import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../../models/announcement.dart';
import '../../providers/announcements_provider.dart';
import '../../theme/m3_motion.dart';
import '../../utils/snackbar.dart';
import '../../widgets/app_breakpoints.dart';

/// All user roles available for announcement visibility.
const _allRoles = ['admin', 'dispatcher', 'programmer', 'it_staff', 'standard'];

/// Default visible roles (standard is excluded by default).
const _defaultVisibleRoles = ['admin', 'dispatcher', 'programmer', 'it_staff'];

/// Human-readable labels for each role.
const _roleLabels = {
  'admin': 'Admin',
  'dispatcher': 'Dispatcher',
  'programmer': 'Programmer',
  'it_staff': 'IT Staff',
  'standard': 'Standard',
};

/// Shows the create/edit announcement dialog.
///
/// On mobile, uses a full-screen bottom sheet; on desktop, a centered dialog.
Future<void> showCreateAnnouncementDialog(
  BuildContext context, {
  Announcement? editing,
}) async {
  final width = MediaQuery.sizeOf(context).width;
  if (width < AppBreakpoints.tablet) {
    await m3ShowBottomSheet<void>(
      context: context,
      isScrollControlled: true,
      builder: (ctx) => _CreateAnnouncementContent(editing: editing),
    );
  } else {
    await m3ShowDialog<void>(
      context: context,
      builder: (ctx) => Dialog(
        child: ConstrainedBox(
          constraints: const BoxConstraints(maxWidth: 560),
          child: _CreateAnnouncementContent(editing: editing),
        ),
      ),
    );
  }
}

class _CreateAnnouncementContent extends ConsumerStatefulWidget {
  const _CreateAnnouncementContent({this.editing});

  final Announcement? editing;

  @override
  ConsumerState<_CreateAnnouncementContent> createState() =>
      _CreateAnnouncementContentState();
}

class _CreateAnnouncementContentState
    extends ConsumerState<_CreateAnnouncementContent> {
  late final TextEditingController _titleCtrl;
  late final TextEditingController _bodyCtrl;
  late Set<String> _selectedRoles;
  bool _isTemplate = false;
  bool _submitting = false;

  // Template selection
  String? _selectedTemplateId;

  @override
  void initState() {
    super.initState();
    final source = widget.editing;
    _titleCtrl = TextEditingController(text: source?.title ?? '');
    _bodyCtrl = TextEditingController(text: source?.body ?? '');
    _selectedRoles = source != null
        ? Set<String>.from(source.visibleRoles)
        : Set<String>.from(_defaultVisibleRoles);
    _isTemplate = widget.editing?.isTemplate ?? false;
  }

  @override
  void dispose() {
    _titleCtrl.dispose();
    _bodyCtrl.dispose();
    super.dispose();
  }

  bool get _canSubmit {
    final hasContent =
        _titleCtrl.text.trim().isNotEmpty && _bodyCtrl.text.trim().isNotEmpty;
    final hasRoles = _selectedRoles.isNotEmpty;
    return hasContent && hasRoles && !_submitting;
  }

  void _applyTemplate(Announcement template) {
    setState(() {
      _selectedTemplateId = template.id;
      _titleCtrl.text = template.title;
      _bodyCtrl.text = template.body;
      _selectedRoles = Set<String>.from(template.visibleRoles);
    });
  }

  void _clearTemplate() {
    setState(() {
      _selectedTemplateId = null;
    });
  }

  Future<void> _submit() async {
    if (!_canSubmit) return;
    setState(() => _submitting = true);
    try {
      final ctrl = ref.read(announcementsControllerProvider);
      if (widget.editing != null) {
        await ctrl.updateAnnouncement(
          id: widget.editing!.id,
          title: _titleCtrl.text.trim(),
          body: _bodyCtrl.text.trim(),
          visibleRoles: _selectedRoles.toList(),
          isTemplate: _isTemplate,
        );
      } else {
        await ctrl.createAnnouncement(
          title: _titleCtrl.text.trim(),
          body: _bodyCtrl.text.trim(),
          visibleRoles: _selectedRoles.toList(),
          isTemplate: _isTemplate,
          templateId: _selectedTemplateId,
        );
      }
      if (mounted) Navigator.of(context).pop();
    } on AnnouncementNotificationException {
      // Saved successfully; only push notification delivery failed.
      if (mounted) {
        final messenger = ScaffoldMessenger.of(context);
        Navigator.of(context).pop();
        messenger.showSnackBar(
          const SnackBar(
            content: Text('Posted, but some notifications failed to send.'),
          ),
        );
      }
    } catch (e) {
      if (mounted) showErrorSnackBar(context, 'Failed to save: $e');
    } finally {
      if (mounted) setState(() => _submitting = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final cs = Theme.of(context).colorScheme;
    final tt = Theme.of(context).textTheme;
    final isEditing = widget.editing != null;

    // Get available templates from the stream (filter client-side)
    final templates = ref
        .watch(announcementsProvider)
        .valueOrNull
        ?.where((a) => a.isTemplate)
        .toList() ?? [];

    return SingleChildScrollView(
      padding: const EdgeInsets.all(24),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          // Dialog title
          Text(
            isEditing ? 'Edit Announcement' : 'New Announcement',
            style: tt.titleLarge?.copyWith(fontWeight: FontWeight.w600),
          ),
          const SizedBox(height: 20),

          // Template selector (only for new announcements)
          if (!isEditing && templates.isNotEmpty) ...[
            DropdownButtonFormField<String?>(
              decoration: InputDecoration(
                labelText: 'Post from template (optional)',
                border: const OutlineInputBorder(),
                suffixIcon: _selectedTemplateId != null
                    ? IconButton(
                        icon: const Icon(Icons.clear),
                        tooltip: 'Clear template',
                        onPressed: _clearTemplate,
                      )
                    : null,
              ),
              key: ValueKey(_selectedTemplateId),
              initialValue: _selectedTemplateId,
              items: [
                const DropdownMenuItem<String?>(
                  value: null,
                  child: Text('No template'),
                ),
                ...templates.map(
                  (t) => DropdownMenuItem<String?>(
                    value: t.id,
                    child: Text(
                      t.title.isEmpty ? '(Untitled)' : t.title,
                      overflow: TextOverflow.ellipsis,
                    ),
                  ),
                ),
              ],
              onChanged: (id) {
                if (id == null) {
                  _clearTemplate();
                } else {
                  final tmpl = templates.firstWhere((t) => t.id == id);
                  _applyTemplate(tmpl);
                }
              },
            ),
            const SizedBox(height: 16),
          ],

          // Title field
          TextField(
            controller: _titleCtrl,
            decoration: const InputDecoration(
              labelText: 'Title',
              border: OutlineInputBorder(),
            ),
            textInputAction: TextInputAction.next,
            onChanged: (_) => setState(() {}),
          ),
          const SizedBox(height: 16),

          // Body field
          TextField(
            controller: _bodyCtrl,
            decoration: const InputDecoration(
              labelText: 'Body',
              border: OutlineInputBorder(),
              alignLabelWithHint: true,
            ),
            maxLines: 6,
            minLines: 3,
            onChanged: (_) => setState(() {}),
          ),
          const SizedBox(height: 16),

          // Role visibility
          Text('Visible to:', style: tt.labelLarge),
          const SizedBox(height: 8),
          Wrap(
            spacing: 8,
            runSpacing: 6,
            children: _allRoles.map((role) {
              final selected = _selectedRoles.contains(role);
              return FilterChip(
                label: Text(_roleLabels[role] ?? role),
                selected: selected,
                onSelected: (val) {
                  setState(() {
                    if (val) {
                      _selectedRoles.add(role);
                    } else {
                      _selectedRoles.remove(role);
                    }
                  });
                },
              );
            }).toList(),
          ),
          const SizedBox(height: 16),

          // Template toggle
          SwitchListTile(
            contentPadding: EdgeInsets.zero,
            title: Text('Save as template', style: tt.bodyMedium),
            subtitle: Text(
              'Templates can be selected when creating new announcements.',
              style: tt.bodySmall?.copyWith(color: cs.onSurfaceVariant),
            ),
            value: _isTemplate,
            onChanged: (val) => setState(() => _isTemplate = val),
          ),
          const SizedBox(height: 20),

          // Action buttons
          Row(
            mainAxisAlignment: MainAxisAlignment.end,
            children: [
              TextButton(
                onPressed: () => Navigator.of(context).pop(),
                child: const Text('Cancel'),
              ),
              const SizedBox(width: 12),
              FilledButton(
                onPressed: _canSubmit ? _submit : null,
                child: _submitting
                    ? const SizedBox(
                        width: 20,
                        height: 20,
                        child: CircularProgressIndicator(
                            strokeWidth: 2, color: Colors.white),
                      )
                    : Text(isEditing ? 'Save' : 'Post'),
              ),
            ],
          ),
        ],
      ),
    );
  }
}