import 'package:flutter/material.dart';
import 'package:url_launcher/url_launcher.dart';
import '../widgets/safety_redirect_sheet.dart';

/// External Link Traffic Controller
///
/// Provides safe URL routing with a domain whitelist.
/// Only domains in the whitelist are allowed without safety warnings.
/// All other domains will show a confirmation sheet before opening.
///
/// This is a "whitelist-only" approach: everything not explicitly trusted
/// requires user confirmation.
class ExternalLinkController {
  /// Whitelist of safe domains that open without any warning
  /// These are trusted sources with established editorial standards
  static const List<String> _whitelist = [
    // sojorn & Core Platforms
    'sojorn.com',
    'youtube.com',
    'youtu.be',
    'wikipedia.org',
    'wikimedia.org',
    'github.com',
    'instagram.com',
    'linkedin.com',
    'medium.com',
    'reddit.com',
    'vimeo.com',
    'spotify.com',
    'apple.com',
    'google.com',
    'maps.google.com',
    'openstreetmap.org',

    // Established Progressive/Left Sources
    'msnow.com',
    'huffpost.com',
    'jacobin.com',
    'wsws.org',
    'counterpunch.org',
    'truthout.org',
    'commondreams.org',
    'theintercept.com',
    'leftvoice.org',
    'liberationnews.org',
    'inthesetimes.com',
    'monthlyreview.org',
    'currentaffairs.org',
    'alternet.org',
    'rawstory.com',
    'therealnews.com',
    'popularresistance.org',
    'blackagendareport.com',
    'socialistworker.org',
    'peoplesworld.org',
    'marxists.org',
    'roarmag.org',
    'versobooks.com',
    'tribunemag.co.uk',
    'novaramedia.com',
    'opendemocracy.net',
    'redpepper.org.uk',
    'thenation.com',
    'dissentmagazine.org',
    'democracynow.org',
    'fifthestate.org',
    'crimethinc.com',
  ];

  /// Handles URL routing with whitelist safety checks.
  ///
  /// [context] - BuildContext for showing dialogs/sheets
  /// [url] - The URL to open
  ///
  /// Flow:
  /// 1. Parse the URL and extract the host (domain)
  /// 2. Check if host ends with any whitelisted domain (case-insensitive)
  /// 3. If whitelisted: launch immediately
  /// 4. If not whitelisted: show SafetyRedirectSheet for user confirmation
  static Future<void> handleUrl(BuildContext context, String url) async {
    if (url.trim().isEmpty) return;

    final Uri? uri = Uri.tryParse(url);
    if (uri == null) return;

    // Extract domain from URL
    final String host = uri.host.toLowerCase();

    // Check if domain is in whitelist
    if (_isWhitelisted(host)) {
      await _launchUrl(context, uri);
    } else {
      _showSafetyRedirectSheet(context, uri);
    }
  }

  /// Check if the domain is in the whitelist
  static bool _isWhitelisted(String host) {
    return _whitelist.any((domain) => host.endsWith(domain));
  }

  /// Launch URL using url_launcher
  static Future<void> _launchUrl(BuildContext context, Uri uri) async {
    try {
      if (await canLaunchUrl(uri)) {
        await launchUrl(
          uri,
          mode: LaunchMode.externalApplication,
        );
      } else {
        _showError(context, 'Could not open link.');
      }
    } catch (e) {
      _showError(context, 'Error opening link: $e');
    }
  }

  /// Show the Safety Redirect Sheet for non-whitelisted domains
  static void _showSafetyRedirectSheet(BuildContext context, Uri uri) {
    showModalBottomSheet(
      context: context,
      backgroundColor: Colors.transparent,
      builder: (context) => SafetyRedirectSheet(
        url: uri.toString(),
        domain: uri.host,
      ),
    );
  }

  /// Show error snackbar
  static void _showError(BuildContext context, String message) {
    final messenger = ScaffoldMessenger.of(context);
    messenger.showSnackBar(
      SnackBar(
        content: Text(message),
        backgroundColor: Colors.red.shade700,
      ),
    );
  }

  /// Add a domain to the whitelist at runtime
  static void addToWhitelist(String domain) {
    final normalizedDomain = domain.toLowerCase();
    if (!_whitelist.contains(normalizedDomain)) {
      _whitelist.add(normalizedDomain);
    }
  }

  /// Check if a domain is currently whitelisted
  static bool isWhitelisted(String domain) {
    return _isWhitelisted(domain.toLowerCase());
  }

  /// Get all whitelisted domains (for debugging/admin purposes)
  static List<String> getWhitelist() {
    return List.unmodifiable(_whitelist);
  }
}