smarter canvas updates, only update when a change is detected

Management/Services/Canvas/CanvasServiceUtils.cs

@@ -0,0 +1,58 @@
+using RestSharp;
+
+namespace Management.Services.Canvas;
+public class CanvasServiceUtils
+{
+  private const string BaseUrl = "https://snow.instructure.com/api/v1/";
+  private readonly IWebRequestor webRequestor;
+  public CanvasServiceUtils(IWebRequestor webRequestor)
+  {
+    this.webRequestor = webRequestor;
+  }
+
+  internal async Task<IEnumerable<T>> PaginatedRequest<T>(RestRequest request)
+  {
+    var requestCount = 1;
+    request.AddQueryParameter("per_page", "100");
+    var (data, response) = await webRequestor.GetAsync<T>(request);
+
+    if (response.ErrorMessage?.Length > 0)
+    {
+      System.Console.WriteLine("error in response");
+      System.Console.WriteLine(response.ErrorMessage);
+      throw new Exception("error in response");
+    }
+
+    var returnData = data != null ? new T[] { data } : new T[] { };
+    var nextUrl = getNextUrl(response.Headers);
+
+    while (nextUrl is not null)
+    {
+      requestCount += 1;
+      RestRequest nextRequest = new RestRequest(nextUrl);
+      var (nextData, nextResponse) = await webRequestor.GetAsync<T>(nextRequest);
+      if (nextData is not null)
+        returnData = returnData.Append(nextData).ToArray();
+      nextUrl = getNextUrl(nextResponse.Headers);
+    }
+
+    System.Console.WriteLine($"Requesting {typeof(T)} took {requestCount} requests");
+
+    return returnData;
+  }
+
+  protected static string? getNextUrl(IEnumerable<HeaderParameter>? headers) =>
+    headers
+      ?.ToList()
+      .Find(h => h.Name == "Link")
+      ?.Value?.ToString()
+      ?.Split(",")
+      .Where(url => url.Contains("rel=\"next\""))
+      .FirstOrDefault()
+      ?.Split(";")
+      .FirstOrDefault()
+      ?.TrimEnd('>')
+      .TrimStart('<')
+      .Replace(" ", "")
+      .Replace(BaseUrl, "");
+}