class InputField extends StatelessWidget {
  final String hint;
  final TextEditingController controller;
  final FocusNode focusNode;
  final bool obscureText;
  final String Function(String value) validator;
  final VoidCallback onEditingComplete;
  final TextInputType keyboardType;
  final TextInputAction textInputAction;

  InputField({
    @required this.hint,
    @required this.controller,
    @required this.validator,
    @required this.focusNode,
    this.onEditingComplete,
    this.obscureText = false,
    this.keyboardType = TextInputType.text,
    this.textInputAction = TextInputAction.done,
  });

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: EdgeInsets.symmetric(horizontal: 20),
      child: TextFormField(
        focusNode: focusNode,
        controller: controller,
        maxLines: 1,
        expands: false,
        enableInteractiveSelection: true,
        autovalidate: true,
        obscureText: obscureText,
        textCapitalization: TextCapitalization.words,
        keyboardType: keyboardType,
        onEditingComplete: onEditingComplete,
        decoration: InputDecoration(
          border: OutlineInputBorder(
            borderRadius: BorderRadius.circular(100),
          ),
          hintText: hint,
          contentPadding: EdgeInsets.only(left: 16),
        ),
        validator: validator,
      ),
    );
  }
}

class _EmailAuthScreenState extends State<EmailAuthScreen> {
  final _formKey = GlobalKey<FormState>();

  final TextEditingController _emailController = TextEditingController();
  final TextEditingController _passController = TextEditingController();

  FocusNode _emailFocus;
  FocusNode _passFocus;

  @override
  void initState() {
    super.initState();
    _emailFocus = FocusNode();
    _passFocus = FocusNode();
  }

  @override
  void dispose() {
    _emailFocus.dispose();
    _passFocus.dispose();

    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.transparent,
      ),
      body: Center(
        child: SingleChildScrollView(
          child: Form(
            key: _formKey,
            child: Column(
              mainAxisSize: MainAxisSize.min,
              crossAxisAlignment: CrossAxisAlignment.center,
              children: <Widget>[
                Text( 
                  'Log into your account',
                  style: TextStyle(
                    fontSize: 24,
                    fontWeight: FontWeight.w600,
                  ),
                ),
                InputField(
                  focusNode: _emailFocus,
                  controller: _emailController,
                  hint: 'Email address',
                  keyboardType: TextInputType.emailAddress,
                  textInputAction: TextInputAction.next,
                  onEditingComplete: () => _passFocus.requestFocus(),
                  validator: (value) {
                    if (value.isEmpty) {
                      return 'Email cannot be empty';
                    }
                    if (!value.contains('@') || !value.contains('.')) {
                      return 'Invalid email address';
                    }
                    return null;
                  },
                ),
                SizedBox(height: 35),
                InputField(
                  focusNode: _passFocus,
                  controller: _passController,
                  hint: 'Password',
                  obscureText: true,
                  textInputAction: TextInputAction.go,
                  onEditingComplete: () {
                    _emailFocus.unfocus();
                    _passFocus.unfocus();
                  },
                  validator: (value) {
                    if (value.isEmpty) {
                      return 'Password cannot be empty';
                    }
                    if (value.length < 6) {
                      return 'Password cannot be less than 6 characters';
                    }
                    return null;
                  },
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}

[√] Flutter (Channel beta, v1.17.0-3.2.pre, on Microsoft Windows [Version 10.0.18362.175], locale en-GH)
    • Flutter version 1.17.0-3.2.pre at D:\flutter
    • Framework revision 2a7bc389f2 (7 days ago), 2020-04-21 20:34:20 -0700
    • Engine revision 4c8c31f591
    • Dart version 2.8.0 (build 2.8.0-dev.20.10)

 
[√] Android toolchain - develop for Android devices (Android SDK version 29.0.1)
    • Android SDK at C:\Users\debra\AppData\Local\Android\Sdk
    • Platform android-29, build-tools 29.0.1
    • ANDROID_HOME = C:\Users\debra\AppData\Local\Android\Sdk
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b03)
    • All Android licenses accepted.

[√] Chrome - develop for the web
    • Chrome at C:\Program Files (x86)\Google\Chrome\Application\chrome.exe

[√] Android Studio (version 3.5)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin version 39.0.3
    • Dart plugin version 191.8423
    • Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b03)

[√] VS Code (version 1.44.2)
    • VS Code at C:\Users\debra\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.9.1

[√] Connected device (3 available)
    • SM A305F   • R58M62W011R • android-arm64  • Android 10 (API 29)
    • Chrome     • chrome      • web-javascript • Google Chrome 81.0.4044.122
    • Web Server • web-server  • web-javascript • Flutter Tools

• No issues found!