import 'dart:async';
import 'dart:math' as math;
import 'dart:ui';

import 'package:flutter/cupertino.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_icons/flutter_icons.dart';
import 'package:get/get.dart';
import 'package:google_fonts/google_fonts.dart';

void main() {
  SystemChrome.setSystemUIOverlayStyle(Styles.baseSystemUIStyle);
  runApp(BMIApp());
}

enum Gender { female, male }

abstract class Styles {
  static const primaryColor = Color(0xFFEB1555);
  static const backgroundColor = Color(0xFF0A0D22);

  static var lighTheme = ThemeData.light().copyWith(
    primaryColor: primaryColor,
    colorScheme: ColorScheme.light(primary: primaryColor),
    scaffoldBackgroundColor: Colors.grey.shade300,
  );

  static var darkTheme = ThemeData.dark().copyWith(
    primaryColor: primaryColor,
    colorScheme: ColorScheme.dark(primary: primaryColor),
    scaffoldBackgroundColor: Styles.backgroundColor,
  );

  static SystemUiOverlayStyle baseSystemUIStyle =
      SystemUiOverlayStyle.dark.copyWith(
    statusBarColor: Colors.transparent,
    systemNavigationBarColor: Styles.primaryColor,
  );

  static Color get iconColor {
    return Get.isDarkMode ? Colors.white : Colors.redAccent;
  }

  static Color get textColor {
    return Get.isDarkMode ? Colors.white : Color(0xff656565);
  }

  static final bigValueTextStyle = GoogleFonts.nunitoSans(
    fontWeight: FontWeight.w800,
    color: Colors.white,
    fontSize: 46,
    fontFeatures: [
      FontFeature.proportionalFigures(),
      FontFeature.tabularFigures()
    ],
  );

  static const yourResultTextStyle =
      TextStyle(fontSize: 44, fontWeight: FontWeight.w600, color: Colors.white);

  static const resultStatusTextStyle =
      TextStyle(fontWeight: FontWeight.bold, fontSize: 22);

  static const cmTextStyle =
      TextStyle(fontWeight: FontWeight.w200, fontSize: 12);

  static const resultPointsTextStyle =
      TextStyle(fontWeight: FontWeight.w800, color: Colors.white, fontSize: 90);

  static const resultTextStyle = TextStyle(
      fontWeight: FontWeight.normal, color: Colors.white, fontSize: 22);

  static const cardLabelTextStyle =
      TextStyle(fontWeight: FontWeight.w300, color: Colors.white54);
}

class BMIApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return GetMaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'BMI calculator (GetX)',
      theme: Styles.lighTheme,
      darkTheme: Styles.darkTheme,
      themeMode: ThemeMode.dark,
      initialBinding: BindingsBuilder(() {
        Get.put(BMIHomeController());
      }),
      home: BMIHome(),
    );
  }
}

enum BMIStatus { overweight, normal, underweight }

class BmiCalculator {
  BMIStatus status = BMIStatus.normal;
  double points = 0;
  String text = 'You have a higher than normal';
  double _bmi = 0;

  void calculateBMI({double weight, double height}) {
    _bmi = weight / math.pow(height / 100, 2);
    points = _bmi;

    // update values.
    if (_bmi >= 25) {
      status = BMIStatus.overweight;
      text = 'You have a higher than normal body weight. Try to exercise more';
    } else if (_bmi > 18.5) {
      status = BMIStatus.normal;
      text = 'You have a normal body weight. Good job!';
    } else {
      status = BMIStatus.underweight;
      text =
          'You have a lower than normal body weight. You can eat a bit more.';
    }
  }
}

class BMIHomeController extends GetxController {
  // result status colors
  static const _bmiStatusColors = {
    BMIStatus.overweight: Colors.redAccent,
    BMIStatus.normal: Colors.lightGreenAccent,
    BMIStatus.underweight: Colors.yellow,
  };

  final gender = Gender.female.obs;
  final height = 180.0.obs;

  final minHeight = 120.0;
  final maxHeight = 240.0;

  final weight = 85.obs;
  final age = 19.obs;

  final _calculator = BmiCalculator();

  Color get resultStatusColor => _bmiStatusColors[_calculator.status];

  String get resultStatusTitle =>
      describeEnum(_calculator.status).toUpperCase();

  get resultText => _calculator.text;

  get resultPointsString => _calculator.points.toStringAsFixed(1);

  @override
  void onInit() {
    _constrainValue(weight, min: 10);
    _constrainValue(age, min: 18);
  }

  void _constrainValue(RxInt value, {int min = 0}) {
    ever(value, (_) {
      value.value = min;
    }, condition: () => value.value < min);
  }

  double getGenderOpacity(Gender value) => gender.value == value ? 1 : .25;

  String get heightString => height.value.toStringAsFixed(1);

  void handleCalculateTap() {
    _calculator.calculateBMI(
      height: height.value,
      weight: weight.value.toDouble(),
    );
    Get.to(BMIResult());
  }

  void handleReCalculateTap() => Get.back();

  void toggleTheme() {
    Get.changeThemeMode(Get.isDarkMode ? ThemeMode.light : ThemeMode.dark);
  }

  Timer _buttonTicker;

  /// custom timer ticker
  void handleTickButton(RxInt value, bool isPressed, int dir) {
    if (isPressed) {
      int countdownWait = 8;
      int waitTicker = 0;
      _buttonTicker = Timer.periodic(48.milliseconds, (_) {
        if (countdownWait <= 0 || ++waitTicker % countdownWait == 0) {
          countdownWait--;
          value.value += dir;
        }
      });
    } else {
      _buttonTicker?.cancel();
      value.value += dir;
    }
  }
}

class BMIAppbar extends StatelessWidget implements PreferredSizeWidget {
  final bool centerTitle;

  const BMIAppbar({Key key, this.centerTitle = false}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    context.theme;
    final BMIHomeController controller = Get.find();
    final canPop = Navigator.canPop(context);

    return AppBar(
      brightness: Get.isDarkMode ? Brightness.dark : Brightness.light,
      backgroundColor: Colors.transparent,
      leading: Visibility(
        visible: canPop,
        child: BackButton(
          color: Styles.iconColor,
          onPressed: Get.back,
        ),
      ),
      elevation: 0,
      title: Text(
        'BMI CALCULATOR',
        style: TextStyle(color: Styles.textColor),
      ),
      centerTitle: centerTitle,
      actions: [
        CupertinoButton(
          child: Icon(
              Get.isDarkMode ? Icons.brightness_2 : Icons.brightness_2_outlined,
              size: 16),
          onPressed: controller.toggleTheme,
        ),
      ],
    );
  }

  @override
  Size get preferredSize => Size.fromHeight(kToolbarHeight);
}

class BMIResult extends GetView<BMIHomeController> {
  @override
  Widget build(BuildContext context) {
    context.theme;
    return Scaffold(
        appBar: BMIAppbar(
          centerTitle: false,
        ),
        body: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            Text(
              'Your Result',
              style: Styles.yourResultTextStyle.copyWith(
                color: Styles.textColor,
              ),
            ).paddingSymmetric(vertical: 12, horizontal: 12),
            Expanded(
              child: AppCard(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.center,
                  mainAxisAlignment: MainAxisAlignment.spaceAround,
                  children: [
                    Text(
                      controller.resultStatusTitle,
                      style: Styles.resultStatusTextStyle.copyWith(
                        color: controller.resultStatusColor,
                      ),
                    ),
                    Text(
                      controller.resultPointsString,
                      style: Styles.resultPointsTextStyle.copyWith(
                        color: Styles.textColor,
                      ),
                    ),
                    Text(
                      controller.resultText,
                      style: Styles.resultTextStyle.copyWith(
                        color: Styles.textColor,
                      ),
                      textAlign: TextAlign.center,
                    ),
                  ],
                ).paddingAll(12),
              ).paddingSymmetric(vertical: 12, horizontal: 12),
            ),
            AppMainButton(
              label: 'RE-CALCULATE',
              onTap: controller.handleReCalculateTap,
            ),
          ],
        ));
  }
}

class BMIHome extends GetView<BMIHomeController> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: BMIAppbar(centerTitle: true),
      body: Column(
        children: [
          Expanded(child: GenderSelector()),
          Expanded(child: HeightPane()),
          Expanded(child: WeightSelector().paddingOnly(bottom: 0)),
          AppMainButton(
            label: 'CALCULATE',
            onTap: controller.handleCalculateTap,
          ),
        ],
      ),
    );
  }
}

class CardLabel extends StatelessWidget {
  final String text;
  final double size;

  const CardLabel(this.text, {this.size = 16, Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    context.theme;
    return Text(
      text,
      style: Styles.cardLabelTextStyle.copyWith(
        fontSize: size,
        color: Styles.textColor.withOpacity(.54),
      ),
    );
  }
}

class WeightSelector extends GetView<BMIHomeController> {
  @override
  Widget build(BuildContext context) {
    return Row(
      children: [
        Expanded(
            child: CounterPane(
          label: 'WEIGHT',
          onButtonState: (state, dir) =>
              controller.handleTickButton(controller.weight, state, dir),
          realValue: controller.weight,
        ).paddingAll(12)),
        Expanded(
            child: CounterPane(
          label: 'AGE',
          onButtonState: (state, dir) =>
              controller.handleTickButton(controller.age, state, dir),
          realValue: controller.age,
        ).paddingAll(12)),
      ],
    );
  }
}

class CounterPane extends StatelessWidget {
  final String label;
  final RxInt realValue;
  final Function(bool, int) onButtonState;

  const CounterPane({
    Key key,
    this.label,
    this.onButtonState,
    this.realValue,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    context.theme;
    return AppCard(
      padding: EdgeInsets.all(4),
      child: Column(
        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: [
          CardLabel(label),
          Obx(
            () => Text(
              '$realValue',
              style: Styles.bigValueTextStyle.copyWith(color: Styles.textColor),
            ),
          ),
          Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              AppIconButton.more(
                onHighlight: onButtonState,
              ),
              SizedBox(width: 8),
              AppIconButton.less(
                onHighlight: onButtonState,
//                onTap: () => realValue(realValue() - 1),
              ),
            ],
          )
        ],
      ),
    );
  }
}

class AppIconButton extends StatelessWidget {
  final Function(int) onTap;
  final Function(bool, int) onHighlight;
  final IconData iconData;
  final int dir;

  const AppIconButton(
      {Key key, this.iconData, this.onTap, this.onHighlight, this.dir = 0})
      : super(key: key);

  AppIconButton.more({this.onTap, this.onHighlight})
      : iconData = Icons.add,
        dir = 1,
        super();

  AppIconButton.less({this.onTap, this.onHighlight})
      : iconData = Icons.remove,
        dir = -1,
        super();

  @override
  Widget build(BuildContext context) {
    context.theme;
    return FlatButton(
      visualDensity: VisualDensity.compact,
      shape: const CircleBorder(),
      minWidth: 48,
      height: 54,
      materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
//      padding: EdgeInsets.zero,
      child: Icon(
        iconData,
        size: 34,
        color: Styles.iconColor,
      ),
      onHighlightChanged: (flag) => onHighlight?.call(flag, dir),
      onPressed: () => onTap?.call(dir),
      color: Styles.iconColor.withOpacity(.12),
    );
  }
}

class HeightPane extends GetView<BMIHomeController> {
  @override
  Widget build(BuildContext context) {
    context.theme;
    return AppCard(
      padding: EdgeInsets.symmetric(horizontal: 24, vertical: 8),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          Center(child: CardLabel('HEIGHT')),
          Center(
            child: Row(
              mainAxisSize: MainAxisSize.min,
              crossAxisAlignment: CrossAxisAlignment.baseline,
              children: [
                Obx(
                  () => Text(
                    controller.heightString,
                    textAlign: TextAlign.right,
                    style: Styles.bigValueTextStyle
                        .copyWith(color: Styles.textColor),
                  ),
                ),
                Text(' cm', style: Styles.cmTextStyle),
              ],
            ),
          ),
          Obx(
            () => Slider.adaptive(
              min: controller.minHeight,
              max: controller.maxHeight,
              value: controller.height(),
              onChanged: controller.height,
              activeColor: Styles.primaryColor,
//              activeColor: Styles.textColor,
//              thumbColor: Get.theme.primaryColor,
            ),
          ),
        ],
      ),
    ).paddingAll(12);
  }
}

class GenderSelector extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Row(
      children: [
        Expanded(child: AppToggle.male().paddingAll(12)),
        Expanded(child: AppToggle.female().paddingAll(12)),
      ],
    );
  }
}

class AppMainButton extends StatelessWidget {
  final VoidCallback onTap;
  final String label;

  const AppMainButton({Key key, this.onTap, this.label}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: double.infinity,
      height: 70,
      child: FlatButton(
        color: Get.theme.primaryColor,
        onPressed: onTap,
        shape: const ContinuousRectangleBorder(),
        child: Text(
          label,
          style: Get.textTheme.headline5.copyWith(
            color: Colors.white,
            fontWeight: FontWeight.bold,
          ),
        ),
      ),
    );
  }
}

class AppCard extends StatelessWidget {
  final Widget child;
  final EdgeInsets padding;

  const AppCard({
    Key key,
    this.child,
    this.padding,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    context.theme;
    return Container(
      padding: padding,
      clipBehavior: Clip.antiAlias,
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(8),
//        color: Colors.white.withOpacity(.06),
        color: Styles.textColor.withOpacity(.06),
      ),
      child: child,
    );
  }
}

class AppToggle extends GetView<BMIHomeController> {
  final String label;
  final Widget icon;
  final Gender gender;

  const AppToggle({Key key, this.label, this.icon, this.gender})
      : super(key: key);

  AppToggle.male()
      : label = 'MALE',
        gender = Gender.male,
        icon = Icon(Ionicons.md_male),
        super();

  AppToggle.female()
      : label = 'FEMALE',
        gender = Gender.female,
        icon = Icon(Ionicons.md_female),
        super();

  @override
  Widget build(BuildContext context) {
    context.theme;
    return AppCard(
      child: FlatButton(
        onPressed: () => controller.gender(gender),
        padding: EdgeInsets.all(12),
        shape: const ContinuousRectangleBorder(),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: [
            Expanded(
              child: FittedBox(
                child: Obx(
                  () => Opacity(
                    opacity: controller.getGenderOpacity(gender),
                    child: IconTheme(
                      data: IconThemeData(color: Styles.iconColor),
                      child: icon,
                    ),
                  ),
                ),
              ),
            ),
            SizedBox(height: 12),
            CardLabel(label),
          ],
        ),
      ),
    );
  }
}