Request, res *restful.Response) {
		w := res.ResponseWriter

		// TODO: we either want to remove timeout or document it (if we
		// document, move timeout out of this function and declare it in
		// api_installer)
		timeout := parseTimeout(req.Request.URL.Query().Get("timeout"))

		namespace, name, err := scope.Namer.Name(req)
		if err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}

		obj := r.New()
		ctx := scope.ContextFunc(req)
		ctx = api.WithNamespace(ctx, namespace)

		// PATCH requires same permission as UPDATE
		if admit.Handles(admission.Update) {
			userInfo, _ := api.UserFrom(ctx)
			err = admit.Admit(admission.NewAttributesRecord(obj, scope.Kind, namespace, scope.Resource, admission.Update, userInfo))
			if err != nil {
				errorJSON(err, scope.Codec, w)
				return
			}
		}

		versionedObj, err := converter.ConvertToVersion(obj, scope.APIVersion)
		if err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}

		original, err := r.Get(ctx, name)
		if err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}

		originalObjJS, err := scope.Codec.Encode(original)
		if err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}
		patchJS, err := readBody(req.Request)
		if err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}
		contentType := req.HeaderParameter("Content-Type")
		patchedObjJS, err := getPatchedJS(contentType, originalObjJS, patchJS, versionedObj)
		if err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}

		if err := scope.Codec.DecodeInto(patchedObjJS, obj); err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}
		if err := checkName(obj, name, namespace, scope.Namer); err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}

		result, err := finishRequest(timeout, func() (runtime.Object, error) {
			// update should never create as previous get would fail
			obj, _, err := r.Update(ctx, obj)
			return obj, err
		})
		if err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}

		if err := setSelfLink(result, req, scope.Namer); err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}

		write(http.StatusOK, scope.APIVersion, scope.Codec, result, w, req.Request)
	}
}