import 'dart:async';
import 'dart:math' as math show min;

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

import '../../models/announcement.dart';
import '../../providers/announcements_provider.dart';
import '../../providers/profile_provider.dart';
import '../../theme/m3_motion.dart';
import '../../utils/app_time.dart';
import '../../utils/snackbar.dart';
import '../../widgets/app_page_header.dart';
import '../../widgets/m3_card.dart';
import '../../widgets/profile_avatar.dart';
import '../../widgets/responsive_body.dart';
import 'announcement_comments_section.dart';
import 'create_announcement_dialog.dart';

class AnnouncementsScreen extends ConsumerStatefulWidget {
  const AnnouncementsScreen({super.key});

  @override
  ConsumerState<AnnouncementsScreen> createState() =>
      _AnnouncementsScreenState();
}

class _AnnouncementsScreenState extends ConsumerState<AnnouncementsScreen> {
  final Set<String> _expandedComments = {};

  @override
  Widget build(BuildContext context) {
    final announcementsAsync = ref.watch(announcementsProvider);
    final profiles = ref.watch(profilesProvider).valueOrNull ?? [];
    final currentProfile = ref.watch(currentProfileProvider).valueOrNull;
    final currentUserId = ref.watch(currentUserIdProvider);
    final role = currentProfile?.role ?? 'standard';
    final canCreate = const ['admin', 'dispatcher', 'programmer', 'it_staff']
        .contains(role);

    final hasValue = announcementsAsync.hasValue;
    final hasError = announcementsAsync.hasError;
    final items = announcementsAsync.valueOrNull ?? [];
    final showSkeleton = !hasValue && !hasError;

    return Scaffold(
      floatingActionButton: canCreate
          ? M3ExpandedFab(
              heroTag: 'announcement_fab',
              onPressed: () => showCreateAnnouncementDialog(context),
              icon: const Icon(Icons.add),
              label: const Text('New Announcement'),
            )
          : null,
      body: ResponsiveBody(
        child: CustomScrollView(
          slivers: [
            SliverToBoxAdapter(
              child: AppPageHeader(title: 'Announcements'),
            ),

            if (hasError && !hasValue)
              SliverFillRemaining(
                child: Center(
                  child: Text(
                    'Failed to load announcements.',
                    style: Theme.of(context)
                        .textTheme
                        .bodyMedium
                        ?.copyWith(
                            color: Theme.of(context).colorScheme.error),
                  ),
                ),
              )
            else if (showSkeleton)
              SliverList(
                delegate: SliverChildBuilderDelegate(
                  (context, index) => _buildPlaceholderCard(context),
                  childCount: 5,
                ),
              )
            else if (items.isEmpty)
              SliverFillRemaining(
                child: Center(
                  child: Column(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      Icon(Icons.campaign_outlined,
                          size: 64,
                          color: Theme.of(context)
                              .colorScheme
                              .onSurfaceVariant),
                      const SizedBox(height: 12),
                      Text('No announcements yet',
                          style: Theme.of(context)
                              .textTheme
                              .bodyLarge
                              ?.copyWith(
                                  color: Theme.of(context)
                                      .colorScheme
                                      .onSurfaceVariant)),
                    ],
                  ),
                ),
              )
            else
              SliverList(
                delegate: SliverChildBuilderDelegate(
                  (context, index) {
                    final announcement = items[index];
                    final delay = Duration(
                        milliseconds: math.min(index, 8) * 60);
                    return M3FadeSlideIn(
                      key: ValueKey(announcement.id),
                      delay: delay,
                      child: _AnnouncementCard(
                        announcement: announcement,
                        profiles: profiles,
                        currentUserId: currentUserId,
                        currentUserRole: role,
                        canCreate: canCreate,
                        isExpanded:
                            _expandedComments.contains(announcement.id),
                        onToggleComments: () {
                          setState(() {
                            if (_expandedComments.contains(announcement.id)) {
                              _expandedComments.remove(announcement.id);
                            } else {
                              _expandedComments.add(announcement.id);
                            }
                          });
                        },
                        onEdit: () => showCreateAnnouncementDialog(
                          context,
                          editing: announcement,
                        ),
                        onDelete: () async {
                          final confirm = await showDialog<bool>(
                            context: context,
                            builder: (ctx) => AlertDialog(
                              title: const Text('Delete Announcement'),
                              content: const Text(
                                  'Are you sure you want to delete this announcement?'),
                              actions: [
                                TextButton(
                                  onPressed: () =>
                                      Navigator.of(ctx).pop(false),
                                  child: const Text('Cancel'),
                                ),
                                FilledButton(
                                  onPressed: () =>
                                      Navigator.of(ctx).pop(true),
                                  child: const Text('Delete'),
                                ),
                              ],
                            ),
                          );
                          if (confirm == true && mounted) {
                            await ref
                                .read(announcementsControllerProvider)
                                .deleteAnnouncement(announcement.id);
                            showSuccessSnackBarGlobal('Announcement deleted.');
                          }
                        },
                        onBannerSettings: () => showBannerSettingsDialog(
                          context,
                          announcement: announcement,
                        ),
                      ),
                    );
                  },
                  childCount: items.length,
                ),
              ),
            const SliverPadding(padding: EdgeInsets.only(bottom: 80)),
          ],
        ),
      ),
    );
  }

  Widget _buildPlaceholderCard(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 6),
      child: M3Card.elevated(
        child: Padding(
          padding: const EdgeInsets.all(16),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Row(
                children: [
                  M3ShimmerBox(
                    width: 36,
                    height: 36,
                    borderRadius: BorderRadius.circular(18),
                  ),
                  const SizedBox(width: 10),
                  Expanded(
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        M3ShimmerBox(width: 120, height: 13),
                        const SizedBox(height: 5),
                        M3ShimmerBox(width: 64, height: 10),
                      ],
                    ),
                  ),
                ],
              ),
              const SizedBox(height: 14),
              M3ShimmerBox(width: 200, height: 15),
              const SizedBox(height: 8),
              M3ShimmerBox(height: 12),
              const SizedBox(height: 5),
              M3ShimmerBox(width: 240, height: 12),
              const SizedBox(height: 5),
              M3ShimmerBox(width: 160, height: 12),
            ],
          ),
        ),
      ),
    );
  }
}

// ─────────────────────────────────────────────────────────────────────────────
// Announcement card
// ─────────────────────────────────────────────────────────────────────────────

class _AnnouncementCard extends ConsumerStatefulWidget {
  const _AnnouncementCard({
    required this.announcement,
    required this.profiles,
    required this.currentUserId,
    required this.currentUserRole,
    required this.canCreate,
    required this.isExpanded,
    required this.onToggleComments,
    required this.onEdit,
    required this.onDelete,
    required this.onBannerSettings,
  });

  final Announcement announcement;
  final List profiles;
  final String? currentUserId;
  final String currentUserRole;
  final bool canCreate;
  final bool isExpanded;
  final VoidCallback onToggleComments;
  final VoidCallback onEdit;
  final VoidCallback onDelete;
  final VoidCallback onBannerSettings;

  @override
  ConsumerState<_AnnouncementCard> createState() => _AnnouncementCardState();
}

class _AnnouncementCardState extends ConsumerState<_AnnouncementCard> {
  static const _cooldownSeconds = 60;
  DateTime? _sentAt;

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

  int get _secondsRemaining {
    if (_sentAt == null) return 0;
    final elapsed = DateTime.now().difference(_sentAt!).inSeconds;
    return (_cooldownSeconds - elapsed).clamp(0, _cooldownSeconds);
  }

  bool get _inCooldown => _secondsRemaining > 0;

  bool get _isOwner =>
      widget.announcement.authorId == widget.currentUserId;

  bool get _isAdmin => widget.currentUserRole == 'admin';

  bool get _canManageBanner => _isOwner || _isAdmin;

  bool get _canResend => _isOwner || _isAdmin;

  Future<void> _resendNotification() async {
    try {
      await ref
          .read(announcementsControllerProvider)
          .resendAnnouncementNotification(widget.announcement);
      if (mounted) setState(() => _sentAt = DateTime.now());
    } on AnnouncementNotificationException {
      if (mounted) setState(() => _sentAt = DateTime.now());
    } catch (e) {
      if (mounted) showErrorSnackBar(context, 'Failed to send: $e');
    }
  }

  @override
  Widget build(BuildContext context) {
    final cs = Theme.of(context).colorScheme;
    final tt = Theme.of(context).textTheme;

    // Resolve author
    String authorName = 'Unknown';
    String? avatarUrl;
    for (final p in widget.profiles) {
      if (p.id == widget.announcement.authorId) {
        authorName = p.fullName;
        avatarUrl = p.avatarUrl;
        break;
      }
    }

    // Comment count
    final commentsAsync =
        ref.watch(announcementCommentsProvider(widget.announcement.id));
    final commentCount = commentsAsync.valueOrNull?.length ?? 0;

    // Rebuild UI when cooldown is active.
    if (_inCooldown) {
      Future.delayed(const Duration(milliseconds: 500), () {
        if (mounted) setState(() {});
      });
    }

    final hasBanner = widget.announcement.bannerEnabled;

    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 6),
      child: M3Card.elevated(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Padding(
              padding: const EdgeInsets.fromLTRB(16, 16, 8, 0),
              child: Row(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  ProfileAvatar(
                    fullName: authorName,
                    avatarUrl: avatarUrl,
                    radius: 20,
                  ),
                  const SizedBox(width: 10),
                  Expanded(
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        Text(
                          authorName,
                          style: tt.titleSmall
                              ?.copyWith(fontWeight: FontWeight.w600),
                          overflow: TextOverflow.ellipsis,
                        ),
                        const SizedBox(height: 2),
                        Row(
                          children: [
                            Flexible(
                              child: Text(
                                _relativeTime(widget.announcement.createdAt),
                                style: tt.labelSmall
                                    ?.copyWith(color: cs.onSurfaceVariant),
                              ),
                            ),
                            if (hasBanner) ...[
                              const SizedBox(width: 6),
                              Tooltip(
                                message: widget.announcement.isBannerActive
                                    ? 'Banner active'
                                    : 'Banner (inactive)',
                                child: Icon(
                                  Icons.campaign,
                                  size: 14,
                                  color: widget.announcement.isBannerActive
                                      ? cs.primary
                                      : cs.onSurfaceVariant,
                                ),
                              ),
                            ],
                          ],
                        ),
                      ],
                    ),
                  ),
                  // Popup menu: owner sees Edit/Delete/Banner;
                  // admin-only sees Delete/Banner
                  if (_isOwner || _canManageBanner)
                    PopupMenuButton<String>(
                      onSelected: (value) {
                        switch (value) {
                          case 'edit':
                            widget.onEdit();
                          case 'delete':
                            widget.onDelete();
                          case 'banner':
                            widget.onBannerSettings();
                        }
                      },
                      itemBuilder: (context) => [
                        if (_isOwner)
                          const PopupMenuItem(
                              value: 'edit', child: Text('Edit')),
                        if (_isOwner || _isAdmin)
                          const PopupMenuItem(
                              value: 'delete', child: Text('Delete')),
                        if (_canManageBanner)
                          PopupMenuItem(
                            value: 'banner',
                            child: Row(
                              children: [
                                Icon(Icons.campaign_outlined,
                                    size: 18,
                                    color: Theme.of(context)
                                        .colorScheme
                                        .primary),
                                const SizedBox(width: 8),
                                const Text('Banner Settings'),
                              ],
                            ),
                          ),
                      ],
                    ),
                ],
              ),
            ),
            // Title + Body
            Padding(
              padding: const EdgeInsets.fromLTRB(16, 12, 16, 0),
              child: Text(
                widget.announcement.title,
                style: tt.titleMedium?.copyWith(fontWeight: FontWeight.w600),
              ),
            ),
            Padding(
              padding: const EdgeInsets.fromLTRB(16, 6, 16, 0),
              child: Text(widget.announcement.body, style: tt.bodyMedium),
            ),
            // Visible roles chips
            Padding(
              padding: const EdgeInsets.fromLTRB(16, 10, 16, 0),
              child: Wrap(
                spacing: 6,
                runSpacing: 4,
                children: widget.announcement.visibleRoles.map((role) {
                  return Chip(
                    label: Text(_roleLabel(role), style: tt.labelSmall),
                    visualDensity: VisualDensity.compact,
                    padding: EdgeInsets.zero,
                    materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
                  );
                }).toList(),
              ),
            ),
            // Bottom action row
            Padding(
              padding: const EdgeInsets.fromLTRB(8, 4, 8, 0),
              child: Row(
                children: [
                  TextButton.icon(
                    onPressed: widget.onToggleComments,
                    icon: Icon(
                      widget.isExpanded
                          ? Icons.expand_less
                          : Icons.comment_outlined,
                      size: 18,
                    ),
                    label: Text(
                      commentCount > 0
                          ? '$commentCount comment${commentCount == 1 ? '' : 's'}'
                          : 'Comment',
                    ),
                    style: TextButton.styleFrom(
                      foregroundColor: cs.onSurfaceVariant,
                      textStyle: tt.labelMedium,
                    ),
                  ),
                  const Spacer(),
                  if (_canResend)
                    SizedBox(
                      width: 40,
                      height: 40,
                      child: _inCooldown
                          ? Tooltip(
                              message: '$_secondsRemaining s remaining',
                              child: Stack(
                                alignment: Alignment.center,
                                children: [
                                  SizedBox(
                                    width: 28,
                                    height: 28,
                                    child: CircularProgressIndicator(
                                      value: _secondsRemaining /
                                          _cooldownSeconds,
                                      strokeWidth: 2.5,
                                      color: cs.primary,
                                      backgroundColor: cs.primary
                                          .withValues(alpha: 0.15),
                                    ),
                                  ),
                                  Text(
                                    '$_secondsRemaining',
                                    style: tt.labelSmall?.copyWith(
                                      fontSize: 9,
                                      color: cs.primary,
                                    ),
                                  ),
                                ],
                              ),
                            )
                          : IconButton(
                              tooltip: 'Resend notifications',
                              padding: EdgeInsets.zero,
                              onPressed: _resendNotification,
                              icon: Icon(
                                Icons.notifications_active_outlined,
                                color: cs.primary,
                                size: 20,
                              ),
                            ),
                    ),
                ],
              ),
            ),
            // Comments section
            if (widget.isExpanded)
              AnnouncementCommentsSection(
                  announcementId: widget.announcement.id),
          ],
        ),
      ),
    );
  }
}

// ─────────────────────────────────────────────────────────────────────────────
// Helpers
// ─────────────────────────────────────────────────────────────────────────────

String _relativeTime(DateTime dt) {
  final now = AppTime.now();
  final diff = now.difference(dt);
  if (diff.inMinutes < 1) return 'Just now';
  if (diff.inMinutes < 60) return '${diff.inMinutes}m ago';
  if (diff.inHours < 24) return '${diff.inHours}h ago';
  if (diff.inDays < 7) return '${diff.inDays}d ago';
  return AppTime.formatDate(dt);
}

String _roleLabel(String role) {
  const labels = {
    'admin': 'Admin',
    'dispatcher': 'Dispatcher',
    'programmer': 'Programmer',
    'it_staff': 'IT Staff',
    'standard': 'Standard',
  };
  return labels[role] ?? role;
}