mohemm-flutter-app/lib/widgets/otp_widget.dart

import 'dart:async';

import 'package:flutter/animation.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/services.dart';

typedef OnDone = void Function(String text);

class ProvidedPinBoxTextAnimation {
  static AnimatedSwitcherTransitionBuilder scalingTransition = (child, animation) {
    return ScaleTransition(
      child: child,
      scale: animation,
    );
  };

  static AnimatedSwitcherTransitionBuilder defaultNoTransition = (Widget child, Animation<double> animation) {
    return child;
  };
}

class OTPWidget extends StatefulWidget {
  final int maxLength;
  final TextEditingController? controller;

  final Color defaultBorderColor;
  final Color pinBoxColor;
  final double pinBoxBorderWidth;
  final double pinBoxRadius;
  final bool hideDefaultKeyboard;

  final TextStyle? pinTextStyle;
  final double pinBoxHeight;
  final double pinBoxWidth;
  final OnDone? onDone;
  final bool hasError;
  final Color errorBorderColor;
  final Color textBorderColor;
  final Function(String)? onTextChanged;
  final bool autoFocus;
  final FocusNode? focusNode;
  final AnimatedSwitcherTransitionBuilder? pinTextAnimatedSwitcherTransition;
  final Duration pinTextAnimatedSwitcherDuration;
  final TextDirection textDirection;
  final TextInputType keyboardType;
  final EdgeInsets pinBoxOuterPadding;

  const OTPWidget({
    Key? key,
    this.maxLength =  4,
    this.controller,
    this.pinBoxWidth = 70.0,
    this.pinBoxHeight = 70.0,
    this.pinTextStyle,
    this.onDone,
    this.defaultBorderColor = Colors.black,
    this.textBorderColor = Colors.black,
    this.pinTextAnimatedSwitcherTransition,
    this.pinTextAnimatedSwitcherDuration = const Duration(),
    this.hasError =  false,
    this.errorBorderColor =  Colors.red,
    this.onTextChanged,
    this.autoFocus = false,
    this.focusNode,
    this.textDirection = TextDirection.ltr,
    this.keyboardType =TextInputType.number,
    this.pinBoxOuterPadding = const EdgeInsets.symmetric(horizontal: 4.0),
    this.pinBoxColor = Colors.white,
    this.pinBoxBorderWidth = 2.0,
    this.pinBoxRadius = 0,
    this.hideDefaultKeyboard = false,
  }) : super(key: key);

  @override
  State<StatefulWidget> createState() {
    return OTPWidgetState();
  }
}

class OTPWidgetState extends State<OTPWidget> with SingleTickerProviderStateMixin {
  AnimationController? _highlightAnimationController;
  FocusNode? focusNode;
  String text = "";
  int currentIndex = 0;
  List<String> strList = [];
  bool hasFocus = false;

  @override
  void didUpdateWidget(OTPWidget oldWidget) {
    super.didUpdateWidget(oldWidget);
    focusNode = widget.focusNode ?? focusNode;

    if (oldWidget.maxLength < widget.maxLength) {
      setState(() {
        currentIndex = text.length;
      });
      widget.controller?.text = text;
      widget.controller?.selection = TextSelection.collapsed(offset: text.length);
    } else if (oldWidget.maxLength > widget.maxLength && widget.maxLength > 0 && text.length > 0 && text.length > widget.maxLength) {
      setState(() {
        text = text.substring(0, widget.maxLength);
        currentIndex = text.length;
      });
      widget.controller?.text = text;
      widget.controller?.selection = TextSelection.collapsed(offset: text.length);
    }
  }

  void calculateStrList() {
    if (strList.length > widget.maxLength) {
      strList.length = widget.maxLength;
    }
    while (strList.length < widget.maxLength) {
      strList.add("");
    }
  }

  @override
  void initState() {
    super.initState();
    focusNode = widget.focusNode ?? FocusNode();

    _initTextController();
    calculateStrList();
    widget.controller?.addListener(_controllerListener);
    focusNode?.addListener(_focusListener);
  }

  void _controllerListener() {
    if (mounted == true) {
      setState(() {
        _initTextController();
      });
      var onTextChanged = widget.onTextChanged;
      if (onTextChanged != null) {
        onTextChanged(widget.controller?.text ?? "");
      }
    }
  }

  void _focusListener() {
    if (mounted == true) {
      setState(() {
        hasFocus = focusNode?.hasFocus ?? false;
      });
    }
  }

  void _initTextController() {
    if (widget.controller == null) {
      return;
    }
    strList.clear();
    var text = widget.controller?.text ?? "";
    if (text.isNotEmpty) {
      if (text.length > widget.maxLength) {
        throw Exception("TextEditingController length exceeded maxLength!");
      }
    }
    for (var i = 0; i < text.length; i++) {
      strList.add(text[i]);
    }
  }

  double get _width {
    var width = 0.0;
    for (var i = 0; i < widget.maxLength; i++) {
      width += widget.pinBoxWidth;
      if (i == 0) {
        width += widget.pinBoxOuterPadding.left;
      } else if (i + 1 == widget.maxLength) {
        width += widget.pinBoxOuterPadding.right;
      } else {
        width += widget.pinBoxOuterPadding.left;
      }
    }
    return width;
  }

  @override
  void dispose() {
    if (widget.focusNode == null) {
      focusNode?.dispose();
    } else {
      focusNode?.removeListener(_focusListener);
    }
    _highlightAnimationController?.dispose();
    widget.controller?.removeListener(_controllerListener);

    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: <Widget>[
        _otpTextInput(),
        _touchPinBoxRow(),
      ],
    );
  }

  Widget _touchPinBoxRow() {
    return widget.hideDefaultKeyboard
        ? _pinBoxRow(context)
        : GestureDetector(
            behavior: HitTestBehavior.opaque,
            onTap: () {
              if (hasFocus) {
                FocusScope.of(context).requestFocus(FocusNode());
                Future.delayed(Duration(milliseconds: 100), () {
                  FocusScope.of(context).requestFocus(focusNode);
                });
              } else {
                FocusScope.of(context).requestFocus(focusNode);
              }
            },
            child: _pinBoxRow(context),
          );
  }

  Widget _otpTextInput() {
    var transparentBorder = OutlineInputBorder(
      borderSide: BorderSide(
        color: Colors.transparent,
        width: 0.0,
      ),
    );
    return Container(
      width: _width,
      height: widget.pinBoxHeight,
      child: TextField(
        autofocus: !kIsWeb ? widget.autoFocus : false,
        enableInteractiveSelection: false,
        focusNode: focusNode,
        controller: widget.controller,
        keyboardType: widget.keyboardType,
        inputFormatters: widget.keyboardType == TextInputType.number ? <TextInputFormatter>[FilteringTextInputFormatter.digitsOnly] : null,
        style: TextStyle(
          height: 0.1,
          color: Colors.transparent,
        ),
        decoration: InputDecoration(
          contentPadding: EdgeInsets.all(0),
          focusedErrorBorder: transparentBorder,
          errorBorder: transparentBorder,
          disabledBorder: transparentBorder,
          enabledBorder: transparentBorder,
          focusedBorder: transparentBorder,
          counterText: null,
          counterStyle: null,
          helperStyle: TextStyle(
            height: 0.0,
            color: Colors.transparent,
          ),
          labelStyle: TextStyle(height: 0.1),
          fillColor: Colors.transparent,
          border: InputBorder.none,
        ),
        cursorColor: Colors.transparent,
        showCursor: false,
        maxLength: widget.maxLength,
        onChanged: _onTextChanged,
      ),
    );
  }

  void _onTextChanged(text) {
    var onTextChanged = widget.onTextChanged;
    if (onTextChanged != null) {
      onTextChanged(text);
    }
    setState(() {
      this.text = text;
      if (text.length >= currentIndex) {
        for (int i = currentIndex; i < text.length; i++) {
          strList[i] = text[i];
        }
      }
      currentIndex = text.length;
    });
    if (text.length == widget.maxLength) {
      FocusScope.of(context).requestFocus(FocusNode());
      var onDone = widget.onDone;
      if (onDone != null) {
        onDone(text);
      }
    }
  }

  Widget _pinBoxRow(BuildContext context) {
    calculateStrList();
    List<Widget> pinCodes = List.generate(widget.maxLength, (int i) {
      return _buildPinCode(i, context);
    });
    return Row(children: pinCodes, mainAxisSize: MainAxisSize.min);
  }

  Widget _buildPinCode(int i, BuildContext context) {
    Color borderColor;
    Color pinBoxColor = widget.pinBoxColor;

    if (widget.hasError) {
      borderColor = widget.errorBorderColor;
    } else if (i < text.length) {
      borderColor = widget.textBorderColor;
    } else {
      borderColor = widget.defaultBorderColor;
      pinBoxColor = widget.pinBoxColor;
    }

    EdgeInsets insets;
    if (i == 0) {
      insets = EdgeInsets.only(
        left: 0,
        top: widget.pinBoxOuterPadding.top,
        right: widget.pinBoxOuterPadding.right,
        bottom: widget.pinBoxOuterPadding.bottom,
      );
    } else if (i == strList.length - 1) {
      insets = EdgeInsets.only(
        left: widget.pinBoxOuterPadding.left,
        top: widget.pinBoxOuterPadding.top,
        right: 0,
        bottom: widget.pinBoxOuterPadding.bottom,
      );
    } else {
      insets = widget.pinBoxOuterPadding;
    }
    return Container(
      key: ValueKey<String>("container$i"),
      alignment: Alignment.center,
      padding: EdgeInsets.symmetric(vertical: 4.0, horizontal: 1.0),
      margin: insets,
      child: _animatedTextBox(strList[i], i),
      decoration: BoxDecoration(
        border: Border.all(
          color: borderColor,
          width: widget.pinBoxBorderWidth,
        ),
        color: pinBoxColor,
        borderRadius: BorderRadius.circular(widget.pinBoxRadius),
      ),
      width: widget.pinBoxWidth,
      height: widget.pinBoxHeight,
    );
  }

  Widget _animatedTextBox(String text, int i) {
    if (widget.pinTextAnimatedSwitcherTransition != null) {
      return AnimatedSwitcher(
        duration: widget.pinTextAnimatedSwitcherDuration,
        transitionBuilder: widget.pinTextAnimatedSwitcherTransition ??
            (Widget child, Animation<double> animation) {
              return child;
            },
        child: Text(
          text,
          key: ValueKey<String>("$text$i"),
          style: widget.pinTextStyle,
        ),
      );
    } else {
      return Text(
        text,
        key: ValueKey<String>("${strList[i]}$i"),
        style: widget.pinTextStyle,
      );
    }
  }
}