import "dart:async";

import "package:bus_running_record/models/channels/text_channel.dart";
import "package:shadcn_flutter/shadcn_flutter.dart";
import "package:supabase_flutter/supabase_flutter.dart";

class TextChannelView extends StatefulWidget {
  const TextChannelView({required this.channel, super.key});

  final TextChannel channel;

  @override
  State<TextChannelView> createState() => _TextChannelViewState();
}

class _TextChannelViewState extends State<TextChannelView> {
  RealtimeChannel? _messagesRealtimeChannel;
  bool _loadingMessages = false;
  bool _sendingMessage = false;
  String? _messageError;
  String _draftMessage = "";
  int _composerNonce = 0;
  List<TextChannelMessage> _messages = const [];

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!mounted) return;
      unawaited(_initializeChannel());
    });
  }

  @override
  void didUpdateWidget(covariant TextChannelView oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.channel.id == widget.channel.id) return;
    unawaited(_initializeChannel());
  }

  Future<void> _initializeChannel() async {
    await _unsubscribeFromRealtimeMessages();
    if (!mounted) return;
    setState(() {
      _messages = const [];
      _messageError = null;
      _draftMessage = "";
      _composerNonce += 1;
    });
    await _subscribeToRealtimeMessages();
    await _loadMessages();
  }

  Future<void> _loadMessages() async {
    if (_loadingMessages) return;
    setState(() {
      _loadingMessages = true;
      _messageError = null;
    });

    try {
      final messages = await widget.channel.listMessages();
      if (!mounted) return;
      setState(() {
        _messages = messages;
      });
    } catch (error, stackTrace) {
      debugPrint("[TextChannelView] loadMessages failed: $error");
      debugPrintStack(stackTrace: stackTrace);
      if (!mounted) return;
      setState(() {
        _messageError = error.toString();
      });
    } finally {
      if (mounted) {
        setState(() {
          _loadingMessages = false;
        });
      }
    }
  }

  Future<void> _subscribeToRealtimeMessages() async {
    if (_messagesRealtimeChannel != null) return;

    final realtime = widget.channel.subscribeToMessages(
      onMessageChanged: () {
        if (!mounted) return;
        unawaited(_loadMessages());
      },
      onStatus: (status, error) {
        if (status == RealtimeSubscribeStatus.subscribed) return;
        if (status == RealtimeSubscribeStatus.channelError ||
            status == RealtimeSubscribeStatus.timedOut) {
          debugPrint(
            "[TextChannelView] realtime subscribe issue ($status) for channel ${widget.channel.id}: $error",
          );
        }
      },
    );

    _messagesRealtimeChannel = realtime;
  }

  Future<void> _unsubscribeFromRealtimeMessages() async {
    final realtime = _messagesRealtimeChannel;
    _messagesRealtimeChannel = null;
    if (realtime == null) return;

    try {
      await widget.channel.unsubscribe(realtime);
      debugPrint("[TextChannelView] realtime unsubscribed");
    } catch (error, stackTrace) {
      debugPrint("[TextChannelView] realtime unsubscribe failed: $error");
      debugPrintStack(stackTrace: stackTrace);
    }
  }

  Future<void> _sendMessage() async {
    final content = _draftMessage.trim();
    if (content.isEmpty || _sendingMessage) return;

    setState(() {
      _sendingMessage = true;
      _messageError = null;
    });

    try {
      await widget.channel.sendMessage(content);
      if (!mounted) return;
      setState(() {
        _draftMessage = "";
        _composerNonce += 1;
      });
      await _loadMessages();
    } catch (error, stackTrace) {
      debugPrint("[TextChannelView] sendMessage failed: $error");
      debugPrintStack(stackTrace: stackTrace);
      if (!mounted) return;
      setState(() {
        _messageError = error.toString();
      });
    } finally {
      if (mounted) {
        setState(() {
          _sendingMessage = false;
        });
      }
    }
  }

  Widget _buildMessageList() {
    if (_loadingMessages) {
      return const Center(child: CircularProgressIndicator());
    }

    if (_messages.isEmpty) {
      return Center(child: Text("No messages yet. Say hi.").small.muted);
    }

    final currentUserId = widget.channel.client.auth.currentUser?.id ?? "";
    return SingleChildScrollView(
      padding: const EdgeInsets.symmetric(vertical: 8),
      child: Column(
        children: [
          for (var i = 0; i < _messages.length; i++) ...[
            MessageBubble(message: _messages[i], currentUserId: currentUserId),
            if (i != _messages.length - 1) const Gap(2),
          ],
        ],
      ),
    );
  }

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

  @override
  Widget build(BuildContext context) {

    double bottomPadding = MediaQuery.of(context).padding.bottom;

    return Column(
      children: [
        Expanded(child: _buildMessageList()),
        if (_messageError != null)
          Padding(
            padding: const EdgeInsets.only(left: 12, right: 12),
            child: Text(
              _messageError!,
              style: TextStyle(
                color: Theme.of(context).colorScheme.destructive,
              ),
            ).small,
          ),
        Container(
          margin: const EdgeInsets.symmetric(horizontal: 12),
          clipBehavior: Clip.none,
          height: 60,
          child: TextField(
            key: ValueKey("composer-$_composerNonce"),
            initialValue: "",
            placeholder: Text("Message #${widget.channel.slug}"),
            enabled: !_sendingMessage,
            onChanged: (value) {
              _draftMessage = value;
            },
            onSubmitted: (_) => unawaited(_sendMessage()),
            features: [
              InputFeature.leading(
                IconButton.ghost(
                  icon: const Icon(LucideIcons.plus).iconSmall,
                  onPressed: () {},
                ),
              ),
            ],
          ),
        ),
        Gap(bottomPadding + 12),
      ],
    );
  }
}

class MessageBubble extends StatelessWidget {
  const MessageBubble({
    required this.message,
    required this.currentUserId,
    super.key,
  });

  final TextChannelMessage message;
  final String currentUserId;

  String _formatTime() {
    final createdAt = message.createdAt?.toLocal();
    if (createdAt == null) {
      return "";
    }
    final paddedHour = createdAt.hour.toString().padLeft(2, "0");
    final paddedMinute = createdAt.minute.toString().padLeft(2, "0");
    return "$paddedHour:$paddedMinute";
  }

  String _senderLabel() {
    final authorUserId = message.authorUserId;
    final isCurrentUser =
        currentUserId.isNotEmpty && authorUserId == currentUserId;
    if (isCurrentUser) {
      return "You";
    }

    if (authorUserId.length >= 8) {
      return "User ${authorUserId.substring(0, 8)}";
    }
    return "User $authorUserId";
  }

  @override
  Widget build(BuildContext context) {
    final timeText = _formatTime();
    final senderLabel = _senderLabel();
    final shouldShowTime = timeText.isNotEmpty;
    final senderInitials = Avatar.getInitials(senderLabel);

    return Container(
      width: double.infinity,
      padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Avatar(initials: senderInitials),
          const Gap(10),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Row(
                  children: [
                    Text(senderLabel).small.semiBold,
                    if (shouldShowTime) ...[
                      const Gap(8),
                      Text(timeText).xSmall.muted,
                    ],
                  ],
                ),
                const Gap(2),
                Text(message.content).small,
              ],
            ),
          ),
        ],
      ),
    );
  }
}