import 'dart:convert';

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

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

class TeachAnything extends BaseProvider {
  @override
  String get name => 'TeachAnything';

  @override
  String get url => 'https://www.teach-anything.com';

  @override
  bool get working => true;

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

  @override
  List<String> get models => ['gemma'];

  @override
  String get defaultModel => 'gemma';

  @override
  Stream<String> createAsyncGenerator(
    String model,
    List<Message> messages, {
    bool stream = false,
  }) async* {
    try {
      yield await _rest(messages);
      return;
    } catch (e) {
      debugPrint('TeachAnything REST failed, trying origin WebView: $e');
    }
    yield await _viaWebView(messages);
  }

  Future<String> _rest(List<Message> messages) async {
    final prompt = formatPrompt(messages);
    final req = http.Request('POST', Uri.parse('$url/api/generate'));
    req.headers.addAll({
      'accept': '*/*',
      'accept-language': 'en-US,en;q=0.9',
      'cache-control': 'no-cache',
      'content-type': 'application/json',
      'origin': url,
      'referer': '$url/',
      'user-agent': kDesktopUserAgent,
    });
    req.body = jsonEncode({'prompt': prompt});

    final response = await g4fHttp.send(req).timeout(requestTimeout);
    if (response.statusCode != 200) {
      throw Exception('$name returned status ${response.statusCode}');
    }
    final fullText = utf8.decode(await response.stream.toBytes()).trim();
    if (!looksLikeModelOutput(fullText)) throw Exception('$name empty');
    return fullText;
  }

  Future<String> _viaWebView(List<Message> messages) async {
    final promptJson = jsonEncode(formatPrompt(messages));
    final raw = await runOriginWebView(
      originUrl: url,
      timeout: requestTimeout,
      functionBody: '''
        const prompt = $promptJson;
        const r = await fetch('/api/generate', {
          method: 'POST',
          headers: { 'content-type': 'application/json', 'accept': '*/*' },
          credentials: 'same-origin',
          body: JSON.stringify({ prompt })
        });
        if (!r.ok) throw new Error('status ' + r.status);
        return await r.text();
      ''',
    );
    final text = raw.trim();
    if (!looksLikeModelOutput(text)) {
      throw Exception(
        'TeachAnything WebView unusable: ${text.substring(0, text.length.clamp(0, 180))}',
      );
    }
    return text;
  }
}