using LanguageExt;

public struct Node<T> where T : IComparable
{
  public List<Node<T>> Children;
  public T Val { get; set; }
  public Node(T val)
  {
    Val = val;
    Children = new List<Node<T>>();
  }
  public Node<T> Insert(Node<T> node)
  {
    if (!node.Val.Equals(Val))
      Children.Add(node);
    return this;
  }

  public void Print()
  {
    Console.WriteLine($"[ {Val} ]");
    if (Children.Count > 0)
    {
      Console.WriteLine($"Children of {Val} / total={Children.Count}:");
      foreach (Node<T> child in Children)
        child.Print();
    }
  }
}

public static partial class Node
{
  public static Node<TResult>
    Traverse<T, TResult>(this Node<T> source, Func<T, TResult> f)
    where T : IComparable
    where TResult : IComparable
  {
    Node<TResult> result = new(f(source.Val));
    foreach (Node<T> child in source.Children)
      result.Children.Add(Traverse<T, TResult>(child, f));
    return result;
  }

  public static void
    ForAll<SrcT, AccT> (this Node<SrcT> source, Action<SrcT, AccT> f, AccT result)
    where SrcT : IComparable
  {
    f(source.Val, result);
    foreach (Node<SrcT> child in source.Children)
      ForAll(child, f, result);
  }
}

class Program
{
  public static async Task<Either<Exception, string>>
    TryLoadCommentAsync(HttpClient client, int id)
  {
    try
    {
      return await client.GetStringAsync($"http://kit.local/comment/?id={id}");
    }
    catch (HttpRequestException e)
    {
      return e;
    }
  }

  public static Either<List<Exception>, Node<Either<Exception, string>>>
    TryLoadComments(Node<int> tree)
  {
    using HttpClient client = new();

    /* traverse tree */
    var IdToResult = (int x) =>
    {
      var task = TryLoadCommentAsync(client, x);
      return task.Result;
    };
    var commentTree = Node.Traverse(tree, IdToResult);

    /* exceptions */
    List<Exception> errList = new();
    var CollectExceptions = (Either<Exception, string> val, List<Exception> result) =>
    {
      if (val.IsLeft)
        result.Add((Exception)val); /* really */
    };

    Node.ForAll(commentTree, CollectExceptions, errList);

    if (errList.Length() > 0)
      return errList;

    return commentTree;
  }

  public static void Main()
  {
    /* create tree */
    Node<int> a = new(100);
    Node<int> b = new(101);
    Node<int> c = new(102);

    Node<int> bb = new(1000);
    b.Insert(bb);

    Node<int> tree = new(10);
    tree.Insert(a).Insert(b).Insert(c);

    Node<int> root = new(1);
    root.Insert(tree);

    Console.WriteLine("Source:");
    root.Print();

    var result = TryLoadComments(root);
    Console.WriteLine("Result:");
    if (result.IsRight)
      ((Node<Either<Exception, string>>)result) /* really */
        .Print();
    else
      ((List<Exception>)result)
        .ForEach((Exception e) => { Console.WriteLine(e.ToString()); });
  }
}