import 'dart:async';

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:stacked/stacked.dart';

import '../../about/external/data/GroupMessage.dart';
import '../../about/external/initial/GroupMessageRequest.dart';
import '../../about/internal/application/TextType.dart';
import '../../designs/AmbientBackground.dart';
import '../../designs/GlassSurface.dart';
import '../../designs/MemberAvatar.dart';
import '../../designs/Responsive.dart';
import '../../designs/input/InputFields.dart';
import '../../designs/text/Text.dart';
import '../../utils/Colors.dart';
import '../../utils/CommonUtils.dart';
import 'ConnectGroupChat.dart';
import 'GroupChat.dart';
import 'ViewGroupChat.dart';

class GroupChatState extends State<GroupChat> implements ConnectGroupChat {
  ViewGroupChat? _model;

  List<GroupMessage> _messages = <GroupMessage>[];

  final TextEditingController _input = TextEditingController();

  Timer? _poll;

  /// How often the open chat looks for new messages.
  static const Duration _pollEvery = Duration(seconds: 4);

  static const List<String> _quickReplies = <String>[
    "Done for today",
    "On my way",
    "Need a push",
    "Who's in tomorrow?",
  ];

  @override
  void dispose() {
    _poll?.cancel();
    _input.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return ViewModelBuilder<ViewGroupChat>.reactive(
      viewModelBuilder: () => ViewGroupChat(context, this),
      onViewModelReady: (viewModel) {
        _model = viewModel;
        _initiate();
      },
      builder: (context, viewModel, child) => LayoutBuilder(
        builder: (BuildContext context, BoxConstraints constraints) {
          return Responsive(
            mobile: _mobileView(constraints),
            tablet: _mobileView(constraints),
            desktop: _mobileView(constraints),
          );
        },
      ),
    );
  }

  void _initiate() {
    _model?.loadMessages(widget.group.id);
    _poll = Timer.periodic(_pollEvery, _onPoll);
  }

  // ── Handlers ──────────────────────────────────────────────────────────────

  void _onBack() {
    Navigator.pop(context, true);
  }

  void _onPoll(Timer timer) {
    _model?.refresh(widget.group.id);
  }

  void _onSend(String value) {
    final String body = value.trim();
    if (body.isEmpty) {
      return;
    }

    _input.clear();
    _model?.send(GroupMessageRequest(groupId: widget.group.id, body: body));
  }

  void _onSendPressed() {
    _onSend(_input.text);
  }

  void _onQuickReply(String reply) {
    _onSend(reply);
  }

  // ── Views ─────────────────────────────────────────────────────────────────

  Widget _mobileView(BoxConstraints constraints) {
    final List<GroupMessage> newestFirst = _messages.reversed.toList();

    return Scaffold(
      backgroundColor: colorAmbientMid,
      body: AmbientBackground(
        child: Column(
          children: [
            _topBar(),
            Expanded(
              child: ListView.builder(
                reverse: true,
                padding: const EdgeInsets.fromLTRB(16, 12, 16, 12),
                itemCount: newestFirst.length,
                itemBuilder: (context, index) {
                  final GroupMessage message = newestFirst[index];
                  final GroupMessage? older = index + 1 < newestFirst.length
                      ? newestFirst[index + 1]
                      : null;
                  final bool newDay = older == null ||
                      !_sameDay(older.sentAt, message.sentAt);

                  return Column(
                    crossAxisAlignment: CrossAxisAlignment.stretch,
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      if (newDay) _dayLabel(message.sentAt),
                      _message(message, older),
                    ],
                  );
                },
              ),
            ),
            _composer(),
          ],
        ),
      ),
    );
  }

  Widget _topBar() {
    final Color accent = goalColor(widget.group.colourHex);

    return Container(
      decoration: BoxDecoration(
        gradient: LinearGradient(
          begin: Alignment.topLeft,
          end: Alignment.bottomRight,
          colors: <Color>[
            Color.lerp(accent, colorHeaderBottom, 0.55)!,
            colorHeaderBottom,
          ],
        ),
      ),
      padding: EdgeInsets.fromLTRB(
          16, MediaQuery.of(context).padding.top + 10, 16, 14),
      child: Row(
        children: [
          glassCircle(CupertinoIcons.arrow_left, _onBack,
              size: 46, onDark: true),
          const SizedBox(width: 14),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              mainAxisSize: MainAxisSize.min,
              children: [
                text(widget.group.name, 19, TextType.Medium,
                    color: colorWhite,
                    maxLines: 1,
                    overflow: TextOverflow.ellipsis),
                const SizedBox(height: 3),
                text(
                    widget.group.members
                        .map((member) => member.me ? "you" : member.name)
                        .join(", "),
                    12,
                    TextType.Regular,
                    color: colorHeaderMuted,
                    maxLines: 1,
                    overflow: TextOverflow.ellipsis),
              ],
            ),
          ),
          const SizedBox(width: 10),
          avatarStack(
              widget.group.members.map((member) => member.name).toList(), 30,
              max: 3, border: colorHeaderBottom),
        ],
      ),
    );
  }

  Widget _dayLabel(DateTime? moment) {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 14),
      child: Center(
        child: Container(
          padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 5),
          color: colorWhite.withValues(alpha: 0.7),
          child: text(_dayName(moment), 11, TextType.Medium,
              color: colorInkSoft),
        ),
      ),
    );
  }

  /// Text as bubbles, check-ins and nudges as cards in the thread, system
  /// notes as a quiet centred line.
  Widget _message(GroupMessage message, GroupMessage? older) {
    if (message.isSystem) {
      return Padding(
        padding: const EdgeInsets.symmetric(vertical: 8),
        child: text(
          "${message.mine ? "You" : message.authorName} ${message.body}",
          12,
          TextType.Regular,
          color: colorInkSoft,
          align: TextAlign.center,
        ),
      );
    }

    if (message.isCheckIn || message.isNudge) {
      return _eventCard(message);
    }

    // Consecutive lines from one person share a single name and portrait.
    final bool grouped = older != null &&
        older.authorId == message.authorId &&
        !older.isSystem &&
        !older.isCheckIn &&
        !older.isNudge &&
        _sameDay(older.sentAt, message.sentAt);

    if (message.mine) {
      return Padding(
        padding: EdgeInsets.only(top: grouped ? 4 : 12, left: 64),
        child: Align(
          alignment: Alignment.centerRight,
          child: Container(
            padding: const EdgeInsets.fromLTRB(14, 11, 14, 10),
            color: colorNight,
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.end,
              mainAxisSize: MainAxisSize.min,
              children: [
                text(message.body, 15, TextType.Regular,
                    color: colorWhite, height: 1.4),
                const SizedBox(height: 4),
                text(_time(message.sentAt), 10, TextType.Regular,
                    color: colorHeaderMuted),
              ],
            ),
          ),
        ),
      );
    }

    final Color tone = _authorColour(message.authorName);

    return Padding(
      padding: EdgeInsets.only(top: grouped ? 4 : 12, right: 56),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.end,
        children: [
          grouped
              ? const SizedBox(width: 34)
              : memberAvatar(message.authorName, 34),
          const SizedBox(width: 8),
          Flexible(
            child: Container(
              padding: const EdgeInsets.fromLTRB(14, 10, 14, 10),
              decoration: BoxDecoration(
                color: colorWhite,
                border: Border.all(color: colorGlassBorder),
              ),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                mainAxisSize: MainAxisSize.min,
                children: [
                  if (!grouped) ...[
                    text(message.authorName, 12, TextType.Medium, color: tone),
                    const SizedBox(height: 3),
                  ],
                  text(message.body, 15, TextType.Regular,
                      color: colorInk, height: 1.4),
                  const SizedBox(height: 4),
                  text(_time(message.sentAt), 10, TextType.Regular,
                      color: colorInkSoft),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }

  /// A check-in or a nudge, set apart from the talk so the work is visible.
  Widget _eventCard(GroupMessage message) {
    final bool checkIn = message.isCheckIn;
    final String who = message.mine ? "You" : message.authorName;

    return Padding(
      padding: const EdgeInsets.only(top: 12),
      child: Container(
        padding: const EdgeInsets.fromLTRB(12, 12, 14, 12),
        decoration: BoxDecoration(
          color: checkIn ? colorStandingGoodBg : colorOverdueWarmEnd,
          border: Border(
            left: BorderSide(
              color: checkIn ? colorPositive : colorBarStandard,
              width: 4,
            ),
          ),
        ),
        child: Row(
          children: [
            memberAvatar(message.authorName, 34),
            const SizedBox(width: 12),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                mainAxisSize: MainAxisSize.min,
                children: [
                  Row(
                    children: [
                      Icon(
                        checkIn
                            ? CupertinoIcons.checkmark_seal_fill
                            : CupertinoIcons.hand_point_right_fill,
                        size: 13,
                        color: checkIn ? colorPositive : colorWarning,
                      ),
                      const SizedBox(width: 5),
                      text(checkIn ? "CHECK-IN" : "NUDGE", 10, TextType.Bold,
                          color: checkIn ? colorPositive : colorWarning,
                          letterSpacing: 1.0),
                      const Spacer(),
                      text(_time(message.sentAt), 10, TextType.Regular,
                          color: colorInkSoft),
                    ],
                  ),
                  const SizedBox(height: 4),
                  text("$who ${message.body}", 14, TextType.Regular,
                      color: colorInk, height: 1.4),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _composer() {
    return Container(
      color: colorWhite,
      padding: EdgeInsets.fromLTRB(
          0, 10, 0, MediaQuery.of(context).padding.bottom + 10),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          SizedBox(
            height: 38,
            child: ListView.separated(
              scrollDirection: Axis.horizontal,
              padding: const EdgeInsets.symmetric(horizontal: 16),
              itemCount: _quickReplies.length,
              separatorBuilder: (context, index) => const SizedBox(width: 8),
              itemBuilder: (context, index) => GestureDetector(
                onTap: () => _onQuickReply(_quickReplies[index]),
                child: Container(
                  padding: const EdgeInsets.symmetric(horizontal: 14),
                  alignment: Alignment.center,
                  color: colorAmbientMid,
                  child: text(_quickReplies[index], 13, TextType.Regular,
                      color: colorInk),
                ),
              ),
            ),
          ),
          const SizedBox(height: 8),
          Padding(
            padding: const EdgeInsets.fromLTRB(16, 0, 10, 0),
            child: Row(
              children: [
                Expanded(
                  child: quickAddField(_input, "Message the group", _onSend),
                ),
                const SizedBox(width: 8),
                GestureDetector(
                  onTap: _onSendPressed,
                  child: Container(
                    width: 50,
                    height: 50,
                    color: colorNight,
                    child: Icon(CupertinoIcons.paperplane_fill,
                        size: 20, color: colorLime),
                  ),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }

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

  Color _authorColour(String name) {
    return goalAccents[sceneSeed(name) % goalAccents.length];
  }

  bool _sameDay(DateTime? a, DateTime? b) {
    if (a == null || b == null) return false;
    final DateTime x = a.toLocal();
    final DateTime y = b.toLocal();
    return x.year == y.year && x.month == y.month && x.day == y.day;
  }

  String _dayName(DateTime? moment) {
    if (moment == null) return "";
    final DateTime now = DateTime.now();
    if (_sameDay(moment, now)) return "Today";
    if (_sameDay(moment, now.subtract(const Duration(days: 1)))) {
      return "Yesterday";
    }
    return formatDate(moment.toLocal());
  }

  String _time(DateTime? moment) {
    if (moment == null) return "";
    final DateTime local = moment.toLocal();
    return "${local.hour.toString().padLeft(2, "0")}:${local.minute.toString().padLeft(2, "0")}";
  }

  // ── ConnectGroupChat ──────────────────────────────────────────────────────

  @override
  void onMessagesLoaded(List<GroupMessage> messages) {
    if (!mounted) return;
    setState(() {
      _messages = messages;
    });
  }

  @override
  void onMessageSent(GroupMessage message) {
    if (!mounted) return;
    setState(() {
      _messages = <GroupMessage>[..._messages, message];
    });
  }

  @override
  void onSendFailed(String body) {
    if (!mounted) return;
    _input.text = body;
  }
}