tm_app/lib/views/tenders/widgets/tender_card_shimmer.dart

import 'package:flutter/material.dart';
import 'package:tm_app/core/theme/colors.dart';
import 'package:tm_app/core/utils/size_config.dart';

class TenderCardShimmer extends StatelessWidget {
  const TenderCardShimmer({super.key, this.isDesktop = false});

  final bool isDesktop;

  @override
  Widget build(BuildContext context) {
    return _Shimmer(
      child: Container(
        width: double.infinity,
        margin: EdgeInsets.symmetric(horizontal: 16.0.w()),
        height: isDesktop ? 350.0.h() : 587.0.h(),
        padding: EdgeInsets.all(16.0.w()),
        decoration: BoxDecoration(
          color: AppColors.grey0,
          borderRadius: BorderRadius.circular(12),
          border: Border.all(color: AppColors.grey30),
        ),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            _bar(width: isDesktop ? 120.0.w() : 140.0.w(), height: 14.0.h()),
            SizedBox(height: 16.0.h()),
            _block(height: isDesktop ? 58.0.h() : 70.0.h()),
            SizedBox(height: isDesktop ? 12.0.h() : 20.0.h()),
            _bar(width: double.infinity, height: 18.0.h()),
            SizedBox(height: 8.0.h()),
            _fractionBar(widthFactor: 0.72, height: 18.0.h()),
            SizedBox(height: 16.0.h()),
            _bar(width: double.infinity, height: 14.0.h()),
            SizedBox(height: 8.0.h()),
            _bar(width: double.infinity, height: 14.0.h()),
            SizedBox(height: 8.0.h()),
            _fractionBar(widthFactor: 0.55, height: 14.0.h()),
            const Spacer(),
            Row(
              children: [
                _circle(size: 24.0.h()),
                SizedBox(width: 8.0.w()),
                _bar(width: 60.0.w(), height: 14.0.h()),
                const Spacer(),
                _pill(width: 108.0.w(), height: 40.0.h()),
              ],
            ),
          ],
        ),
      ),
    );
  }

  Widget _bar({required double width, required double height}) {
    return Container(
      width: width,
      height: height,
      decoration: BoxDecoration(
        color: AppColors.grey20,
        borderRadius: BorderRadius.circular(6),
      ),
    );
  }

  Widget _fractionBar({required double widthFactor, required double height}) {
    return FractionallySizedBox(
      widthFactor: widthFactor,
      alignment: AlignmentDirectional.centerStart,
      child: _bar(width: double.infinity, height: height),
    );
  }

  Widget _block({required double height}) {
    return Container(
      width: double.infinity,
      height: height,
      decoration: BoxDecoration(
        color: AppColors.grey20,
        borderRadius: BorderRadius.circular(4),
      ),
    );
  }

  Widget _pill({required double width, required double height}) {
    return Container(
      width: width,
      height: height,
      decoration: BoxDecoration(
        color: AppColors.grey20,
        borderRadius: BorderRadius.circular(100),
      ),
    );
  }

  Widget _circle({required double size}) {
    return Container(
      width: size,
      height: size,
      decoration: BoxDecoration(
        color: AppColors.grey20,
        shape: BoxShape.circle,
      ),
    );
  }
}

class _Shimmer extends StatefulWidget {
  const _Shimmer({required this.child});

  final Widget child;

  @override
  State<_Shimmer> createState() => _ShimmerState();
}

class _ShimmerState extends State<_Shimmer>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      vsync: this,
      duration: const Duration(milliseconds: 1400),
    )..repeat();
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _controller,
      child: widget.child,
      builder: (context, child) {
        return ShaderMask(
          blendMode: BlendMode.srcATop,
          shaderCallback: (bounds) {
            final shimmerWidth = bounds.width * 0.8;
            final offset = (bounds.width + shimmerWidth) * _controller.value;
            return LinearGradient(
              begin: Alignment.centerLeft,
              end: Alignment.centerRight,
              colors: [AppColors.grey20, AppColors.grey10, AppColors.grey20],
              stops: const [0.25, 0.5, 0.75],
              transform: _SlidingGradientTransform(
                slidePercent: (offset - shimmerWidth) / bounds.width,
              ),
            ).createShader(bounds);
          },
          child: child,
        );
      },
    );
  }
}

class _SlidingGradientTransform extends GradientTransform {
  const _SlidingGradientTransform({required this.slidePercent});

  final double slidePercent;

  @override
  Matrix4 transform(Rect bounds, {TextDirection? textDirection}) {
    return Matrix4.translationValues(bounds.width * slidePercent, 0, 0);
  }
}