Copies comments from a Disqus export to GitHub Discussions for giscus

DisqusToGiscus.cs

using System.Diagnostics;
using System.Text.RegularExpressions;
using System.Xml.Linq;
using Octokit.GraphQL;
using Octokit.GraphQL.Model;

var disqus = XElement.Load("disqus-export.xml");
var ns = disqus.GetDefaultNamespace();
var dsq = disqus.GetNamespaceOfPrefix("dsq")!;
var threads = new Dictionary<long, Thread>();
var posts = new Dictionary<long, Post>();
foreach (var element in disqus.Elements())
{
    if (element.Name.LocalName == "thread")
    {
        threads.Add(
            long.Parse(element.Attribute(dsq + "id")!.Value),
            new Thread
            {
                Link = new Uri(element.Element(ns + "link")!.Value)
            });
    }
    else if (element.Name.LocalName == "post")
    {
        if (element.Element(ns + "isDeleted")!.Value != "false"
            || element.Element(ns + "isSpam")!.Value != "false")
            continue;

        var id = long.Parse(element.Attribute(dsq + "id")!.Value);
        var author = element.Element(ns + "author")!;
        var parent = element.Element(ns + "parent")?.Attribute(dsq + "id")!.Value;
        posts.Add(
            id,
            new Post
            {
                Id = id,
                Message = element.Element(ns + "message")!.Value,
                CreatedAt = DateTime.Parse(element.Element(ns + "createdAt")!.Value).ToUniversalTime(),
                Author = new Author
                {
                    Name = author.Element(ns + "name")!.Value,
                    Username = author.Element(ns + "username")?.Value
                },
                ThreadId = long.Parse(element.Element(ns + "thread")!.Attribute(dsq + "id")!.Value),
                ParentId = parent is null
                    ? null
                    : long.Parse(parent)
            });
    }
}

// TODO: Use an API key with "public_repo"
var connection = new Connection(new ProductHeaderValue("Disqus"), "TODO");

var repository = new Query()
    // TODO: Update to your repo and user
    .Repository("bricelam.github.io", "bricelam");
var repositoryId = await connection.Run(
    repository
        .Select(r => r.Id));

var categories = await connection.Run(
    repository.DiscussionCategories()
        .AllPages()
        .Select(
            c => new
            {
                c.Id,
                c.Name
            }));
var categoryId = categories
        .First(c => c.Name == "General")
        .Id;

var discussions = await connection.Run(
    repository.Discussions(categoryId: categoryId)
        .AllPages()
        .Select(
            d => new
            {
                d.Id,
                d.Number,
                d.Title
            }));

foreach (var post in posts.Values
    .OrderBy(p => p.CreatedAt)
    // TODO: If an error is encountered, uncomment and paste the last id tired below
    //.SkipWhile(p => p.Id != 1000000000L)
    )
{
    Console.WriteLine(post.Id);

    var thread = threads[post.ThreadId];
    if (thread.NotFound)
    {
        continue;
    }
    else if (!thread.DiscussionId.HasValue)
    {
        string html;
        try
        {
            html = await new HttpClient().GetStringAsync(thread.Link);
            var redirectMatch = Regex.Match(html, @"<meta http-equiv=""refresh"" content=""0; url=(.+)"">");
            if (redirectMatch.Success)
                html = await new HttpClient().GetStringAsync(redirectMatch.Groups[1].Value);
        }
        catch (HttpRequestException ex)
        {
            Debug.Assert(ex.StatusCode == System.Net.HttpStatusCode.NotFound);
            thread.NotFound = true;
            Console.WriteLine($"404: {thread.Link}");

            continue;
        }

        var title = Regex.Match(html, @"<meta property=""og:title"" content=""(.+)"" />").Groups[1].Value;

        var discussion = discussions.FirstOrDefault(d => d.Title == title);
        thread.DiscussionId = discussion?.Id;
        thread.DiscussionNumber = discussion?.Number;
        if (!thread.DiscussionId.HasValue)
        {
            var description = Regex.Match(html, @"<meta property=""og:description"" content=""(.+)"" />").Groups[1].Value;

            var discussion1 = await connection.Run(
                new Mutation()
                    .CreateDiscussion(
                        new CreateDiscussionInput
                        {
                            RepositoryId = repositoryId,
                            Title = title,
                            Body = $"""
                                   # {title}

                                   {description}

                                   {thread.Link}
                                   """,
                            CategoryId = categoryId
                        })
                    .Select(
                        d => new
                        {
                            d.Discussion.Id,
                            d.Discussion.Number
                        }));

            thread.DiscussionId = discussion1.Id;
            thread.DiscussionNumber = discussion1.Number;

            // TODO: Fine-tune these
            System.Threading.Thread.Sleep(10000);
        }
    }

    Debug.Assert(thread.DiscussionId.HasValue);
    Debug.Assert(thread.DiscussionNumber.HasValue);

    var username = !string.IsNullOrEmpty(post.Author.Username)
        ? $"[{post.Author.Name}](https://disqus.com/by/{post.Author.Username})"
        : post.Author.Name;

    Post? parent = null;
    var current = post;
    while (current.ParentId.HasValue
        // TODO: Handle deleted parents better
        && posts.ContainsKey(current.ParentId.Value))
    {
        current = posts[current.ParentId.Value];
        parent = current;
    }

    // When continuing after an error, we may need to find the corresponding comment again
    if (parent is not null
        && parent.CommentId is null)
    {
        var username1 = !string.IsNullOrEmpty(parent.Author.Username)
            ? $"[{parent.Author.Name}](https://disqus.com/by/{parent.Author.Username})"
            : parent.Author.Name;
        var comments = await connection.Run(
            repository
                .Discussion(thread.DiscussionNumber.Value)
                .Comments()
                .AllPages()
                .Select(
                    c => new
                    {
                        c.Id,
                        c.Body
                    }));
        parent.CommentId = comments.First(c => c.Body.StartsWith($"_From **{username1}** on {parent.CreatedAt:MMMM d, yyyy H:mm}_")).Id;
    }

    post.CommentId = await connection.Run(
        new Mutation()
            .AddDiscussionComment(
                new AddDiscussionCommentInput
                {
                    DiscussionId = thread.DiscussionId.Value,
                    ReplyToId = parent?.CommentId,
                    // TODO: Update the URL below
                    Body = $"""
                           _From **{username}** on {post.CreatedAt:MMMM d, yyyy H:mm}_

                           {post.Message}

                           _Copied from original comment on [Disqus](https://disqus.com/home/forum/TODO)_
                           """
                })
            .Select(c => c.Comment.Id));

    // TODO: Fine-tune these
    System.Threading.Thread.Sleep(10000);
}

class Thread
{
    public required Uri Link { get; set; }

    public ID? DiscussionId { get; set; }
    public int? DiscussionNumber { get; set; }
    public bool NotFound { get; set; }
}

class Post
{
    public required long Id { get; set; }
    public required string Message { get; set; }
    public required DateTime CreatedAt { get; set; }
    public required Author Author { get; set; }
    public required long ThreadId { get; set; }
    public long? ParentId { get; set; }

    public ID? CommentId { get; set; }
}

class Author
{
    public required string Name { get; set; }
    public string? Username { get; set; }
}