ansi-fahrplan/NetworkMethods.cs

using Newtonsoft.Json;
using System.Net;

namespace Fahrplan.Network;

/// <summary>
/// Class to help get the plan from the CCC API
/// </summary>
public class PlanPuller () {
	public const string PlanJsonUrl = "https://fahrplan.events.ccc.de/congress/2024/fahrplan/schedule/export/schedule.json";
	public const string LocalPlanFilename = "ansi-fahrplan.json";

	/// <summary>
	/// Pulls the current fahrplan, stores it in a temp
	/// directory and returns the parsed JSON object.
	/// If another plan already exists in the temp directory
	/// and is not older than three minutes, a new plan
	/// will not yet be pulled to save on web requests
	/// </summary>
	/// <param name="forcePull">If true, skips checking the timestamp on the plan cache</param>
	/// <returns>Parsed Fahrplan JSON object</returns>
	public async static Task<Plan.Root> GetFahrplanAsync (bool forcePull = false) {
		var localPlanFileFullpath =
			Path.GetTempPath () +
			LocalPlanFilename;

		if (File.Exists (localPlanFileFullpath)) {
			var fileInfo = new FileInfo (localPlanFileFullpath);

			// File is not older than three minutes, return cached file
			if (fileInfo.LastWriteTime + TimeSpan.FromMinutes (3) > DateTime.Now) {
				var reader = fileInfo.OpenText ();
				var content = await reader.ReadToEndAsync ();

				return JsonConvert.DeserializeObject<Plan.Root> (content);
			}
		}

		var httpClient = new HttpClient ();

		// Be a good netizen, add a proper UA string
		httpClient.DefaultRequestHeaders.Add ("User-Agent", "AnsiFahrplan/1.0 (by Snep, c3@diskcat.com)");

		var response = await httpClient.GetAsync (new Uri (PlanJsonUrl));

		response.EnsureSuccessStatusCode ();
		var responseContent = await response.Content.ReadAsStringAsync ();

		try {
			File.WriteAllText (localPlanFileFullpath, responseContent);
		} catch (Exception ex) {
			Console.Error.WriteLine ("Warning: Failed to write Plan cache file: " + ex.Message);
		}

		return JsonConvert.DeserializeObject<Plan.Root> (responseContent);
	}
}