using System;
using System.Net.Http;
using System.Threading.Tasks;
using Newtonsoft.Json;

public class ChatGptBot
{
    private readonly string apiKey;
    private readonly string apiUrl = "https://api.openai.com/v1/chat/completions";
    private readonly HttpClient client;

    public ChatGptBot(string apiKey)
    {
        this.apiKey = apiKey;
        this.client = new HttpClient();
        this.client.DefaultRequestHeaders.Add("Authorization", $"Bearer {this.apiKey}");
    }

    public async Task<string> GetResponseAsync(string userMessage)
    {
        var requestBody = new
        {
            model = "gpt-3.5-turbo", // You can change this to a different model if needed
            messages = new[]
            {
                new { role = "system", content = "You are a helpful assistant." },
                new { role = "user", content = userMessage }
            }
        };

        var jsonContent = JsonConvert.SerializeObject(requestBody);
        var content = new StringContent(jsonContent, System.Text.Encoding.UTF8, "application/json");

        try
        {
            var response = await client.PostAsync(apiUrl, content);
            response.EnsureSuccessStatusCode();
            var responseBody = await response.Content.ReadAsStringAsync();
            var chatResponse = JsonConvert.DeserializeObject<ChatGptResponse>(responseBody);
            return chatResponse.Choices[0].Message.Content;
        }
        catch (Exception ex)
        {
            return $"Error: {ex.Message}";
        }
    }

    public class ChatGptResponse
    {
        public Choice[] Choices { get; set; }

        public class Choice
        {
            public Message Message { get; set; }
        }

        public class Message
        {
            public string Content { get; set; }
        }
    }
}