sm-emby-share/lib/features/detail/widgets/detail_backdrop.dart

import 'dart:io' show Platform;
import 'dart:ui' show ImageFilter;

import 'package:flutter/material.dart';

import '../../../shared/widgets/smart_image.dart';


class DetailBackdrop extends StatefulWidget {
  const DetailBackdrop({
    super.key,
    required this.scrollProgress,
    required this.backdropUrl,
    required this.fallbackUrls,
    required this.embyBaseUrl,
    required this.imageHeaders,
    this.gradientEndColor = const Color(0xFF08090c),
  });

  final ValueNotifier<double> scrollProgress;
  final String backdropUrl;
  final List<String> fallbackUrls;


  final String embyBaseUrl;
  final Map<String, String>? imageHeaders;

  final Color gradientEndColor;

  @override
  State<DetailBackdrop> createState() => _DetailBackdropState();
}

class _DetailBackdropState extends State<DetailBackdrop> {
  bool _backdropFailed = false;

  @override
  void didUpdateWidget(DetailBackdrop oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.backdropUrl != widget.backdropUrl) {
      _backdropFailed = false;
    }
  }

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: [
        Positioned.fill(
          child: _backdropFailed
              ? _buildFallbackGradient()
              : RepaintBoundary(
                  child: ValueListenableBuilder<double>(
                    valueListenable: widget.scrollProgress,
                    builder: (_, p, child) {
                      final maxSigma = Platform.isAndroid ? 6.0 : 10.0;
                      var sigma = p > 0.01 ? p * maxSigma : 0.0;
                      if (Platform.isAndroid && sigma > 0) {
                        sigma = (sigma / 1.5).roundToDouble() * 1.5;
                      }
                      final blurred = ImageFiltered(
                        imageFilter: ImageFilter.blur(
                          sigmaX: sigma,
                          sigmaY: sigma,
                        ),
                        child: child,
                      );
                      if (Platform.isAndroid) return blurred;
                      return Transform.scale(
                        scale: 1.0 + p * 0.15,
                        child: blurred,
                      );
                    },
                    child: _buildImageStack(),
                  ),
                ),
        ),

        Positioned.fill(
          child: ValueListenableBuilder<double>(
            valueListenable: widget.scrollProgress,
            builder: (_, p, _) {
              return IgnorePointer(
                child: ColoredBox(
                  color: Colors.black.withValues(alpha: 0.10 + p * 0.3),
                ),
              );
            },
          ),
        ),

        Positioned.fill(
          child: IgnorePointer(child: _buildBottomGradient(context)),
        ),
      ],
    );
  }


  Widget _buildBottomGradient(BuildContext context) {
    final size = MediaQuery.sizeOf(context);

    final coverage = (size.width * 9.0 / 16.0 / size.height).clamp(0.0, 1.0);


    final rampStart = coverage >= 0.95
        ? 0.5
        : (coverage * 0.55).clamp(0.1, 0.5);
    final rampEnd = coverage >= 0.95
        ? 0.75
        : (coverage * 0.85).clamp(0.25, 0.75);

    return DecoratedBox(
      decoration: BoxDecoration(
        gradient: LinearGradient(
          begin: Alignment.topCenter,
          end: Alignment.bottomCenter,
          stops: [0.0, rampStart, rampEnd, 1.0],
          colors: [
            Colors.transparent,
            Colors.transparent,
            widget.gradientEndColor.withValues(alpha: 0.85),
            widget.gradientEndColor,
          ],
        ),
      ),
    );
  }

  Widget _buildFallbackGradient() {
    return IgnorePointer(
      child: DecoratedBox(
        decoration: BoxDecoration(
          gradient: LinearGradient(
            begin: Alignment.topCenter,
            end: Alignment.bottomCenter,
            stops: const [0.0, 0.6, 1.0],
            colors: [
              widget.gradientEndColor.withValues(alpha: 0.5),
              widget.gradientEndColor.withValues(alpha: 0.85),
              widget.gradientEndColor,
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildImageStack() {
    return _buildArtworkImage(
      fit: BoxFit.fitWidth,
      alignment: Alignment.topCenter,
    );
  }

  Widget _buildArtworkImage({
    required BoxFit fit,
    required Alignment alignment,
    int? memCacheWidth,
  }) {
    final placeholder = DecoratedBox(
      decoration: BoxDecoration(
        gradient: LinearGradient(
          begin: Alignment.topCenter,
          end: Alignment.bottomCenter,
          colors: [
            widget.gradientEndColor.withValues(alpha: 0.3),
            widget.gradientEndColor,
          ],
        ),
      ),
    );

    final imageStack = Stack(
      fit: StackFit.expand,
      children: [
        ColoredBox(color: widget.gradientEndColor),
        SmartImage(
          url: widget.backdropUrl,
          fallbackUrls: widget.fallbackUrls,
          fit: fit,
          alignment: alignment,
          borderRadius: 0,
          memCacheWidth: memCacheWidth,
          placeholder: placeholder,
          onError: () {
            if (mounted && !_backdropFailed) {
              setState(() => _backdropFailed = true);
            }
          },
          resolveHttpHeaders: (url) =>
              widget.embyBaseUrl.isNotEmpty &&
                  url.startsWith(widget.embyBaseUrl)
              ? widget.imageHeaders
              : null,
        ),
      ],
    );
    return imageStack;
  }
}