[#3] Add shadow state handler. Send null values for missing objects w…

cmd/aws-connector/main.go

@@ -22,6 +22,7 @@ import (
 	"github.com/eclipse-kanto/aws-connector/flags"
 	"github.com/eclipse-kanto/aws-connector/routing/message/handlers"
 	"github.com/eclipse-kanto/aws-connector/routing/message/handlers/passthrough"
+	"github.com/eclipse-kanto/aws-connector/routing/message/handlers/state"
 
 	"github.com/eclipse-kanto/suite-connector/config"
 	suiteFlags "github.com/eclipse-kanto/suite-connector/flags"
@@ -80,10 +81,14 @@ func main() {
 	logger.Infof("Starting aws connector %s", version)
 	suiteFlags.ConfigCheck(logger, *fConfigFile)
 
+	shadowStateHandler := state.CreateDefaultShadowStateHandler()
+	cloudHandlers := []handlers.MessageHandler{
+		shadowStateHandler,
+	}
+
 	deviceHandlers := []handlers.MessageHandler{
-		passthrough.CreateDefaultDeviceHandler(),
+		passthrough.CreateDefaultDeviceHandler(shadowStateHandler.(passthrough.ShadowStateHolder)),
 	}
-	cloudHandlers := []handlers.MessageHandler{}
 
 	if err := app.MainLoop(settings, logger, deviceHandlers, cloudHandlers); err != nil {
 		logger.Error("Init failure", err, nil)

routing/message/handlers/passthrough/device_handler.go

@@ -43,25 +43,24 @@ const (
 	topicRootShadow = "$aws/things/%s/shadow/%s"
 	// Used to update feature of root thing or attributes of child thing.
 	topicNamedShadow = "$aws/things/%s/shadow/name/%s/%s"
-	// Used to update feature of child thing.
-	topicComplexNamedShadow = "$aws/things/%s/shadow/name/%s:%s/%s"
 
 	topicUpdate = "update"
 	topicDelete = "delete"
 )
 
 type deviceHandler struct {
-	tenantID       string
-	deviceID       string
-	payloadFilters []*regexp.Regexp
-	topicFilter    *regexp.Regexp
-	logger         watermill.LoggerAdapter
-	defaultHandler message.HandlerFunc
+	tenantID          string
+	deviceID          string
+	payloadFilters    []*regexp.Regexp
+	topicFilter       *regexp.Regexp
+	logger            watermill.LoggerAdapter
+	defaultHandler    message.HandlerFunc
+	shadowStateHolder ShadowStateHolder
 }
 
 // CreateDefaultDeviceHandler instantiates a new passthrough handler that forwards messages received from local message broker on event and telemetry topics as device-to-cloud messages.
-func CreateDefaultDeviceHandler() handlers.MessageHandler {
-	return &deviceHandler{}
+func CreateDefaultDeviceHandler(shadowStateHolder ShadowStateHolder) handlers.MessageHandler {
+	return &deviceHandler{shadowStateHolder: shadowStateHolder}
 }
 
 // Init gets the device ID that is needed for the message forwarding towards AWS IoT Hub.
@@ -109,7 +108,7 @@ func (h *deviceHandler) HandleMessage(msg *message.Message) ([]*message.Message,
 }
 
 // toShadowTopic convert Ditto topic to its corresponding device shadow topic and if its an update message.
-func (h *deviceHandler) toShadowTopic(topic *protocol.Topic, featureName string, value interface{}) (res string, update bool) {
+func (h *deviceHandler) toShadowTopic(topic *protocol.Topic, featureName string, value interface{}) (res string, update bool, shadowID string) {
 	target := topicUpdate
 	if topic.Action == protocol.ActionDelete && h.isEntireShadow(value) {
 		target = topicDelete
@@ -122,17 +121,19 @@ func (h *deviceHandler) toShadowTopic(topic *protocol.Topic, featureName string,
 	if len(h.deviceID) == len(topicID) {
 		if featureName == "" {
 			// Update root thing attributes.
-			return fmt.Sprintf(topicRootShadow, h.deviceID, target), update
+			return fmt.Sprintf(topicRootShadow, h.deviceID, target), update, h.deviceID
 		}
 		// Update root thing feature.
-		return fmt.Sprintf(topicNamedShadow, h.deviceID, featureName, target), update
+		return fmt.Sprintf(topicNamedShadow, h.deviceID, featureName, target), update, featureName
 	}
 	if featureName == "" {
 		// Update child thing attributes.
-		return fmt.Sprintf(topicNamedShadow, h.deviceID, topicID[len(h.deviceID)+1:], target), update
+		shadowID = topicID[len(h.deviceID)+1:]
+		return fmt.Sprintf(topicNamedShadow, h.deviceID, shadowID, target), update, shadowID
 	}
 	// Update child thing feature.
-	return fmt.Sprintf(topicComplexNamedShadow, h.deviceID, topicID[len(h.deviceID)+1:], featureName, target), update
+	shadowID = fmt.Sprintf("%s:%s", topicID[len(h.deviceID)+1:], featureName)
+	return fmt.Sprintf(topicNamedShadow, h.deviceID, shadowID, target), update, shadowID
 }
 
 // isDittoRequest returns true if provided message is Ditto request to the connected device.
@@ -187,10 +188,11 @@ func integrate(path []string, value interface{}) interface{} {
 
 // toShadowMessage convert Ditto data to device shadow message.
 func (h *deviceHandler) toShadowMessage(env *protocol.Envelope, featureName string, value interface{}) *message.Message {
-	topic, update := h.toShadowTopic(env.Topic, featureName, value)
+	topic, update, shadowID := h.toShadowTopic(env.Topic, featureName, value)
 
 	var payload message.Payload
 	if update {
+		value = h.mergeWithCurrentShadowState(shadowID, value, env)
 		// Adds shadow prefix infront: ["state", "reported"]
 		value = integrate([]string{valueStateTag, valueReportedTag}, value)
 		payload, _ = json.Marshal(value)
@@ -203,6 +205,102 @@ func (h *deviceHandler) toShadowMessage(env *protocol.Envelope, featureName stri
 	return message
 }
 
+func (h deviceHandler) mergeWithCurrentShadowState(featureName string, newState interface{}, envelope *protocol.Envelope) interface{} {
+	if envelope.Topic.Action != protocol.ActionModify {
+		return newState
+	}
+
+	if h.shadowStateHolder == nil {
+		return newState
+	}
+
+	currentState := h.shadowStateHolder.GetCurrentShadowState(featureName)
+	if currentState == nil {
+		return newState
+	}
+
+	if subpath, ok := isSinglePropertyOrAttributeUpdate(envelope.Path); ok {
+		return mergeSubpaths(currentState, newState, strings.Split(subpath, "/"))
+	}
+
+	return merge(currentState, newState)
+}
+
+func isSinglePropertyOrAttributeUpdate(path string) (string, bool) {
+	if propertiesIndex := strings.Index(path, valuePropertiesTag); propertiesIndex >= 0 {
+		return path[propertiesIndex+len(valuePropertiesTag):], true
+	}
+
+	if attributesIndex := strings.Index(path, valueAttributesTag); attributesIndex >= 0 {
+		return path[attributesIndex+len(valueAttributesTag):], true
+	}
+
+	return "", false
+}
+
+func mergeSubpaths(currentState interface{}, newState interface{}, propertyPath []string) interface{} {
+	currentStateMap, isCurrentStateMap := currentState.(map[string]interface{})
+	newStateMap, isNewStateMap := newState.(map[string]interface{})
+
+	if !isCurrentStateMap || !isNewStateMap {
+		return newState
+	}
+
+	if len(propertyPath) == 0 {
+		return merge(currentState, newState)
+	}
+
+	propertyName := propertyPath[0]
+
+	if len(propertyName) == 0 {
+		return mergeSubpaths(currentState, newState, propertyPath[1:])
+	}
+
+	newStateMap[propertyName] = mergeSubpaths(currentStateMap[propertyName], newStateMap[propertyName], propertyPath[1:])
+
+	return newStateMap
+
+}
+
+func merge(currentState interface{}, newState interface{}) interface{} {
+	newState = mergeAsMaps(currentState, newState)
+	newState = mergeAsArrays(currentState, newState)
+
+	return newState
+}
+
+func mergeAsMaps(currentState interface{}, newState interface{}) interface{} {
+	currentStateMap, isCurrentStateMap := currentState.(map[string]interface{})
+	newStateMap, isNewStateMap := newState.(map[string]interface{})
+
+	if !isCurrentStateMap || !isNewStateMap {
+		return newState
+	}
+	for key, currentValue := range currentStateMap {
+		if newValue, exists := newStateMap[key]; !exists {
+			newStateMap[key] = nil
+		} else {
+			newStateMap[key] = merge(currentValue, newValue)
+		}
+	}
+
+	return newStateMap
+}
+
+func mergeAsArrays(currentState interface{}, newState interface{}) interface{} {
+	currentStateArray, isCurrentStateArray := currentState.([]interface{})
+	newStateArray, isNewStateArray := newState.([]interface{})
+
+	if !isCurrentStateArray || !isNewStateArray {
+		return newState
+	}
+
+	for i := 0; i < len(newStateArray) && i < len(currentStateArray); i++ {
+		newStateArray[i] = merge(currentStateArray[i], newStateArray[i])
+	}
+	return newStateArray
+}
+
 // getFeatureProperties return all feature properties, including the definition.
 func (h *deviceHandler) getFeatureProperties(obj interface{}) (interface{}, bool) {
 	res := map[string]interface{}{}