import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import '../theme/app_theme.dart';

/// Manages dynamic branding and app theme settings fetched from the Odoo backend.
/// Automatically handles offline caching via SharedPreferences.
class ThemeManager extends ChangeNotifier {
  static final ThemeManager instance = ThemeManager._internal();

  ThemeManager._internal();

  Color _primaryColor = AppTheme.primary;
  Color _secondaryColor = AppTheme.secondary;
  String _brandLogo = '';

  Color get primaryColor => _primaryColor;
  Color get secondaryColor => _secondaryColor;
  String get brandLogo => _brandLogo;

  ThemeData get themeData => AppTheme.getTheme(
        primaryColor: _primaryColor,
        secondaryColor: _secondaryColor,
      );

  /// Initialize cached settings on app launch
  Future<void> initialize() async {
    final prefs = await SharedPreferences.getInstance();
    final primHex = prefs.getString('theme_primary_color');
    final secHex = prefs.getString('theme_secondary_color');
    _brandLogo = prefs.getString('theme_brand_logo') ?? '';

    if (primHex != null) {
      _primaryColor = _parseHexColor(primHex) ?? AppTheme.primary;
    }
    if (secHex != null) {
      _secondaryColor = _parseHexColor(secHex) ?? AppTheme.secondary;
    }
  }

  /// Update theme options and persist them to SharedPreferences
  Future<void> updateConfig({
    required String primaryHex,
    required String secondaryHex,
    required String brandLogoB64,
  }) async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.setString('theme_primary_color', primaryHex);
    await prefs.setString('theme_secondary_color', secondaryHex);
    await prefs.setString('theme_brand_logo', brandLogoB64);

    _primaryColor = _parseHexColor(primaryHex) ?? AppTheme.primary;
    _secondaryColor = _parseHexColor(secondaryHex) ?? AppTheme.secondary;
    _brandLogo = brandLogoB64;
    notifyListeners();
  }

  Color? _parseHexColor(String hexString) {
    try {
      final buffer = StringBuffer();
      if (hexString.length == 6 || hexString.length == 7) buffer.write('ff');
      buffer.write(hexString.replaceFirst('#', ''));
      return Color(int.parse(buffer.toString(), radix: 16));
    } catch (_) {
      return null;
    }
  }
}