import "dart:ui" show ImageFilter;

import "package:flutter/widgets.dart";

import "package:garage_ui/theme/garage_theme.dart";

/// The entrance a Garage pane dialog makes: blurred backdrop, dimmed scrim,
/// fade and scale in, width clamped to the viewport.
///
/// This lived twice in Arcs & Angles - once for the titled pane and once for
/// the Blender-language one - identical apart from the shell widget wrapped
/// around the content. The presentation is the generic half, so it lives here
/// and [builder] supplies the shell.
///
/// [builder] is handed an `onClose` that pops the route, or null when
/// [dismissible] is false, so the shell can wire its own close affordance.
/// Content pops with its own result the usual way.
Future<T?> showPaneOverlay<T>({
  required BuildContext context,
  required Widget Function(BuildContext context, VoidCallback? onClose) builder,
  double maxWidth = 450,
  bool dismissible = true,
  String? barrierLabel,
  Duration duration = const Duration(milliseconds: 180),
  double blurSigma = 3,
  double scrimOpacity = 0.35,
  double enterScale = 0.93,
  double viewportInset = 24,
}) {
  // read before the route is pushed so it reflects the theme at the call site
  // rather than whatever sits above the navigator.
  final scrim = GarageTheme.of(context).colorScheme.background;

  return showGeneralDialog<T>(
    context: context,
    barrierDismissible: false,
    barrierColor: const Color(0x00000000),
    barrierLabel: barrierLabel,
    transitionDuration: duration,
    pageBuilder: (ctx, anim, secondaryAnim) => const SizedBox.shrink(),
    transitionBuilder: (ctx, anim, secondaryAnim, _) {
      final fade = CurvedAnimation(parent: anim, curve: Curves.easeOut);
      final scale = Tween<double>(
        begin: enterScale,
        end: 1.0,
      ).animate(CurvedAnimation(parent: anim, curve: Curves.easeOut));

      final screenW = MediaQuery.sizeOf(ctx).width;
      final maxW = (screenW - viewportInset).clamp(0.0, maxWidth);

      void close() => Navigator.of(ctx).pop();

      return Stack(
        children: [
          Positioned.fill(
            child: FadeTransition(
              opacity: fade,
              child: BackdropFilter(
                filter: ImageFilter.blur(sigmaX: blurSigma, sigmaY: blurSigma),
                child: GestureDetector(
                  // a dismiss scrim, not a control - Escape and the dialog's
                  // own close button are the reachable ways out. Left in the
                  // tree it reads as a full-screen unnamed button.
                  excludeFromSemantics: true,
                  onTap: dismissible ? close : null,
                  child: ColoredBox(
                    color: scrim.withValues(alpha: scrimOpacity),
                  ),
                ),
              ),
            ),
          ),
          Center(
            child: FadeTransition(
              opacity: fade,
              child: ScaleTransition(
                scale: scale,
                child: ConstrainedBox(
                  constraints: BoxConstraints(minWidth: maxW, maxWidth: maxW),
                  child: builder(ctx, dismissible ? close : null),
                ),
              ),
            ),
          ),
        ],
      );
    },
  );
}