nc-photos/app/lib/theme.dart

import 'package:flutter/material.dart';
import 'package:nc_photos/pref.dart';

class AppTheme extends StatelessWidget {
  const AppTheme({
    Key? key,
    required this.child,
    this.brightnessOverride,
  }) : super(key: key);

  factory AppTheme.light({
    Key? key,
    required Widget child,
  }) =>
      AppTheme(
        key: key,
        brightnessOverride: Brightness.light,
        child: child,
      );

  factory AppTheme.dark({
    Key? key,
    required Widget child,
  }) =>
      AppTheme(
        key: key,
        brightnessOverride: Brightness.dark,
        child: child,
      );

  @override
  Widget build(BuildContext context) {
    return Theme(
      data: _buildThemeData(context),
      child: DefaultTextStyle(
        style: _buildTextStyle(context),
        child: child,
      ),
    );
  }

  static ThemeData buildThemeData(BuildContext context) {
    final theme = Theme.of(context);
    return theme.brightness == Brightness.light
        ? buildLightThemeData()
        : buildDarkThemeData();
  }

  static AppBarTheme getContextualAppBarTheme(BuildContext context) {
    final theme = Theme.of(context);
    if (theme.brightness == Brightness.light) {
      return theme.appBarTheme.copyWith(
        backgroundColor: Colors.grey[800],
        foregroundColor: Colors.white.withOpacity(.87),
      );
    } else {
      return theme.appBarTheme.copyWith(
        backgroundColor: Colors.grey[200],
        foregroundColor: Colors.black87,
      );
    }
  }

  static Color getSelectionOverlayColor(BuildContext context) {
    return Theme.of(context).brightness == Brightness.light
        ? primarySwatchLight[100]!.withOpacity(0.7)
        : primarySwatchDark[700]!.withOpacity(0.7);
  }

  static Color getOverscrollIndicatorColor(BuildContext context) {
    return Theme.of(context).brightness == Brightness.light
        ? Colors.grey[800]!
        : Colors.grey[200]!;
  }

  static Color getRootPickerContentBoxColor(BuildContext context) {
    return Colors.blue[200]!;
  }

  static Color getPrimaryTextColor(BuildContext context) {
    return Theme.of(context).brightness == Brightness.light
        ? primaryTextColorLight
        : primaryTextColorDark;
  }

  static Color getSecondaryTextColor(BuildContext context) {
    return Theme.of(context).brightness == Brightness.light
        ? Colors.black.withOpacity(.6)
        : Colors.white60;
  }

  static Color getPrimaryTextColorInverse(BuildContext context) =>
      Theme.of(context).brightness == Brightness.light
          ? primaryTextColorDark
          : primaryTextColorLight;

  static Color getAppBarDarkModeSwitchColor(BuildContext context) {
    return Colors.black87;
  }

  static Color getAppBarDarkModeSwitchTrackColor(BuildContext context) {
    return Colors.white.withOpacity(.5);
  }

  static Color getListItemBackgroundColor(BuildContext context) {
    return Theme.of(context).brightness == Brightness.light
        ? Colors.black26
        : Colors.white12;
  }

  static Color getUnfocusedIconColor(BuildContext context) {
    return Theme.of(context).brightness == Brightness.light
        ? unfocusedIconColorLight
        : unfocusedIconColorDark;
  }

  static ThemeData buildLightThemeData() {
    final theme = ThemeData(
      brightness: Brightness.light,
      primarySwatch: AppTheme.primarySwatchLight,
    );
    final appBarTheme = theme.appBarTheme.copyWith(
      backgroundColor: theme.scaffoldBackgroundColor,
      foregroundColor: theme.colorScheme.onSurface,
    );
    return theme.copyWith(appBarTheme: appBarTheme);
  }

  static ThemeData buildDarkThemeData() {
    final Color background;
    final Color popup;
    if (Pref().isUseBlackInDarkThemeOr(false)) {
      background = Colors.black;
      popup = Colors.grey[900]!;
    } else {
      // in the material spec, black is suggested to be 0x121212, but the one
      // used in flutter by default is 0x303030, why?
      background = Colors.grey[850]!;
      popup = Colors.grey[800]!;
    }

    final theme = ThemeData(
      brightness: Brightness.dark,
      primarySwatch: AppTheme.primarySwatchDark,
      scaffoldBackgroundColor: background,
      dialogBackgroundColor: popup,
      bottomNavigationBarTheme: BottomNavigationBarThemeData(
        backgroundColor: background,
      ),
      popupMenuTheme: PopupMenuThemeData(
        color: popup,
      ),
      checkboxTheme: CheckboxThemeData(
        fillColor: _CheckboxDarkColorProperty(),
      ),
    );
    final appBarTheme = theme.appBarTheme.copyWith(
      backgroundColor: background,
      foregroundColor: theme.colorScheme.onSurface,
    );
    return theme.copyWith(appBarTheme: appBarTheme);
  }

  ThemeData _buildThemeData(BuildContext context) {
    return (brightnessOverride ?? Theme.of(context).brightness) ==
            Brightness.light
        ? buildLightThemeData()
        : buildDarkThemeData();
  }

  TextStyle _buildTextStyle(BuildContext context) {
    return (brightnessOverride ?? Theme.of(context).brightness) ==
            Brightness.light
        ? const TextStyle(color: AppTheme.primaryTextColorLight)
        : TextStyle(color: AppTheme.primaryTextColorDark);
  }

  static const primarySwatchLight = Colors.blue;
  static const primarySwatchDark = Colors.cyan;

  static const primaryTextColorLight = Colors.black87;
  static final primaryTextColorDark = Colors.white.withOpacity(.87);

  static const unfocusedIconColorLight = Colors.black54;
  static const unfocusedIconColorDark = Colors.white70;

  static const widthLimitedContentMaxWidth = 550.0;

  /// Make a TextButton look like a default FlatButton. See
  /// https://flutter.dev/go/material-button-migration-guide
  static final flatButtonStyle = TextButton.styleFrom(
    primary: Colors.black87,
    minimumSize: const Size(88, 36),
    padding: const EdgeInsets.symmetric(horizontal: 16.0),
    shape: const RoundedRectangleBorder(
      borderRadius: BorderRadius.all(Radius.circular(2.0)),
    ),
  );

  final Widget child;
  final Brightness? brightnessOverride;
}

class _CheckboxDarkColorProperty implements MaterialStateProperty<Color?> {
  @override
  resolve(Set<MaterialState> states) {
    if (states.contains(MaterialState.selected)) {
      return Colors.cyanAccent[400];
    } else {
      return null;
    }
  }
}