import 'dart:io';
import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';

class AppConfig {
  // ─── API Configuration ────────────────────────────────────────────────────
  //
  // Dual-Mode Configuration, tried in this order at every app startup:
  // 1. Local/LAN backend (fast, low-latency - the common case when the phone
  //    and backend are on the same Wi-Fi).
  // 2. Public Ngrok tunnel (fallback for when the phone is off that network,
  //    or the LAN URL below is stale).
  // Whichever responds first with a real backend (not a dead route/tunnel
  // error page) wins; if neither does, LAN is used as the default so error
  // messages point at the expected local backend rather than a dead tunnel.
  //

  // LAN / WiFi / Emulator URL (port 8000 = nginx gateway)
  // - Physical Device on same Wi-Fi: use the backend machine's current LAN IP
  // - Android Emulator: use 'http://10.0.2.2:8000/api/v1'
  // - iOS Simulator: use 'http://localhost:8000/api/v1'
  static const String _lanBaseUrl = 'http://192.168.70.4:8000/api/v1';

  // Ngrok public tunnel URL (update ini setiap ngrok di-restart)
  static const String _ngrokBaseUrl = 'https://unlocated-waylon-potently.ngrok-free.dev/api/v1';

  // Dynamic Base URL determined at startup
  static String apiBaseUrl = _lanBaseUrl;

  /// Dynamic URL resolver: tries the LAN backend first, then the public
  /// Ngrok tunnel, and picks whichever responds with a real backend.
  static Future<void> initializeApiBaseUrl() async {
    debugPrint('AppConfig: Checking local/LAN backend at $_lanBaseUrl...');
    if (await _isBackendReachable(_lanBaseUrl)) {
      apiBaseUrl = _lanBaseUrl;
      debugPrint('AppConfig: LAN backend is ACTIVE. API Base URL: $apiBaseUrl');
      return;
    }
    debugPrint('AppConfig: LAN backend not reachable, trying public Ngrok tunnel at $_ngrokBaseUrl...');

    if (await _isBackendReachable(_ngrokBaseUrl)) {
      apiBaseUrl = _ngrokBaseUrl;
      debugPrint('AppConfig: Ngrok tunnel is ACTIVE. API Base URL: $apiBaseUrl');
      return;
    }

    apiBaseUrl = _lanBaseUrl;
    debugPrint('AppConfig: Neither LAN nor Ngrok reachable. Defaulting to LAN API Base URL: $apiBaseUrl');
  }

  /// Probes [baseUrl]/auth/login with a throwaway request to check whether a
  /// real backend answers behind it - not a timed-out connection, a dead
  /// tunnel, or a router/error page pretending to be a response.
  static Future<bool> _isBackendReachable(String baseUrl) async {
    final client = HttpClient();
    client.connectionTimeout = const Duration(seconds: 2);
    try {
      final uri = Uri.parse('$baseUrl/auth/login');
      final request = await client.postUrl(uri);

      // Bypasses the Ngrok browser-warning interstitial; harmless for LAN.
      request.headers.add('ngrok-skip-browser-warning', 'true');
      request.headers.contentType = ContentType.json;
      request.write('{}');

      final response = await request.close();

      final contentType = response.headers.contentType?.mimeType ?? '';
      final ngrokErrorCode = response.headers.value('ngrok-error-code');

      debugPrint('AppConfig: Probe $baseUrl -> status ${response.statusCode}, '
          'Content-Type: $contentType, Ngrok-Error-Code: $ngrokErrorCode');

      // A real backend behind this URL:
      // 1. Should not return an ngrok-error-code header (dead/offline tunnel).
      // 2. The response content-type should be JSON (our login API returns JSON).
      // 3. Status code should not be 502, 503, or 504 (gateway/proxy errors).
      return ngrokErrorCode == null &&
          contentType.contains('json') &&
          response.statusCode != 502 &&
          response.statusCode != 503 &&
          response.statusCode != 504;
    } catch (e) {
      debugPrint('AppConfig: Probe $baseUrl failed: $e');
      return false;
    } finally {
      client.close();
    }
  }

  static const String loginEndpoint = '/auth/login';
  static const String uploadDocumentEndpoint = '/documents/upload';
  static const String fetchDocumentsEndpoint = '/documents';
  static const String masterSkusEndpoint = '/master/skus';
  static const String scanProductEndpoint = '/scan-product';

  
  // App Constants
  static const String appName = 'Prima Mart Scanner';
  static const String appVersion = '1.0.0';

  // Colors - Prima Fresh Mart Theme
  static const Color primaryColor = Color(0xFF6EBE4A); // Prima Green
  static const Color secondaryColor = Color(0xFF005DAA); // Prima Blue
  static const Color accentColor = Color(0xFFFFCC00); // Prima Yellow
  static const Color backgroundColor = Color(0xFFF8F9FA); // Off-white
  static const Color surfaceColor = Colors.white;
  static const Color errorColor = Color(0xFFD32F2F);
  static const Color successColor = Color(0xFF388E3C);
  // DO mode color — orange cue used throughout for the DO Scan mode:
  //   document_card.dart top-label, documents_tab_switcher.dart active DO tab,
  //   camera_drawer_mode_toggle.dart DO segment decoration. Formalized as a
  //   shared constant so all three call sites pull from one place (was an
  //   ad-hoc Colors.orange.shade700 inline in document_card.dart).
  static const Color doModeColor = Color(0xFFF57C00); // == Colors.orange.shade700
  
  // Text Colors
  static const Color textPrimary = Color(0xFF212121);
  static const Color textSecondary = Color(0xFF757575);
  static const Color textOnPrimary = Colors.white;

  // Spacing System (Margin & Padding)
  static const double spaceXS = 4.0;
  static const double spaceSmall = 8.0;
  static const double spaceMedium = 12.0;
  static const double spaceLarge = 16.0;
  static const double spaceXL = 24.0;
  static const double spaceXXL = 32.0;

  static const EdgeInsets paddingXS = EdgeInsets.all(spaceXS);
  static const EdgeInsets paddingSmall = EdgeInsets.all(spaceSmall);
  static const EdgeInsets paddingMedium = EdgeInsets.all(spaceMedium);
  static const EdgeInsets paddingLarge = EdgeInsets.all(spaceLarge);
  static const EdgeInsets paddingXL = EdgeInsets.all(spaceXL);
  static const EdgeInsets screenPadding = EdgeInsets.symmetric(horizontal: spaceXL, vertical: spaceLarge);

  // Border Radii
  static const double borderRadiusSmall = 8.0;
  static const double borderRadiusMedium = 12.0;
  static const double borderRadiusLarge = 16.0;
  static const double borderRadiusXL = 24.0;

  // Typography Config
  // Using Google Fonts - Inter for clean, modern look
  static TextStyle get h1 => GoogleFonts.inter(
        fontSize: 32,
        fontWeight: FontWeight.bold,
        color: textPrimary,
      );

  static TextStyle get h2 => GoogleFonts.inter(
        fontSize: 24,
        fontWeight: FontWeight.w600,
        color: textPrimary,
      );

  static TextStyle get h3 => GoogleFonts.inter(
        fontSize: 20,
        fontWeight: FontWeight.w600,
        color: textPrimary,
      );

  static TextStyle get bodyLarge => GoogleFonts.inter(
        fontSize: 16,
        fontWeight: FontWeight.normal,
        color: textPrimary,
      );

  static TextStyle get bodyMedium => GoogleFonts.inter(
        fontSize: 14,
        fontWeight: FontWeight.normal,
        color: textPrimary,
      );

  static TextStyle get bodySmall => GoogleFonts.inter(
        fontSize: 12,
        fontWeight: FontWeight.normal,
        color: textSecondary,
      );

  // Theme Data Builder
  static ThemeData get lightTheme {
    return ThemeData(
      primaryColor: primaryColor,
      scaffoldBackgroundColor: backgroundColor,
      colorScheme: const ColorScheme.light(
        primary: primaryColor,
        secondary: secondaryColor,
        surface: surfaceColor,
        error: errorColor,
      ),
      appBarTheme: AppBarTheme(
        backgroundColor: surfaceColor,
        elevation: 0,
        centerTitle: true,
        iconTheme: const IconThemeData(color: textPrimary),
        titleTextStyle: h2.copyWith(color: textPrimary),
      ),
      elevatedButtonTheme: ElevatedButtonThemeData(
        style: ElevatedButton.styleFrom(
          backgroundColor: primaryColor,
          foregroundColor: textOnPrimary,
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(12),
          ),
          padding: const EdgeInsets.symmetric(vertical: 16, horizontal: 24),
          textStyle: bodyLarge.copyWith(fontWeight: FontWeight.w600),
        ),
      ),
      inputDecorationTheme: InputDecorationTheme(
        filled: true,
        fillColor: surfaceColor,
        contentPadding: const EdgeInsets.symmetric(horizontal: 16, vertical: 16),
        border: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide(color: Colors.grey.shade300),
        ),
        enabledBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide(color: Colors.grey.shade300),
        ),
        focusedBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: const BorderSide(color: primaryColor, width: 2),
        ),
        labelStyle: bodyMedium.copyWith(color: textSecondary),
      ),
    );
  }
}