import 'dart:async';
import 'dart:convert';
import 'dart:io';

import 'package:flutter/foundation.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';

import '../http_client.dart';
import '../http_util.dart';
import '../models.dart';
import 'base_provider.dart';

/// Cookie to plant on the origin before the page loads (Python fake Copilot cookies).
class CookieSeed {
  const CookieSeed({
    required this.name,
    required this.value,
    this.domain,
    this.path = '/',
    this.isSecure = true,
  });

  final String name;
  final String value;
  final String? domain;
  final String path;
  final bool isSecure;
}

/// Load [originUrl] in a real Chromium WebView and run async JS on that origin.
///
/// This is the Android analog of g4f nodriver: same-origin `fetch` / WebSocket
/// after Cloudflare, not a generic fetch from about:blank (CORS → `{}`).
///
/// `evaluateJavascript` does not await Promises on Android and stringifies
/// them as `{}`. Always use `callAsyncJavaScript`.
Future<String> runOriginWebView({
  required String originUrl,
  required String functionBody,
  Duration timeout = const Duration(seconds: 70),
  List<CookieSeed> seeds = const [],
}) async {
  if (kIsWeb ||
      (!Platform.isAndroid &&
          !Platform.isIOS &&
          !Platform.isMacOS &&
          !Platform.isWindows)) {
    throw UnsupportedError('Origin WebView is not supported on this platform.');
  }

  final originUri = Uri.parse(originUrl);
  final cookieManager = CookieManager.instance();
  for (final seed in seeds) {
    try {
      await cookieManager.setCookie(
        url: WebUri(originUrl),
        name: seed.name,
        value: seed.value,
        domain: seed.domain ?? originUri.host,
        path: seed.path,
        isSecure: seed.isSecure,
      );
    } catch (e) {
      debugPrint('WebView setCookie ${seed.name}: $e');
    }
  }

  final completer = Completer<String>();
  var started = false;
  HeadlessInAppWebView? view;

  Future<void> importCookies() async {
    try {
      final cookies = await cookieManager.getCookies(url: WebUri(originUrl));
      for (final c in cookies) {
        g4fCookies.set(
          name: c.name,
          value: '${c.value}',
          domain: c.domain ?? originUri.host,
          path: c.path ?? '/',
          secure: c.isSecure ?? originUri.scheme == 'https',
          hostOnly: c.domain == null || c.domain == originUri.host,
        );
      }
    } catch (e) {
      debugPrint('WebView import cookies: $e');
    }
  }

  Future<void> runScript(
    InAppWebViewController controller, {
    bool force = false,
  }) async {
    if (started || completer.isCompleted) return;
    final title = (await controller.getTitle() ?? '').toLowerCase();
    final challenge = title.contains('just a moment') ||
        title.contains('attention required') ||
        title.contains('cloudflare');
    if (challenge && !force) return;
    started = true;
    try {
      await Future<void>.delayed(const Duration(milliseconds: 800));
      await importCookies();

      final result = await controller.callAsyncJavaScript(
        functionBody: functionBody,
      );
      if (result?.error != null && result!.error!.trim().isNotEmpty) {
        throw Exception(result.error);
      }
      final value = result?.value;
      if (value == null) {
        throw Exception('WebView script returned null');
      }
      final raw = value is String ? value : jsonEncode(value);
      if (!completer.isCompleted) completer.complete(raw);
    } catch (e) {
      if (!completer.isCompleted) completer.completeError(e);
    }
  }

  view = HeadlessInAppWebView(
    initialUrlRequest: URLRequest(url: WebUri(originUrl)),
    initialSettings: InAppWebViewSettings(
      javaScriptEnabled: true,
      domStorageEnabled: true,
      thirdPartyCookiesEnabled: true,
      incognito: false,
      userAgent: kDesktopUserAgent,
      isFraudulentWebsiteWarningEnabled: false,
      cacheEnabled: true,
    ),
    onLoadStop: (controller, url) async {
      await runScript(controller);
    },
    onConsoleMessage: (controller, consoleMessage) {
      debugPrint('WebView Console: ${consoleMessage.message}');
    },
  );

  await view.run();

  final ticker = Timer.periodic(const Duration(seconds: 3), (t) async {
    if (completer.isCompleted) {
      t.cancel();
      return;
    }
    final controller = view?.webViewController;
    if (controller != null) {
      await runScript(controller, force: t.tick >= 5);
    }
  });

  try {
    return await completer.future.timeout(timeout);
  } finally {
    ticker.cancel();
    await importCookies();
    await view.dispose();
  }
}

String wrapIifeAsFunctionBody(String iife) {
  return '''
    const __out = await $iife;
    if (__out == null) return '';
    if (typeof __out === 'string') return __out;
    try { return JSON.stringify(__out); } catch (e) { return String(__out); }
  ''';
}

abstract class WebViewBaseProvider extends BaseProvider {
  @override
  bool get isWebView => true;

  @override
  Duration get requestTimeout => const Duration(seconds: 90);

  /// The origin to load so Cloudflare / same-origin fetch can run.
  String get baseUrl;

  /// The specific API endpoint to call via JS `fetch`.
  String get apiEndpoint;

  @override
  Stream<String> createAsyncGenerator(
    String model,
    List<Message> messages, {
    bool stream = false,
  }) async* {
    final raw = await runOriginWebView(
      originUrl: baseUrl,
      functionBody: wrapIifeAsFunctionBody(
        buildJsFetchCode(model, messages, stream),
      ),
      timeout: requestTimeout,
    );
    yield parseResponse(raw);
  }

  /// Builds an IIFE that returns the API body (string or JSON).
  String buildJsFetchCode(String model, List<Message> messages, bool stream);

  /// Parses the raw string returned by the JS code into the final AI answer.
  String parseResponse(String rawResponse);
}