import 'package:flutter/material.dart';

import 'bridge.dart';
import 'state.dart';
import 'timeline.dart';

void main() {
  runApp(const MainApp());
}

class MainApp extends StatefulWidget {
  const MainApp({super.key});

  @override
  State<MainApp> createState() => _MainAppState();
}

class _MainAppState extends State<MainApp> {
  TimelineState? _state;
  List<TimelineGroup> _groups = const [];
  List<TimelineEntry> _entries = const [];
  TimelineViewportNotifier? _viewport;

  @override
  void initState() {
    super.initState();
    _initBridge();
  }

  @override
  void dispose() {
    _viewport?.dispose();
    super.dispose();
  }

  void _initBridge() {
    final initial = readInitialState();
    if (initial != null) {
      _applyState(TimelineState.fromJson(initial));
    }

    onStateUpdated((json) {
      _applyState(TimelineState.fromJson(json));
    });
  }

  void _applyState(TimelineState state) {
    final groups = _convertGroups(state.timeline.groups);
    final entries = _convertEntries(state.timeline.groups);
    final domain = _computeDomain(entries);

    setState(() {
      _state = state;
      _groups = groups;
      _entries = entries;

      _viewport ??= TimelineViewportNotifier(
        start: domain.start,
        end: domain.end,
      );
    });

    _emitContentHeight();
  }

  List<TimelineGroup> _convertGroups(List<TimelineGroupData> groups) {
    return [for (final g in groups) TimelineGroup(id: g.id, title: g.title)];
  }

  List<TimelineEntry> _convertEntries(List<TimelineGroupData> groups) {
    final entries = <TimelineEntry>[];
    for (final group in groups) {
      for (final item in group.items) {
        final start = DateTime.parse(item.start);
        final end = item.end != null
            ? DateTime.parse(item.end!)
            : start.add(const Duration(days: 1));

        entries.add(
          TimelineEntry(
            id: item.id,
            groupId: group.id,
            start: start,
            end: end,
            lane: item.lane,
          ),
        );
      }
    }
    return entries;
  }

  ({DateTime start, DateTime end}) _computeDomain(List<TimelineEntry> entries) {
    if (entries.isEmpty) {
      final now = DateTime.now();
      return (
        start: now.subtract(const Duration(days: 30)),
        end: now.add(const Duration(days: 30)),
      );
    }

    var earliest = entries.first.start;
    var latest = entries.first.end;
    for (final e in entries) {
      if (e.start.isBefore(earliest)) earliest = e.start;
      if (e.end.isAfter(latest)) latest = e.end;
    }

    // Add 10% padding on each side
    final span = latest.difference(earliest);
    final padding = Duration(milliseconds: (span.inMilliseconds * 0.1).round());
    return (start: earliest.subtract(padding), end: latest.add(padding));
  }

  void _onEntryMoved(
    TimelineEntry entry,
    DateTime newStart,
    String newGroupId,
    int newLane,
  ) {
    final duration = entry.end.difference(entry.start);
    final newEnd = newStart.add(duration);

    emitEvent('entry_moved', {
      'entryId': entry.id,
      'newStart': newStart.toIso8601String(),
      'newEnd': newEnd.toIso8601String(),
      'newGroupId': newGroupId,
      'newLane': newLane,
    });
  }

  void _emitContentHeight() {
    var totalHeight = 0.0;
    for (final group in _groups) {
      totalHeight += ZTimelineConstants.groupHeaderHeight;
      final groupEntries = _entries.where((e) => e.groupId == group.id);
      var maxLane = 0;
      for (final e in groupEntries) {
        if (e.lane > maxLane) maxLane = e.lane;
      }
      final lanesCount = maxLane.clamp(0, 1000);
      totalHeight +=
          lanesCount * ZTimelineConstants.laneHeight +
          (lanesCount > 0
              ? (lanesCount - 1) * ZTimelineConstants.laneVerticalSpacing
              : 0) +
          ZTimelineConstants.verticalOuterPadding * 2;
    }
    emitEvent('content_height', {'height': totalHeight});
  }

  String _labelForEntry(TimelineEntry entry) {
    final state = _state;
    if (state == null) return entry.id;

    for (final group in state.timeline.groups) {
      for (final item in group.items) {
        if (item.id == entry.id) return item.title;
      }
    }
    return entry.id;
  }

  static const _groupColors = [
    Color(0xFF4285F4), // blue
    Color(0xFF34A853), // green
    Color(0xFFFBBC04), // yellow
    Color(0xFFEA4335), // red
    Color(0xFF9C27B0), // purple
    Color(0xFF00BCD4), // cyan
    Color(0xFFFF9800), // orange
    Color(0xFF795548), // brown
  ];

  Color _colorForEntry(TimelineEntry entry) {
    final groupIndex = _groups.indexWhere((g) => g.id == entry.groupId);
    if (groupIndex < 0) return _groupColors[0];
    return _groupColors[groupIndex % _groupColors.length];
  }

  @override
  Widget build(BuildContext context) {
    final viewport = _viewport;

    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData.dark(useMaterial3: true),
      home: Scaffold(
        backgroundColor: Colors.transparent,
        body: _state == null || viewport == null
            ? const Center(child: Text('Waiting for state...'))
            : ZTimelineScope(
                viewport: viewport,
                child: ZTimelineInteractor(
                  child: ZTimelineView(
                    groups: _groups,
                    entries: _entries,
                    viewport: viewport,
                    labelBuilder: _labelForEntry,
                    colorBuilder: _colorForEntry,
                    enableDrag: true,
                    onEntryMoved: _onEntryMoved,
                  ),
                ),
              ),
      ),
    );
  }
}