import 'package:flutter/material.dart';

import '../data/hub.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);
      _refresh();
    } catch (e) {
      _showError('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);
      _refresh();
    } catch (e) {
      _showError('reject failed: $e');
    }
  }

  void _showError(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)',
          ),
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(ctx, null),
            child: const Text('Cancel'),
          ),
          FilledButton(
            onPressed: () => Navigator.pop(ctx, controller.text),
            child: const Text('Reject'),
          ),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Scaffold(
      appBar: AppBar(
        title: const Text('Pending Approvals'),
        centerTitle: false,
        actions: [
          IconButton(
            icon: const Icon(Icons.refresh),
            tooltip: 'Reload',
            onPressed: _refresh,
          ),
        ],
      ),
      body: FutureBuilder<List<PendingApproval>>(
        future: _future,
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return const Center(child: CircularProgressIndicator());
          }
          if (snapshot.hasError) {
            return Center(
              child: Padding(
                padding: const EdgeInsets.all(32),
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    Icon(
                      Icons.cloud_off_outlined,
                      size: 48,
                      color: theme.colorScheme.error,
                    ),
                    const SizedBox(height: 16),
                    Text('Hub unreachable: ${snapshot.error}'),
                    const SizedBox(height: 16),
                    FilledButton.tonal(
                      onPressed: _refresh,
                      child: const Text('Retry'),
                    ),
                  ],
                ),
              ),
            );
          }
          final pending = snapshot.data ?? [];
          if (pending.isEmpty) {
            return Center(
              child: Padding(
                padding: const EdgeInsets.all(32),
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    Icon(
                      Icons.check_circle_outline,
                      size: 64,
                      color: theme.colorScheme.primary
                          .withValues(alpha: 0.5),
                    ),
                    const SizedBox(height: 16),
                    Text(
                      'No pending approvals.',
                      style: theme.textTheme.titleMedium?.copyWith(
                        color: theme.colorScheme.onSurfaceVariant,
                      ),
                    ),
                  ],
                ),
              ),
            );
          }
          return ListView.separated(
            padding: const EdgeInsets.all(24),
            itemCount: pending.length,
            separatorBuilder: (_, _) => const SizedBox(height: 16),
            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 Card(
      elevation: 0,
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(12),
        side: BorderSide(color: theme.colorScheme.outlineVariant),
      ),
      child: Padding(
        padding: const EdgeInsets.all(20),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                Icon(
                  Icons.pending_outlined,
                  color: theme.colorScheme.tertiary,
                  size: 20,
                ),
                const SizedBox(width: 8),
                Text(
                  '${approval.flowName} → ${approval.stepId}',
                  style: theme.textTheme.titleMedium?.copyWith(
                    fontWeight: FontWeight.w600,
                  ),
                ),
                const Spacer(),
                if (approval.expiresAt != null)
                  Text(
                    _expiresIn(approval.expiresAt!),
                    style: theme.textTheme.bodySmall?.copyWith(
                      color: theme.colorScheme.onSurfaceVariant,
                    ),
                  ),
              ],
            ),
            const SizedBox(height: 16),
            Text(
              approval.prompt,
              style: theme.textTheme.bodyLarge,
            ),
            if (approval.showPreview != null) ...[
              const SizedBox(height: 12),
              Container(
                width: double.infinity,
                padding: const EdgeInsets.all(12),
                decoration: BoxDecoration(
                  color: theme.colorScheme.surfaceContainerHighest,
                  borderRadius: BorderRadius.circular(8),
                ),
                child: Text(
                  approval.showPreview!,
                  style: theme.textTheme.bodySmall?.copyWith(
                    fontFamily: 'monospace',
                  ),
                ),
              ),
            ],
            const SizedBox(height: 16),
            Row(
              children: [
                Text(
                  'approval id: ${approval.id}',
                  style: theme.textTheme.bodySmall?.copyWith(
                    fontFamily: 'monospace',
                    color: theme.colorScheme.onSurfaceVariant,
                  ),
                ),
                const Spacer(),
                OutlinedButton.icon(
                  onPressed: onReject,
                  icon: const Icon(Icons.close),
                  label: const Text('Reject'),
                ),
                const SizedBox(width: 8),
                FilledButton.icon(
                  onPressed: onApprove,
                  icon: const Icon(Icons.check),
                  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 'expires in ${minutes}m';
    final hours = remaining.inHours;
    return 'expires in ${hours}h';
  }
}