import 'dart:async';

import 'package:flutter/material.dart';

import '../data/hub.dart';
import '../theme/theme.dart';
import '../theme/tokens.dart';
import '../widgets/widgets.dart';

class AuditPage extends StatefulWidget {
  const AuditPage({super.key});

  @override
  State<AuditPage> createState() => _AuditPageState();
}

class _AuditPageState extends State<AuditPage> {
  String _typeFilter = 'all';
  List<AuditEvent> _events = const [];
  String? _error;
  bool _initialLoaded = false;
  Timer? _poller;

  @override
  void initState() {
    super.initState();
    _refresh();
    _poller = Timer.periodic(
      const Duration(seconds: 2),
      (_) => _refresh(),
    );
  }

  @override
  void dispose() {
    _poller?.cancel();
    super.dispose();
  }

  Future<void> _refresh() async {
    try {
      final events = await HubService.instance.recentEvents(limit: 100);
      if (!mounted) return;
      setState(() {
        _events = events;
        _error = null;
        _initialLoaded = true;
      });
    } catch (e) {
      if (!mounted) return;
      setState(() {
        _error = e.toString();
        _initialLoaded = true;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final filtered = _typeFilter == 'all'
        ? _events
        : _events.where((e) => e.type.startsWith(_typeFilter)).toList();

    return Scaffold(
      backgroundColor: theme.scaffoldBackgroundColor,
      appBar: AppBar(
        title: const Text('Audit'),
        actions: [
          Padding(
            padding: const EdgeInsets.only(right: FaiSpace.lg),
            child: _FilterChips(
              value: _typeFilter,
              onChanged: (v) => setState(() => _typeFilter = v),
            ),
          ),
        ],
      ),
      body: Column(
        children: [
          _LiveStatusBar(eventCount: filtered.length, error: _error),
          Expanded(
            child: !_initialLoaded
                ? const Center(child: CircularProgressIndicator())
                : _error != null && _events.isEmpty
                    ? FaiEmptyState(
                        icon: Icons.cloud_off_outlined,
                        iconColor: theme.colorScheme.error,
                        title: 'Hub unreachable',
                        hint: 'Start the hub with `fai serve`.',
                      )
                    : filtered.isEmpty
                        ? const FaiEmptyState(
                            icon: Icons.timeline_outlined,
                            title: 'No events yet',
                            hint:
                                'Run a flow to populate the audit stream.\nEvents appear here within seconds.',
                          )
                        : ListView.separated(
                            padding: const EdgeInsets.all(FaiSpace.xl),
                            itemCount: filtered.length,
                            separatorBuilder: (_, _) =>
                                const SizedBox(height: FaiSpace.xs),
                            itemBuilder: (context, i) {
                              final e = filtered[i];
                              return FaiDataRow(
                                accent: _toneFor(e.type, theme),
                                leading: _formatTime(e.timestamp),
                                title: e.type,
                                subtitle: _contextLine(e),
                                trailing: e.durationMs != null
                                    ? '${e.durationMs}ms'
                                    : null,
                              );
                            },
                          ),
          ),
        ],
      ),
    );
  }

  String _formatTime(DateTime ts) =>
      '${ts.hour.toString().padLeft(2, '0')}:${ts.minute.toString().padLeft(2, '0')}:${ts.second.toString().padLeft(2, '0')}';

  String _contextLine(AuditEvent e) {
    final parts = <String>[];
    if (e.flowName != null) parts.add(e.flowName!);
    if (e.stepId != null) parts.add(' › ${e.stepId}');
    if (e.moduleName != null) parts.add('  via ${e.moduleName}');
    if (e.error != null) parts.add('  [error: ${e.error}]');
    return parts.join('');
  }

  Color _toneFor(String type, ThemeData theme) {
    if (type.endsWith('.failed')) return theme.colorScheme.error;
    if (type.endsWith('.completed')) return theme.colorScheme.primary;
    if (type.endsWith('.started')) return FaiColors.warning;
    return theme.colorScheme.outline;
  }
}

class _FilterChips extends StatelessWidget {
  final String value;
  final ValueChanged<String> onChanged;

  const _FilterChips({required this.value, required this.onChanged});

  @override
  Widget build(BuildContext context) {
    const items = [
      ('all', 'all'),
      ('flow.', 'flow'),
      ('step.', 'step'),
      ('module.', 'module'),
    ];
    return Row(
      children: [
        for (final (v, label) in items)
          Padding(
            padding: const EdgeInsets.only(left: FaiSpace.xs),
            child: _ChipButton(
              label: label,
              selected: value == v,
              onTap: () => onChanged(v),
            ),
          ),
      ],
    );
  }
}

class _ChipButton extends StatefulWidget {
  final String label;
  final bool selected;
  final VoidCallback onTap;

  const _ChipButton({
    required this.label,
    required this.selected,
    required this.onTap,
  });

  @override
  State<_ChipButton> createState() => _ChipButtonState();
}

class _ChipButtonState extends State<_ChipButton> {
  bool _hovered = false;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final fg = widget.selected
        ? theme.colorScheme.primary
        : _hovered
            ? theme.colorScheme.onSurface
            : theme.colorScheme.onSurfaceVariant;
    final bg = widget.selected
        ? theme.colorScheme.primary.withValues(alpha: 0.12)
        : _hovered
            ? theme.colorScheme.surfaceContainerHigh
            : Colors.transparent;
    return MouseRegion(
      onEnter: (_) => setState(() => _hovered = true),
      onExit: (_) => setState(() => _hovered = false),
      cursor: SystemMouseCursors.click,
      child: GestureDetector(
        onTap: widget.onTap,
        child: AnimatedContainer(
          duration: FaiMotion.fast,
          padding: const EdgeInsets.symmetric(
            horizontal: FaiSpace.md,
            vertical: 6,
          ),
          decoration: BoxDecoration(
            color: bg,
            borderRadius: BorderRadius.circular(FaiRadius.sm),
            border: Border.all(
              color: widget.selected
                  ? theme.colorScheme.primary.withValues(alpha: 0.3)
                  : Colors.transparent,
            ),
          ),
          child: Text(
            widget.label,
            style: FaiTheme.mono(
              size: 11,
              weight: widget.selected ? FontWeight.w500 : FontWeight.w400,
              color: fg,
            ),
          ),
        ),
      ),
    );
  }
}

class _LiveStatusBar extends StatelessWidget {
  final int eventCount;
  final String? error;

  const _LiveStatusBar({required this.eventCount, required this.error});

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final live = error == null;
    return Container(
      width: double.infinity,
      padding: const EdgeInsets.symmetric(
        horizontal: FaiSpace.xl,
        vertical: FaiSpace.sm,
      ),
      decoration: BoxDecoration(
        color: theme.colorScheme.surfaceContainerHigh,
        border: Border(
          bottom: BorderSide(color: theme.colorScheme.outlineVariant),
        ),
      ),
      child: Row(
        children: [
          FaiStatusDot(
            color: live ? FaiColors.success : FaiColors.danger,
            pulsing: live,
          ),
          const SizedBox(width: FaiSpace.sm),
          Text(
            live
                ? 'live · polling 2s · $eventCount event${eventCount == 1 ? '' : 's'}'
                : 'disconnected · $error',
            style: theme.textTheme.bodySmall?.copyWith(
              color: theme.colorScheme.onSurfaceVariant,
            ),
          ),
          const Spacer(),
          if (live)
            Row(
              children: [
                Icon(
                  Icons.shield_outlined,
                  size: 12,
                  color: theme.colorScheme.primary,
                ),
                const SizedBox(width: 4),
                Text(
                  'hash chain verified',
                  style: theme.textTheme.bodySmall?.copyWith(
                    color: theme.colorScheme.primary,
                    fontWeight: FontWeight.w500,
                  ),
                ),
              ],
            ),
        ],
      ),
    );
  }
}