Enable measurement value conversion when unit changes

android_app/app/src/main/java/com/health/openscale/core/data/Enums.kt

@@ -178,8 +178,11 @@ enum class MeasurementTypeKey(
 
 enum class UnitType(val displayName: String) {
     KG("kg"),
+    LB("lb"),
+    ST("st"),
     PERCENT("%"),
     CM("cm"),
+    INCH("in"),
     KCAL("kcal"),
     NONE("")
 }

android_app/app/src/main/java/com/health/openscale/core/database/DatabaseRepository.kt

@@ -179,6 +179,9 @@ class DatabaseRepository(
     fun getValuesForMeasurement(measurementId: Int): Flow<List<MeasurementValue>> =
         measurementValueDao.getValuesForMeasurement(measurementId)
 
+    fun getValuesForType(typeId: Int): Flow<List<MeasurementValue>> =
+        measurementValueDao.getValuesForType(typeId)
+
     // --- Measurement Type Operations ---
 
     fun getAllMeasurementTypes(): Flow<List<MeasurementType>> = measurementTypeDao.getAll()

android_app/app/src/main/java/com/health/openscale/core/database/MeasurementValueDao.kt

@@ -40,4 +40,7 @@ interface MeasurementValueDao {
 
     @Query("SELECT * FROM MeasurementValue WHERE measurementId = :measurementId")
     fun getValuesForMeasurement(measurementId: Int): Flow<List<MeasurementValue>>
+
+    @Query("SELECT * FROM MeasurementValue WHERE typeId = :typeId")
+    fun getValuesForType(typeId: Int): Flow<List<MeasurementValue>>
 }

android_app/app/src/main/java/com/health/openscale/core/utils/Converters.kt

@@ -18,6 +18,7 @@
 package com.health.openscale.core.utils
 
 import com.health.openscale.core.data.MeasureUnit
+import com.health.openscale.core.data.UnitType
 import com.health.openscale.core.data.WeightUnit
 
 
@@ -174,4 +175,64 @@ object Converters {
         toInt32Be(data, 0, value)
         return data
     }
+
+    /**
+     * Converts a Float value from one UnitType to another, if a conversion is defined.
+     * Returns the original value if no conversion is applicable or units are the same.
+     *
+     * @param value The float value to convert.
+     * @param fromUnit The original UnitType of the value.
+     * @param toUnit The target UnitType for the value.
+     * @return The converted float value, or the original value if no conversion is done.
+     */
+    @JvmStatic
+    fun convertFloatValueUnit(value: Float, fromUnit: UnitType, toUnit: UnitType): Float {
+        if (fromUnit == toUnit) return value
+
+        // KG -> Andere Gewichtseinheiten
+        if (fromUnit == UnitType.KG) {
+            return when (toUnit) {
+                UnitType.LB -> fromKilogram(value, WeightUnit.LB)
+                UnitType.ST -> fromKilogram(value, WeightUnit.ST)
+                else -> value // Keine Umrechnung zu anderen Typen von KG aus
+            }
+        }
+        // LB -> Andere Gewichtseinheiten (erst zu KG, dann zum Ziel)
+        if (fromUnit == UnitType.LB) {
+            val kgValue = toKilogram(value, WeightUnit.LB)
+            return when (toUnit) {
+                UnitType.KG -> kgValue
+                UnitType.ST -> fromKilogram(kgValue, WeightUnit.ST)
+                else -> value
+            }
+        }
+        // ST -> Andere Gewichtseinheiten (erst zu KG, dann zum Ziel)
+        if (fromUnit == UnitType.ST) {
+            val kgValue = toKilogram(value, WeightUnit.ST)
+            return when (toUnit) {
+                UnitType.KG -> kgValue
+                UnitType.LB -> fromKilogram(kgValue, WeightUnit.LB)
+                else -> value
+            }
+        }
+
+        // CM -> Andere Längeneinheiten
+        if (fromUnit == UnitType.CM) {
+            return when (toUnit) {
+                UnitType.INCH -> fromCentimeter(value, MeasureUnit.INCH)
+                else -> value
+            }
+        }
+
+        if (fromUnit == UnitType.INCH) {
+            val cmValue = toCentimeter(value, MeasureUnit.INCH)
+            return when (toUnit) {
+                UnitType.CM -> cmValue
+                else -> value
+            }
+        }
+
+        return value
+    }
+
 }

android_app/app/src/main/java/com/health/openscale/ui/screen/settings/MeasurementTypeDetailScreen.kt

@@ -35,6 +35,7 @@ import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.QuestionMark
 import androidx.compose.material.icons.filled.Save
+import androidx.compose.material3.AlertDialog
 import androidx.compose.material3.DropdownMenuItem
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.ExposedDropdownMenuBox
@@ -48,6 +49,7 @@ import androidx.compose.material3.OutlinedTextFieldDefaults
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Switch
 import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
 import androidx.compose.material3.TextFieldDefaults
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
@@ -76,6 +78,7 @@ import com.health.openscale.ui.screen.SharedViewModel
 import com.health.openscale.ui.screen.dialog.ColorPickerDialog
 import com.health.openscale.ui.screen.dialog.IconPickerDialog
 import com.health.openscale.ui.screen.dialog.getIconResIdByName
+import kotlin.text.lowercase
 
 /**
  * Composable screen for creating or editing a [MeasurementType].
@@ -117,6 +120,9 @@ fun MeasurementTypeDetailScreen(
     var showColorPicker by remember { mutableStateOf(false) }
     var showIconPicker by remember { mutableStateOf(false) }
 
+    var showConfirmDialog by remember { mutableStateOf(false) }
+    var pendingUpdatedType by remember { mutableStateOf<MeasurementType?>(null) }
+
     val titleEdit = stringResource(R.string.measurement_type_detail_title_edit)
     val titleAdd = stringResource(R.string.measurement_type_detail_title_add)
 
@@ -144,11 +150,20 @@ fun MeasurementTypeDetailScreen(
                     )
 
                     if (isEdit) {
-                        settingsViewModel.updateMeasurementType(updatedType)
+                        val unitChanged = existingType!!.unit != updatedType.unit
+                        val inputTypesAreFloat = existingType!!.inputType == InputFieldType.FLOAT && updatedType.inputType == InputFieldType.FLOAT
+
+                        if (unitChanged && inputTypesAreFloat) {
+                            pendingUpdatedType = updatedType
+                            showConfirmDialog = true
+                        } else {
+                            settingsViewModel.updateMeasurementType(updatedType)
+                            navController.popBackStack()
+                        }
                     } else {
                         settingsViewModel.addMeasurementType(updatedType)
+                        navController.popBackStack()
                     }
-                    navController.popBackStack()
                 } else {
                     Toast.makeText(context, R.string.toast_enter_valid_data, Toast.LENGTH_SHORT).show()
                 }
@@ -156,6 +171,40 @@ fun MeasurementTypeDetailScreen(
         )
     }
 
+    if (showConfirmDialog && existingType != null && pendingUpdatedType != null) {
+        AlertDialog(
+            onDismissRequest = { showConfirmDialog = false },
+            title = { Text(stringResource(R.string.measurement_type_dialog_confirm_unit_change_title)) },
+            text = {
+                Text(
+                    stringResource(
+                        R.string.measurement_type_dialog_confirm_unit_change_message,
+                        existingType!!.getDisplayName(context),
+                        existingType!!.unit.name.lowercase().replaceFirstChar { it.uppercase() },
+                        pendingUpdatedType!!.unit.name.lowercase().replaceFirstChar { it.uppercase() }
+                    )
+                )
+            },
+            confirmButton = {
+                TextButton(onClick = {
+                    settingsViewModel.updateMeasurementTypeAndConvertDataViewModelCentric(
+                        originalType = existingType!!,
+                        updatedType = pendingUpdatedType!!
+                    )
+                    showConfirmDialog = false
+                    navController.popBackStack()
+                }) {
+                    Text(stringResource(R.string.confirm_button))
+                }
+            },
+            dismissButton = {
+                TextButton(onClick = { showConfirmDialog = false }) {
+                    Text(stringResource(R.string.cancel_button))
+                }
+            }
+        )
+    }
+
     Column(
         modifier = Modifier
             .padding(16.dp)

android_app/app/src/main/java/com/health/openscale/ui/screen/settings/SettingsViewModel.kt

@@ -19,6 +19,7 @@ package com.health.openscale.ui.screen.settings
 
 import android.content.ContentResolver
 import android.net.Uri
+import androidx.compose.material3.SnackbarDuration
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import com.github.doyaaaaaken.kotlincsv.dsl.csvReader
@@ -31,6 +32,7 @@ import com.health.openscale.core.data.MeasurementTypeKey
 import com.health.openscale.core.data.MeasurementValue
 import com.health.openscale.core.data.User
 import com.health.openscale.core.model.MeasurementWithValues
+import com.health.openscale.core.utils.Converters
 import com.health.openscale.core.utils.LogManager
 import com.health.openscale.ui.screen.SharedViewModel
 import kotlinx.coroutines.Dispatchers
@@ -1141,6 +1143,148 @@ class SettingsViewModel(
         }
     }
 
+    /**
+     * Updates an existing measurement type in the database.
+     * If the unit has changed for a FLOAT type, it will also convert associated measurement values.
+     * This version performs operations sequentially without a single overarching repository transaction
+     * and relies on the ViewModel for orchestration.
+     *
+     * @param originalType The MeasurementType as it was BEFORE any edits in the UI.
+     *                     Crucially contains the original unit and ID.
+     * @param updatedType  The MeasurementType object with potentially updated information from the UI
+     *                     (new name, new unit, new color, etc.).
+     * @param showSnackbarMaster Boolean to control if a snackbar is shown after the entire operation.
+     *                           Individual snackbars for errors might still appear.
+     */
+    fun updateMeasurementTypeAndConvertDataViewModelCentric(
+        originalType: MeasurementType,
+        updatedType: MeasurementType,
+        showSnackbarMaster: Boolean = true
+    ) {
+        viewModelScope.launch {
+            LogManager.i(
+                TAG,
+                "ViewModelCentric Update: Type ID ${originalType.id}. Original Unit: ${originalType.unit}, New Unit: ${updatedType.unit}"
+            )
+
+            var conversionErrorOccurred = false
+            var valuesConvertedCount = 0
+
+            if (originalType.unit != updatedType.unit && originalType.inputType == InputFieldType.FLOAT && updatedType.inputType == InputFieldType.FLOAT) {
+                LogManager.i(
+                    TAG,
+                    "Unit changed for FLOAT type ID ${originalType.id} from ${originalType.unit} to ${updatedType.unit}. Converting values."
+                )
+
+                try {
+                    val valuesToConvert = repository.getValuesForType(originalType.id).first() // .first() um den aktuellen Wert des Flows zu erhalten
+
+                    if (valuesToConvert.isNotEmpty()) {
+                        LogManager.d(TAG, "Found ${valuesToConvert.size} values of type ID ${originalType.id} to potentially convert.")
+                        val updatedValuesBatch = mutableListOf<MeasurementValue>()
+
+                        valuesToConvert.forEach { valueToConvert ->
+                            valueToConvert.floatValue?.let { currentFloatVal ->
+                                val convertedFloat = Converters.convertFloatValueUnit(
+                                    value = currentFloatVal,
+                                    fromUnit = originalType.unit,
+                                    toUnit = updatedType.unit
+                                )
+
+                                if (convertedFloat != currentFloatVal) {
+                                    updatedValuesBatch.add(valueToConvert.copy(floatValue = convertedFloat))
+                                    valuesConvertedCount++
+                                }
+                            }
+                        }
+
+                        if (updatedValuesBatch.isNotEmpty()) {
+                            LogManager.d(TAG, "Updating ${updatedValuesBatch.size} values in batch for type ID ${originalType.id}.")
+                            // Aktualisiere jeden Wert einzeln. Dein Repository.updateMeasurementValue
+                            // stößt die Neuberechnung der abgeleiteten Werte an.
+                            updatedValuesBatch.forEach { repository.updateMeasurementValue(it) }
+                            LogManager.d(TAG, "Batch update of ${updatedValuesBatch.size} values completed for type ID ${originalType.id}.")
+                        } else {
+                            LogManager.i(TAG, "No values required actual conversion or update for type ID ${originalType.id} after checking.")
+                        }
+                    } else {
+                        LogManager.i(TAG, "No values found for type ID ${originalType.id} to convert.")
+                    }
+                } catch (e: Exception) {
+                    LogManager.e(TAG, "Error during value conversion/update for type ID ${originalType.id}", e)
+                    conversionErrorOccurred = true
+                    //  Verwende hier getDisplayName vom originalType, da updatedType möglicherweise noch nicht committet wurde.
+                    sharedViewModel.showSnackbar(
+                        messageResId = R.string.measurement_type_update_error_conversion_failed,
+                        formatArgs = listOf(originalType.name ?: originalType.key.toString())
+                    )
+                }
+            } else if (originalType.unit != updatedType.unit) {
+                LogManager.i(
+                    TAG,
+                    "Unit changed for type ID ${originalType.id}, but InputType is not FLOAT (Original: ${originalType.inputType}, Updated: ${updatedType.inputType}). No value conversion performed."
+                )
+            }
+
+            if (!conversionErrorOccurred) {
+                try {
+                    val finalTypeToUpdate = MeasurementType(
+                        id = originalType.id,
+                        key = originalType.key,
+                        name = updatedType.name,
+                        color = updatedType.color,
+                        icon = updatedType.icon,
+                        unit = updatedType.unit,
+                        inputType = updatedType.inputType,
+                        displayOrder = originalType.displayOrder,
+                        isDerived = originalType.isDerived,
+                        isEnabled = updatedType.isEnabled,
+                        isPinned = updatedType.isPinned,
+                        isOnRightYAxis = updatedType.isOnRightYAxis
+                    )
+
+                    repository.updateMeasurementType(finalTypeToUpdate)
+                    LogManager.i(
+                        TAG,
+                        "MeasurementType (ID: ${originalType.id}) updated successfully to new unit '${finalTypeToUpdate.unit}'."
+                    )
+
+                    if (showSnackbarMaster) {
+                        if (valuesConvertedCount > 0) {
+                            sharedViewModel.showSnackbar(
+                                messageResId =  R.string.measurement_type_updated_and_values_converted_successfully,
+                                formatArgs = listOf(updatedType.name ?: updatedType.key.toString(), valuesConvertedCount.toString()) // Context für getDisplayName wäre besser
+                            )
+                        } else if (originalType.unit != updatedType.unit && originalType.inputType == InputFieldType.FLOAT) {
+                            sharedViewModel.showSnackbar(
+                                messageResId = R.string.measurement_type_updated_unit_changed_no_values_converted,
+                                formatArgs = listOf(updatedType.name ?: updatedType.key.toString()) // Context für getDisplayName wäre besser
+                            )
+                        }
+                        else {
+                            sharedViewModel.showSnackbar(
+                                messageResId = R.string.measurement_type_updated_successfully,
+                                formatArgs = listOf(updatedType.name ?: updatedType.key.toString()) // Context für getDisplayName wäre besser
+                            )
+                        }
+                    }
+                    // sharedViewModel.refreshMeasurementTypes() // Optional, wenn die Liste sich nicht automatisch aktualisiert
+                } catch (e: Exception) {
+                    LogManager.e(TAG, "Error updating MeasurementType (ID: ${originalType.id}) itself", e)
+                    sharedViewModel.showSnackbar(
+                        messageResId = R.string.measurement_type_updated_error,
+                        formatArgs = listOf(originalType.name ?: originalType.key.toString()) // Context für getDisplayName wäre besser
+                    )
+                }
+            } else {
+                LogManager.w(
+                    TAG,
+                    "Skipped updating MeasurementType definition (ID: ${originalType.id}) due to prior value conversion error."
+                )
+            }
+        }
+    }
+
     /**
      * Updates an existing measurement type in the database.
      * This operation is performed in a background coroutine.

android_app/app/src/main/res/values-de/strings.xml

@@ -152,6 +152,11 @@
     <string name="measurement_type_deleted_error">Fehler beim Löschen der Messart \'%1$s\'.</string>
     <string name="measurement_type_updated_successfully">Messart \'%1$s\' erfolgreich aktualisiert.</string>
     <string name="measurement_type_updated_error">Fehler beim Aktualisieren der Messart \'%1$s\'.</string>
+    <string name="measurement_type_updated_and_values_converted_successfully">Typ \'%1$s\' aktualisiert und %2$s Wert(e) erfolgreich konvertiert.</string>
+    <string name="measurement_type_update_error_conversion_failed">Fehler beim Konvertieren der Werte für Typ \'%1$s\'. Die Typdefinition wurde nicht aktualisiert.</string>
+    <string name="measurement_type_updated_unit_changed_no_values_converted">Typ \'%1$s\' aktualisiert. Einheit geändert, aber es mussten keine vorhandenen Werte konvertiert werden.</string>
+    <string name="measurement_type_dialog_confirm_unit_change_title">Einheitenänderung bestätigen</string>
+    <string name="measurement_type_dialog_confirm_unit_change_message">Wenn Sie die Einheit für \'%1$s\' von %2$s auf %3$s ändern, werden alle vorhandenen Datenpunkte konvertiert. Dieser Vorgang kann einige Zeit dauern und kann nicht einfach rückgängig gemacht werden. Möchten Sie fortfahren?</string>
 
     <!-- Bluetooth -->
     <string name="info_bluetooth_connection_error_scale_offline">Verbindung zur Waage fehlgeschlagen, bitte stellen Sie sicher, dass sie eingeschaltet ist.</string>

android_app/app/src/main/res/values/strings.xml

@@ -151,8 +151,13 @@
     <string name="measurement_type_added_error">Error adding measurement type \'%1$s\'.</string>
     <string name="measurement_type_deleted_successfully">Measurement type \'%1$s\' deleted successfully.</string>
     <string name="measurement_type_deleted_error">Error deleting measurement type \'%1$s\'.</string>
-    <string name="measurement_type_updated_successfully">Measurement type \'%1$s\' updated successfully.</string>
     <string name="measurement_type_updated_error">Error updating measurement type \'%1$s\'.</string>
+    <string name="measurement_type_updated_successfully">Measurement type \'%1$s\' updated successfully.</string>
+    <string name="measurement_type_updated_and_values_converted_successfully">Type \'%1$s\' updated and %2$s value(s) converted successfully.</string>
+    <string name="measurement_type_update_error_conversion_failed">Error converting values for type \'%1$s\'. The type definition was not updated.</string>
+    <string name="measurement_type_updated_unit_changed_no_values_converted">Type \'%1$s\' updated. Unit changed, but no existing values required conversion.</string>
+    <string name="measurement_type_dialog_confirm_unit_change_title">Confirm Unit Change</string>
+    <string name="measurement_type_dialog_confirm_unit_change_message">Changing the unit for \'%1$s\' from %2$s to %3$s will convert all existing data points. This action may take some time and cannot be easily undone. Do you want to proceed?</string>
 
     <!-- Bluetooth -->
     <string name="info_bluetooth_connection_error_scale_offline">Could not connect to scale, please ensure it is on.</string>