import 'dart:async';

import 'package:flutter/material.dart';
import 'package:intl/intl.dart';

/// Black night screen with a very dim clock. Tapping anywhere returns.
class NightModeOverlay extends StatefulWidget {
  const NightModeOverlay({super.key, required this.onDismiss});

  final VoidCallback onDismiss;

  @override
  State<NightModeOverlay> createState() => _NightModeOverlayState();
}

class _NightModeOverlayState extends State<NightModeOverlay> {
  late DateTime _now = DateTime.now();
  Timer? _timer;

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

  void _scheduleTick() {
    _timer?.cancel();
    final now = DateTime.now();
    final next = DateTime(
      now.year,
      now.month,
      now.day,
      now.hour,
      now.minute,
    ).add(const Duration(minutes: 1));
    _timer = Timer(next.difference(now) + const Duration(milliseconds: 80), () {
      if (!mounted) return;
      setState(() => _now = DateTime.now());
      _scheduleTick();
    });
  }

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

  @override
  Widget build(BuildContext context) {
    final locale = Localizations.localeOf(context).toLanguageTag();
    final use24Hour = MediaQuery.alwaysUse24HourFormatOf(context);
    final time = (use24Hour ? DateFormat.Hm(locale) : DateFormat.jm(locale))
        .format(_now);

    return Semantics(
      button: true,
      label: 'Exit night mode',
      child: GestureDetector(
        behavior: HitTestBehavior.opaque,
        onTap: widget.onDismiss,
        child: ColoredBox(
          color: Colors.black,
          child: Center(
            child: Text(
              time,
              maxLines: 1,
              style: TextStyle(
                color: Colors.white.withValues(alpha: 0.12),
                fontSize: 84,
                fontWeight: FontWeight.w300,
                height: 1,
                fontFeatures: const [FontFeature.tabularFigures()],
              ),
            ),
          ),
        ),
      ),
    );
  }
}