import 'package:buzz/shared/widgets/feedback_snackbar.dart';

import 'dart:async';
import 'dart:math' show max;

import '../../shared/widgets/ios_message_create_button.dart';
import '../../shared/widgets/ios_glass_navigation_button.dart';
import '../../shared/widgets/ios_scroll_to_top.dart';
import '../../shared/widgets/top_edge_fade.dart';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_hooks/flutter_hooks.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';
import 'package:buzz/shared/theme/buzz_icons.dart';

import '../../shared/identity_names/identity_names_provider.dart';
import '../../shared/mentions/agent_identity_provider.dart';
import '../../shared/mentions/mention_tags.dart';
import '../../shared/relay/relay.dart';
import '../../shared/theme/theme.dart';
import '../../shared/utils/string_utils.dart';
import '../../shared/widgets/sheet_action_section.dart';
import '../../shared/widgets/avatar_image.dart';
import '../../shared/widgets/anchored_popover_menu.dart';
import '../../shared/widgets/bee_refresh_indicator.dart';
import '../../shared/widgets/buzz_loading_indicator.dart';
import '../../shared/widgets/message_author_meta.dart';
import '../../shared/widgets/modal_presentation.dart';
import '../channels/channel.dart';
import '../channels/channel_detail_page.dart';
import '../channels/channel_identity_names_provider.dart';
import '../channels/channel_management_provider.dart';
import '../channels/channels_provider.dart';
import '../channels/dm_channel_labels.dart';
import '../channels/message_content.dart';
import '../../shared/read_state/read_state_format.dart';
import '../../shared/reminders/remind_me_later_sheet.dart';
import '../../shared/reminders/reminder_service.dart'
    show ReminderTarget, reminderServiceProvider;
import '../channels/thread_follows/thread_follows_provider.dart';
import '../../shared/read_state/read_state_provider.dart';
import '../../shared/profile/user_cache_provider.dart';
import '../../shared/profile/user_profile.dart';
import 'activity_provider.dart';
import 'compose_drafts_provider.dart';
import 'dm_resurface.dart';
import 'feed_item.dart';
import 'inbox_item.dart';
import 'inbox_local_state_provider.dart';
import 'inbox_read_state.dart';
import 'reminders_provider.dart' hide ReminderTarget;

part 'activity_page/header_actions.dart';
part 'activity_page/inbox_row.dart';
part 'activity_page/lists.dart';
part 'activity_page/status_views.dart';

EdgeInsets _activityScrollPadding(
  BuildContext context, {
  double horizontal = 0,
  double top = Grid.xxs,
  double bottom = Grid.xxs,
}) => EdgeInsets.fromLTRB(
  horizontal,
  top,
  horizontal,
  MediaQuery.paddingOf(context).bottom + bottom,
);

/// Conversation-oriented Activity inbox.
///
/// Matches desktop's Home inbox item design and semantics (see
/// `desktop/src/features/home/ui/InboxListPane.tsx`): full sender avatar +
/// name, contextual "Mentioned in #channel"-style label, unread dot + time,
/// message preview — while keeping mobile's list → canonical destination
/// navigation. Row taps deep-link to the represented message (oldest unread
/// for grouped conversations) rather than just opening the channel.
const _activityTypeOptions = {
  InboxFilter.all: 'All',
  InboxFilter.thread: 'Threads',
  InboxFilter.mention: 'Mentions',
  InboxFilter.dm: 'DMs',
  InboxFilter.reminders: 'Reminders',
  InboxFilter.drafts: 'Drafts',
};

class ActivityPage extends HookConsumerWidget {
  const ActivityPage({this.tabReselection, super.key});

  /// Notifies this page when its already-selected tab is tapped again.
  final ValueListenable<int>? tabReselection;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final feedAsync = ref.watch(activityProvider);
    final channelsAsync = ref.watch(channelsProvider);
    final filter = useState(InboxFilter.all);
    final unreadOnly = useState(false);
    final sender = useState('Anyone');
    final agents = ref.watch(knownAgentPubkeysProvider);
    final profiles = ref.watch(userCacheProvider);
    final scrollController = useScrollController();
    final reducedMotion = MediaQuery.disableAnimationsOf(context);
    useEffect(() {
      final tabReselection = this.tabReselection;
      if (tabReselection == null) return null;

      void scrollToTop() {
        if (!scrollController.hasClients) return;
        final position = scrollController.position;
        if (position.pixels <= position.minScrollExtent + 0.5) return;
        if (reducedMotion) {
          scrollController.jumpTo(position.minScrollExtent);
          return;
        }
        unawaited(
          scrollController.animateTo(
            position.minScrollExtent,
            duration: const Duration(milliseconds: 260),
            curve: Curves.easeOutCubic,
          ),
        );
      }

      tabReselection.addListener(scrollToTop);
      return () => tabReselection.removeListener(scrollToTop);
    }, [tabReselection, scrollController, reducedMotion]);
    final headerTitleStyle = context.textTheme.titleMedium?.copyWith(
      fontSize: 22,
      fontWeight: FontWeight.w600,
      color: navigationPrimaryForeground(context),
    );
    final filterHeight =
        max(48.0, MediaQuery.textScalerOf(context).scale(16) * 1.4 + 16) +
        Grid.xxs;

    final readState = ref.watch(readStateProvider);
    final localState = ref.watch(inboxLocalStateProvider);
    final drafts = ref.watch(composeDraftsProvider);
    final allItems = ref.watch(inboxItemsProvider);
    final myPk = ref.watch(myPubkeyProvider);

    // Cache the last non-empty feed so the UI doesn't flash on rebuild.
    final hasLoadedOnce = useRef(false);
    if (feedAsync.hasValue) hasLoadedOnce.value = true;

    final channels = channelsAsync.asData?.value ?? const <Channel>[];
    final channelById = {for (final c in channels) c.id: c};

    int? markerOf(String contextId) => readState.effectiveTimestamp(contextId);
    bool isDone(InboxItem item) => isInboxItemDone(
      item,
      markerOf: markerOf,
      localUnreadOverrides: localState.unreadIds,
      localDoneSet: localState.doneIds,
    );

    // Rows mark channel bot members as agents, so the sender filter does too.
    final channelAgents = <String, Set<String>>{};
    bool includesSender(FeedItem e) {
      if (sender.value == 'Anyone') return true;
      final pk = e.pubkey.toLowerCase();
      final channelId = e.channelId;
      final known = channelId == null
          ? agents
          : channelAgents.putIfAbsent(
              channelId,
              () => ref.watch(agentMentionPubkeysProvider(channelId)),
            );
      final isAgent = known.contains(pk) || profiles[pk]?.ownerPubkey != null;
      return sender.value == 'Agents' ? isAgent : !isAgent;
    }

    // Mentions, Threads and sender filters apply to each event before
    // regrouping, so a row shows the matching activity rather than a later
    // unrelated message from the same conversation.
    final candidates = buildInboxItems(
      allItems
          .expand((i) => i.groupItems)
          .where(
            (e) =>
                (filter.value != InboxFilter.mention ||
                    e.category == 'mention') &&
                (filter.value != InboxFilter.thread || isThreadReply(e.tags)) &&
                includesSender(e),
          ),
      isDmChannel: (id) =>
          (channelById[id]?.isDm ?? false) ||
          ref.read(channelsProvider.notifier).hiddenDmIds.contains(id),
    );
    final rowsArePartial =
        filter.value == InboxFilter.thread ||
        filter.value == InboxFilter.mention ||
        sender.value != 'Anyone';
    final visibleItems = [
      for (final item in candidates)
        if (matchesInboxFilter(item, filter.value) &&
            (!unreadOnly.value || !isDone(item)))
          item,
    ];

    // Preload sender profiles for visible rows, and for every author while a
    // sender filter needs their agent ownership.
    final preloadPubkeys = {
      if (sender.value != 'Anyone')
        for (final item in allItems)
          for (final e in item.groupItems) e.pubkey.toLowerCase(),
      for (final item in visibleItems) item.item.pubkey.toLowerCase(),
      for (final item in visibleItems)
        ...mentionedPubkeysFromTags(item.item.tags),
    }.toList()..sort();
    final preloadPubkeysKey = preloadPubkeys.join('\u0000');
    useEffect(() {
      ref.read(userCacheProvider.notifier).preload(preloadPubkeys);
      return null;
    }, [preloadPubkeysKey]);

    // A filtered row holds only part of its conversation. Its synced thread
    // or channel marker is one watermark, so advance it through every event
    // that is now read (shown here, or already read) and stop just before the
    // first unread event the filter hides. Shown events past that point get
    // local per-message marks until the hidden one is read too.
    void markPartialRowRead(
      InboxItem item,
      String channelId, {
      required bool isDmRow,
    }) {
      final notifier = ref.read(readStateProvider.notifier);
      final shown = {
        for (final e in [item.item, ...item.groupItems]) e.id: e,
      };
      final rootId = isDmRow ? null : item.threadRootId;
      bool inContext(FeedItem e) =>
          e.channelId == channelId &&
          (rootId == null ||
              (isThreadReply(e.tags) &&
                  threadReferenceOf(e.tags).rootId == rootId));
      final events = {
        for (final e in [
          ...allItems.expand((i) => i.groupItems),
          ...shown.values,
        ])
          if (inContext(e)) e.id: e,
      }.values.toList()..sort((a, b) => a.createdAt.compareTo(b.createdAt));
      int? cap;
      for (final e in events) {
        if (!shown.containsKey(e.id) &&
            !isInboxEventRead(e, markerOf: markerOf)) {
          cap = e.createdAt - 1;
          break;
        }
        cap = e.createdAt;
      }
      if (cap != null) {
        notifier.markContextRead(
          rootId == null ? channelId : threadContextKey(rootId),
          cap,
        );
      }
      for (final e in shown.values) {
        if (inContext(e) && cap != null && e.createdAt <= cap) continue;
        notifier.markContextRead(msgContextKey(e.id), e.createdAt);
      }
    }

    void markItemRead(InboxItem item) {
      final notifier = ref.read(readStateProvider.notifier);
      ref
          .read(inboxLocalStateProvider.notifier)
          .clearUnread(groupedInboxItemIds(item));
      final isDmRow = item.conversationId.startsWith('dm:');
      final partialChannelId = rowsArePartial ? item.item.channelId : null;
      if (partialChannelId != null) {
        markPartialRowRead(item, partialChannelId, isDmRow: isDmRow);
        return;
      }
      // A DM row can group replies under several thread roots; its channel
      // marker reads all of them.
      final threadRootId = isDmRow ? null : item.threadRootId;
      if (threadRootId != null) {
        notifier.markContextRead(
          threadContextKey(threadRootId),
          item.latestActivityAt,
        );
        final channelRead = groupedChannelReadTimestamp(item);
        if (channelRead != null) {
          notifier.markContextRead(
            channelRead.channelId,
            channelRead.timestamp,
          );
        }
        return;
      }
      final channelId = item.item.channelId;
      if (channelId != null) {
        notifier.markContextRead(channelId, item.latestActivityAt);
        ref
            .read(channelsProvider.notifier)
            .clearObservedUnreadCoveredByRead(channelId, item.latestActivityAt);
        return;
      }
      ref.read(inboxLocalStateProvider.notifier).markDone(item.id);
    }

    void markItemUnread(InboxItem item) {
      ref
          .read(inboxLocalStateProvider.notifier)
          .markUnread(groupedInboxItemIds(item));
    }

    Future<void> openItem(InboxItem item) async {
      final channelId = item.item.channelId;
      if (channelId == null) {
        ScaffoldMessenger.maybeOf(context)?.showFeedbackSnackBar(
          const SnackBar(content: Text('No linked channel')),
          kind: ToastKind.error,
        );
        return;
      }
      var channel = channelById[channelId];
      if (channel == null &&
          myPk != null &&
          ref.read(channelsProvider.notifier).hiddenDmIds.contains(channelId)) {
        final expectedPubkey = myPk.toLowerCase();
        final expectedRelayUrl = ref.read(relayConfigProvider).baseUrl;
        bool isCurrentScope() =>
            context.mounted &&
            ref.read(myPubkeyProvider)?.toLowerCase() == expectedPubkey &&
            ref.read(relayConfigProvider).baseUrl == expectedRelayUrl;
        try {
          final members = await ref.read(
            channelMembersProvider(channelId).future,
          );
          if (!isCurrentScope()) return;
          final peers = dmPeerPubkeysFromMembers(
            members.map((member) => member.pubkey),
            expectedPubkey,
          );
          if (peers.isEmpty) {
            throw StateError('Could not determine the DM membership.');
          }
          final reopened = await ref
              .read(channelActionsProvider)
              .openDm(pubkeys: peers.toList());
          if (!isCurrentScope()) return;
          if (reopened.id != channelId) {
            throw StateError('Relay reopened a different DM conversation.');
          }
          channel = reopened;
        } catch (error) {
          if (!isCurrentScope()) return;
          if (!context.mounted) return;
          ScaffoldMessenger.maybeOf(context)?.showFeedbackSnackBar(
            SnackBar(content: Text('Could not reopen conversation: $error')),
            kind: ToastKind.error,
          );
          return;
        }
      }
      if (channel == null) {
        if (!context.mounted) return;
        ScaffoldMessenger.maybeOf(context)?.showFeedbackSnackBar(
          const SnackBar(content: Text('Channel not found here')),
          kind: ToastKind.error,
        );
        return;
      }
      final resolvedChannel = channel;

      // Deep-link to the represented message: oldest unread in the group,
      // falling back to the latest event.
      final target = item.deepLinkTarget(
        (event) => isInboxEventRead(event, markerOf: markerOf),
      );
      final thread = threadReferenceOf(target.tags);
      final threadRootId = isBroadcastReply(target.tags)
          ? null
          : thread.parentId;

      if (!context.mounted) return;
      Navigator.of(context).push(
        MaterialPageRoute<void>(
          builder: (_) => ChannelDetailPage(
            channel: resolvedChannel,
            initialMessageId: target.id,
            initialThreadRootId: threadRootId,
            initialThreadRouteBehavior:
                InitialThreadRouteBehavior.replaceCurrentRoute,
          ),
        ),
      );
    }

    void openDraft(ComposeDraft draft) {
      final channel = channelById[draft.channelId];
      if (channel == null) {
        ScaffoldMessenger.maybeOf(context)?.showFeedbackSnackBar(
          const SnackBar(content: Text('Draft’s channel unavailable')),
          kind: ToastKind.error,
        );
        return;
      }
      Navigator.of(context).push(
        MaterialPageRoute<void>(
          builder: (_) => ChannelDetailPage(
            channel: channel,
            initialThreadRootId: draft.threadHeadId,
            initialThreadRouteBehavior:
                InitialThreadRouteBehavior.replaceCurrentRoute,
          ),
        ),
      );
    }

    void openReminder(Reminder reminder) {
      final target = reminder.target;
      if (target == null) {
        ScaffoldMessenger.maybeOf(context)?.showFeedbackSnackBar(
          const SnackBar(content: Text('Reminder has no linked message')),
          kind: ToastKind.error,
        );
        return;
      }
      final channel = channelById[target.channelId];
      if (channel == null) {
        ScaffoldMessenger.maybeOf(context)?.showFeedbackSnackBar(
          const SnackBar(content: Text('Reminder’s channel unavailable')),
          kind: ToastKind.error,
        );
        return;
      }
      Navigator.of(context).push(
        MaterialPageRoute<void>(
          builder: (_) => ChannelDetailPage(
            channel: channel,
            initialMessageId: target.eventId,
          ),
        ),
      );
    }

    Future<void> refresh() async {
      await Future.wait([
        ref.read(activityProvider.notifier).refresh(),
        ref.read(remindersProvider.notifier).refresh(),
      ]);
    }

    late final Widget body;
    if (filter.value == InboxFilter.reminders) {
      body = _RemindersList(
        scrollController: scrollController,
        onOpen: openReminder,
        onRefresh: refresh,
      );
    } else if (filter.value == InboxFilter.drafts) {
      body = _DraftsList(
        drafts: drafts,
        scrollController: scrollController,
        channelById: channelById,
        myPubkey: myPk,
        onOpen: openDraft,
        onDelete: (draft) =>
            ref.read(composeDraftsProvider.notifier).remove(draft.key),
      );
    } else if (feedAsync.hasError && allItems.isEmpty) {
      body = _ErrorView(onRetry: refresh);
    } else if (!hasLoadedOnce.value && allItems.isEmpty) {
      body = _LoadingSkeleton(scrollController: scrollController);
    } else if (visibleItems.isEmpty) {
      body = _EmptyFilterState(
        filter: filter.value,
        unreadOnly: unreadOnly.value,
      );
    } else {
      body = BeeRefreshIndicator(
        onRefresh: refresh,
        child: CustomScrollView(
          controller: scrollController,
          slivers: [
            DecoratedSliver(
              decoration: BoxDecoration(
                color: context.colors.surface,
                borderRadius: const BorderRadius.vertical(
                  top: Radius.circular(Radii.dialog),
                ),
              ),
              sliver: SliverPadding(
                padding: _activityScrollPadding(context),
                sliver: SliverList.builder(
                  itemCount: visibleItems.length,
                  itemBuilder: (context, index) {
                    final item = visibleItems[index];
                    final channel = item.item.channelId != null
                        ? channelById[item.item.channelId]
                        : null;
                    return Column(
                      crossAxisAlignment: CrossAxisAlignment.stretch,
                      children: [
                        _InboxRow(
                          key: ValueKey(item.id),
                          item: item,
                          channel: channel,
                          currentPubkey: myPk,
                          isDone: isDone(item),
                          onTap: () => unawaited(openItem(item)),
                          onMarkRead: () => markItemRead(item),
                          onMarkUnread: () => markItemUnread(item),
                        ),
                      ],
                    );
                  },
                ),
              ),
            ),
          ],
        ),
      );
    }

    return IosScrollToTop(
      child: Scaffold(
        backgroundColor: context.colors.surface,
        body: SafeArea(
          bottom: false,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              Padding(
                padding: const EdgeInsets.symmetric(
                  horizontal: Grid.gutter,
                  vertical: Grid.xxs,
                ),
                child: Row(
                  children: [
                    defaultTargetPlatform == TargetPlatform.iOS
                        ? Padding(
                            padding: const EdgeInsets.only(right: Grid.twelve),
                            child: IosGlassNavigationButton(
                              icon: IosGlassNavigationIcon.close,
                              semanticLabel: 'Close activity',
                              width: 44,
                              height: 44,
                              controlSize: 44,
                              foregroundColor: navigationPrimaryForeground(
                                context,
                              ),
                              onPressed: () => Navigator.of(context).pop(),
                            ),
                          )
                        : IconButton(
                            tooltip: 'Close activity',
                            icon: const Icon(BuzzIcons.x),
                            onPressed: () => Navigator.of(context).pop(),
                          ),
                    Expanded(child: Text('Activity', style: headerTitleStyle)),
                  ],
                ),
              ),
              SizedBox(
                height: filterHeight,
                child: SingleChildScrollView(
                  key: const ValueKey('activity-filters'),
                  scrollDirection: Axis.horizontal,
                  padding: const EdgeInsets.symmetric(
                    horizontal: Grid.gutter,
                    vertical: Grid.half,
                  ),
                  child: Row(
                    children: [
                      _ActivityMenuButton<InboxFilter>(
                        controlKey: 'activity-type-menu',
                        popoverKey: 'activity-type-popover',
                        semanticLabel:
                            'Activity type, ${_activityTypeOptions[filter.value]}',
                        value: filter.value,
                        active: filter.value != InboxFilter.all,
                        options: _activityTypeOptions,
                        onChanged: (value) => filter.value = value,
                      ),
                      const SizedBox(width: Grid.xxs),
                      _ActivityMenuButton<String>(
                        controlKey: 'activity-sender-menu',
                        popoverKey: 'activity-sender-popover',
                        semanticLabel: 'From ${sender.value}',
                        value: sender.value,
                        active: sender.value != 'Anyone',
                        options: const {
                          'Anyone': 'Anyone',
                          'People': 'People',
                          'Agents': 'Agents',
                        },
                        onChanged: (value) => sender.value = value,
                      ),
                      const SizedBox(width: Grid.xxs),
                      _UnreadFilterButton(
                        selected: unreadOnly.value,
                        onPressed: () => unreadOnly.value = !unreadOnly.value,
                      ),
                    ],
                  ),
                ),
              ),
              Expanded(
                child: TopEdgeFade(
                  key: const ValueKey('activity-content-viewport'),
                  child: body,
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}