implement portion/carbs mesurement calculation, add buttons for glucose conversion

lib/models/meal.dart

@@ -1,5 +1,7 @@
 import 'package:parse_server_sdk_flutter/parse_server_sdk.dart';
 
+enum PortionCarbsParameter { carbsRatio, portionSize, carbsPerPortion }
+
 class Meal {
   late String? objectId;
   late String value;

lib/screens/bolus/bolus_detail.dart

@@ -135,6 +135,34 @@ class _BolusDetailScreenState extends State<BolusDetailScreen> {
     }
   }
 
+  void convertBetweenMgPerDlAndMmolPerL({GlucoseMeasurement? calculateFrom}) {
+    // TODO figure out why this isnt happening automatically
+    int? mgPerDl;
+    double? mmolPerL;
+
+    if (calculateFrom != GlucoseMeasurement.mmolPerL &&
+        _mgPerDlController.text != '') {
+      mgPerDl = int.tryParse(_mgPerDlController.text);
+    }
+    if (calculateFrom != GlucoseMeasurement.mgPerDl &&
+        _mmolPerLController.text != '') {
+      mmolPerL = double.tryParse(_mmolPerLController.text);
+    }
+
+    if (mgPerDl != null && mmolPerL == null) {
+      setState(() {
+        _mmolPerLController.text =
+            Utils.convertMgPerDlToMmolPerL(mgPerDl!).toString();
+      });
+    }
+    if (mmolPerL != null && mgPerDl == null) {
+      setState(() {
+        _mgPerDlController.text =
+            Utils.convertMmolPerLToMgPerDl(mmolPerL!).toString();
+      });
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     bool isNew = widget.bolus == null;
@@ -221,7 +249,6 @@ class _BolusDetailScreenState extends State<BolusDetailScreen> {
                   },
                 ),
                 Row(
-                  // TODO: improve conversion of mg/dl and mmol/l
                   children: [
                     glucoseMeasurement == GlucoseMeasurement.mgPerDl ||
                             glucoseDisplayMode == GlucoseDisplayMode.both ||
@@ -234,16 +261,8 @@ class _BolusDetailScreenState extends State<BolusDetailScreen> {
                                 suffixText: 'mg/dl',
                               ),
                               controller: _mgPerDlController,
-                              onChanged: (_) {
+                              onChanged: (_) =>
-                                setState(() {
+                                  convertBetweenMgPerDlAndMmolPerL,
-                                  _mmolPerLController
-                                      .text = Utils.convertMgPerDlToMmolPerL(
-                                          int.tryParse(
-                                                  _mmolPerLController.text) ??
-                                              0)
-                                      .toString();
-                                });
-                              },
                               keyboardType:
                                   const TextInputType.numberWithOptions(),
                               validator: (value) {
@@ -256,6 +275,15 @@ class _BolusDetailScreenState extends State<BolusDetailScreen> {
                             ),
                           )
                         : Container(),
+                    glucoseDisplayMode == GlucoseDisplayMode.both ||
+                            glucoseDisplayMode ==
+                                GlucoseDisplayMode.bothForDetail
+                        ? IconButton(
+                            onPressed: () => convertBetweenMgPerDlAndMmolPerL(
+                                calculateFrom: GlucoseMeasurement.mmolPerL),
+                            icon: const Icon(Icons.calculate),
+                          )
+                        : Container(),
                     glucoseMeasurement == GlucoseMeasurement.mmolPerL ||
                             glucoseDisplayMode == GlucoseDisplayMode.both ||
                             glucoseDisplayMode ==
@@ -267,16 +295,8 @@ class _BolusDetailScreenState extends State<BolusDetailScreen> {
                                 suffixText: 'mmol/l',
                               ),
                               controller: _mmolPerLController,
-                              onChanged: (_) {
+                              onChanged: (_) =>
-                                setState(() {
+                                  convertBetweenMgPerDlAndMmolPerL,
-                                  _mgPerDlController
-                                      .text = Utils.convertMmolPerLToMgPerDl(
-                                          double.tryParse(
-                                                  _mgPerDlController.text) ??
-                                              0)
-                                      .toString();
-                                });
-                              },
                               keyboardType:
                                   const TextInputType.numberWithOptions(
                                       decimal: true),
@@ -290,6 +310,15 @@ class _BolusDetailScreenState extends State<BolusDetailScreen> {
                             ),
                           )
                         : Container(),
+                    glucoseDisplayMode == GlucoseDisplayMode.both ||
+                            glucoseDisplayMode ==
+                                GlucoseDisplayMode.bothForDetail
+                        ? IconButton(
+                            onPressed: () => convertBetweenMgPerDlAndMmolPerL(
+                                calculateFrom: GlucoseMeasurement.mgPerDl),
+                            icon: const Icon(Icons.calculate),
+                          )
+                        : Container(),
                   ],
                 ),
               ],

lib/screens/log/log_meal_detail.dart

@@ -11,6 +11,7 @@ import 'package:diameter/models/meal_portion_type.dart';
 import 'package:diameter/models/meal_source.dart';
 import 'package:diameter/navigation.dart';
 import 'package:diameter/settings.dart';
+import 'package:diameter/utils/utils.dart';
 import 'package:flutter/material.dart';
 
 class LogMealDetailScreen extends StatefulWidget {
@@ -83,6 +84,49 @@ class _LogMealDetailScreenState extends State<LogMealDetailScreen> {
     _carbsRatioAccuracies = Accuracy.fetchAllForCarbsRatio();
   }
 
+  Future<void> onSelectMeal(String? objectId) async {
+    if (objectId != null) {
+      Meal? meal = await Meal.get(objectId);
+      if (meal != null) {
+        setState(() {
+          _meal = objectId;
+          _valueController.text = meal.value;
+          if (meal.carbsRatio != null) {
+            _carbsRatioController.text = meal.carbsRatio.toString();
+          }
+          if (meal.portionSize != null) {
+            _portionSizeController.text = meal.portionSize.toString();
+          }
+          if (meal.carbsPerPortion != null) {
+            _carbsPerPortionController.text = meal.carbsPerPortion.toString();
+          }
+          if (meal.delayedBolusRate != null) {
+            _delayedBolusRateController.text = meal.delayedBolusRate.toString();
+          }
+          if (meal.delayedBolusDuration != null) {
+            _delayedBolusDurationController.text =
+                meal.delayedBolusDuration.toString();
+          }
+          if (meal.source != null) {
+            _source = meal.source;
+          }
+          if (meal.category != null) {
+            _category = meal.category;
+          }
+          if (meal.portionType != null) {
+            _portionType = meal.portionType;
+          }
+          if (meal.portionSizeAccuracy != null) {
+            _portionSizeAccuracy = meal.portionSizeAccuracy;
+          }
+          if (meal.carbsRatioAccuracy != null) {
+            _carbsRatioAccuracy = meal.carbsRatioAccuracy;
+          }
+        });
+      }
+    }
+  }
+
   void handleSaveAction() async {
     if (_logMealForm.currentState!.validate()) {
       bool isNew = widget.logMeal == null;
@@ -175,6 +219,48 @@ class _LogMealDetailScreenState extends State<LogMealDetailScreen> {
     }
   }
 
+  void calculateThirdMeasurementOfPortionCarbsRelation(
+      {PortionCarbsParameter? parameterToBeCalculated}) {
+    double? carbsRatio;
+    double? portionSize;
+    double? carbsPerPortion;
+
+    if (parameterToBeCalculated != PortionCarbsParameter.carbsRatio &&
+        _carbsRatioController.text != '') {
+      carbsRatio = double.tryParse(_carbsRatioController.text);
+    }
+    if (parameterToBeCalculated != PortionCarbsParameter.portionSize &&
+        _portionSizeController.text != '') {
+      portionSize = double.tryParse(_portionSizeController.text);
+    }
+    if (parameterToBeCalculated != PortionCarbsParameter.carbsPerPortion &&
+        _carbsRatioController.text != '') {
+      carbsPerPortion = double.tryParse(_carbsPerPortionController.text);
+    }
+
+    if (carbsRatio != null && portionSize != null && carbsPerPortion == null) {
+      setState(() {
+        _carbsPerPortionController.text =
+            Utils.calculateCarbsPerPortion(carbsRatio!, portionSize!)
+                .toString();
+      });
+    }
+    if (carbsRatio == null && portionSize != null && carbsPerPortion != null) {
+      setState(() {
+        _carbsRatioController.text =
+            Utils.calculateCarbsRatio(carbsPerPortion!, portionSize!)
+                .toString();
+      });
+    }
+    if (carbsRatio != null && portionSize == null && carbsPerPortion != null) {
+      setState(() {
+        _portionSizeController.text =
+            Utils.calculatePortionSize(carbsRatio!, carbsPerPortion!)
+                .toString();
+      });
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     bool isNew = widget.logMeal == null;
@@ -190,7 +276,6 @@ class _LogMealDetailScreenState extends State<LogMealDetailScreen> {
             StyledForm(
               formState: _logMealForm,
               fields: [
-                // TODO: autofill all associated fields on selecting a meal
                 TextFormField(
                   controller: _valueController,
                   decoration: const InputDecoration(
@@ -210,9 +295,7 @@ class _LogMealDetailScreenState extends State<LogMealDetailScreen> {
                   getItemValue: (item) => item.objectId,
                   renderItem: (item) => Text(item.value),
                   onChanged: (value) {
-                    setState(() {
+                    onSelectMeal(value);
-                      _meal = value;
-                    });
                   },
                 ),
                 StyledFutureDropdownButton<MealSource>(
@@ -251,43 +334,103 @@ class _LogMealDetailScreenState extends State<LogMealDetailScreen> {
                     });
                   },
                 ),
-                // TODO: if 2 out of the 3 following fields are given, calc 3rd
+                Row(
-                TextFormField(
+                  children: [
+                    Expanded(
+                      child: TextFormField(
                         decoration: const InputDecoration(
                           labelText: 'Carbs ratio',
                           suffixText: '%',
                         ),
                         controller: _carbsRatioController,
-                  keyboardType:
+                        keyboardType: const TextInputType.numberWithOptions(
-                      const TextInputType.numberWithOptions(decimal: true),
+                            decimal: true),
+                        onChanged: (_) =>
+                            calculateThirdMeasurementOfPortionCarbsRelation(),
                       ),
-                TextFormField(
+                    ),
+                    IconButton(
+                      onPressed: () =>
+                          calculateThirdMeasurementOfPortionCarbsRelation(
+                              parameterToBeCalculated:
+                                  PortionCarbsParameter.carbsRatio),
+                      icon: const Icon(Icons.calculate),
+                    ),
+                  ],
+                ),
+                Row(
+                  mainAxisSize: MainAxisSize.min,
+                  children: [
+                    Expanded(
+                      child: TextFormField(
                         decoration: InputDecoration(
                           labelText: 'Portion size',
-                    suffixText: nutritionMeasurement ==
+                          suffixText:
-                            NutritionMeasurement.grams
+                              nutritionMeasurement == NutritionMeasurement.grams
                                   ? 'g'
-                        : nutritionMeasurement == NutritionMeasurement.ounces
+                                  : nutritionMeasurement ==
+                                          NutritionMeasurement.ounces
                                       ? 'oz'
                                       : '',
+                          alignLabelWithHint: true,
                         ),
                         controller: _portionSizeController,
-                  keyboardType:
+                        keyboardType: const TextInputType.numberWithOptions(
-                      const TextInputType.numberWithOptions(decimal: true),
+                            decimal: true),
+                        onChanged: (_) =>
+                            calculateThirdMeasurementOfPortionCarbsRelation(),
                       ),
-                TextFormField(
+                    ),
+                    IconButton(
+                      onPressed: () =>
+                          calculateThirdMeasurementOfPortionCarbsRelation(
+                              parameterToBeCalculated:
+                                  PortionCarbsParameter.portionSize),
+                      icon: const Icon(Icons.calculate),
+                    ),
+                  ],
+                ),
+                StyledFutureDropdownButton<Accuracy>(
+                  selectedItem: _portionSizeAccuracy,
+                  label: 'Portion Size Accuracy',
+                  items: _portionSizeAccuracies,
+                  getItemValue: (item) => item.objectId,
+                  renderItem: (item) => Text(item.value),
+                  onChanged: (value) {
+                    setState(() {
+                      _portionSizeAccuracy = value;
+                    });
+                  },
+                ),
+                Row(
+                  children: [
+                    Expanded(
+                      child: TextFormField(
                         decoration: InputDecoration(
                           labelText: 'Carbs per portion',
-                    suffixText: nutritionMeasurement ==
+                          suffixText:
-                            NutritionMeasurement.grams
+                              nutritionMeasurement == NutritionMeasurement.grams
                                   ? 'g'
-                        : nutritionMeasurement == NutritionMeasurement.ounces
+                                  : nutritionMeasurement ==
+                                          NutritionMeasurement.ounces
                                       ? 'oz'
                                       : '',
                         ),
                         controller: _carbsPerPortionController,
-                  keyboardType:
+                        keyboardType: const TextInputType.numberWithOptions(
-                      const TextInputType.numberWithOptions(decimal: true),
+                            decimal: true),
+                        onChanged: (_) =>
+                            calculateThirdMeasurementOfPortionCarbsRelation(),
+                      ),
+                    ),
+                    IconButton(
+                      onPressed: () =>
+                          calculateThirdMeasurementOfPortionCarbsRelation(
+                              parameterToBeCalculated:
+                                  PortionCarbsParameter.carbsPerPortion),
+                      icon: const Icon(Icons.calculate),
+                    ),
+                  ],
                 ),
                 StyledFutureDropdownButton<Accuracy>(
                   selectedItem: _carbsRatioAccuracy,
@@ -328,19 +471,6 @@ class _LogMealDetailScreenState extends State<LogMealDetailScreen> {
                   keyboardType:
                       const TextInputType.numberWithOptions(decimal: true),
                 ),
-                // TODO: autofill the following fields on selecting a source
-                StyledFutureDropdownButton<Accuracy>(
-                  selectedItem: _portionSizeAccuracy,
-                  label: 'Portion Size Accuracy',
-                  items: _portionSizeAccuracies,
-                  getItemValue: (item) => item.objectId,
-                  renderItem: (item) => Text(item.value),
-                  onChanged: (value) {
-                    setState(() {
-                      _portionSizeAccuracy = value;
-                    });
-                  },
-                ),
                 TextFormField(
                   controller: _notesController,
                   decoration: const InputDecoration(

lib/screens/meal/meal_detail.dart

@@ -9,6 +9,7 @@ import 'package:diameter/models/meal_portion_type.dart';
 import 'package:diameter/models/meal_source.dart';
 import 'package:diameter/navigation.dart';
 import 'package:diameter/settings.dart';
+import 'package:diameter/utils/utils.dart';
 import 'package:flutter/material.dart';
 
 class MealDetailScreen extends StatefulWidget {
@@ -23,13 +24,13 @@ class MealDetailScreen extends StatefulWidget {
 
 class _MealDetailScreenState extends State<MealDetailScreen> {
   final GlobalKey<FormState> _mealForm = GlobalKey<FormState>();
-  final _valueController = TextEditingController();
+  final _valueController = TextEditingController(text: '');
-  final _carbsRatioController = TextEditingController();
+  final _carbsRatioController = TextEditingController(text: '');
-  final _portionSizeController = TextEditingController();
+  final _portionSizeController = TextEditingController(text: '');
-  final _carbsPerPortionController = TextEditingController();
+  final _carbsPerPortionController = TextEditingController(text: '');
-  final _delayedBolusRateController = TextEditingController();
+  final _delayedBolusRateController = TextEditingController(text: '');
-  final _delayedBolusDurationController = TextEditingController();
+  final _delayedBolusDurationController = TextEditingController(text: '');
-  final _notesController = TextEditingController();
+  final _notesController = TextEditingController(text: '');
   String? _source;
   String? _category;
   String? _portionType;
@@ -158,6 +159,73 @@ class _MealDetailScreenState extends State<MealDetailScreen> {
     }
   }
 
+  Future<void> onSelectMealSource(String? objectId) async {
+    if (objectId != null) {
+      MealSource? mealSource = await MealSource.get(objectId);
+      if (mealSource != null) {
+        setState(() {
+          _source = objectId;
+          if (mealSource.defaultCarbsRatioAccuracy != null) {
+            _carbsRatioAccuracy =
+                mealSource.defaultCarbsRatioAccuracy.toString();
+          }
+          if (mealSource.defaultPortionSizeAccuracy != null) {
+            _portionSizeAccuracy =
+                mealSource.defaultPortionSizeAccuracy.toString();
+          }
+          if (mealSource.defaultMealCategory != null) {
+            _category = mealSource.defaultMealCategory.toString();
+          }
+          if (mealSource.defaultMealPortionType != null) {
+            _portionType = mealSource.defaultMealPortionType.toString();
+          }
+        });
+      }
+    }
+  }
+
+  void calculateThirdMeasurementOfPortionCarbsRelation(
+      {PortionCarbsParameter? parameterToBeCalculated}) {
+    double? carbsRatio;
+    double? portionSize;
+    double? carbsPerPortion;
+
+    if (parameterToBeCalculated != PortionCarbsParameter.carbsRatio &&
+        _carbsRatioController.text != '') {
+      carbsRatio = double.tryParse(_carbsRatioController.text);
+    }
+    if (parameterToBeCalculated != PortionCarbsParameter.portionSize &&
+        _portionSizeController.text != '') {
+      portionSize = double.tryParse(_portionSizeController.text);
+    }
+    if (parameterToBeCalculated != PortionCarbsParameter.carbsPerPortion &&
+        _carbsRatioController.text != '') {
+      carbsPerPortion = double.tryParse(_carbsPerPortionController.text);
+    }
+
+    if (carbsRatio != null && portionSize != null && carbsPerPortion == null) {
+      setState(() {
+        _carbsPerPortionController.text =
+            Utils.calculateCarbsPerPortion(carbsRatio!, portionSize!)
+                .toString();
+      });
+    }
+    if (carbsRatio == null && portionSize != null && carbsPerPortion != null) {
+      setState(() {
+        _carbsRatioController.text =
+            Utils.calculateCarbsRatio(carbsPerPortion!, portionSize!)
+                .toString();
+      });
+    }
+    if (carbsRatio != null && portionSize == null && carbsPerPortion != null) {
+      setState(() {
+        _portionSizeController.text =
+            Utils.calculatePortionSize(carbsRatio!, carbsPerPortion!)
+                .toString();
+      });
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     bool isNew = widget.meal == null;
@@ -192,12 +260,9 @@ class _MealDetailScreenState extends State<MealDetailScreen> {
                   getItemValue: (item) => item.objectId,
                   renderItem: (item) => Text(item.value),
                   onChanged: (value) {
-                    setState(() {
+                    onSelectMealSource(value);
-                      _source = value;
-                    });
                   },
                 ),
-                // TODO: autofill the following fields on selecting a source
                 StyledFutureDropdownButton<MealCategory>(
                   selectedItem: _category,
                   label: 'Meal Category',
@@ -222,44 +287,103 @@ class _MealDetailScreenState extends State<MealDetailScreen> {
                     });
                   },
                 ),
-                // TODO: if 2 out of the 3 following fields are given, calc 3rd
+                Row(
-                TextFormField(
+                  children: [
+                    Expanded(
+                      child: TextFormField(
                         decoration: const InputDecoration(
                           labelText: 'Carbs ratio',
                           suffixText: '%',
                         ),
                         controller: _carbsRatioController,
-                  keyboardType:
+                        keyboardType: const TextInputType.numberWithOptions(
-                      const TextInputType.numberWithOptions(decimal: true),
+                            decimal: true),
+                        onChanged: (_) =>
+                            calculateThirdMeasurementOfPortionCarbsRelation(),
                       ),
-                TextFormField(
+                    ),
+                    IconButton(
+                      onPressed: () =>
+                          calculateThirdMeasurementOfPortionCarbsRelation(
+                              parameterToBeCalculated:
+                                  PortionCarbsParameter.carbsRatio),
+                      icon: const Icon(Icons.calculate),
+                    ),
+                  ],
+                ),
+                Row(
+                  mainAxisSize: MainAxisSize.min,
+                  children: [
+                    Expanded(
+                      child: TextFormField(
                         decoration: InputDecoration(
                           labelText: 'Portion size',
-                    suffixText: nutritionMeasurement ==
+                          suffixText:
-                            NutritionMeasurement.grams
+                              nutritionMeasurement == NutritionMeasurement.grams
                                   ? 'g'
-                        : nutritionMeasurement == NutritionMeasurement.ounces
+                                  : nutritionMeasurement ==
+                                          NutritionMeasurement.ounces
                                       ? 'oz'
                                       : '',
                           alignLabelWithHint: true,
                         ),
                         controller: _portionSizeController,
-                  keyboardType:
+                        keyboardType: const TextInputType.numberWithOptions(
-                      const TextInputType.numberWithOptions(decimal: true),
+                            decimal: true),
+                        onChanged: (_) =>
+                            calculateThirdMeasurementOfPortionCarbsRelation(),
                       ),
-                TextFormField(
+                    ),
+                    IconButton(
+                      onPressed: () =>
+                          calculateThirdMeasurementOfPortionCarbsRelation(
+                              parameterToBeCalculated:
+                                  PortionCarbsParameter.portionSize),
+                      icon: const Icon(Icons.calculate),
+                    ),
+                  ],
+                ),
+                StyledFutureDropdownButton<Accuracy>(
+                  selectedItem: _portionSizeAccuracy,
+                  label: 'Portion Size Accuracy',
+                  items: _portionSizeAccuracies,
+                  getItemValue: (item) => item.objectId,
+                  renderItem: (item) => Text(item.value),
+                  onChanged: (value) {
+                    setState(() {
+                      _portionSizeAccuracy = value;
+                    });
+                  },
+                ),
+                Row(
+                  children: [
+                    Expanded(
+                      child: TextFormField(
                         decoration: InputDecoration(
                           labelText: 'Carbs per portion',
-                    suffixText: nutritionMeasurement ==
+                          suffixText:
-                            NutritionMeasurement.grams
+                              nutritionMeasurement == NutritionMeasurement.grams
                                   ? 'g'
-                        : nutritionMeasurement == NutritionMeasurement.ounces
+                                  : nutritionMeasurement ==
+                                          NutritionMeasurement.ounces
                                       ? 'oz'
                                       : '',
                         ),
                         controller: _carbsPerPortionController,
-                  keyboardType:
+                        keyboardType: const TextInputType.numberWithOptions(
-                      const TextInputType.numberWithOptions(decimal: true),
+                            decimal: true),
+                        onChanged: (_) =>
+                            calculateThirdMeasurementOfPortionCarbsRelation(),
+                      ),
+                    ),
+                    IconButton(
+                      onPressed: () =>
+                          calculateThirdMeasurementOfPortionCarbsRelation(
+                              parameterToBeCalculated:
+                                  PortionCarbsParameter.carbsPerPortion),
+                      icon: const Icon(Icons.calculate),
+                    ),
+                  ],
                 ),
                 StyledFutureDropdownButton<Accuracy>(
                   selectedItem: _carbsRatioAccuracy,
@@ -291,19 +415,6 @@ class _MealDetailScreenState extends State<MealDetailScreen> {
                   keyboardType:
                       const TextInputType.numberWithOptions(decimal: true),
                 ),
-                // TODO: autofill the following fields on selecting a source
-                StyledFutureDropdownButton<Accuracy>(
-                  selectedItem: _portionSizeAccuracy,
-                  label: 'Portion Size Accuracy',
-                  items: _portionSizeAccuracies,
-                  getItemValue: (item) => item.objectId,
-                  renderItem: (item) => Text(item.value),
-                  onChanged: (value) {
-                    setState(() {
-                      _portionSizeAccuracy = value;
-                    });
-                  },
-                ),
                 TextFormField(
                   controller: _notesController,
                   decoration: const InputDecoration(

lib/utils/utils.dart

@@ -1,9 +1,31 @@
+import 'dart:math';
+
 class Utils {
+  static double roundToDecimalPlaces(double value, int places) {
+    double mod = pow(10.0, places).toDouble();
+    return ((value * mod).round().toDouble() / mod);
+  }
+
   static double convertMgPerDlToMmolPerL(int mgPerDl) {
-    return (mgPerDl / 18.018).roundToDouble();
+    return Utils.roundToDecimalPlaces(mgPerDl * 0.0555, 2);
   }
 
   static int convertMmolPerLToMgPerDl(double mmolPerL) {
     return (mmolPerL * 18.018).round();
   }
+
+  static double calculateCarbsPerPortion(
+      double carbsRatio, double portionSize) {
+    return Utils.roundToDecimalPlaces(carbsRatio * portionSize / 100, 2);
+  }
+
+  static double calculateCarbsRatio(
+      double carbsPerPortion, double portionSize) {
+    return Utils.roundToDecimalPlaces(carbsPerPortion * 100 / portionSize, 2);
+  }
+
+  static double calculatePortionSize(
+      double carbsRatio, double carbsPerPortion) {
+    return Utils.roundToDecimalPlaces(carbsPerPortion * 100 / carbsRatio, 2);
+  }
 }