smooth-app/packages/smooth_app/lib/widgets/smooth_app_bar.dart

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:smooth_app/generic_lib/widgets/smooth_back_button.dart';
import 'package:smooth_app/l10n/app_localizations.dart';

/// A custom [AppBar] with an action mode.
/// If [action mode] is true, please provide at least an [actionModeTitle].
class SmoothAppBar extends StatelessWidget implements PreferredSizeWidget {
  SmoothAppBar({
    this.leading,
    this.automaticallyImplyLeading = true,
    this.actionModeTitle,
    this.actionModeSubTitle,
    this.title,
    this.subTitle,
    this.actionModeActions,
    this.actions,
    this.flexibleSpace,
    this.bottom,
    this.elevation = 1.0,
    this.scrolledUnderElevation = 0.0,
    this.notificationPredicate,
    this.shadowColor,
    this.elevationColor,
    this.backgroundColor,
    this.foregroundColor,
    this.iconTheme,
    this.actionsIconTheme,
    this.primary = true,
    this.centerTitle,
    this.excludeHeaderSemantics = false,
    this.titleSpacing,
    this.shape,
    this.toolbarOpacity = 1.0,
    this.bottomOpacity = 1.0,
    this.toolbarHeight,
    this.leadingWidth,
    this.toolbarTextStyle,
    this.titleTextStyle,
    this.systemOverlayStyle,
    this.actionMode = false,
    this.actionModeCloseTooltip,
    this.onLeaveActionMode,
    this.ignoreSemanticsForSubtitle = false,
    this.forceMaterialTransparency = false,
    this.clipBehavior,
    super.key,
  }) : assert(!actionMode || actionModeTitle != null),
       assert(
         elevationColor == null || elevation >= 0.0,
         'elevationColor requires a valid elevation',
       ),
       preferredSize = _PreferredAppBarSize(
         toolbarHeight,
         bottom?.preferredSize.height,
       );

  final Widget? leading;
  final bool automaticallyImplyLeading;
  final Widget? title;
  final Widget? subTitle;
  final Widget? actionModeTitle;
  final Widget? actionModeSubTitle;
  final List<Widget>? actions;
  final List<Widget>? actionModeActions;
  final Widget? flexibleSpace;
  final PreferredSizeWidget? bottom;
  final double elevation;
  final double? scrolledUnderElevation;
  final ScrollNotificationPredicate? notificationPredicate;
  final Color? shadowColor;
  final Color? elevationColor;
  final Color? backgroundColor;
  final Color? foregroundColor;
  final IconThemeData? iconTheme;
  final IconThemeData? actionsIconTheme;
  final bool primary;
  final bool? centerTitle;
  final bool excludeHeaderSemantics;
  final double? titleSpacing;
  final double toolbarOpacity;
  final double bottomOpacity;
  @override
  final Size preferredSize;
  final ShapeBorder? shape;
  final double? toolbarHeight;
  final double? leadingWidth;
  final TextStyle? toolbarTextStyle;
  final TextStyle? titleTextStyle;
  final SystemUiOverlayStyle? systemOverlayStyle;
  final bool? ignoreSemanticsForSubtitle;
  final bool forceMaterialTransparency;
  final Clip? clipBehavior;

  final VoidCallback? onLeaveActionMode;
  final String? actionModeCloseTooltip;
  final bool actionMode;

  @override
  Widget build(BuildContext context) {
    final ModalRoute<dynamic>? parentRoute = ModalRoute.of(context);

    Widget child = actionMode
        ? _createActionModeAppBar(context)
        : _createAppBar(context, parentRoute);

    /// Elevation support is removed with Material 3.0
    if (elevation > 0.0) {
      child = Material(
        color: elevationColor,
        elevation: elevation,
        child: child,
      );
    }

    return AnimatedSwitcher(
      duration: const Duration(milliseconds: 100),
      transitionBuilder: (Widget child, Animation<double> animation) {
        return FadeTransition(
          opacity: Tween<double>(begin: 0.0, end: 1.0).animate(animation),
          child: child,
        );
      },
      child: child,
    );
  }

  Widget _createAppBar(BuildContext context, ModalRoute<dynamic>? parentRoute) {
    final bool useCloseButton =
        parentRoute is PageRoute<dynamic> && parentRoute.fullscreenDialog;
    Widget? leadingWidget = leading;
    if (leadingWidget == null &&
        automaticallyImplyLeading &&
        parentRoute?.impliesAppBarDismissal == true &&
        !useCloseButton) {
      leadingWidget = const SmoothBackButton();
    }

    return AppBar(
      leading: leadingWidget,
      automaticallyImplyLeading: automaticallyImplyLeading,
      title: title != null
          ? _AppBarTitle(
              title: title!,
              subTitle: subTitle,
              titleTextStyle: titleTextStyle,
              color: foregroundColor,
            )
          : null,
      actions: actions,
      flexibleSpace: flexibleSpace,
      bottom: bottom,
      scrolledUnderElevation: scrolledUnderElevation,
      notificationPredicate:
          notificationPredicate ?? defaultScrollNotificationPredicate,
      shadowColor: shadowColor,
      surfaceTintColor:
          backgroundColor ?? Theme.of(context).appBarTheme.backgroundColor,
      backgroundColor: backgroundColor,
      foregroundColor: foregroundColor,
      iconTheme: iconTheme,
      actionsIconTheme: actionsIconTheme,
      primary: primary,
      centerTitle: centerTitle,
      excludeHeaderSemantics: excludeHeaderSemantics,
      titleSpacing: titleSpacing,
      shape: shape,
      toolbarOpacity: toolbarOpacity,
      bottomOpacity: bottomOpacity,
      toolbarHeight: toolbarHeight,
      leadingWidth: leadingWidth,
      toolbarTextStyle: toolbarTextStyle,
      systemOverlayStyle: systemOverlayStyle,
      forceMaterialTransparency: forceMaterialTransparency,
      clipBehavior: clipBehavior,
    );
  }

  Widget _createActionModeAppBar(BuildContext context) => IconTheme(
    data: IconThemeData(color: PopupMenuTheme.of(context).color),
    child: AppBar(
      leading: _ActionModeCloseButton(
        tooltip: AppLocalizations.of(context).cancel,
        onPressed: () {
          onLeaveActionMode?.call();
        },
      ),
      automaticallyImplyLeading: false,
      title: actionModeTitle != null
          ? _AppBarTitle(
              title: actionModeTitle!,
              titleTextStyle: titleTextStyle,
              subTitle: actionModeSubTitle,
              ignoreSemanticsForSubtitle: ignoreSemanticsForSubtitle,
            )
          : null,
      actions: actionModeActions,
      flexibleSpace: flexibleSpace,
      bottom: bottom,
      scrolledUnderElevation: scrolledUnderElevation,
      shadowColor: shadowColor,
      surfaceTintColor:
          backgroundColor ?? Theme.of(context).appBarTheme.backgroundColor,
      backgroundColor: backgroundColor,
      foregroundColor: foregroundColor,
      iconTheme: iconTheme,
      actionsIconTheme: actionsIconTheme,
      primary: primary,
      centerTitle: centerTitle,
      excludeHeaderSemantics: excludeHeaderSemantics,
      titleSpacing: titleSpacing,
      shape: shape,
      toolbarOpacity: toolbarOpacity,
      bottomOpacity: bottomOpacity,
      toolbarHeight: toolbarHeight,
      leadingWidth: leadingWidth,
      toolbarTextStyle: toolbarTextStyle,
      titleTextStyle: titleTextStyle,
      systemOverlayStyle: systemOverlayStyle,
    ),
  );
}

class _PreferredAppBarSize extends Size {
  const _PreferredAppBarSize(this.toolbarHeight, this.bottomHeight)
    : super.fromHeight((toolbarHeight ?? kToolbarHeight) + (bottomHeight ?? 0));

  final double? toolbarHeight;
  final double? bottomHeight;
}

class _ActionModeCloseButton extends StatelessWidget {
  const _ActionModeCloseButton({this.tooltip, this.onPressed});

  final VoidCallback? onPressed;
  final String? tooltip;

  @override
  Widget build(BuildContext context) {
    assert(debugCheckHasMaterialLocalizations(context));
    return IconButton(
      icon: const Icon(Icons.close),
      tooltip: tooltip ?? MaterialLocalizations.of(context).closeButtonTooltip,
      color: PopupMenuTheme.of(context).color,
      onPressed: () {
        if (onPressed != null) {
          onPressed!();
        } else {
          Navigator.maybePop(context);
        }
      },
    );
  }
}

class _AppBarTitle extends StatelessWidget {
  const _AppBarTitle({
    required this.title,
    required this.titleTextStyle,
    required this.subTitle,
    this.color,
    this.ignoreSemanticsForSubtitle,
  });

  final Widget title;
  final TextStyle? titleTextStyle;
  final Widget? subTitle;
  final bool? ignoreSemanticsForSubtitle;
  final Color? color;

  @override
  Widget build(BuildContext context) {
    final ThemeData theme = Theme.of(context);

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: <Widget>[
        DefaultTextStyle(
          maxLines: subTitle != null ? 1 : 2,
          overflow: TextOverflow.ellipsis,
          style:
              (titleTextStyle ??
                      AppBarTheme.of(context).titleTextStyle ??
                      theme.appBarTheme.titleTextStyle?.copyWith(
                        fontWeight: FontWeight.w500,
                      ) ??
                      theme.textTheme.titleLarge?.copyWith(
                        fontWeight: FontWeight.w500,
                      ) ??
                      const TextStyle(
                        fontSize: 20.0,
                        fontWeight: FontWeight.w500,
                      ))
                  .copyWith(color: color),
          child: title,
        ),
        if (subTitle != null)
          DefaultTextStyle(
            style: (theme.textTheme.bodyMedium ?? const TextStyle()).copyWith(
              color: color,
            ),
            child: ExcludeSemantics(
              excluding: ignoreSemanticsForSubtitle ?? false,
              child: subTitle,
            ),
          ),
      ],
    );
  }
}