[FA-misc] Translation engine work

FictionArchive.Service.TranslationService/Services/TranslationEngines/NanoGpt/NanoGptApiClient.cs

@@ -0,0 +1,34 @@
+using System.Net.Http.Json;
+
+namespace FictionArchive.Service.TranslationService.Services.TranslationEngines.NanoGpt;
+
+public class NanoGptApiClient
+{
+    private readonly HttpClient _httpClient;
+    private readonly ILogger<NanoGptApiClient> _logger;
+
+    public NanoGptApiClient(HttpClient httpClient, ILogger<NanoGptApiClient> logger)
+    {
+        _httpClient = httpClient;
+        _logger = logger;
+    }
+
+    public async Task<NanoGptChatResponse> CompleteAsync(
+        string model,
+        IReadOnlyList<NanoGptMessage> messages,
+        double temperature,
+        CancellationToken ct = default)
+    {
+        var request = new NanoGptChatRequest(model, messages, temperature);
+
+        using var response = await _httpClient.PostAsJsonAsync("v1/chat/completions", request, ct);
+        response.EnsureSuccessStatusCode();
+
+        var body = await response.Content.ReadFromJsonAsync<NanoGptChatResponse>(ct);
+        if (body is null)
+        {
+            throw new InvalidOperationException("NanoGPT returned an empty response body.");
+        }
+        return body;
+    }
+}