using InnovEnergy.Lib.Utils;
using Sawmill;

namespace InnovEnergy.Lib.SrcGen.Trees;


public class ForwardTree<T> : IRewritable<ForwardTree<T>> where T : notnull
{
    public T                             Node     { get; }
    public IReadOnlyList<ForwardTree<T>> Children { get; }
    public Boolean                       IsLeaf => Children.Count == 0;
        
    public ForwardTree(T node) : this(node, Array.Empty<ForwardTree<T>>())
    {
    }
    
    public ForwardTree(T node, IReadOnlyList<ForwardTree<T>> children)
    {
        Node     = node;
        Children = children;
    }

    public ForwardTree<T> WithNode(T node) => new ForwardTree<T>(node, Children);
    public ForwardTree<T> WithNode(Func<T, T> makeNode) => new ForwardTree<T>(makeNode(Node), Children);

    public override String ToString()
    {
        var node = Node.ToString()!;
        return Children.Aggregate(node, (s, c) => s + "\n" + c.ToString().Indent(node.Length));
    }

    Int32 IRewritable<ForwardTree<T>>.CountChildren() => Children.Count;

    void IRewritable<ForwardTree<T>>.GetChildren(Span<ForwardTree<T>> childrenReceiver)
    {
        for (var i = 0; i < Children.Count; i++)
            childrenReceiver[i] = Children[i];
    }

    ForwardTree<T> IRewritable<ForwardTree<T>>.SetChildren(ReadOnlySpan<ForwardTree<T>> newChildren)
    {
        return new ForwardTree<T>(Node, newChildren.ToArray());
    }
    
    
}