Feature: HTTP power meter: support changing sign

include/Configuration.h

@@ -75,6 +75,7 @@ struct POWERMETER_HTTP_PHASE_CONFIG_T {
     uint16_t Timeout;
     char JsonPath[POWERMETER_MAX_HTTP_JSON_PATH_STRLEN + 1];
     Unit PowerUnit;
+    bool SignInverted;
 };
 using PowerMeterHttpConfig = struct POWERMETER_HTTP_PHASE_CONFIG_T;
 

include/HttpPowerMeter.h

@@ -26,7 +26,7 @@ private:
     String extractParam(String& authReq, const String& param, const char delimit);
     String getcNonce(const int len);
     String getDigestAuth(String& authReq, const String& username, const String& password, const String& method, const String& uri, unsigned int counter);
-    bool tryGetFloatValueForPhase(int phase, const char* jsonPath, Unit_t unit);
+    bool tryGetFloatValueForPhase(int phase, const char* jsonPath, Unit_t unit, bool signInverted);
     void prepareRequest(uint32_t timeout, const char* httpHeader, const char* httpValue);
     String sha256(const String& data);
 };

src/Configuration.cpp

@@ -176,6 +176,7 @@ bool ConfigurationClass::write()
         powermeter_phase["timeout"] = config.PowerMeter.Http_Phase[i].Timeout;
         powermeter_phase["json_path"] = config.PowerMeter.Http_Phase[i].JsonPath;
         powermeter_phase["unit"] = config.PowerMeter.Http_Phase[i].PowerUnit;
+        powermeter_phase["sign_inverted"] = config.PowerMeter.Http_Phase[i].SignInverted;
     }
 
     JsonObject powerlimiter = doc.createNestedObject("powerlimiter");
@@ -429,6 +430,7 @@ bool ConfigurationClass::read()
         config.PowerMeter.Http_Phase[i].Timeout = powermeter_phase["timeout"] | POWERMETER_HTTP_TIMEOUT;
         strlcpy(config.PowerMeter.Http_Phase[i].JsonPath, powermeter_phase["json_path"] | "", sizeof(config.PowerMeter.Http_Phase[i].JsonPath));
         config.PowerMeter.Http_Phase[i].PowerUnit = powermeter_phase["unit"] | PowerMeterHttpConfig::Unit::Watts;
+        config.PowerMeter.Http_Phase[i].SignInverted = powermeter_phase["sign_inverted"] | false;
     }
 
     JsonObject powerlimiter = doc["powerlimiter"];

src/HttpPowerMeter.cpp

@@ -42,7 +42,7 @@ bool HttpPowerMeterClass::updateValues()
             continue;
         }
 
-        if(!tryGetFloatValueForPhase(i, phaseConfig.JsonPath, phaseConfig.PowerUnit)) {
+        if(!tryGetFloatValueForPhase(i, phaseConfig.JsonPath, phaseConfig.PowerUnit, phaseConfig.SignInverted)) {
             MessageOutput.printf("[HttpPowerMeter] Getting the power of phase %d (from JSON fetched with Phase 1 config) failed.\r\n", i + 1);
             MessageOutput.printf("%s\r\n", httpPowerMeterError);
             return false;
@@ -161,7 +161,7 @@ bool HttpPowerMeterClass::httpRequest(int phase, WiFiClient &wifiClient, const S
 
     // TODO(schlimmchen): postpone calling tryGetFloatValueForPhase, as it
     // will be called twice for each phase when doing separate requests.
-    return tryGetFloatValueForPhase(phase, config.JsonPath, config.PowerUnit);
+    return tryGetFloatValueForPhase(phase, config.JsonPath, config.PowerUnit, config.SignInverted);
 }
 
 String HttpPowerMeterClass::extractParam(String& authReq, const String& param, const char delimit) {
@@ -219,7 +219,7 @@ String HttpPowerMeterClass::getDigestAuth(String& authReq, const String& usernam
     return authorization;
 }
 
-bool HttpPowerMeterClass::tryGetFloatValueForPhase(int phase, const char* jsonPath, Unit_t unit)
+bool HttpPowerMeterClass::tryGetFloatValueForPhase(int phase, const char* jsonPath, Unit_t unit, bool signInverted)
 {
     FirebaseJson json;
     json.setJsonData(httpResponse);
@@ -229,7 +229,9 @@ bool HttpPowerMeterClass::tryGetFloatValueForPhase(int phase, const char* jsonPa
         return false;
     }
 
-    power[phase] = value.to<float>(); // this is supposed to be in Watts
+    // this value is supposed to be in Watts and positive if energy is consumed.
+    power[phase] = value.to<float>();
+
     switch (unit) {
         case Unit_t::MilliWatts:
             power[phase] /= 1000;
@@ -240,6 +242,9 @@ bool HttpPowerMeterClass::tryGetFloatValueForPhase(int phase, const char* jsonPa
         default:
             break;
     }
+
+    if (signInverted) { power[phase] *= -1; }
+
     return true;
 }
 

src/WebApi_powermeter.cpp

@@ -40,6 +40,7 @@ void WebApiPowerMeterClass::decodeJsonPhaseConfig(JsonObject const& json, PowerM
     config.Timeout = json["timeout"].as<uint16_t>();
     strlcpy(config.JsonPath, json["json_path"].as<String>().c_str(), sizeof(config.JsonPath));
     config.PowerUnit = json["unit"].as<PowerMeterHttpConfig::Unit>();
+    config.SignInverted = json["sign_inverted"].as<bool>();
 }
 
 void WebApiPowerMeterClass::onStatus(AsyncWebServerRequest* request)
@@ -75,6 +76,7 @@ void WebApiPowerMeterClass::onStatus(AsyncWebServerRequest* request)
         phaseObject["timeout"] = config.PowerMeter.Http_Phase[i].Timeout;
         phaseObject["json_path"] = String(config.PowerMeter.Http_Phase[i].JsonPath);
         phaseObject["unit"] = config.PowerMeter.Http_Phase[i].PowerUnit;
+        phaseObject["sign_inverted"] = config.PowerMeter.Http_Phase[i].SignInverted;
     }
 
     response->setLength();

webapp/src/locales/de.json

@@ -576,6 +576,8 @@
         "httpJsonPath": "JSON Pfad",
         "httpJsonPathDescription": "JSON Pfad um den Leistungswert zu finden. Es verwendet die Selektions-Syntax von mobizt/FirebaseJson. Beispiele gibt es oben.",
         "httpUnit": "Einheit",
+        "httpSignInverted": "Vorzeichen umkehren",
+        "httpSignInvertedHint": "Positive Werte werden als Leistungsabnahme aus dem Netz interpretiert. Diese Option muss aktiviert werden, wenn das Vorzeichen des Wertes die gegenteilige Bedeutung hat.",
         "httpTimeout": "Timeout",
         "testHttpRequest": "Testen"
     },

webapp/src/locales/en.json

@@ -581,6 +581,8 @@
         "httpJsonPath": "JSON path",
         "httpJsonPathDescription": "JSON path to find the power value in the response. This uses the JSON path query syntax from mobizt/FirebaseJson. See above for examples.",
         "httpUnit": "Unit",
+        "httpSignInverted": "Change Sign",
+        "httpSignInvertedHint": "Is is expected that positive values denote power usage from the grid. Check this option if the sign of this value has the opposite meaning.",
         "httpTimeout": "Timeout",
         "testHttpRequest": "Run test",
         "milliSeconds": "ms"

webapp/src/types/PowerMeterConfig.ts

@@ -10,6 +10,7 @@ export interface PowerMeterHttpPhaseConfig {
     json_path: string;
     timeout: number;
     unit: number;
+    sign_inverted: boolean;
 }
 
 export interface PowerMeterConfig {

webapp/src/views/PowerMeterAdminView.vue

@@ -202,6 +202,12 @@
                                 </div>
                             </div>
 
+                            <InputElement
+                                :label="$t('powermeteradmin.httpSignInverted')"
+                                v-model="http_phase.sign_inverted"
+                                :tooltip="$t('powermeteradmin.httpSignInvertedHint')"
+                                type="checkbox" />
+
                             <div class="text-center mb-3">
                                 <button type="button" class="btn btn-danger" @click="testHttpRequest(index)">
                                     {{ $t('powermeteradmin.testHttpRequest') }}