Azure Function To Fix Hashnode Sitemap

HashnodeSitemapFunction.cs

using System;
using System.IO;
using System.Threading.Tasks;
using System.Web.Http;
using System.Xml.Serialization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using System.Collections.Generic;
using System.Globalization;
using System.Xml.Linq;

namespace ApiChat.Functions.OneTimeFunctions;

public static class HashnodeSitemapFunction
{
    [FunctionName("HashnodeSitemapFunction")]
    public static async Task<IActionResult> Run(
        [HttpTrigger(AuthorizationLevel.Anonymous, "get", Route = "sitemap-fix")] HttpRequest req,
        ILogger log)
    {
        log.LogInformation("C# HashnodeSitemapFunction processed a request.");

        string url = req.Query["url"];

        if (string.IsNullOrEmpty(url))
        {
            return new BadRequestErrorMessageResult("url parameter is required");
        }

        var client = new System.Net.Http.HttpClient();
        var response = await client.GetAsync(url);
        response.EnsureSuccessStatusCode();

        // read response xml to string
        var responseString = await response.Content.ReadAsStringAsync();

        // deserialize and rebuild
        var sitemapNodes = new List<SitemapNode>();
        try
        {
            var serializer = new XmlSerializer(typeof(UrlSet));
            var sitemap = (UrlSet)serializer.Deserialize(new StringReader(responseString));

            foreach (var urlSetUrl in sitemap.Urls)
            {
                if (!Enum.TryParse<SitemapFrequency>(urlSetUrl.ChangeFreq, true, out var frequency))
                {
                    frequency = SitemapFrequency.Never;
                }

                sitemapNodes.Add(new SitemapNode()
                {
                    Url = urlSetUrl.Loc,
                    Frequency = frequency,
                    LastModified = urlSetUrl.LastMod,
                    Priority = (double?)urlSetUrl.Priority
                });
            }
        }
        catch (Exception e)
        {
            log.LogError(e, "Failed to parse sitemap");
            return new BadRequestErrorMessageResult($"Failed to parse sitemap with error: {e.Message}");
        }

        return new ContentResult
        {
            Content = GetSitemapDocument(sitemapNodes),
            ContentType = "application/xml",
            StatusCode = 200
        };
    }

    [XmlRoot("urlset", Namespace = "http://www.sitemaps.org/schemas/sitemap/0.9")]
    public class UrlSet
    {
        [XmlElement("url")]
        public List<Url> Urls { get; set; }
    }

    public class Url
    {
        [XmlElement("loc")]
        public string Loc { get; set; }

        [XmlElement("changefreq")]
        public string? ChangeFreq { get; set; }

        [XmlElement("priority")]
        public decimal? Priority { get; set; }

        [XmlElement("lastmod")]
        public DateTime? LastMod { get; set; }
    }

    internal class SitemapNode
    {
        public SitemapFrequency? Frequency { get; set; }
        public DateTime? LastModified { get; set; }
        public double? Priority { get; set; }
        public string Url { get; set; }
    }

    internal enum SitemapFrequency
    {
        Never,
        Yearly,
        Monthly,
        Weekly,
        Daily,
        Hourly,
        Always
    }

    /// <summary>
    /// Serializes to raw XML.
    /// </summary>
    private static string GetSitemapDocument(IEnumerable<SitemapNode> sitemapNodes)
    {
        XNamespace xmlns = "http://www.sitemaps.org/schemas/sitemap/0.9";
        var root = new XElement(xmlns + "urlset");

        foreach (var sitemapNode in sitemapNodes)
        {
            var urlElement = new XElement(
                xmlns + "url",
                new XElement(xmlns + "loc", Uri.EscapeUriString(sitemapNode.Url)),
                sitemapNode.Frequency == null
                    ? null
                    : new XElement(
                        xmlns + "changefreq",
                        sitemapNode.Frequency.Value.ToString().ToLowerInvariant()),
                sitemapNode.Priority == null
                    ? null
                    : new XElement(
                        xmlns + "priority",
                        sitemapNode.Priority.Value.ToString("F1", CultureInfo.InvariantCulture)),
                sitemapNode.LastModified == null
                    ? null
                    : new XElement(
                        xmlns + "lastmod",
                        sitemapNode.LastModified.Value.ToLocalTime().ToString("yyyy-MM-ddTHH:mm:sszzz")));
            root.Add(urlElement);
        }

        var document = new XDocument(root);
        return document.ToString();
    }
}