import 'package:flutter/material.dart';

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

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

  @override
  State<DoctorPage> createState() => _DoctorPageState();
}

class _DoctorPageState extends State<DoctorPage> {
  late Future<DoctorSnapshot> _future;

  @override
  void initState() {
    super.initState();
    _future = HubService.instance.doctor();
  }

  void _refresh() => setState(() {
        _future = HubService.instance.doctor();
      });

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Theme.of(context).scaffoldBackgroundColor,
      appBar: AppBar(
        title: const Text('Doctor'),
        actions: [
          IconButton(
            icon: const Icon(Icons.refresh, size: 18),
            tooltip: 'Re-check',
            onPressed: _refresh,
          ),
          const SizedBox(width: FaiSpace.sm),
        ],
      ),
      body: FutureBuilder<DoctorSnapshot>(
        future: _future,
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return const Center(child: CircularProgressIndicator());
          }
          if (snapshot.hasError) {
            return FaiEmptyState(
              icon: Icons.cloud_off_outlined,
              iconColor: Theme.of(context).colorScheme.error,
              title: 'Hub unreachable',
              hint: 'Start the hub with `fai serve`.',
              action: FilledButton.tonal(
                onPressed: _refresh,
                child: const Text('Retry'),
              ),
            );
          }
          final s = snapshot.data!;
          final showUpdate = s.update.updateAvailable ||
              (!s.update.manifestReachable &&
                  s.update.localVersion.isNotEmpty);
          return ListView(
            padding: const EdgeInsets.all(FaiSpace.xl),
            children: [
              if (showUpdate) _UpdateBanner(status: s.update),
              if (showUpdate) const SizedBox(height: FaiSpace.lg),
              _SummaryStrip(snapshot: s),
              const SizedBox(height: FaiSpace.xl),
              _Section(
                title: 'Event log',
                child: _EventLogPanel(snapshot: s),
              ),
              const SizedBox(height: FaiSpace.lg),
              _Section(
                title: 'Modules & approvals',
                child: _ModulesPanel(snapshot: s),
              ),
              const SizedBox(height: FaiSpace.lg),
              _Section(
                title: 'Host services',
                child: _ServicesPanel(snapshot: s),
              ),
            ],
          );
        },
      ),
    );
  }
}

class _Section extends StatelessWidget {
  final String title;
  final Widget child;

  const _Section({required this.title, required this.child});

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Padding(
          padding: const EdgeInsets.only(left: FaiSpace.xs, bottom: FaiSpace.sm),
          child: Text(
            title.toUpperCase(),
            style: theme.textTheme.labelSmall?.copyWith(
              color: theme.colorScheme.onSurfaceVariant,
              letterSpacing: 0.6,
              fontSize: 10,
            ),
          ),
        ),
        child,
      ],
    );
  }
}

class _SummaryStrip extends StatelessWidget {
  final DoctorSnapshot snapshot;

  const _SummaryStrip({required this.snapshot});

  @override
  Widget build(BuildContext context) {
    return Row(
      children: [
        _StatTile(
          label: 'Modules',
          value: snapshot.moduleCount.toString(),
          subtitle: '${snapshot.capabilityCount} capabilities',
          icon: Icons.extension_outlined,
        ),
        const SizedBox(width: FaiSpace.md),
        _StatTile(
          label: 'Approvals',
          value: snapshot.pendingApprovals.toString(),
          subtitle: 'pending',
          icon: Icons.inbox_outlined,
          tone: snapshot.pendingApprovals > 0
              ? FaiPillTone.warning
              : FaiPillTone.neutral,
        ),
        const SizedBox(width: FaiSpace.md),
        _StatTile(
          label: 'Audit',
          value: snapshot.chainHealthy ? '✓' : '⚠',
          subtitle:
              '${snapshot.eventChainVerified}/${snapshot.eventChainTotal} chain',
          icon: Icons.shield_outlined,
          tone: snapshot.chainHealthy
              ? FaiPillTone.success
              : FaiPillTone.danger,
        ),
        const SizedBox(width: FaiSpace.md),
        _StatTile(
          label: 'Services',
          value: snapshot.services.length.toString(),
          subtitle: 'declared',
          icon: Icons.dns_outlined,
        ),
      ],
    );
  }
}

class _StatTile extends StatelessWidget {
  final String label;
  final String value;
  final String subtitle;
  final IconData icon;
  final FaiPillTone tone;

  const _StatTile({
    required this.label,
    required this.value,
    required this.subtitle,
    required this.icon,
    this.tone = FaiPillTone.neutral,
  });

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final accentColor = switch (tone) {
      FaiPillTone.success => FaiColors.success,
      FaiPillTone.warning => FaiColors.warning,
      FaiPillTone.danger => theme.colorScheme.error,
      _ => theme.colorScheme.primary,
    };
    return Expanded(
      child: FaiCard(
        accentLeft: accentColor,
        padding: const EdgeInsets.all(FaiSpace.lg),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                Icon(icon, size: 14, color: theme.colorScheme.onSurfaceVariant),
                const SizedBox(width: FaiSpace.xs),
                Flexible(
                  child: Text(
                    label.toUpperCase(),
                    overflow: TextOverflow.ellipsis,
                    style: theme.textTheme.labelSmall?.copyWith(
                      color: theme.colorScheme.onSurfaceVariant,
                      letterSpacing: 0.5,
                      fontSize: 10,
                    ),
                  ),
                ),
              ],
            ),
            const SizedBox(height: FaiSpace.sm),
            Text(
              value,
              style: theme.textTheme.displaySmall?.copyWith(
                color: accentColor,
                fontWeight: FontWeight.w700,
              ),
            ),
            const SizedBox(height: 2),
            Text(
              subtitle,
              style: theme.textTheme.bodySmall?.copyWith(
                color: theme.colorScheme.onSurfaceVariant,
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class _EventLogPanel extends StatelessWidget {
  final DoctorSnapshot snapshot;

  const _EventLogPanel({required this.snapshot});

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final healthy = snapshot.chainHealthy;
    return FaiCard(
      child: Row(
        children: [
          Icon(
            healthy ? Icons.verified_outlined : Icons.gpp_bad_outlined,
            size: 24,
            color: healthy ? FaiColors.success : theme.colorScheme.error,
          ),
          const SizedBox(width: FaiSpace.lg),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  healthy
                      ? 'Hash chain intact'
                      : 'Tampering detected',
                  style: theme.textTheme.titleMedium?.copyWith(
                    fontWeight: FontWeight.w600,
                  ),
                ),
                const SizedBox(height: 2),
                Text(
                  healthy
                      ? '${snapshot.eventChainTotal} events · prev_event_sha256 verified end-to-end'
                      : '${snapshot.eventChainVerified} of ${snapshot.eventChainTotal} verified before mismatch at ${snapshot.eventChainTamperedAt}',
                  style: theme.textTheme.bodySmall?.copyWith(
                    color: theme.colorScheme.onSurfaceVariant,
                  ),
                ),
              ],
            ),
          ),
          FaiPill(
            label: healthy ? 'WORM-1' : 'TAMPER',
            tone: healthy ? FaiPillTone.success : FaiPillTone.danger,
          ),
        ],
      ),
    );
  }
}

class _ModulesPanel extends StatelessWidget {
  final DoctorSnapshot snapshot;

  const _ModulesPanel({required this.snapshot});

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return FaiCard(
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Row(
            children: [
              Icon(
                Icons.extension_outlined,
                size: 18,
                color: theme.colorScheme.onSurfaceVariant,
              ),
              const SizedBox(width: FaiSpace.sm),
              Text(
                '${snapshot.moduleCount} modules · ${snapshot.capabilityCount} capabilities',
                style: theme.textTheme.bodyMedium,
              ),
              const Spacer(),
              FaiPill(
                label: snapshot.moduleCount > 0 ? 'loaded' : 'empty',
                tone: snapshot.moduleCount > 0
                    ? FaiPillTone.success
                    : FaiPillTone.neutral,
              ),
            ],
          ),
          const Divider(height: FaiSpace.xl),
          Row(
            children: [
              Icon(
                Icons.inbox_outlined,
                size: 18,
                color: theme.colorScheme.onSurfaceVariant,
              ),
              const SizedBox(width: FaiSpace.sm),
              Text(
                snapshot.pendingApprovals == 0
                    ? 'No pending approvals'
                    : '${snapshot.pendingApprovals} approval${snapshot.pendingApprovals == 1 ? '' : 's'} awaiting review',
                style: theme.textTheme.bodyMedium,
              ),
              const Spacer(),
              if (snapshot.pendingApprovals > 0)
                FaiPill(
                  label: 'attention',
                  tone: FaiPillTone.warning,
                ),
            ],
          ),
        ],
      ),
    );
  }
}

class _ServicesPanel extends StatelessWidget {
  final DoctorSnapshot snapshot;

  const _ServicesPanel({required this.snapshot});

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    if (snapshot.services.isEmpty) {
      return FaiCard(
        child: Row(
          children: [
            Icon(
              Icons.dns_outlined,
              size: 18,
              color: theme.colorScheme.onSurfaceVariant,
            ),
            const SizedBox(width: FaiSpace.sm),
            Text(
              'No host services declared',
              style: theme.textTheme.bodyMedium?.copyWith(
                color: theme.colorScheme.onSurfaceVariant,
              ),
            ),
            const Spacer(),
            Text(
              'add to ~/.fai/config.yaml under services:',
              style: FaiTheme.mono(
                size: 11,
                color: theme.colorScheme.onSurfaceVariant,
              ),
            ),
          ],
        ),
      );
    }
    return FaiCard(
      padding: EdgeInsets.zero,
      child: Column(
        children: [
          for (var i = 0; i < snapshot.services.length; i++) ...[
            if (i > 0)
              Divider(
                height: 1,
                color: theme.colorScheme.outlineVariant,
              ),
            Padding(
              padding: const EdgeInsets.all(FaiSpace.lg),
              child: Row(
                children: [
                  Icon(
                    Icons.dns_outlined,
                    size: 16,
                    color: theme.colorScheme.primary,
                  ),
                  const SizedBox(width: FaiSpace.sm),
                  Text(
                    snapshot.services[i].name,
                    style: theme.textTheme.titleSmall?.copyWith(
                      fontWeight: FontWeight.w600,
                    ),
                  ),
                  const SizedBox(width: FaiSpace.md),
                  Text(
                    snapshot.services[i].endpoint,
                    style: FaiTheme.mono(
                      size: 11,
                      color: theme.colorScheme.onSurfaceVariant,
                    ),
                  ),
                  const Spacer(),
                  for (final tag in snapshot.services[i].tags) ...[
                    FaiPill(label: tag, tone: FaiPillTone.neutral),
                    const SizedBox(width: FaiSpace.xs),
                  ],
                ],
              ),
            ),
          ],
        ],
      ),
    );
  }
}

class _UpdateBanner extends StatelessWidget {
  final UpdateStatus status;

  const _UpdateBanner({required this.status});

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final available = status.updateAvailable;
    final iconData = available
        ? Icons.system_update_alt_outlined
        : Icons.cloud_off_outlined;
    final iconColor = available
        ? theme.colorScheme.primary
        : theme.colorScheme.onSurfaceVariant;
    final title = available
        ? 'Update available — ${status.latestVersion}'
        : 'Release host unreachable';
    final body = available
        ? 'Channel ${status.channel} now offers ${status.latestVersion}. '
            'Apply with: fai update apply --channel ${status.channel}'
        : (status.reason ?? 'Could not contact the release feed for ${status.channel}.');
    return FaiCard(
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Icon(iconData, size: 20, color: iconColor),
          const SizedBox(width: FaiSpace.md),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  title,
                  style: theme.textTheme.titleSmall?.copyWith(
                    fontWeight: FontWeight.w600,
                  ),
                ),
                const SizedBox(height: 2),
                Text(
                  body,
                  style: FaiTheme.mono(
                    size: 11,
                    color: theme.colorScheme.onSurfaceVariant,
                  ),
                ),
                if (available && status.releaseNotesUrl != null) ...[
                  const SizedBox(height: 4),
                  Text(
                    'notes: ${status.releaseNotesUrl}',
                    style: FaiTheme.mono(
                      size: 11,
                      color: theme.colorScheme.primary,
                    ),
                  ),
                ],
              ],
            ),
          ),
          FaiPill(
            label: available ? 'new' : 'offline',
            tone: available ? FaiPillTone.success : FaiPillTone.neutral,
          ),
        ],
      ),
    );
  }
}