import "package:flutter/material.dart";
import "package:shared_preferences/shared_preferences.dart";

import "models.dart";

/// App-wide appearance preferences (theme / locale / date format / font size),
/// mirroring the web app's prefs.js. Persisted to SharedPreferences so the
/// chosen theme survives a restart before /api/me loads, and exposed as a
/// ChangeNotifier so MaterialApp and date formatting react to changes.
class AppSettings extends ChangeNotifier {
  static const _kTheme = "cc_theme";
  static const _kLocale = "cc_locale";
  static const _kDateFormat = "cc_dateFormat";
  static const _kFontSize = "cc_fontSize";

  String theme = "system"; // light | dark | system
  String locale = "en-US";
  String dateFormat = "YMD"; // YMD | DMY_NUM | DMY | MDY
  String fontSize = "medium"; // small | medium | large

  Future<void> loadFromStorage() async {
    final prefs = await SharedPreferences.getInstance();
    theme = prefs.getString(_kTheme) ?? theme;
    locale = prefs.getString(_kLocale) ?? locale;
    dateFormat = prefs.getString(_kDateFormat) ?? dateFormat;
    fontSize = prefs.getString(_kFontSize) ?? fontSize;
    notifyListeners();
  }

  Future<void> _persist() async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.setString(_kTheme, theme);
    await prefs.setString(_kLocale, locale);
    await prefs.setString(_kDateFormat, dateFormat);
    await prefs.setString(_kFontSize, fontSize);
  }

  /// Sync from a freshly fetched profile (login, boot, settings saves).
  void applyFromProfile(UserProfile p) {
    theme = p.theme;
    locale = p.locale;
    dateFormat = p.dateFormat;
    fontSize = p.fontSize;
    _persist();
    notifyListeners();
  }

  /// Optimistically apply a single changed field (used by Settings so the UI
  /// reacts instantly while the PATCH is in flight).
  void patch({String? theme, String? locale, String? dateFormat, String? fontSize}) {
    if (theme != null) this.theme = theme;
    if (locale != null) this.locale = locale;
    if (dateFormat != null) this.dateFormat = dateFormat;
    if (fontSize != null) this.fontSize = fontSize;
    _persist();
    notifyListeners();
  }

  ThemeMode get themeMode => switch (theme) {
        "light" => ThemeMode.light,
        "dark" => ThemeMode.dark,
        _ => ThemeMode.system,
      };

  double get textScale => switch (fontSize) {
        "small" => 0.9375,
        "large" => 1.125,
        _ => 1.0,
      };
}