Garmin: Improve developer field decoding

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/fit/DevFieldDefinition.java

@@ -13,6 +13,8 @@ public class DevFieldDefinition {
     private final int developerDataIndex;
     private BaseType baseType;
     private String name;
+    private int nativeMesgNum = -1;
+    private int nativeFieldNum = -1;
 
     public DevFieldDefinition(int fieldDefinitionNumber, int size, int developerDataIndex, String name) {
         this.fieldDefinitionNumber = fieldDefinitionNumber;
@@ -59,6 +61,22 @@ public class DevFieldDefinition {
         this.name = name;
     }
 
+    public int getNativeMesgNum() {
+        return nativeMesgNum;
+    }
+
+    public void setNativeMesgNum(final int nativeMesgNum) {
+        this.nativeMesgNum = nativeMesgNum;
+    }
+
+    public int getNativeFieldNum() {
+        return nativeFieldNum;
+    }
+
+    public void setNativeFieldNum(final int nativeFieldNum) {
+        this.nativeFieldNum = nativeFieldNum;
+    }
+
     @Override
     public boolean equals(Object o) {
         if (o == null || getClass() != o.getClass()) return false;

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/fit/RecordData.java

@@ -137,13 +137,39 @@ public class RecordData {
         }
     }
 
-    public Object getFieldByNumber(int number) {
-        for (FieldData fieldData :
-                fieldDataList) {
+    /**
+     * Returns the field that matches the given **native** number, taking into account dev fields. If a dev field exists that
+     * has the same native number as a native field, it has precedence.
+     */
+    public Object getFieldByNumber(final int number) {
+        // Developer fields are all added after regular fields in the constructor
+        final int regularFieldCount = recordDefinition.getFieldDefinitions() != null ?
+                recordDefinition.getFieldDefinitions().size() : 0;
+
+        // First, check whether we have a developer field that maps to the native field. If it exists, it has priority
+        final List<DevFieldDefinition> devFieldDefinitions = recordDefinition.getDevFieldDefinitions();
+        if (devFieldDefinitions != null) {
+            for (int i = 0; i < devFieldDefinitions.size(); i++) {
+                final DevFieldDefinition devField = devFieldDefinitions.get(i);
+
+                if (devField.getNativeMesgNum() == globalFITMessage.getNumber() && devField.getNativeFieldNum() == number) {
+                    // Get the corresponding FieldData for this developer field
+                    final int fieldDataIndex = regularFieldCount + i;
+                    if (fieldDataIndex < fieldDataList.size()) {
+                        return fieldDataList.get(fieldDataIndex).decode();
+                    }
+                }
+            }
+        }
+
+        // Next, check whether there is any native field that matches the number
+        for (int i = 0; i < regularFieldCount; i++) {
+            final FieldData fieldData = fieldDataList.get(i);
             if (fieldData.getNumber() == number) {
                 return fieldData.decode();
             }
         }
+
         return null;
     }
 

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/fit/RecordDefinition.java

@@ -118,6 +118,16 @@ public class RecordDefinition {
                     BaseType baseType = BaseType.fromIdentifier((int) recordData.getFieldByName("fit_base_type_id"));
                     devFieldDef.setBaseType(baseType);
                     devFieldDef.setName((String) recordData.getFieldByName("field_name"));
+
+                    final Object nativeMesgNum = recordData.getFieldByName("native_mesg_num");
+                    final Object nativeFieldNum = recordData.getFieldByName("native_field_num");
+
+                    if (nativeMesgNum instanceof Integer integer) {
+                        devFieldDef.setNativeMesgNum(integer);
+                    }
+                    if (nativeFieldNum instanceof Integer integer) {
+                        devFieldDef.setNativeFieldNum(integer);
+                    }
                 }
             } catch (Exception e) {
                 //ignore

app/src/test/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/GarminSupportTest.java

@@ -512,6 +512,8 @@ public class GarminSupportTest extends TestBase {
 
         FitFile fitFile = FitFile.parseIncoming(fileContents);
         Assert.assertEquals(expectedOutput, fitFile.toString());
+        // Field 0 is not overwritten by the developer field
+        Assert.assertNull(fitFile.getRecords().get(3).getFieldByNumber(0));
         getAllFitFieldValues(fitFile);
     }
 
@@ -615,11 +617,6 @@ public class GarminSupportTest extends TestBase {
                 } catch (Exception e) {
                     String recordName = record.getClass().getSimpleName();
                     String message = methodName + " failed for " + recordName;
-                    if ("FitRecord".equals(recordName) && "getLatitude".equals(methodName)) {
-                        // TODO GarminSupportTest.TestFitFileDevelopersField -> FitRecord / getLatitude
-                        // FIXME java.lang.ClassCastException: class java.lang.Integer cannot be cast to class java.lang.Double
-                        continue;
-                    }
                     throw new AssertionError(message, e);
                 }
             }