import 'package:flutter/material.dart';

import '../../../models/network/network_device.dart';
import '../../../models/network/network_link.dart';

/// Collapsible legend overlay explaining device role border colours and link
/// type colours. Positioned at the bottom-left of the topology canvas view.
class TopologyLegend extends StatefulWidget {
  const TopologyLegend({super.key});

  @override
  State<TopologyLegend> createState() => _TopologyLegendState();
}

class _TopologyLegendState extends State<TopologyLegend>
    with SingleTickerProviderStateMixin {
  bool _expanded = false;
  late final AnimationController _anim;
  late final Animation<double> _fade;

  @override
  void initState() {
    super.initState();
    _anim = AnimationController(
      vsync: this,
      duration: const Duration(milliseconds: 200),
    );
    _fade = CurvedAnimation(parent: _anim, curve: Curves.easeOut);
  }

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

  void _toggle() {
    setState(() => _expanded = !_expanded);
    if (_expanded) {
      _anim.forward();
    } else {
      _anim.reverse();
    }
  }

  Color _roleColor(ColorScheme cs, NetworkDeviceRole role) {
    switch (role) {
      case NetworkDeviceRole.core:
        return cs.error;
      case NetworkDeviceRole.distribution:
        return cs.tertiary;
      case NetworkDeviceRole.access:
        return cs.primary;
      case NetworkDeviceRole.edge:
        return cs.secondary;
      case NetworkDeviceRole.endpoint:
        return cs.outline;
    }
  }

  Color _linkColor(ColorScheme cs, NetworkLinkKind kind) {
    switch (kind) {
      case NetworkLinkKind.copper:
        return cs.primary;
      case NetworkLinkKind.fiber:
        return cs.tertiary;
      case NetworkLinkKind.wireless:
        return cs.secondary;
      case NetworkLinkKind.virtual:
        return cs.outline;
      case NetworkLinkKind.unknown:
        return cs.outline;
    }
  }

  @override
  Widget build(BuildContext context) {
    final cs = Theme.of(context).colorScheme;
    final tt = Theme.of(context).textTheme;

    return Column(
      mainAxisSize: MainAxisSize.min,
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        // Expand/collapse toggle chip
        Material(
          color: cs.surfaceContainerHigh,
          borderRadius: BorderRadius.circular(20),
          elevation: 2,
          child: InkWell(
            onTap: _toggle,
            borderRadius: BorderRadius.circular(20),
            child: Padding(
              padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 6),
              child: Row(
                mainAxisSize: MainAxisSize.min,
                children: [
                  Icon(
                    Icons.legend_toggle_outlined,
                    size: 16,
                    color: cs.onSurfaceVariant,
                  ),
                  const SizedBox(width: 6),
                  Text(
                    'Legend',
                    style: tt.labelSmall?.copyWith(
                      color: cs.onSurfaceVariant,
                      fontWeight: FontWeight.w600,
                    ),
                  ),
                  const SizedBox(width: 4),
                  AnimatedRotation(
                    turns: _expanded ? 0.5 : 0,
                    duration: const Duration(milliseconds: 200),
                    child: Icon(
                      Icons.expand_more,
                      size: 16,
                      color: cs.onSurfaceVariant,
                    ),
                  ),
                ],
              ),
            ),
          ),
        ),
        // Expandable panel
        FadeTransition(
          opacity: _fade,
          child: SizeTransition(
            sizeFactor: _fade,
            axisAlignment: -1,
            child: Padding(
              padding: const EdgeInsets.only(top: 6),
              child: Material(
                color: cs.surfaceContainerHigh,
                borderRadius: BorderRadius.circular(12),
                elevation: 3,
                child: Padding(
                  padding: const EdgeInsets.all(12),
                  child: SizedBox(
                    width: 200,
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      mainAxisSize: MainAxisSize.min,
                      children: [
                        // ── Device Roles ─────────────────────────────
                        Text(
                          'Device Roles',
                          style: tt.labelSmall?.copyWith(
                            color: cs.onSurfaceVariant,
                            fontWeight: FontWeight.w700,
                            letterSpacing: 0.8,
                          ),
                        ),
                        const SizedBox(height: 6),
                        for (final role in NetworkDeviceRole.values)
                          _LegendRow(
                            color: _roleColor(cs, role),
                            label: role.label,
                            isLine: false,
                          ),
                        const SizedBox(height: 10),
                        Divider(
                            height: 1,
                            color: cs.outlineVariant.withValues(alpha: 0.5)),
                        const SizedBox(height: 10),
                        // ── Link Types ───────────────────────────────
                        Text(
                          'Link Types',
                          style: tt.labelSmall?.copyWith(
                            color: cs.onSurfaceVariant,
                            fontWeight: FontWeight.w700,
                            letterSpacing: 0.8,
                          ),
                        ),
                        const SizedBox(height: 6),
                        for (final kind in NetworkLinkKind.values)
                          _LegendRow(
                            color: _linkColor(cs, kind),
                            label: kind.label,
                            isLine: true,
                          ),
                      ],
                    ),
                  ),
                ),
              ),
            ),
          ),
        ),
      ],
    );
  }
}

class _LegendRow extends StatelessWidget {
  const _LegendRow({
    required this.color,
    required this.label,
    required this.isLine,
  });

  final Color color;
  final String label;
  final bool isLine;

  @override
  Widget build(BuildContext context) {
    final tt = Theme.of(context).textTheme;
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 2),
      child: Row(
        children: [
          if (isLine)
            // Coloured line segment for link types
            Container(
              width: 20,
              height: 3,
              decoration: BoxDecoration(
                color: color,
                borderRadius: BorderRadius.circular(2),
              ),
            )
          else
            // Coloured square for device roles (border indicator)
            Container(
              width: 12,
              height: 12,
              decoration: BoxDecoration(
                border: Border.all(color: color, width: 2),
                borderRadius: BorderRadius.circular(3),
              ),
            ),
          const SizedBox(width: 8),
          Text(
            label,
            style: tt.labelSmall?.copyWith(
              color: Theme.of(context).colorScheme.onSurface,
            ),
          ),
        ],
      ),
    );
  }
}