using System.Net.Http.Headers;
using System.Text;
using System.Text.Json;

namespace Admin.NET.Plugin.AiDOP.ChatBI;

public sealed class DeepSeekChatClient : ITransient
{
    private readonly IHttpClientFactory _httpClientFactory;

    public DeepSeekChatClient(IHttpClientFactory httpClientFactory)
    {
        _httpClientFactory = httpClientFactory;
    }

    public async Task<string?> CompleteAsync(string systemPrompt, string userPrompt, CancellationToken cancellationToken = default)
    {
        var options = App.GetConfig<DeepSeekOptions>("DeepSeekSettings", true);
        if (options == null || string.IsNullOrWhiteSpace(options.ApiUrl) || string.IsNullOrWhiteSpace(options.ApiKey))
            return null;

        var client = _httpClientFactory.CreateClient("AidopChatBI.DeepSeek");
        using var request = new HttpRequestMessage(HttpMethod.Post, options.ApiUrl);
        request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", options.ApiKey);

        var body = new
        {
            model = "deepseek-chat",
            messages = new[]
            {
                new { role = "system", content = systemPrompt },
                new { role = "user", content = userPrompt }
            },
            temperature = 0.2,
            max_tokens = 1200
        };
        request.Content = new StringContent(JsonSerializer.Serialize(body), Encoding.UTF8, "application/json");

        using var response = await client.SendAsync(request, cancellationToken);
        if (!response.IsSuccessStatusCode)
            return null;

        var json = await response.Content.ReadAsStringAsync(cancellationToken);
        using var doc = JsonDocument.Parse(json);
        if (!doc.RootElement.TryGetProperty("choices", out var choices) || choices.GetArrayLength() == 0)
            return null;

        var message = choices[0].GetProperty("message");
        return message.TryGetProperty("content", out var content) ? content.GetString()?.Trim() : null;
    }
}