workouttest_app/lib/view/exercise_new_page.dart

import 'package:aitrainer_app/localization/app_language.dart';
import 'package:aitrainer_app/localization/app_localization.dart';
import 'package:aitrainer_app/viewmodel/exercise_changing_view_model.dart';
import 'package:flutter/services.dart';
import 'package:intl/intl.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
//import 'package:datetime_picker_formfield/datetime_picker_formfield.dart';

class ExerciseNewPage extends StatefulWidget{
  _ExerciseNewPageState createState() => _ExerciseNewPageState();
}

class _ExerciseNewPageState extends State {
  final List excluded = [43,44];
  final _formKey = GlobalKey<FormState>();

  @override
  Widget build(BuildContext context) {

    return Consumer<ExerciseChangingViewModel>(
        builder: (context, model, child ) {
          String exerciseName = "";
          String customerName = "";
          if ( model != null ) {
            if ( model.exerciseViewModel == null ) {
              model.createNewModel();
            }
            model.exerciseViewModel.createNew();
            customerName = model != null && model.customer != null
                ? model.customer.name + " " +
                model.customer.firstName
                : "Please select a customer";

            exerciseName = model != null &&
                model.exerciseType != null
                ? model.exerciseType.name
                : "Please select an exercise";
          }

        AppLanguage appLanguage = AppLanguage();
        var date = DateTime.now();
        String dateName = DateFormat(DateFormat.YEAR_MONTH_DAY, appLanguage.appLocal.toString()).format(date.toUtc()) +
            " " +DateFormat(DateFormat.HOUR_MINUTE, appLanguage.appLocal.toString()).format(date.toUtc());

       return Form(
           key: _formKey,
           autovalidate: true,
          child: Scaffold(
            resizeToAvoidBottomInset: false,
            appBar: AppBar(
              leading: IconButton(
                icon: Icon(Icons.arrow_back, color: Colors.deepOrange),
                onPressed: () => {
                  Navigator.of(context).pop()
                                 },
              ),
              title: Text(AppLocalizations.of(context).translate(exerciseName) + " " +
                  AppLocalizations.of(context).translate('Save Exercise'),
                  style: TextStyle(fontWeight: FontWeight.bold, fontSize: 18, color: Colors.deepOrange)),
              backgroundColor: Colors.white70,
            ),
            body: Container(
              decoration: BoxDecoration(
                image: DecorationImage(
                image: AssetImage('asset/image/WT_login.png'),
                fit: BoxFit.cover,
                //height: double.infinity,
                //width: double.infinity,
                alignment: Alignment.center,
                ),
              ),
                child: Container(
                padding: const EdgeInsets.only (top: 65, left:25, right: 100),
                  child: Column(
                      mainAxisAlignment: MainAxisAlignment.spaceAround,
                      children: <Widget>[
                        columnQuantityUnit(model),
                        columnQuantity(model),

                        Column(
                            children: [
                              Row(
                                mainAxisAlignment: MainAxisAlignment.center,
                                children: [
                                  new InkWell(
                                    child: new Text(dateName,
                                        style: TextStyle( fontSize: 16,color: Colors.blue)),
                                  ),
                                  ButtonTheme(
                                    minWidth: 30.0,
                                    height: 30.0,
                                    child: FlatButton(

                                      padding: EdgeInsets.only(bottom: 0),
                                      color: Colors.transparent,
                                      splashColor: Colors.black26,
                                      child: Row(
                                        children: [

                                          Icon(Icons.arrow_forward_ios, color: Colors.orange,)
                                      ]),
                                      onPressed:() { print("date change");},

                                    )),
                                ],
                              ),

                              new InkWell(
                                child: new Text(AppLocalizations.of(context).translate('Exercise date and time'),
                                    style: TextStyle( fontSize: 16)),
                              ),

                            ]),
                      RaisedButton(
                        textColor: Colors.white,
                        color: Colors.deepOrange,
                        focusColor: Colors.white,
                        onPressed: () =>
                        {
                          if (_formKey.currentState.validate()) {
                            //model = ExerciseChangingViewModel(model.exerciseViewModel),

                            if ( ! excluded.contains(model.exerciseType.exerciseTypeId) ) {
                                model.addExercise(),
                            },
                            Navigator.pop(context),
                          }
                        },
                        child: Text("Save", style: TextStyle(fontSize: 16),)
                      ),

                      ]),
                )
              ),
          ),
      );
    });
  }

  Column columnQuantityUnit( ExerciseChangingViewModel model) {
    Column column = Column();
    if ( model.exerciseType != null && model.exerciseType.unitQuantity == "1") {
      column = Column(
          children: [
            TextFormField(
              autovalidate: true,
              textAlign: TextAlign.center,
              initialValue: "0",
              style: TextStyle(fontSize: 30,
                  color: Colors.lightBlue,
                  fontWeight: FontWeight.bold),
              validator: (input) {
                return validateNumberInput(input);
              },
              inputFormatters: [
                WhitelistingTextInputFormatter(RegExp(r"[\d.]"))
              ],
              onFieldSubmitted: (input) => {
                print ("UnitQuantity value $input"),
                model.exerciseViewModel.setUnitQuantity(
                    double.parse(input))
              },

            ),
            new InkWell(
              child: new Text(AppLocalizations.of(context).translate(
                  model.exerciseType.unitQuantityUnit),
                  style: TextStyle(fontSize: 16)),
            ),

          ]);
    };
    return column;
  }

  Column columnQuantity( ExerciseChangingViewModel model) {
    Column column = Column();

      column = Column(
          children: [
            TextFormField(
              autovalidate: true,
              textAlign: TextAlign.center,
              initialValue: "0",
              style: TextStyle(fontSize: 60,
                  color: Colors.deepOrange,
                  fontWeight: FontWeight.bold),
              validator: (input) {
                return validateNumberInput(input);
              },
              inputFormatters: [
                  WhitelistingTextInputFormatter(RegExp(r"[\d.]"))
              ],
              onFieldSubmitted: (input) =>
              {
                  print ("Quantity value $input"),
                  model.exerciseViewModel.setQuantity(
                      double.parse(input)),
                  model.exerciseViewModel.setUnit(model.exerciseType.unit)

              }
            ),
            new InkWell(
              child: new Text(AppLocalizations.of(context).translate(model.exerciseType.unit),
                  style: TextStyle(fontSize: 16)),
            ),

          ]);

    return column;
  }

  String  validateNumberInput( input ) {
    String error = AppLocalizations.of(context).translate("Please type the right quantity 0-10000");
    dynamic rc = ( input != null && input.length > 0);
    if ( ! rc ) {
      return null;
    }

    Pattern pattern = r'^\d+(?:\.\d+)?$';
    RegExp regex = new RegExp(pattern);
    if (!regex.hasMatch(input)) {
      return error;
    }

    rc = double.tryParse(input);
    if ( rc == null ) {
      return error;
    }



    if ( ! ( double.parse(input) < 10000 && double.parse(input) > 0) ) {
      return error;
    }

    return null;
  }
}