[fineoffsetweatherstation] Fix false low battery for voltage sensors on HTTP API (#21000)

* [fineoffsetweatherstation] Fix false low battery for voltage sensors on HTTP API

Signed-off-by: Andreas Berger <andreas@berger-freelancer.com>

bundles/org.openhab.binding.fineoffsetweatherstation/src/main/java/org/openhab/binding/fineoffsetweatherstation/internal/domain/Sensor.java

@@ -50,13 +50,26 @@ public enum Sensor {
     WN20(LOW_HIGH),
     WN38(VOLTAGE_FINE_STEPS);
 
-    private final BatteryStatus.Type batteryStatusTpe;
+    private final BatteryStatus.Type batteryStatusType;
 
-    Sensor(BatteryStatus.Type batteryStatusTpe) {
-        this.batteryStatusTpe = batteryStatusTpe;
+    Sensor(BatteryStatus.Type batteryStatusType) {
+        this.batteryStatusType = batteryStatusType;
     }
 
     public BatteryStatus getBatteryStatus(byte data) {
-        return new BatteryStatus(batteryStatusTpe, data);
+        return new BatteryStatus(batteryStatusType, data);
+    }
+
+    /**
+     * Interprets the battery field as reported by the Ecowitt HTTP API. Unlike the binary protocol, the HTTP API
+     * reports the battery of voltage-based sensors already as a 0-5 level (5 = full) rather than a raw voltage, so
+     * those are read as {@link BatteryStatus.Type#LEVEL}; all other sensor types share the binary encoding.
+     */
+    public BatteryStatus getHttpBatteryStatus(byte data) {
+        BatteryStatus.Type type = switch (batteryStatusType) {
+            case VOLTAGE_BROAD_STEPS, VOLTAGE_FINE_STEPS -> LEVEL;
+            default -> batteryStatusType;
+        };
+        return new BatteryStatus(type, data);
     }
 }

bundles/org.openhab.binding.fineoffsetweatherstation/src/main/java/org/openhab/binding/fineoffsetweatherstation/internal/domain/SensorGatewayBinding.java

@@ -138,6 +138,10 @@ public enum SensorGatewayBinding {
         return sensor.getBatteryStatus(data);
     }
 
+    public BatteryStatus getHttpBatteryStatus(byte data) {
+        return sensor.getHttpBatteryStatus(data);
+    }
+
     public Sensor getSensor() {
         return sensor;
     }

bundles/org.openhab.binding.fineoffsetweatherstation/src/main/java/org/openhab/binding/fineoffsetweatherstation/internal/service/EcowittDataParser.java

@@ -191,7 +191,7 @@ public class EcowittDataParser {
         } catch (NumberFormatException e) {
             return;
         }
-        BatteryStatus batteryStatus = sensorGatewayBinding.getBatteryStatus((byte) parseInt(asString(obj, "batt")));
+        BatteryStatus batteryStatus = sensorGatewayBinding.getHttpBatteryStatus((byte) parseInt(asString(obj, "batt")));
         int signal = parseInt(asString(obj, "signal"));
         result.put(sensorGatewayBinding, new SensorDevice(id, sensorGatewayBinding, batteryStatus, signal));
     }

bundles/org.openhab.binding.fineoffsetweatherstation/src/test/java/org/openhab/binding/fineoffsetweatherstation/internal/service/EcowittDataParserTest.java

@@ -130,6 +130,19 @@ class EcowittDataParserTest {
                         new Tuple("WH25", 0xB9, 4, true));
     }
 
+    @Test
+    void testVoltageSensorBatteryReportedAsLevel() {
+        // unlike the binary protocol, where the WH51 battery field is a raw voltage (val * 0.1 V), the Ecowitt HTTP
+        // API reports it already as a 0-5 level (5 = full). It must therefore not be misread as 0.5 V and flagged low.
+        Map<SensorGatewayBinding, SensorDevice> sensors = parser.parseSensors(List.of("[{\"img\":\"wh51\","
+                + "\"type\":\"14\",\"name\":\"Soil moisture CH1\",\"id\":\"FBF08\",\"batt\":\"5\",\"rssi\":\"-85\","
+                + "\"signal\":\"4\",\"idst\":\"1\"}]"), false);
+        Assertions.assertThat(sensors.values())
+                .extracting(device -> device.getSensorGatewayBinding().getSensor().name(),
+                        device -> device.getBatteryStatus().isLow(), device -> device.getBatteryStatus().getLevel())
+                .containsExactly(new Tuple("WH51", false, 5));
+    }
+
     @Test
     void testSystemInfo() {
         @Nullable