import 'package:flutter/material.dart';

class GetModalBottomSheetRoute<T> extends PopupRoute<T> {
  GetModalBottomSheetRoute({
    this.builder,
    this.theme,
    this.barrierLabel,
    this.backgroundColor,
    this.elevation,
    this.shape,
    this.removeTop = true,
    this.clipBehavior,
    this.modalBarrierColor,
    this.isDismissible = true,
    this.enableDrag = true,
    @required this.isScrollControlled,
    RouteSettings settings,
  })  : assert(isScrollControlled != null),
        name = "BOTTOMSHEET: ${builder.hashCode}",
        assert(isDismissible != null),
        assert(enableDrag != null),
        super(settings: settings);

  final WidgetBuilder builder;
  final ThemeData theme;
  final bool isScrollControlled;
  final Color backgroundColor;
  final double elevation;
  final ShapeBorder shape;
  final Clip clipBehavior;
  final Color modalBarrierColor;
  final bool isDismissible;
  final bool enableDrag;
  final String name;

  // remove safearea from top
  final bool removeTop;

  @override
  Duration get transitionDuration => Duration(milliseconds: 700);

  @override
  bool get barrierDismissible => isDismissible;

  @override
  final String barrierLabel;

  @override
  Color get barrierColor => modalBarrierColor ?? Colors.black54;

  AnimationController _animationController;

  @override
  AnimationController createAnimationController() {
    assert(_animationController == null);
    _animationController =
        BottomSheet.createAnimationController(navigator.overlay);
    return _animationController;
  }

  @override
  Widget buildPage(BuildContext context, Animation<double> animation,
      Animation<double> secondaryAnimation) {
    final sheetTheme =
        theme?.bottomSheetTheme ?? Theme.of(context).bottomSheetTheme;
    // By definition, the bottom sheet is aligned to the bottom of the page
    // and isn't exposed to the top padding of the MediaQuery.
    Widget bottomSheet = MediaQuery.removePadding(
      context: context,
      removeTop: removeTop,
      child: Padding(
        padding:
            EdgeInsets.only(bottom: MediaQuery.of(context).viewInsets.bottom),
        child: _GetModalBottomSheet<T>(
          route: this,
          backgroundColor: backgroundColor ??
              sheetTheme?.modalBackgroundColor ??
              sheetTheme?.backgroundColor,
          elevation:
              elevation ?? sheetTheme?.modalElevation ?? sheetTheme?.elevation,
          shape: shape,
          clipBehavior: clipBehavior,
          isScrollControlled: isScrollControlled,
          enableDrag: enableDrag,
        ),
      ),
    );
    if (theme != null) bottomSheet = Theme(data: theme, child: bottomSheet);
    return bottomSheet;
  }
}

class _GetModalBottomSheet<T> extends StatefulWidget {
  const _GetModalBottomSheet({
    Key key,
    this.route,
    this.backgroundColor,
    this.elevation,
    this.shape,
    this.clipBehavior,
    this.isScrollControlled = false,
    this.enableDrag = true,
  })  : assert(isScrollControlled != null),
        assert(enableDrag != null),
        super(key: key);

  final GetModalBottomSheetRoute<T> route;
  final bool isScrollControlled;
  final Color backgroundColor;
  final double elevation;
  final ShapeBorder shape;
  final Clip clipBehavior;
  final bool enableDrag;

  @override
  _GetModalBottomSheetState<T> createState() => _GetModalBottomSheetState<T>();
}

class _GetModalBottomSheetState<T> extends State<_GetModalBottomSheet<T>> {
  String _getRouteLabel(MaterialLocalizations localizations) {
    if ((Theme.of(context).platform == TargetPlatform.android) ||
        (Theme.of(context).platform == TargetPlatform.fuchsia)) {
      return localizations.dialogLabel;
    } else {
      return '';
    }
  }

  @override
  Widget build(BuildContext context) {
    assert(debugCheckHasMediaQuery(context));
    assert(debugCheckHasMaterialLocalizations(context));
    final mediaQuery = MediaQuery.of(context);
    final localizations = MaterialLocalizations.of(context);
    final routeLabel = _getRouteLabel(localizations);

    return AnimatedBuilder(
      animation: widget.route.animation,
      builder: (context, child) {
        // Disable the initial animation when accessible navigation is on so
        // that the semantics are added to the tree at the correct time.
        final animationValue = mediaQuery.accessibleNavigation
            ? 1.0
            : widget.route.animation.value;
        return Semantics(
          scopesRoute: true,
          namesRoute: true,
          label: routeLabel,
          explicitChildNodes: true,
          child: ClipRect(
            child: CustomSingleChildLayout(
              delegate: _GetModalBottomSheetLayout(
                  animationValue, widget.isScrollControlled),
              child: BottomSheet(
                animationController: widget.route._animationController,
                onClosing: () {
                  if (widget.route.isCurrent) {
                    Navigator.pop(context);
                  }
                },
                builder: widget.route.builder,
                backgroundColor: widget.backgroundColor,
                elevation: widget.elevation,
                shape: widget.shape,
                clipBehavior: widget.clipBehavior,
                enableDrag: widget.enableDrag,
              ),
            ),
          ),
        );
      },
    );
  }
}

class _GetModalBottomSheetLayout extends SingleChildLayoutDelegate {
  _GetModalBottomSheetLayout(this.progress, this.isScrollControlled);

  final double progress;
  final bool isScrollControlled;

  @override
  BoxConstraints getConstraintsForChild(BoxConstraints constraints) {
    return BoxConstraints(
      minWidth: constraints.maxWidth,
      maxWidth: constraints.maxWidth,
      minHeight: 0.0,
      maxHeight: isScrollControlled
          ? constraints.maxHeight
          : constraints.maxHeight * 9.0 / 16.0,
    );
  }

  @override
  Offset getPositionForChild(Size size, Size childSize) {
    return Offset(0.0, size.height - childSize.height * progress);
  }

  @override
  bool shouldRelayout(_GetModalBottomSheetLayout oldDelegate) {
    return progress != oldDelegate.progress;
  }
}