class AtText extends SpecialText {
  AtText(TextStyle textStyle, SpecialTextGestureTapCallback onTap,
      {this.showAtBackground = false, this.start})
      : super(flag, ' ', textStyle, onTap: onTap);
  static const String flag = '@';
  final int start;

  /// whether show background for @somebody
  final bool showAtBackground;

  @override
  InlineSpan finishText() {
    final TextStyle textStyle =
        this.textStyle?.copyWith(color: Colors.blue, fontSize: 16.0);

    final String atText = toString();

    return showAtBackground
        ? BackgroundTextSpan(
            background: Paint()..color = Colors.blue.withOpacity(0.15),
            text: atText,
            actualText: atText,
            start: start,

            ///caret can move into special text
            deleteAll: true,
            style: textStyle,
            recognizer: (TapGestureRecognizer()
              ..onTap = () {
                if (onTap != null) {
                  onTap(atText);
                }
              }))
        : SpecialTextSpan(
            text: atText,
            actualText: atText,
            start: start,
            style: textStyle,
            recognizer: (TapGestureRecognizer()
              ..onTap = () {
                if (onTap != null) {
                  onTap(atText);
                }
              }));
  }
}

class MySpecialTextSpanBuilder extends SpecialTextSpanBuilder {
  MySpecialTextSpanBuilder({this.showAtBackground = false});

  /// whether show background for @somebody
  final bool showAtBackground;
  @override
  TextSpan build(String data,
      {TextStyle textStyle, SpecialTextGestureTapCallback onTap}) {
    if (kIsWeb) {
      return TextSpan(text: data, style: textStyle);
    }

    return super.build(data, textStyle: textStyle, onTap: onTap);
  }

  @override
  SpecialText createSpecialText(String flag,
      {TextStyle textStyle, SpecialTextGestureTapCallback onTap, int index}) {
    if (flag == null || flag == '') {
      return null;
    }

    ///index is end index of start flag, so text start index should be index-(flag.length-1)
    if (isStart(flag, AtText.flag)) {
      return AtText(
        textStyle,
        onTap,
        start: index - (AtText.flag.length - 1),
        showAtBackground: showAtBackground,
      );
    } else if (isStart(flag, EmojiText.flag)) {
      return EmojiText(textStyle, start: index - (EmojiText.flag.length - 1));
    } else if (isStart(flag, DollarText.flag)) {
      return DollarText(textStyle, onTap,
          start: index - (DollarText.flag.length - 1));
    }
    return null;
  }
}

class ImageSpan extends ExtendedWidgetSpan {
  ImageSpan(
    ImageProvider image, {
    Key key,
    @required double imageWidth,
    @required double imageHeight,
    EdgeInsets margin,
    int start = 0,
    ui.PlaceholderAlignment alignment = ui.PlaceholderAlignment.bottom,
    String actualText,
    TextBaseline baseline,
    BoxFit fit= BoxFit.scaleDown,
    ImageLoadingBuilder loadingBuilder,
    ImageFrameBuilder frameBuilder,
    String semanticLabel,
    bool excludeFromSemantics = false,
    Color color,
    BlendMode colorBlendMode,
    AlignmentGeometry imageAlignment = Alignment.center,
    ImageRepeat repeat = ImageRepeat.noRepeat,
    Rect centerSlice,
    bool matchTextDirection = false,
    bool gaplessPlayback = false,
    FilterQuality filterQuality = FilterQuality.low,
    GestureTapCallback onTap,
    HitTestBehavior behavior = HitTestBehavior.deferToChild,
  })

const double _kHandleSize = 22.0;

/// Android Material styled text selection controls.

class MyTextSelectionControls extends TextSelectionControls
    with TextSelectionHandleControls {
  MyTextSelectionControls({this.joinZeroWidthSpace = false});
  final bool joinZeroWidthSpace;

  /// Returns the size of the Material handle.
  @override
  Size getHandleSize(double textLineHeight) =>
      const Size(_kHandleSize, _kHandleSize);

  /// Builder for material-style text selection handles.
  @override
  Widget buildHandle(
      BuildContext context, TextSelectionHandleType type, double textLineHeight,
      [VoidCallback? onTap, double? startGlyphHeight, double? endGlyphHeight]) {
    final Widget handle = SizedBox(
      width: _kHandleSize,
      height: _kHandleSize,
      child: Image.asset(
        'assets/40.png',
      ),
    );

    // [handle] is a circle, with a rectangle in the top left quadrant of that
    // circle (an onion pointing to 10:30). We rotate [handle] to point
    // straight up or up-right depending on the handle type.
    switch (type) {
      case TextSelectionHandleType.left: // points up-right
        return Transform.rotate(
          angle: math.pi / 4.0,
          child: handle,
        );
      case TextSelectionHandleType.right: // points up-left
        return Transform.rotate(
          angle: -math.pi / 4.0,
          child: handle,
        );
      case TextSelectionHandleType.collapsed: // points up
        return handle;
    }
  }

  /// Gets anchor for material-style text selection handles.
  ///
  /// See [TextSelectionControls.getHandleAnchor].
  @override
  Offset getHandleAnchor(TextSelectionHandleType type, double textLineHeight,
      [double? startGlyphHeight, double? endGlyphHeight]) {
    switch (type) {
      case TextSelectionHandleType.left:
        return const Offset(_kHandleSize, 0);
      case TextSelectionHandleType.right:
        return Offset.zero;
      default:
        return const Offset(_kHandleSize / 2, -4);
    }
  }
}

class CommonSelectionArea extends StatelessWidget {
  const CommonSelectionArea({
    super.key,
    required this.child,
    this.joinZeroWidthSpace = false,
  });
  final Widget child;
  final bool joinZeroWidthSpace;

  @override
  Widget build(BuildContext context) {
    SelectedContent? _selectedContent;
    return SelectionArea(
      contextMenuBuilder:
          (BuildContext context, SelectableRegionState selectableRegionState) {
        return AdaptiveTextSelectionToolbar.buttonItems(
          buttonItems: <ContextMenuButtonItem>[
            ContextMenuButtonItem(
              onPressed: () {
                // TODO(zmtzawqlp):  how to get Selectable
                // and  _clearSelection is not public
                // https://github.com/flutter/flutter/issues/126980

                //  onCopy: () {
                //   _copy();

                //   // In Android copy should clear the selection.
                //   switch (defaultTargetPlatform) {
                //     case TargetPlatform.android:
                //     case TargetPlatform.fuchsia:
                //       _clearSelection();
                //     case TargetPlatform.iOS:
                //       hideToolbar(false);
                //     case TargetPlatform.linux:
                //     case TargetPlatform.macOS:
                //     case TargetPlatform.windows:
                //       hideToolbar();
                //   }
                // },

                // if (_selectedContent != null) {
                //   String content = _selectedContent!.plainText;
                //   if (joinZeroWidthSpace) {
                //     content = content.replaceAll(zeroWidthSpace, '');
                //   }

                //   Clipboard.setData(ClipboardData(text: content));
                //   selectableRegionState.hideToolbar(true);
                //   selectableRegionState._clearSelection();
                // }

                selectableRegionState
                    .copySelection(SelectionChangedCause.toolbar);

                // remove zeroWidthSpace
                if (joinZeroWidthSpace) {
                  Clipboard.getData('text/plain').then((ClipboardData? value) {
                    if (value != null) {
                      // remove zeroWidthSpace
                      final String? plainText =
                          value.text?.replaceAll(ExtendedTextLibraryUtils.zeroWidthSpace, '');
                      if (plainText != null) {
                        Clipboard.setData(ClipboardData(text: plainText));
                      }
                    }
                  });
                }
              },
              type: ContextMenuButtonType.copy,
            ),
            ContextMenuButtonItem(
              onPressed: () {
                selectableRegionState.selectAll(SelectionChangedCause.toolbar);
              },
              type: ContextMenuButtonType.selectAll,
            ),
            ContextMenuButtonItem(
              onPressed: () {
                launchUrl(Uri.parse(
                    'mailto:zmtzawqlp@live.com?subject=extended_text_share&body=${_selectedContent?.plainText}'));
                selectableRegionState.hideToolbar();
              },
              type: ContextMenuButtonType.custom,
              label: 'like',
            ),
          ],
          anchors: selectableRegionState.contextMenuAnchors,
        );
        // return AdaptiveTextSelectionToolbar.selectableRegion(
        //   selectableRegionState: selectableRegionState,
        // );
      },
      // magnifierConfiguration: TextMagnifierConfiguration(
      //   magnifierBuilder: (
      //     BuildContext context,
      //     MagnifierController controller,
      //     ValueNotifier<MagnifierInfo> magnifierInfo,
      //   ) {
      //     return TextMagnifier(
      //       magnifierInfo: magnifierInfo,
      //     );
      //     // switch (defaultTargetPlatform) {
      //     //   case TargetPlatform.iOS:
      //     //     return CupertinoTextMagnifier(
      //     //       controller: controller,
      //     //       magnifierInfo: magnifierInfo,
      //     //     );
      //     //   case TargetPlatform.android:
      //     //     return TextMagnifier(
      //     //       magnifierInfo: magnifierInfo,
      //     //     );
      //     //   case TargetPlatform.fuchsia:
      //     //   case TargetPlatform.linux:
      //     //   case TargetPlatform.macOS:
      //     //   case TargetPlatform.windows:
      //     //     return null;
      //     // }
      //   },
      // ),
      // selectionControls: MyTextSelectionControls(),
      onSelectionChanged: (SelectedContent? value) {
        print(value?.plainText);
        _selectedContent = value;
      },
      child: child,
    );
  }
}

 return ExtendedTextSelectionPointerHandler(
      //default behavior
       child: result,
    );

 return ExtendedTextSelectionPointerHandler(
      //default behavior
      // child: result,
      //custom your behavior
      builder: (states) {
        return Listener(
          child: result,
          behavior: HitTestBehavior.translucent,
          onPointerDown: (value) {
            for (var state in states) {
              if (!state.containsPosition(value.position)) {
                //clear other selection
                state.clearSelection();
              }
            }
          },
          onPointerMove: (value) {
            //clear other selection
            for (var state in states) {
              state.clearSelection();
            }
          },
        );
      },
    );

  BackgroundTextSpan(
      text:
          "This text has nice background with borderradius,no mattter how many line,it likes nice",
      background: Paint()..color = Colors.indigo,
      clipBorderRadius: BorderRadius.all(Radius.circular(3.0))),

  ExtendedText(
   overflowWidget: TextOverflowWidget(
     position: TextOverflowPosition.end,
     align: TextOverflowAlign.center,
     // just for debug
     debugOverflowRectColor: Colors.red.withOpacity(0.1),
     child: Container(
       child: Row(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[
           const Text('\u2026 '),
           InkWell(
             child: const Text(
               'more',
             ),
             onTap: () {
               launch(
                   'https://github.com/fluttercandies/extended_text');
             },
           )
         ],
       ),
     ),
   ),
  )

  ExtendedText(
      joinZeroWidthSpace: true,
    )

  String input='abc'.joinChar();

     InlineSpan innerTextSpan;
     innerTextSpan = joinChar(
        innerTextSpan,
        Accumulator(),
        zeroWidthSpace,
    );

class MyTextSelectionControls extends TextSelectionControls {

  @override
  void handleCopy(TextSelectionDelegate delegate,
      ClipboardStatusNotifier? clipboardStatus) {
    final TextEditingValue value = delegate.textEditingValue;

    String data = value.selection.textInside(value.text);
    // remove zeroWidthSpace
    data = data.replaceAll(zeroWidthSpace, '');

    Clipboard.setData(ClipboardData(
      text: value.selection.textInside(value.text),
    ));
    clipboardStatus?.update();
    delegate.textEditingValue = TextEditingValue(
      text: value.text,
      selection: TextSelection.collapsed(offset: value.selection.end),
    );
    delegate.bringIntoView(delegate.textEditingValue.selection.extent);
    delegate.hideToolbar();
  }
}

  GradientConfig _config = GradientConfig(
    gradient: const LinearGradient(
      colors: <Color>[Colors.blue, Colors.red],
    ),
    ignoreRegex: GradientConfig.ignoreEmojiRegex,
    ignoreWidgetSpan: true,
    renderMode: GradientRenderMode.fullText,
  );

class IgnoreGradientTextSpan extends TextSpan with IgnoreGradientSpan {
  IgnoreGradientTextSpan({String? text, List<InlineSpan>? children})
      : super(
          text: text,
          children: children,
        );
}