import 'dart:async';

import 'package:flutter/material.dart';

import 'package:adaptive_dialog/adaptive_dialog.dart';
import 'package:collection/collection.dart';
import 'package:flutter_gen/gen_l10n/l10n.dart';
import 'package:future_loading_dialog/future_loading_dialog.dart';
import 'package:matrix/matrix.dart';
import 'package:vrouter/vrouter.dart';

import 'package:fluffychat/pages/chat_list/chat_list.dart';
import 'package:fluffychat/pages/chat_list/chat_list_item.dart';
import 'package:fluffychat/pages/chat_list/search_title.dart';
import 'package:fluffychat/widgets/avatar.dart';
import '../../utils/localized_exception_extension.dart';
import '../../widgets/matrix.dart';

class SpaceView extends StatefulWidget {
  final ChatListController controller;
  final ScrollController scrollController;

  const SpaceView(
    this.controller, {
    Key? key,
    required this.scrollController,
  }) : super(key: key);

  @override
  State<SpaceView> createState() => _SpaceViewState();
}

class _SpaceViewState extends State<SpaceView> {
  SpaceHierarchyCache? cache;

  String? prevBatch;

  void _onJoinSpaceChild(SpaceRoomsChunk spaceChild) async {
    final client = Matrix.of(context).client;
    final space = client.getRoomById(widget.controller.activeSpaceId!);
    if (client.getRoomById(spaceChild.roomId) == null) {
      final result = await showFutureLoadingDialog(
        context: context,
        future: () async {
          await client.joinRoom(spaceChild.roomId,
              serverName: space?.spaceChildren
                  .firstWhereOrNull(
                      (child) => child.roomId == spaceChild.roomId)
                  ?.via);
          if (client.getRoomById(spaceChild.roomId) == null) {
            // Wait for room actually appears in sync
            await client.waitForRoomInSync(spaceChild.roomId, join: true);
          }
        },
      );
      if (result.error != null) return;
      setState(() {
        cache!.refresh(widget.controller.activeSpaceId!);
      });
    }
    if (spaceChild.roomType == 'm.space') {
      if (spaceChild.roomId == widget.controller.activeSpaceId) {
        VRouter.of(context).toSegments(['spaces', spaceChild.roomId]);
      } else {
        widget.controller.setActiveSpace(spaceChild.roomId);
      }
      return;
    }
    VRouter.of(context).toSegments(['rooms', spaceChild.roomId]);
  }

  void _onSpaceChildContextMenu(
      [SpaceRoomsChunk? spaceChild, Room? room]) async {
    final client = Matrix.of(context).client;
    final activeSpaceId = widget.controller.activeSpaceId;
    final activeSpace =
        activeSpaceId == null ? null : client.getRoomById(activeSpaceId);
    final action = await showModalActionSheet<SpaceChildContextAction>(
      context: context,
      title: spaceChild?.name ?? room?.displayname,
      message: spaceChild?.topic ?? room?.topic,
      actions: [
        if (room == null)
          SheetAction(
            key: SpaceChildContextAction.join,
            label: L10n.of(context)!.joinRoom,
            icon: Icons.send_outlined,
          ),
        if (spaceChild != null && (activeSpace?.canSendDefaultStates ?? false))
          SheetAction(
            key: SpaceChildContextAction.removeFromSpace,
            label: L10n.of(context)!.removeFromSpace,
            icon: Icons.delete_sweep_outlined,
          ),
        if (room != null)
          SheetAction(
            key: SpaceChildContextAction.leave,
            label: L10n.of(context)!.leave,
            icon: Icons.delete_outlined,
            isDestructiveAction: true,
          ),
      ],
    );
    if (action == null) return;

    switch (action) {
      case SpaceChildContextAction.join:
        _onJoinSpaceChild(spaceChild!);
        break;
      case SpaceChildContextAction.leave:
        await showFutureLoadingDialog(
          context: context,
          future: room!.leave,
        );
        break;
      case SpaceChildContextAction.removeFromSpace:
        await showFutureLoadingDialog(
          context: context,
          future: () => activeSpace!.removeSpaceChild(spaceChild!.roomId),
        );
        break;
    }
  }

  @override
  Widget build(BuildContext context) {
    cache ??= SpaceHierarchyCache.instance ??=
        SpaceHierarchyCache(client: Matrix.of(context).client);
    final client = Matrix.of(context).client;
    final activeSpaceId = widget.controller.activeSpaceId;
    final allSpaces = client.rooms.where((room) => room.isSpace);
    if (activeSpaceId == null) {
      final rootSpaces = allSpaces
          .where(
            (space) => !allSpaces.any(
              (parentSpace) => parentSpace.spaceChildren
                  .any((child) => child.roomId == space.id),
            ),
          )
          .toList();

      return ListView.builder(
        itemCount: rootSpaces.length,
        controller: widget.scrollController,
        itemBuilder: (context, i) => Material(
          color: Theme.of(context).backgroundColor,
          child: ListTile(
            leading: Avatar(
              mxContent: rootSpaces[i].avatar,
              name: rootSpaces[i].displayname,
            ),
            title: Text(
              rootSpaces[i].displayname,
              maxLines: 1,
              overflow: TextOverflow.ellipsis,
            ),
            subtitle: Text(L10n.of(context)!
                .numChats(rootSpaces[i].spaceChildren.length.toString())),
            onTap: () => widget.controller.setActiveSpace(rootSpaces[i].id),
            onLongPress: () => _onSpaceChildContextMenu(null, rootSpaces[i]),
            trailing: const Icon(Icons.chevron_right_outlined),
          ),
        ),
      );
    }
    return FutureBuilder<GetSpaceHierarchyResponse>(
        future: cache!.getFuture(activeSpaceId, prevBatch),
        builder: (context, snapshot) {
          final response = snapshot.data;
          final error = snapshot.error;
          if (error != null) {
            return Column(
              crossAxisAlignment: CrossAxisAlignment.center,
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                Padding(
                  padding: const EdgeInsets.all(16.0),
                  child: Text(error.toLocalizedString(context)),
                ),
                IconButton(
                  onPressed: () => cache!.refresh(activeSpaceId),
                  icon: const Icon(Icons.refresh_outlined),
                )
              ],
            );
          }
          if (response == null) {
            return const Center(child: CircularProgressIndicator.adaptive());
          }
          final parentSpace = allSpaces.firstWhereOrNull((space) => space
              .spaceChildren
              .any((child) => child.roomId == activeSpaceId));
          final spaceChildren = response.rooms;
          final canLoadMore = response.nextBatch != null;
          return VWidgetGuard(
            onSystemPop: (redirector) async {
              if (parentSpace != null) {
                widget.controller.setActiveSpace(parentSpace.id);
                redirector.stopRedirection();
                return;
              }
            },
            child: ListView.builder(
                itemCount: spaceChildren.length + 1 + (canLoadMore ? 1 : 0),
                controller: widget.scrollController,
                itemBuilder: (context, i) {
                  if (i == 0) {
                    return ListTile(
                      leading: BackButton(
                        onPressed: () =>
                            widget.controller.setActiveSpace(parentSpace?.id),
                      ),
                      title: Text(parentSpace == null
                          ? L10n.of(context)!.allSpaces
                          : parentSpace.displayname),
                      trailing: IconButton(
                        icon: snapshot.connectionState != ConnectionState.done
                            ? const SizedBox.square(
                                dimension: 24,
                                child: CircularProgressIndicator.adaptive(),
                              )
                            : const Icon(Icons.refresh_outlined),
                        onPressed:
                            snapshot.connectionState != ConnectionState.done
                                ? null
                                : () => setState(() {
                                      cache!.refresh(activeSpaceId);
                                    }),
                      ),
                    );
                  }
                  i--;
                  if (canLoadMore && i == spaceChildren.length) {
                    return ListTile(
                      title: TextButton.icon(
                        label: Text(L10n.of(context)!.loadMore),
                        icon: cache?.isRefreshing(activeSpaceId) ?? false
                            ? const SizedBox.square(
                                dimension: 24,
                                child: CircularProgressIndicator(),
                              )
                            : const Icon(Icons.refresh),
                        onPressed: () {
                          prevBatch = snapshot.data!.nextBatch!;
                          setState(() {
                            cache!.refresh(activeSpaceId);
                          });
                        },
                      ),
                    );
                  }
                  final spaceChild = spaceChildren[i];
                  final room = client.getRoomById(spaceChild.roomId);
                  if (room != null && !room.isSpace) {
                    return ChatListItem(
                      room,
                      onLongPress: () =>
                          _onSpaceChildContextMenu(spaceChild, room),
                      activeChat: widget.controller.activeChat == room.id,
                    );
                  }
                  final isSpace = spaceChild.roomType == 'm.space';
                  final topic = spaceChild.topic?.isEmpty ?? true
                      ? null
                      : spaceChild.topic;
                  if (spaceChild.roomId == activeSpaceId) {
                    return SearchTitle(
                      title: spaceChild.name ??
                          spaceChild.canonicalAlias ??
                          'Space',
                      icon: Padding(
                        padding: const EdgeInsets.symmetric(horizontal: 10.0),
                        child: Avatar(
                          size: 24,
                          mxContent: spaceChild.avatarUrl,
                          name: spaceChild.name,
                          fontSize: 9,
                        ),
                      ),
                      color: Theme.of(context)
                          .colorScheme
                          .secondaryContainer
                          .withAlpha(128),
                      trailing: const Padding(
                        padding: EdgeInsets.symmetric(horizontal: 16.0),
                        child: Icon(Icons.edit_outlined),
                      ),
                      onTap: () => _onJoinSpaceChild(spaceChild),
                    );
                  }
                  return ListTile(
                    leading: Avatar(
                      mxContent: spaceChild.avatarUrl,
                      name: spaceChild.name,
                    ),
                    title: Row(
                      children: [
                        Expanded(
                          child: Text(
                            spaceChild.name ??
                                spaceChild.canonicalAlias ??
                                L10n.of(context)!.chat,
                            maxLines: 1,
                            style: const TextStyle(fontWeight: FontWeight.bold),
                          ),
                        ),
                        if (!isSpace) ...[
                          const Icon(
                            Icons.people_outline,
                            size: 16,
                          ),
                          const SizedBox(width: 4),
                          Text(
                            spaceChild.numJoinedMembers.toString(),
                            style: const TextStyle(fontSize: 14),
                          ),
                        ],
                      ],
                    ),
                    onTap: () => _onJoinSpaceChild(spaceChild),
                    onLongPress: () =>
                        _onSpaceChildContextMenu(spaceChild, room),
                    subtitle: Text(
                      topic ??
                          (isSpace
                              ? L10n.of(context)!.enterSpace
                              : L10n.of(context)!.enterRoom),
                      maxLines: 1,
                      style: TextStyle(
                          color: Theme.of(context).colorScheme.onBackground),
                    ),
                    trailing: isSpace
                        ? const Icon(Icons.chevron_right_outlined)
                        : null,
                  );
                }),
          );
        });
  }
}

enum SpaceChildContextAction {
  join,
  leave,
  removeFromSpace,
}

class SpaceHierarchyCache {
  static SpaceHierarchyCache? instance;

  final Client client;
  final Map<String, List<Completer<GetSpaceHierarchyResponse?>>> _requests = {};

  SpaceHierarchyCache({required this.client});

  void refresh(String activeSpaceId) {
    _requests.remove(activeSpaceId);
  }

  bool isRefreshing(String spaceId) =>
      _requests[spaceId] != null &&
      (_requests[spaceId]?.any((element) => !element.isCompleted) ?? false);

  Future<GetSpaceHierarchyResponse> getFuture(
    String activeSpaceId,
    String? prevBatch,
  ) {
    _requests[activeSpaceId] ??= [];
    final completer = Completer<GetSpaceHierarchyResponse?>();
    client
        .getSpaceHierarchy(
          activeSpaceId,
          maxDepth: 1,
          from: prevBatch,
        )
        .then(
          completer.complete,
        )
        .onError(completer.completeError);
    _requests[activeSpaceId]?.add(completer);

    return Future.wait(_requests[activeSpaceId]!.reversed.map(
          (e) => e.future.onError((e, s) => null),
        )).then(
      (value) => SpacesHierarchyMerges.merged(
        value.whereNotNull().toList(),
      ),
    );
  }
}

extension SpacesHierarchyMerges on GetSpaceHierarchyResponse {
  static GetSpaceHierarchyResponse merged(
    List<GetSpaceHierarchyResponse> responses,
  ) {
    final rooms = <SpaceRoomsChunk>[];
    for (final response in responses) {
      for (final newRoom in response.rooms) {
        if (rooms.none(
          (existingRoom) => existingRoom.roomId == newRoom.roomId,
        )) {
          rooms.add(newRoom);
        }
      }
    }
    String? nextBatch;
    if (!responses.any((response) => response.nextBatch == null)) {
      nextBatch = responses.last.nextBatch;
    }
    return GetSpaceHierarchyResponse(rooms: rooms, nextBatch: nextBatch);
  }
}