import 'package:flutter/material.dart';

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

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

  @override
  State<ApprovalsPage> createState() => _ApprovalsPageState();
}

class _ApprovalsPageState extends State<ApprovalsPage> {
  late Future<List<PendingApproval>> _future;
  // Hard-coded reviewer for the MVP; Phase 1+ wires this to an
  // authenticated session.
  final String _reviewer = 'studio-mvp';

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

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

  Future<void> _approve(PendingApproval a) async {
    try {
      await HubService.instance.approve(a.id, _reviewer);
      _toast('approved · ${a.flowName} › ${a.stepId}');
      _refresh();
    } catch (e) {
      _toast('approve failed: $e');
    }
  }

  Future<void> _reject(PendingApproval a) async {
    final reason = await _promptReason(context);
    if (reason == null || reason.isEmpty) return;
    try {
      await HubService.instance.reject(a.id, _reviewer, reason);
      _toast('rejected · ${a.flowName} › ${a.stepId}');
      _refresh();
    } catch (e) {
      _toast('reject failed: $e');
    }
  }

  void _toast(String msg) {
    if (!mounted) return;
    ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(msg)));
  }

  Future<String?> _promptReason(BuildContext context) async {
    final controller = TextEditingController();
    return showDialog<String>(
      context: context,
      builder: (ctx) => AlertDialog(
        title: const Text('Reject approval'),
        content: TextField(
          controller: controller,
          autofocus: true,
          decoration: const InputDecoration(
            labelText: 'Reason (recorded in audit log)',
            border: OutlineInputBorder(),
          ),
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(ctx, null),
            child: const Text('Cancel'),
          ),
          FilledButton(
            onPressed: () => Navigator.pop(ctx, controller.text),
            style: FilledButton.styleFrom(
              backgroundColor: Theme.of(ctx).colorScheme.error,
              foregroundColor: Theme.of(ctx).colorScheme.onError,
            ),
            child: const Text('Reject'),
          ),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Scaffold(
      backgroundColor: theme.scaffoldBackgroundColor,
      appBar: AppBar(
        title: const Text('Approvals'),
        actions: [
          IconButton(
            icon: const Icon(Icons.refresh, size: 18),
            tooltip: 'Reload',
            onPressed: _refresh,
          ),
          const SizedBox(width: FaiSpace.sm),
        ],
      ),
      body: FutureBuilder<List<PendingApproval>>(
        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.colorScheme.error,
              title: 'Hub unreachable',
              hint: 'Start the hub with `fai serve`.',
              action: FilledButton.tonal(
                onPressed: _refresh,
                child: const Text('Retry'),
              ),
            );
          }
          final pending = snapshot.data ?? [];
          if (pending.isEmpty) {
            return const FaiEmptyState(
              icon: Icons.task_alt_outlined,
              title: 'Inbox zero',
              hint:
                  'All caught up. New `system.approval@^0` steps land here automatically.',
            );
          }
          return ListView.separated(
            padding: const EdgeInsets.all(FaiSpace.xl),
            itemCount: pending.length,
            separatorBuilder: (_, _) => const SizedBox(height: FaiSpace.md),
            itemBuilder: (context, i) {
              final a = pending[i];
              return _ApprovalCard(
                approval: a,
                onApprove: () => _approve(a),
                onReject: () => _reject(a),
              );
            },
          );
        },
      ),
    );
  }
}

class _ApprovalCard extends StatelessWidget {
  final PendingApproval approval;
  final VoidCallback onApprove;
  final VoidCallback onReject;

  const _ApprovalCard({
    required this.approval,
    required this.onApprove,
    required this.onReject,
  });

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return FaiCard(
      accentTop: true,
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Row(
            children: [
              FaiPill(
                label: 'pending',
                tone: FaiPillTone.warning,
                icon: Icons.pending_outlined,
              ),
              const SizedBox(width: FaiSpace.sm),
              Expanded(
                child: Text(
                  '${approval.flowName} › ${approval.stepId}',
                  style: theme.textTheme.titleMedium?.copyWith(
                    fontWeight: FontWeight.w600,
                  ),
                ),
              ),
              if (approval.expiresAt != null)
                FaiPill(
                  label: _expiresIn(approval.expiresAt!),
                  tone: FaiPillTone.neutral,
                  icon: Icons.schedule,
                ),
            ],
          ),
          const SizedBox(height: FaiSpace.lg),
          Text(
            approval.prompt,
            style: theme.textTheme.bodyLarge,
          ),
          if (approval.showPreview != null) ...[
            const SizedBox(height: FaiSpace.md),
            Container(
              width: double.infinity,
              padding: const EdgeInsets.all(FaiSpace.md),
              decoration: BoxDecoration(
                color: theme.colorScheme.surfaceContainerHigh,
                borderRadius: BorderRadius.circular(FaiRadius.sm),
                border: Border.all(color: theme.colorScheme.outlineVariant),
              ),
              child: Text(
                approval.showPreview!,
                style: FaiTheme.mono(
                  size: 11,
                  color: theme.colorScheme.onSurface,
                ),
              ),
            ),
          ],
          const SizedBox(height: FaiSpace.lg),
          Row(
            children: [
              Text(
                approval.id,
                style: FaiTheme.mono(
                  size: 10,
                  color: theme.colorScheme.onSurfaceVariant,
                ),
              ),
              const Spacer(),
              OutlinedButton.icon(
                onPressed: onReject,
                icon: const Icon(Icons.close, size: 16),
                label: const Text('Reject'),
                style: OutlinedButton.styleFrom(
                  foregroundColor: theme.colorScheme.error,
                  side: BorderSide(
                    color: theme.colorScheme.error.withValues(alpha: 0.5),
                  ),
                ),
              ),
              const SizedBox(width: FaiSpace.sm),
              FilledButton.icon(
                onPressed: onApprove,
                icon: const Icon(Icons.check, size: 16),
                label: const Text('Approve'),
              ),
            ],
          ),
        ],
      ),
    );
  }

  String _expiresIn(DateTime t) {
    final remaining = t.difference(DateTime.now());
    if (remaining.isNegative) return 'expired';
    final minutes = remaining.inMinutes;
    if (minutes < 60) return '${minutes}m';
    final hours = remaining.inHours;
    return '${hours}h';
  }
}