// Copyright 2019 The Flutter team. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:collection';

import "package:collection/collection.dart";
import 'package:flutter/material.dart';
import 'package:flutter_localized_countries/flutter_localized_countries.dart';
import 'package:gallery/constants.dart';
import 'package:gallery/data/gallery_options.dart';
import 'package:gallery/l10n/gallery_localizations.dart';
import 'package:gallery/layout/adaptive.dart';
import 'package:gallery/pages/about.dart' as about;
import 'package:gallery/pages/backdrop.dart';
import 'package:gallery/pages/home.dart';
import 'package:gallery/pages/settings_list_item.dart';
import 'package:url_launcher/url_launcher.dart';

enum _ExpandableSetting {
  textScale,
  textDirection,
  locale,
  platform,
  theme,
}

class SettingsPage extends StatefulWidget {
  @override
  _SettingsPageState createState() => _SettingsPageState();
}

class _SettingsPageState extends State<SettingsPage> {
  _ExpandableSetting expandedSettingId;
  Map<String, String> _localeNativeNames;

  void onTapSetting(_ExpandableSetting settingId) {
    setState(() {
      if (expandedSettingId == settingId) {
        expandedSettingId = null;
      } else {
        expandedSettingId = settingId;
      }
    });
  }

  @override
  void initState() {
    super.initState();
    LocaleNamesLocalizationsDelegate().getLocaleNativeNames().then(
          (data) => setState(
            () {
              _localeNativeNames = data;
            },
          ),
        );
  }

  /// Given a [Locale], returns a [DisplayOption] with its native name for a
  /// title and its name in the currently selected locale for a subtitle. If the
  /// native name can't be determined, it is omitted. If the locale can't be
  /// determined, the locale code is used.
  DisplayOption _getLocaleDisplayOption(BuildContext context, Locale locale) {
    // TODO: gsw, fil, and es_419 aren't in flutter_localized_countries' dataset
    final localeCode = locale.toString();
    final localeName = LocaleNames.of(context).nameOf(localeCode);
    if (localeName != null) {
      final localeNativeName =
          _localeNativeNames != null ? _localeNativeNames[localeCode] : null;
      return localeNativeName != null
          ? DisplayOption(localeNativeName, subtitle: localeName)
          : DisplayOption(localeName);
    } else {
      switch (localeCode) {
        case 'gsw':
          return DisplayOption('Schwiizertüütsch', subtitle: 'Swiss German');
        case 'fil':
          return DisplayOption('Filipino', subtitle: 'Filipino');
        case 'es_419':
          return DisplayOption(
            'español (Latinoamérica)',
            subtitle: 'Spanish (Latin America)',
          );
      }
    }

    return DisplayOption(localeCode);
  }

  /// Create a sorted — by native name – map of supported locales to their
  /// intended display string, with a system option as the first element.
  LinkedHashMap<Locale, DisplayOption> _getLocaleOptions() {
    var localeOptions = LinkedHashMap.of({
      systemLocaleOption: DisplayOption(
        GalleryLocalizations.of(context).settingsSystemDefault +
            (deviceLocale != null
                ? ' - ${_getLocaleDisplayOption(context, deviceLocale).title}'
                : ''),
      ),
    });
    var supportedLocales =
        List<Locale>.from(GalleryLocalizations.supportedLocales);
    supportedLocales.removeWhere((locale) => locale == deviceLocale);

    final displayLocales = Map<Locale, DisplayOption>.fromIterable(
      supportedLocales,
      value: (dynamic locale) =>
          _getLocaleDisplayOption(context, locale as Locale),
    ).entries.toList()
      ..sort((l1, l2) => compareAsciiUpperCase(l1.value.title, l2.value.title));

    localeOptions.addAll(LinkedHashMap.fromEntries(displayLocales));
    return localeOptions;
  }

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    final options = GalleryOptions.of(context);
    final isDesktop = isDisplayDesktop(context);

    return Material(
      color: colorScheme.secondaryVariant,
      child: Padding(
        padding: isDesktop
            ? EdgeInsets.zero
            : EdgeInsets.only(bottom: galleryHeaderHeight),
        // Remove ListView top padding as it is already accounted for.
        child: MediaQuery.removePadding(
          removeTop: isDesktop,
          context: context,
          child: ListView(
            children: [
              SizedBox(height: firstHeaderDesktopTopPadding),
              Focus(
                focusNode:
                    InheritedBackdropFocusNodes.of(context).frontLayerFocusNode,
                child: Padding(
                  padding: EdgeInsets.symmetric(horizontal: 32),
                  child: ExcludeSemantics(
                    child: Header(
                      color: Theme.of(context).colorScheme.onSurface,
                      text: GalleryLocalizations.of(context).settingsTitle,
                    ),
                  ),
                ),
              ),
              SettingsListItem<double>(
                title: GalleryLocalizations.of(context).settingsTextScaling,
                selectedOption: options.textScaleFactor(
                  context,
                  useSentinel: true,
                ),
                options: LinkedHashMap.of({
                  systemTextScaleFactorOption: DisplayOption(
                    GalleryLocalizations.of(context).settingsSystemDefault,
                  ),
                  0.8: DisplayOption(
                    GalleryLocalizations.of(context).settingsTextScalingSmall,
                  ),
                  1.0: DisplayOption(
                    GalleryLocalizations.of(context).settingsTextScalingNormal,
                  ),
                  2.0: DisplayOption(
                    GalleryLocalizations.of(context).settingsTextScalingLarge,
                  ),
                  3.0: DisplayOption(
                    GalleryLocalizations.of(context).settingsTextScalingHuge,
                  ),
                }),
                onOptionChanged: (newTextScale) => GalleryOptions.update(
                  context,
                  options.copyWith(textScaleFactor: newTextScale),
                ),
                onTapSetting: () => onTapSetting(_ExpandableSetting.textScale),
                isExpanded: expandedSettingId == _ExpandableSetting.textScale,
              ),
              SettingsListItem<CustomTextDirection>(
                title: GalleryLocalizations.of(context).settingsTextDirection,
                selectedOption: options.customTextDirection,
                options: LinkedHashMap.of({
                  CustomTextDirection.localeBased: DisplayOption(
                    GalleryLocalizations.of(context)
                        .settingsTextDirectionLocaleBased,
                  ),
                  CustomTextDirection.ltr: DisplayOption(
                    GalleryLocalizations.of(context).settingsTextDirectionLTR,
                  ),
                  CustomTextDirection.rtl: DisplayOption(
                    GalleryLocalizations.of(context).settingsTextDirectionRTL,
                  ),
                }),
                onOptionChanged: (newTextDirection) => GalleryOptions.update(
                  context,
                  options.copyWith(customTextDirection: newTextDirection),
                ),
                onTapSetting: () =>
                    onTapSetting(_ExpandableSetting.textDirection),
                isExpanded:
                    expandedSettingId == _ExpandableSetting.textDirection,
              ),
              SettingsListItem<Locale>(
                title: GalleryLocalizations.of(context).settingsLocale,
                selectedOption: options.locale == deviceLocale
                    ? systemLocaleOption
                    : options.locale,
                options: _getLocaleOptions(),
                onOptionChanged: (newLocale) {
                  if (newLocale == systemLocaleOption) {
                    newLocale = deviceLocale;
                  }
                  GalleryOptions.update(
                    context,
                    options.copyWith(locale: newLocale),
                  );
                },
                onTapSetting: () => onTapSetting(_ExpandableSetting.locale),
                isExpanded: expandedSettingId == _ExpandableSetting.locale,
              ),
              SettingsListItem<TargetPlatform>(
                title:
                    GalleryLocalizations.of(context).settingsPlatformMechanics,
                selectedOption: options.platform,
                options: LinkedHashMap.of({
                  TargetPlatform.android: DisplayOption(
                    GalleryLocalizations.of(context).settingsPlatformAndroid,
                  ),
                  TargetPlatform.iOS: DisplayOption(
                    GalleryLocalizations.of(context).settingsPlatformIOS,
                  ),
                }),
                onOptionChanged: (newPlatform) => GalleryOptions.update(
                  context,
                  options.copyWith(platform: newPlatform),
                ),
                onTapSetting: () => onTapSetting(_ExpandableSetting.platform),
                isExpanded: expandedSettingId == _ExpandableSetting.platform,
              ),
              SettingsListItem<ThemeMode>(
                title: GalleryLocalizations.of(context).settingsTheme,
                selectedOption: options.themeMode,
                options: LinkedHashMap.of({
                  ThemeMode.system: DisplayOption(
                    GalleryLocalizations.of(context).settingsSystemDefault,
                  ),
                  ThemeMode.dark: DisplayOption(
                    GalleryLocalizations.of(context).settingsDarkTheme,
                  ),
                  ThemeMode.light: DisplayOption(
                    GalleryLocalizations.of(context).settingsLightTheme,
                  ),
                }),
                onOptionChanged: (newThemeMode) => GalleryOptions.update(
                  context,
                  options.copyWith(themeMode: newThemeMode),
                ),
                onTapSetting: () => onTapSetting(_ExpandableSetting.theme),
                isExpanded: expandedSettingId == _ExpandableSetting.theme,
              ),
              SlowMotionSetting(),
              if (!isDesktop) ...[
                SizedBox(height: 16),
                Divider(thickness: 2, height: 0, color: colorScheme.background),
                SizedBox(height: 12),
                SettingsAbout(),
                SettingsFeedback(),
                SizedBox(height: 12),
                Divider(thickness: 2, height: 0, color: colorScheme.background),
                SettingsAttribution(),
              ],
            ],
          ),
        ),
      ),
    );
  }
}

class SettingsAbout extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return _SettingsLink(
      title: GalleryLocalizations.of(context).settingsAbout,
      icon: Icons.info_outline,
      onTap: () {
        about.showAboutDialog(context: context);
      },
    );
  }
}

class SettingsFeedback extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return _SettingsLink(
      title: GalleryLocalizations.of(context).settingsFeedback,
      icon: Icons.feedback,
      onTap: () async {
        final url = 'https://github.com/flutter/flutter/issues/new/choose/';
        if (await canLaunch(url)) {
          await launch(
            url,
            forceSafariVC: false,
          );
        }
      },
    );
  }
}

class SettingsAttribution extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final isDesktop = isDisplayDesktop(context);
    final verticalPadding = isDesktop ? 0.0 : 28.0;
    return MergeSemantics(
      child: Padding(
        padding: EdgeInsetsDirectional.only(
          start: isDesktop ? 48 : 32,
          end: isDesktop ? 0 : 32,
          top: verticalPadding,
          bottom: verticalPadding,
        ),
        child: Text(
          GalleryLocalizations.of(context).settingsAttribution,
          style: Theme.of(context).textTheme.body2.copyWith(
                fontSize: 12,
                color: Theme.of(context).colorScheme.onSecondary,
              ),
          textAlign: isDesktop ? TextAlign.end : TextAlign.start,
        ),
      ),
    );
  }
}

class _SettingsLink extends StatelessWidget {
  final String title;
  final IconData icon;
  final GestureTapCallback onTap;

  _SettingsLink({this.title, this.icon, this.onTap});

  @override
  Widget build(BuildContext context) {
    final textTheme = Theme.of(context).textTheme;
    final colorScheme = Theme.of(context).colorScheme;
    final isDesktop = isDisplayDesktop(context);

    return InkWell(
      onTap: onTap,
      child: Padding(
        padding: EdgeInsetsDirectional.only(
          start: isDesktop ? 48 : 32,
          end: isDesktop ? 0 : 32,
        ),
        child: Row(
          mainAxisSize: MainAxisSize.min,
          children: [
            Icon(
              icon,
              color: colorScheme.onSecondary.withOpacity(0.5),
              size: 24,
            ),
            Flexible(
              child: Padding(
                padding: const EdgeInsetsDirectional.only(
                  start: 16,
                  top: 12,
                  bottom: 12,
                ),
                child: Text(
                  title,
                  style: textTheme.subtitle.apply(
                    color: colorScheme.onSecondary,
                  ),
                  textAlign: isDesktop ? TextAlign.end : TextAlign.start,
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}