import 'dart:convert';
import 'dart:io';
import 'dart:math';

import 'package:flutter/foundation.dart';
import 'package:http/http.dart' as http;
import 'package:uuid/uuid.dart';

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

/// Microsoft Copilot: Cronet session + WebSocket, then origin WebView (nodriver analog).
class CopilotApp extends BaseProvider {
  @override
  String get name => 'CopilotApp';

  @override
  String get url => 'https://copilot.microsoft.com';

  @override
  bool get working => !kIsWeb;

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

  @override
  List<String> get models => ['smart', 'chat', 'reasoning'];

  @override
  String get defaultModel => 'smart';

  static const _ua =
      'CopilotNative/30.0.440505001-prod (Android 14; Google; Pixel 8 Pro)';
  static const _startUrl = 'https://copilot.microsoft.com/c/api/start';

  @override
  Stream<String> createAsyncGenerator(
    String model,
    List<Message> messages, {
    bool stream = false,
  }) async* {
    if (kIsWeb) {
      throw UnsupportedError('CopilotApp requires dart:io (Android/iOS/desktop)');
    }

    final seeds = _fakeCookieSeeds();
    _seedFakeCookies(seeds);
    final prompt = formatPrompt(messages);
    try {
      yield await _viaRestAndWs(model, prompt);
      return;
    } catch (e) {
      debugPrint('Copilot REST/WS failed, trying origin WebView: $e');
    }
    yield await _viaWebView(model, prompt, seeds);
  }

  Future<String> _viaRestAndWs(String model, String prompt) async {
    final startReq = http.Request('POST', Uri.parse(_startUrl));
    startReq.headers.addAll({
      'content-type': 'application/json',
      'user-agent': _ua,
      'origin': url,
      'referer': '$url/',
      'X-Search-UILang': 'en-US',
    });
    startReq.body = jsonEncode({
      'timeZone': 'Europe/Moscow',
      'startNewConversation': true,
      'teenSupportEnabled': true,
      'correctPersonalizationSetting': true,
      'deferredDataUseCapable': true,
    });

    final startRes = await g4fHttp.send(startReq).timeout(const Duration(seconds: 15));
    if (startRes.statusCode != 200) {
      final err = await startRes.stream.bytesToString();
      throw Exception('Copilot start ${startRes.statusCode}: $err');
    }
    final startBody = jsonDecode(utf8.decode(await startRes.stream.toBytes()));
    final conversationId = (startBody['currentConversationId'] ?? '').toString();
    if (conversationId.isEmpty) {
      throw Exception('Copilot: no conversation id');
    }

    final cookieHeader = g4fCookies.headerFor(Uri.parse(url));
    final sessionId = const Uuid().v4();
    final wsUrl =
        'wss://copilot.microsoft.com/c/api/chat?api-version=2&clientSessionId=$sessionId';
    final ws = await WebSocket.connect(
      wsUrl,
      headers: {
        'User-Agent': _ua,
        'Origin': url,
        'Pragma': 'no-cache',
        'Cache-Control': 'no-cache',
        if (cookieHeader.isNotEmpty) 'Cookie': cookieHeader,
      },
    ).timeout(const Duration(seconds: 12));

    try {
      final mode = _modeFor(model);
      var connected = false;
      final collected = StringBuffer();

      await for (final raw in ws.timeout(const Duration(seconds: 35))) {
        if (raw is! String) continue;
        Map<String, dynamic> data;
        try {
          data = jsonDecode(raw) as Map<String, dynamic>;
        } catch (_) {
          continue;
        }
        final event = data['event']?.toString();
        if (event == 'connected' || event == 'received') {
          if (!connected) {
            connected = true;
            ws.add(jsonEncode({
              'event': 'send',
              'conversationId': conversationId,
              'content': [
                {'type': 'text', 'text': prompt},
              ],
              'mode': mode,
            }));
          }
          continue;
        }
        if (event == 'appendText' || event == 'replaceText') {
          final text = data['text']?.toString() ?? '';
          if (text.isNotEmpty) collected.write(text);
        } else if (event == 'done') {
          break;
        } else if (event == 'error') {
          throw Exception('Copilot error: $data');
        }
      }

      final text = collected.toString().trim();
      if (!looksLikeModelOutput(text)) {
        throw Exception('Copilot returned empty response');
      }
      return text;
    } finally {
      await ws.close();
    }
  }

  Future<String> _viaWebView(
    String model,
    String prompt,
    List<CookieSeed> seeds,
  ) async {
    final promptJson = jsonEncode(prompt);
    final modeJson = jsonEncode(_modeFor(model));
    final raw = await runOriginWebView(
      originUrl: url,
      timeout: requestTimeout,
      seeds: seeds,
      functionBody: '''
        const prompt = $promptJson;
        const mode = $modeJson;
        const start = await fetch('/c/api/start', {
          method: 'POST',
          headers: { 'content-type': 'application/json' },
          credentials: 'include',
          body: JSON.stringify({
            timeZone: Intl.DateTimeFormat().resolvedOptions().timeZone || 'UTC',
            startNewConversation: true,
            teenSupportEnabled: true,
            correctPersonalizationSetting: true,
            deferredDataUseCapable: true
          })
        });
        if (!start.ok) {
          throw new Error('start ' + start.status + ' ' + (await start.text()).slice(0, 160));
        }
        const started = await start.json();
        const conversationId = started.currentConversationId;
        if (!conversationId) throw new Error('no conversation id');
        const sessionId = (crypto.randomUUID && crypto.randomUUID()) || String(Math.random()).slice(2);
        return await new Promise((resolve, reject) => {
          const ws = new WebSocket('wss://copilot.microsoft.com/c/api/chat?api-version=2&clientSessionId=' + sessionId);
          let text = '';
          let sent = false;
          const timer = setTimeout(() => { try { ws.close(); } catch (e) {} reject(new Error('ws timeout')); }, 45000);
          ws.onmessage = (e) => {
            let data;
            try { data = JSON.parse(e.data); } catch (err) { return; }
            const event = data.event;
            if ((event === 'connected' || event === 'received') && !sent) {
              sent = true;
              ws.send(JSON.stringify({
                event: 'send',
                conversationId,
                content: [{ type: 'text', text: prompt }],
                mode
              }));
            }
            if (event === 'appendText' || event === 'replaceText') text += data.text || '';
            if (event === 'done') { clearTimeout(timer); ws.close(); resolve(text); }
            if (event === 'error') { clearTimeout(timer); reject(new Error(JSON.stringify(data))); }
          };
          ws.onerror = () => { clearTimeout(timer); reject(new Error('ws error')); };
        });
      ''',
    );
    final text = raw.trim();
    if (!looksLikeModelOutput(text)) {
      throw Exception('Copilot WebView unusable: ${text.substring(0, text.length.clamp(0, 180))}');
    }
    return text;
  }

  void _seedFakeCookies(List<CookieSeed> seeds) {
    final uri = Uri.parse(url);
    for (final seed in seeds) {
      g4fCookies.set(
        name: seed.name,
        value: seed.value,
        domain: seed.domain ?? 'microsoft.com',
        path: seed.path,
        secure: seed.isSecure,
        hostOnly: false,
      );
    }
    // Touch the jar host as well as the parent domain.
    g4fCookies.set(
      name: '_C_ETH',
      value: '1',
      domain: uri.host,
      secure: true,
    );
  }

  List<CookieSeed> _fakeCookieSeeds() {
    return [
      CookieSeed(name: '_C_ETH', value: '1', domain: '.microsoft.com'),
      CookieSeed(name: '_C_Auth', value: '', domain: '.microsoft.com'),
      CookieSeed(name: 'MUID', value: _hex(32), domain: '.microsoft.com'),
      CookieSeed(name: 'MUIDB', value: _hex(32), domain: '.microsoft.com'),
      CookieSeed(
        name: '_EDGE_S',
        value: 'F=1&SID=${_hex(32)}',
        domain: '.microsoft.com',
      ),
      CookieSeed(name: '_EDGE_V', value: '1', domain: '.microsoft.com'),
    ];
  }

  String _modeFor(String model) {
    final m = model.toLowerCase();
    if (m.contains('reason') || m.contains('think') || m.contains('o1')) {
      return 'reasoning';
    }
    if (m.contains('chat') || m.contains('gpt-4')) return 'chat';
    return 'smart';
  }

  String _hex(int len) {
    const hex = '0123456789ABCDEF';
    final r = Random();
    return String.fromCharCodes(
      Iterable.generate(len, (_) => hex.codeUnitAt(r.nextInt(16))),
    );
  }
}