// WaitForRunningBuild waits until the specified build is no longer New or Pending. Returns true if
// the build ran within timeout, false if it did not, and an error if any other error state occurred.
// The last observed Build state is returned.
func WaitForRunningBuild(watcher rest.Watcher, ctx kapi.Context, build *api.Build, timeout time.Duration) (*api.Build, bool, error) {
	fieldSelector := unversioned.FieldSelector{Selector: fields.Set{"metadata.name": build.Name}.AsSelector()}
	options := &unversioned.ListOptions{FieldSelector: fieldSelector, ResourceVersion: build.ResourceVersion}
	w, err := watcher.Watch(ctx, options)
	if err != nil {
		return nil, false, err
	}
	defer w.Stop()

	ch := w.ResultChan()
	observed := build
	expire := time.After(timeout)
	for {
		select {
		case event := <-ch:
			obj, ok := event.Object.(*api.Build)
			if !ok {
				return observed, false, fmt.Errorf("received unknown object while watching for builds")
			}
			observed = obj

			switch obj.Status.Phase {
			case api.BuildPhaseRunning, api.BuildPhaseComplete, api.BuildPhaseFailed, api.BuildPhaseError, api.BuildPhaseCancelled:
				return observed, true, nil
			case api.BuildPhaseNew, api.BuildPhasePending:
			default:
				return observed, false, ErrUnknownBuildPhase
			}
		case <-expire:
			return observed, false, nil
		}
	}
}

// watchForResourceVersion watches for an Add/Modify event matching the given resourceVersion.
// If an error, timeout, or unexpected event is received, an error is returned.
// If an add/modify event is observed with the correct resource version, nil is returned.
func watchForResourceVersion(versioner storage.Versioner, watcher rest.Watcher, resourceVersion string, timeout time.Duration) error {
	// Watch from the previous resource version, so the first watch event is the desired version
	previousVersion, err := previousResourceVersion(versioner, resourceVersion)
	if err != nil {
		return err
	}

	w, err := watcher.Watch(context.TODO(), &kapi.ListOptions{ResourceVersion: previousVersion})
	if err != nil {
		return fmt.Errorf("error verifying resourceVersion %s: %v", resourceVersion, err)
	}
	defer w.Stop()

	select {
	case event := <-w.ResultChan():
		if event.Type != watch.Added && event.Type != watch.Modified {
			return fmt.Errorf("unexpected watch event verifying resourceVersion %s: %q", resourceVersion, event.Type)
		}
		if event.Object == nil {
			return fmt.Errorf("unexpected watch event verifying resourceVersion %s: object was nil", resourceVersion)
		}
		accessor, err := meta.Accessor(event.Object)
		if err != nil {
			return err
		}
		actualResourceVersion := accessor.GetResourceVersion()
		if actualResourceVersion != resourceVersion {
			return fmt.Errorf("unexpected watch event verifying resourceVersion %s: resource version was %s)", resourceVersion, actualResourceVersion)
		}
		return nil

	case <-time.After(timeout):
		return fmt.Errorf("timeout verifying resourceVersion %s", resourceVersion)
	}
}

// ListResource returns a function that handles retrieving a list of resources from a rest.Storage object.
func ListResource(r rest.Lister, rw rest.Watcher, scope RequestScope, forceWatch bool, minRequestTimeout time.Duration) restful.RouteFunction {
	return func(req *restful.Request, res *restful.Response) {
		w := res.ResponseWriter

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

		// Watches for single objects are routed to this function.
		// Treat a /name parameter the same as a field selector entry.
		hasName := true
		_, name, err := scope.Namer.Name(req)
		if err != nil {
			hasName = false
		}

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

		versioned, err := scope.Creater.New(scope.ServerAPIVersion, "ListOptions")
		if err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}
		if err := scope.Codec.DecodeParametersInto(req.Request.URL.Query(), versioned); err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}
		opts := api.ListOptions{}
		if err := scope.Convertor.Convert(versioned, &opts); err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}

		// transform fields
		// TODO: Should this be done as part of convertion?
		fn := func(label, value string) (newLabel, newValue string, err error) {
			return scope.Convertor.ConvertFieldLabel(scope.APIVersion, scope.Kind, label, value)
		}
		if opts.FieldSelector, err = opts.FieldSelector.Transform(fn); err != nil {
			// TODO: allow bad request to set field causes based on query parameters
			err = errors.NewBadRequest(err.Error())
			errorJSON(err, scope.Codec, w)
			return
		}

		if hasName {
			// metadata.name is the canonical internal name.
			// generic.SelectionPredicate will notice that this is
			// a request for a single object and optimize the
			// storage query accordingly.
			nameSelector := fields.OneTermEqualSelector("metadata.name", name)
			if opts.FieldSelector != nil && !opts.FieldSelector.Empty() {
				// It doesn't make sense to ask for both a name
				// and a field selector, since just the name is
				// sufficient to narrow down the request to a
				// single object.
				errorJSON(
					errors.NewBadRequest("both a name and a field selector provided; please provide one or the other."),
					scope.Codec,
					w,
				)
				return
			}
			opts.FieldSelector = nameSelector
		}

		if (opts.Watch || forceWatch) && rw != nil {
			watcher, err := rw.Watch(ctx, &opts)
			if err != nil {
				errorJSON(err, scope.Codec, w)
				return
			}
			// TODO: Currently we explicitly ignore ?timeout= and use only ?timeoutSeconds=.
			timeout := time.Duration(0)
			if opts.TimeoutSeconds != nil {
				timeout = time.Duration(*opts.TimeoutSeconds) * time.Second
			}
			if timeout == 0 && minRequestTimeout > 0 {
				timeout = time.Duration(float64(minRequestTimeout) * (rand.Float64() + 1.0))
			}
			serveWatch(watcher, scope, w, req, timeout)
			return
		}

		result, err := r.List(ctx, &opts)
		if err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}
		if err := setListSelfLink(result, req, scope.Namer); err != nil {
			errorJSON(err, scope.Codec, w)
			return
		}
		write(http.StatusOK, scope.APIVersion, scope.Codec, result, w, req.Request)
	}
}

// ListResource returns a function that handles retrieving a list of resources from a rest.Storage object.
func ListResource(r rest.Lister, rw rest.Watcher, scope RequestScope, forceWatch bool, minRequestTimeout time.Duration) restful.RouteFunction {
	return func(req *restful.Request, res *restful.Response) {
		// For performance tracking purposes.
		trace := util.NewTrace("List " + req.Request.URL.Path)

		w := res.ResponseWriter

		namespace, err := scope.Namer.Namespace(req)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}

		// Watches for single objects are routed to this function.
		// Treat a /name parameter the same as a field selector entry.
		hasName := true
		_, name, err := scope.Namer.Name(req)
		if err != nil {
			hasName = false
		}

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

		opts := api.ListOptions{}
		if err := scope.ParameterCodec.DecodeParameters(req.Request.URL.Query(), scope.Kind.GroupVersion(), &opts); err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}

		// transform fields
		// TODO: DecodeParametersInto should do this.
		if opts.FieldSelector != nil {
			fn := func(label, value string) (newLabel, newValue string, err error) {
				return scope.Convertor.ConvertFieldLabel(scope.Kind.GroupVersion().String(), scope.Kind.Kind, label, value)
			}
			if opts.FieldSelector, err = opts.FieldSelector.Transform(fn); err != nil {
				// TODO: allow bad request to set field causes based on query parameters
				err = errors.NewBadRequest(err.Error())
				scope.err(err, res.ResponseWriter, req.Request)
				return
			}
		}

		if hasName {
			// metadata.name is the canonical internal name.
			// generic.SelectionPredicate will notice that this is
			// a request for a single object and optimize the
			// storage query accordingly.
			nameSelector := fields.OneTermEqualSelector("metadata.name", name)
			if opts.FieldSelector != nil && !opts.FieldSelector.Empty() {
				// It doesn't make sense to ask for both a name
				// and a field selector, since just the name is
				// sufficient to narrow down the request to a
				// single object.
				scope.err(errors.NewBadRequest("both a name and a field selector provided; please provide one or the other."), res.ResponseWriter, req.Request)
				return
			}
			opts.FieldSelector = nameSelector
		}

		if (opts.Watch || forceWatch) && rw != nil {
			watcher, err := rw.Watch(ctx, &opts)
			if err != nil {
				scope.err(err, res.ResponseWriter, req.Request)
				return
			}
			// TODO: Currently we explicitly ignore ?timeout= and use only ?timeoutSeconds=.
			timeout := time.Duration(0)
			if opts.TimeoutSeconds != nil {
				timeout = time.Duration(*opts.TimeoutSeconds) * time.Second
			}
			if timeout == 0 && minRequestTimeout > 0 {
				timeout = time.Duration(float64(minRequestTimeout) * (rand.Float64() + 1.0))
			}
			serveWatch(watcher, scope, req, res, timeout)
			return
		}

		// Log only long List requests (ignore Watch).
		defer trace.LogIfLong(500 * time.Millisecond)
		trace.Step("About to List from storage")
		result, err := r.List(ctx, &opts)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		trace.Step("Listing from storage done")
		numberOfItems, err := setListSelfLink(result, req, scope.Namer)
		if err != nil {
			scope.err(err, res.ResponseWriter, req.Request)
			return
		}
		trace.Step("Self-linking done")
		write(http.StatusOK, scope.Kind.GroupVersion(), scope.Serializer, result, w, req.Request)
		trace.Step(fmt.Sprintf("Writing http response done (%d items)", numberOfItems))
	}
}