SIAB-Scale/lib/screens/main_shell.dart

import 'dart:ui' show ImageFilter;

import 'package:flutter/material.dart';

import 'devices_screen.dart';
import 'timbang_screen.dart';

/// Root scaffold with bottom nav: Devices and Timbang (scale display).
class MainShell extends StatefulWidget {
  const MainShell({super.key});

  @override
  State<MainShell> createState() => _MainShellState();
}

class _MainShellState extends State<MainShell> {
  int _index = 0;

  static const _tabs = [
    (label: 'Devices', icon: Icons.list_alt),
    (label: 'Timbang', icon: Icons.monitor_weight),
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      extendBody: true,
      body: IndexedStack(
        index: _index,
        children: const [
          DevicesScreen(),
          TimbangScreen(),
        ],
      ),
      bottomNavigationBar: _FloatingGlassNavigationBar(
        currentIndex: _index,
        tabs: _tabs,
        onTap: (i) => setState(() => _index = i),
      ),
    );
  }
}

class _FloatingGlassNavigationBar extends StatelessWidget {
  const _FloatingGlassNavigationBar({
    required this.currentIndex,
    required this.tabs,
    required this.onTap,
  });

  final int currentIndex;
  final List<({String label, IconData icon})> tabs;
  final ValueChanged<int> onTap;

  @override
  Widget build(BuildContext context) {
    return SafeArea(
      minimum: const EdgeInsets.fromLTRB(20, 0, 20, 18),
      child: ClipRRect(
        borderRadius: BorderRadius.circular(32),
        child: BackdropFilter(
          filter: ImageFilter.blur(sigmaX: 24, sigmaY: 24),
          child: Container(
            height: 72,
            padding: const EdgeInsets.all(8),
            decoration: BoxDecoration(
              gradient: LinearGradient(
                begin: Alignment.topLeft,
                end: Alignment.bottomRight,
                colors: [
                  Colors.white.withValues(alpha: 0.84),
                  Colors.white.withValues(alpha: 0.62),
                ],
              ),
              borderRadius: BorderRadius.circular(32),
              border: Border.all(color: Colors.white.withValues(alpha: 0.9)),
              boxShadow: [
                BoxShadow(
                  color: const Color(0xFF0F172A).withValues(alpha: 0.13),
                  blurRadius: 34,
                  offset: const Offset(0, 18),
                ),
                BoxShadow(
                  color: const Color(0xFF38BDF8).withValues(alpha: 0.1),
                  blurRadius: 24,
                  offset: const Offset(0, -6),
                ),
              ],
            ),
            child: Row(
              children: [
                for (var i = 0; i < tabs.length; i++)
                  Expanded(
                    child: _GlassNavigationItem(
                      icon: tabs[i].icon,
                      label: tabs[i].label,
                      isSelected: i == currentIndex,
                      onTap: () => onTap(i),
                    ),
                  ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}

class _GlassNavigationItem extends StatelessWidget {
  const _GlassNavigationItem({
    required this.icon,
    required this.label,
    required this.isSelected,
    required this.onTap,
  });

  final IconData icon;
  final String label;
  final bool isSelected;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    const activeColor = Color(0xFF2563EB);
    const inactiveColor = Color(0xFF64748B);

    return Material(
      color: Colors.transparent,
      child: InkWell(
        onTap: onTap,
        borderRadius: BorderRadius.circular(26),
        child: AnimatedContainer(
          duration: const Duration(milliseconds: 220),
          curve: Curves.easeOutCubic,
          alignment: Alignment.center,
          margin: const EdgeInsets.symmetric(horizontal: 2),
          padding: const EdgeInsets.symmetric(horizontal: 10),
          decoration: BoxDecoration(
            gradient: isSelected
                ? LinearGradient(
                    begin: Alignment.topLeft,
                    end: Alignment.bottomRight,
                    colors: [
                      Colors.white.withValues(alpha: 0.95),
                      activeColor.withValues(alpha: 0.12),
                    ],
                  )
                : null,
            color: isSelected ? null : Colors.transparent,
            borderRadius: BorderRadius.circular(26),
            border: Border.all(
              color: isSelected
                  ? Colors.white.withValues(alpha: 0.96)
                  : Colors.transparent,
            ),
            boxShadow: isSelected
                ? [
                    BoxShadow(
                      color: activeColor.withValues(alpha: 0.16),
                      blurRadius: 18,
                      offset: const Offset(0, 8),
                    ),
                  ]
                : null,
          ),
          child: AnimatedScale(
            duration: const Duration(milliseconds: 180),
            curve: Curves.easeOutCubic,
            scale: isSelected ? 1 : 0.96,
            child: Row(
              mainAxisAlignment: MainAxisAlignment.center,
              mainAxisSize: MainAxisSize.min,
              children: [
                Icon(
                  icon,
                  color: isSelected ? activeColor : inactiveColor,
                  size: 22,
                ),
                AnimatedSize(
                  duration: const Duration(milliseconds: 220),
                  curve: Curves.easeOutCubic,
                  child: isSelected
                      ? Row(
                          children: [
                            const SizedBox(width: 8),
                            Text(
                              label,
                              style: const TextStyle(
                                color: Color(0xFF2563EB),
                                fontSize: 13,
                                fontWeight: FontWeight.w900,
                              ),
                            ),
                          ],
                        )
                      : const SizedBox.shrink(),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}