Implemented DLSiteClient.

JSMR.Infrastructure/Http/ApiClient.cs

@@ -0,0 +1,79 @@
+using Microsoft.Extensions.Logging;
+using System.Net.Http.Headers;
+using System.Text;
+using System.Text.Json;
+
+namespace JSMR.Infrastructure.Http;
+
+public abstract class ApiClient(HttpClient http, ILogger logger, JsonSerializerOptions? json = null)
+{
+    protected async Task<T> GetJsonAsync<T>(
+        string url,
+        Action<HttpRequestHeaders>? configureHeaders = null,
+        CancellationToken ct = default
+        )
+    {
+        using var req = new HttpRequestMessage(HttpMethod.Get, url);
+        configureHeaders?.Invoke(req.Headers);
+
+        LogRequest(req);
+
+        using var res = await http.SendAsync(req, HttpCompletionOption.ResponseHeadersRead, ct).ConfigureAwait(false);
+        await EnsureSuccess(res).ConfigureAwait(false);
+
+        var stream = await res.Content.ReadAsStreamAsync(ct).ConfigureAwait(false);
+
+        var model = await JsonSerializer.DeserializeAsync<T>(stream, json, ct).ConfigureAwait(false)
+            ?? throw new InvalidOperationException($"Failed to deserialize JSON to {typeof(T).Name} from {url}.");
+
+        return model;
+    }
+
+    protected async Task<TResponse> PostJsonAsync<TRequest, TResponse>(
+        string url,
+        TRequest payload,
+        Action<HttpRequestHeaders>? configureHeaders = null,
+        CancellationToken ct = default)
+    {
+        var content = new StringContent(JsonSerializer.Serialize(payload, json), Encoding.UTF8, "application/json");
+        using var req = new HttpRequestMessage(HttpMethod.Post, url) { Content = content };
+        configureHeaders?.Invoke(req.Headers);
+
+        LogRequest(req);
+
+        using var res = await http.SendAsync(req, HttpCompletionOption.ResponseHeadersRead, ct).ConfigureAwait(false);
+        await EnsureSuccess(res).ConfigureAwait(false);
+
+        var stream = await res.Content.ReadAsStreamAsync(ct).ConfigureAwait(false);
+
+        var model = await JsonSerializer.DeserializeAsync<TResponse>(stream, json, ct).ConfigureAwait(false)
+            ?? throw new InvalidOperationException($"Failed to deserialize JSON to {typeof(TResponse).Name} from {url}.");
+        
+        return model;
+    }
+
+    protected virtual void LogRequest(HttpRequestMessage req)
+        => logger.LogDebug("HTTP {Method} {Uri}", req.Method, req.RequestUri);
+
+    protected virtual void LogFailure(HttpResponseMessage res, string body)
+        => logger.LogWarning("HTTP {Status} for {Uri}. Body: {Body}", (int)res.StatusCode, res.RequestMessage?.RequestUri, Truncate(body, 500));
+
+    protected static string Truncate(string s, int max) => s.Length <= max ? s : s[..max] + "…";
+
+    protected async Task EnsureSuccess(HttpResponseMessage res)
+    {
+        if (res.IsSuccessStatusCode) return;
+
+        string body;
+        try { body = await res.Content.ReadAsStringAsync().ConfigureAwait(false); }
+        catch { body = "<unable to read body>"; }
+
+        LogFailure(res, body);
+
+        // Throw a richer exception (you can customize per API)
+        throw new HttpRequestException(
+            $"Request to {res.RequestMessage?.RequestUri} failed: {(int)res.StatusCode} {res.ReasonPhrase}. Body: {Truncate(body, 1000)}",
+            null,
+            res.StatusCode);
+    }
+}