import 'package:flutter/material.dart';

import '../../../../api/errors/error_mapper.dart';
import '../../../../extensions/date_time.dart';
import '../../../../state/app/infrastructure/loadable_state/bloc/loadable_state_bloc.dart';
import '../../../../state/app/infrastructure/loadable_state/bloc/loadable_state_state.dart';
import '../../../../state/app/infrastructure/loadable_state/view/loadable_state_background_loading.dart';
import '../../../../state/app/infrastructure/loadable_state/view/loadable_state_error_bar.dart';
import '../../../../state/app/infrastructure/loadable_state/view/loadable_state_error_screen.dart';
import '../../../../state/app/infrastructure/loadable_state/view/loadable_state_primary_loading.dart';
import '../../../../state/app/infrastructure/utility_widgets/bloc_module.dart';
import '../../../../widget/placeholder_view.dart';
import '../../../../widget/user_avatar.dart';
import '../data/chat_message_matcher.dart';
import '../widgets/highlighted_linkify.dart';
import 'chat_search_controller.dart';

/// Renders a [ChatSearchController] with the same loading / error views as
/// `FilesSearchResults`.
class ChatSearchResults extends StatelessWidget {
  final ChatSearchController controller;
  final ValueChanged<ChatSearchHit> onResultTap;

  const ChatSearchResults({
    required this.controller,
    required this.onResultTap,
    super.key,
  });

  @override
  Widget build(BuildContext context) =>
      BlocModule<LoadableStateBloc, LoadableStateState>(
        create: (_) => LoadableStateBloc(),
        child: (context, bloc, _) {
          bloc.reFetch = controller.retry;
          return ListenableBuilder(
            listenable: controller,
            builder: (context, _) => _buildBody(context),
          );
        },
      );

  Widget _buildBody(BuildContext context) {
    if (controller.query.trim().isEmpty) {
      return const PlaceholderView(
        icon: Icons.search,
        text: 'Tippen, um im Chat zu suchen.',
      );
    }
    final combined = controller.combinedResults;
    final hasContent = combined.isNotEmpty;
    final hasError = controller.serverError != null;
    final isLoading = controller.serverLoading;

    final showPrimaryLoading = isLoading && !hasContent;
    final showBackgroundLoading = isLoading && hasContent;
    final showErrorScreen = hasError && !hasContent && !isLoading;
    final showErrorBar = hasError && hasContent;
    final showEmpty = !hasContent && !hasError && !isLoading;

    final errorMessage = hasError
        ? errorToUserMessage(controller.serverError)
        : null;

    return Column(
      children: [
        LoadableStateErrorBar(
          visible: showErrorBar,
          hasContent: hasContent,
          message: errorMessage,
        ),
        LoadableStateBackgroundLoading(visible: showBackgroundLoading),
        Expanded(
          child: Stack(
            children: [
              LoadableStatePrimaryLoading(visible: showPrimaryLoading),
              LoadableStateErrorScreen(
                visible: showErrorScreen,
                message: errorMessage,
              ),
              if (showEmpty)
                const PlaceholderView(
                  icon: Icons.search_off_outlined,
                  text: 'Keine Treffer gefunden.',
                ),
              if (hasContent) _resultList(combined),
            ],
          ),
        ),
      ],
    );
  }

  Widget _resultList(List<ChatSearchHit> hits) {
    final showFooter = controller.canLoadMore || controller.loadingMore;
    return NotificationListener<ScrollNotification>(
      onNotification: (n) {
        if (n.metrics.extentAfter < 400) controller.loadMore();
        return false;
      },
      child: ListView.builder(
        padding: EdgeInsets.zero,
        itemCount: hits.length + (showFooter ? 1 : 0),
        itemBuilder: (context, index) {
          if (index == hits.length) {
            // A short first page never scrolls, so the footer also triggers
            // the next page when it gets built.
            WidgetsBinding.instance.addPostFrameCallback(
              (_) => controller.loadMore(),
            );
            return const Padding(
              padding: EdgeInsets.all(16),
              child: Center(child: CircularProgressIndicator()),
            );
          }
          final hit = hits[index];
          return _ChatSearchTile(
            key: ValueKey(hit.messageId),
            hit: hit,
            query: controller.query,
            onTap: () => onResultTap(hit),
          );
        },
      ),
    );
  }
}

class _ChatSearchTile extends StatelessWidget {
  final ChatSearchHit hit;
  final String query;
  final VoidCallback onTap;

  const _ChatSearchTile({
    required this.hit,
    required this.query,
    required this.onTap,
    super.key,
  });

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final base =
        theme.textTheme.bodyMedium ?? DefaultTextStyle.of(context).style;
    final actorId = hit.actorId;
    final sentAt = hit.sentAt;
    return ListTile(
      leading: actorId != null
          ? UserAvatar(
              id: actorId,
              size: 20,
              semanticLabel: hit.actorDisplayName,
            )
          : const CircleAvatar(radius: 20, child: Icon(Icons.info_outline)),
      title: Row(
        children: [
          Expanded(
            child: Text.rich(
              TextSpan(
                children: buildHighlightedSpans(
                  text: hit.actorDisplayName ?? 'System',
                  query: query,
                  baseStyle: theme.textTheme.titleSmall ?? base,
                ),
              ),
              maxLines: 1,
              overflow: TextOverflow.ellipsis,
            ),
          ),
          if (sentAt != null)
            Padding(
              padding: const EdgeInsets.only(left: 8),
              child: Text(
                sentAt.year == DateTime.now().year
                    ? sentAt.formatDateShortHm()
                    : sentAt.formatDate(),
                style: theme.textTheme.bodySmall,
              ),
            ),
        ],
      ),
      subtitle: Text.rich(
        TextSpan(
          children: buildHighlightedSpans(
            text: hit.text,
            query: query,
            baseStyle: base.copyWith(color: theme.colorScheme.onSurfaceVariant),
          ),
        ),
        maxLines: 3,
        overflow: TextOverflow.ellipsis,
      ),
      onTap: onTap,
    );
  }
}