Add missing metadata fields

src/sensesp/signalk/signalk_metadata.cpp

@@ -1,5 +1,7 @@
 #include "signalk_metadata.h"
 
+#include <cmath>
+
 namespace sensesp {
 
 SKMetadata::SKMetadata(const String& units, const String& display_name,
@@ -9,7 +11,10 @@ SKMetadata::SKMetadata(const String& units, const String& display_name,
       units_{units},
       description_{description},
       short_name_{short_name},
-      timeout_{timeout} {}
+      timeout_{timeout},
+      supports_put_{-1},
+      display_scale_lower_{NAN},
+      display_scale_upper_{NAN} {}
 
 void SKMetadata::add_entry(const String& sk_path, JsonArray& meta) {
   JsonObject json = meta.add<JsonObject>();
@@ -35,6 +40,48 @@ void SKMetadata::add_entry(const String& sk_path, JsonArray& meta) {
   if (this->timeout_ >= 0.0) {
     val["timeout"] = this->timeout_;
   }
+
+  if (!this->example_.isEmpty()) {
+    val["example"] = this->example_;
+  }
+
+  if (this->supports_put_ != -1) {
+    val["supportsPut"] = (this->supports_put_ == 1);
+  }
+
+  if (!std::isnan(this->display_scale_lower_) ||
+      !std::isnan(this->display_scale_upper_)) {
+    JsonObject scale = val["displayScale"].to<JsonObject>();
+    if (!std::isnan(this->display_scale_lower_)) {
+      scale["lower"] = this->display_scale_lower_;
+    }
+    if (!std::isnan(this->display_scale_upper_)) {
+      scale["upper"] = this->display_scale_upper_;
+    }
+  }
+
+  if (!this->zones_.empty()) {
+    JsonArray zones_arr = val["zones"].to<JsonArray>();
+    for (const SKZone& zone : this->zones_) {
+      JsonObject zone_obj = zones_arr.add<JsonObject>();
+      zone_obj["state"] = alarm_state_to_string(zone.state_);
+      zone_obj["message"] = zone.message_;
+      if (!std::isnan(zone.lower_)) zone_obj["lower"] = zone.lower_;
+      if (!std::isnan(zone.upper_)) zone_obj["upper"] = zone.upper_;
+    }
+  }
+}
+
+const char* SKMetadata::alarm_state_to_string(SKAlarmState state) {
+  switch (state) {
+    case SKAlarmState::kNominal:   return "nominal";
+    case SKAlarmState::kNormal:    return "normal";
+    case SKAlarmState::kAlert:     return "alert";
+    case SKAlarmState::kWarn:      return "warn";
+    case SKAlarmState::kAlarm:     return "alarm";
+    case SKAlarmState::kEmergency: return "emergency";
+    default:                       return "normal";
+  }
 }
 
 }  // namespace sensesp

src/sensesp/signalk/signalk_metadata.h

@@ -2,9 +2,39 @@
 #define SENSESP_SIGNALK_SIGNALK_METADATA_H_
 
 #include <ArduinoJson.h>
+#include <cmath>
+#include <vector>
 
 namespace sensesp {
 
+/**
+ * @brief Alarm state values for Signal K Zone metadata.
+ * @see https://demo.signalk.org/documentation/_signalk/server-api/ALARM_STATE.html
+ */
+enum class SKAlarmState {
+  kNominal,
+  kNormal,
+  kAlert,
+  kWarn,
+  kAlarm,
+  kEmergency
+};
+
+/**
+ * @brief Represents a single Signal K alarm zone within metadata.
+ * @see https://demo.signalk.org/documentation/_signalk/server-api/Zone.html
+ */
+struct SKZone {
+  float lower_;    ///< Lower bound of the zone; NAN if not set
+  float upper_;    ///< Upper bound of the zone; NAN if not set
+  String message_;
+  SKAlarmState state_;
+
+  SKZone(SKAlarmState state, const String& message,
+         float lower = NAN, float upper = NAN)
+      : lower_{lower}, upper_{upper}, message_{message}, state_{state} {}
+};
+
 /**
  * @brief Holds Signal K meta data that is associated with
  * the sk_path an SKEmitter class may optionally send to the server.
@@ -28,6 +58,11 @@ class SKMetadata {
   String description_;
   String short_name_;
   float timeout_;
+  String example_;
+  int supports_put_;            ///< -1 = not set, 0 = false, 1 = true
+  float display_scale_lower_;   ///< NAN = not set
+  float display_scale_upper_;   ///< NAN = not set
+  std::vector<SKZone> zones_;
 
   /**
    * @param units The unit of measurement the value represents. See
@@ -49,7 +84,11 @@ class SKMetadata {
              float timeout = -1.0);
 
   /// Default constructor creates a blank Metadata structure
-  SKMetadata() : timeout_{-1} {}
+  SKMetadata()
+      : timeout_{-1},
+        supports_put_{-1},
+        display_scale_lower_{NAN},
+        display_scale_upper_{NAN} {}
 
   /**
    * Adds an entry to the specified meta array that represents this metadata
@@ -59,6 +98,9 @@ class SKMetadata {
    * @param[out] meta The array the metadata entry is supposed to be added to
    */
   virtual void add_entry(const String& sk_path, JsonArray& meta);
+
+ private:
+  static const char* alarm_state_to_string(SKAlarmState state);
 };
 
 }  // namespace sensesp