Babushka/scripts/CSharp/Common/Fight/FighterStack.cs

using System.Collections.Generic;
using Godot.NativeInterop;

namespace Babushka.scripts.CSharp.Common.Fight;

public class FighterStack
{
    private class Node
    {
        public Node next;
        public FightWorld.Fighter fighter;
    }

    private Node? currentNode;

    public FightWorld.Fighter Current => currentNode.fighter;

    public void Next()
    {
        currentNode = currentNode.next;
    }

    public FightWorld.Fighter PeekNext()
    {
        return currentNode.next.fighter;
    }

    public void AddAsLast(FightWorld.Fighter value)
    {
        // if first node
        if (currentNode == null)
        {
            currentNode = new Node { fighter = value };
            currentNode.next = currentNode;
            return;
        }

        var newNode = new Node { fighter = value, next = currentNode };
        var node = currentNode;
        while (node.next != currentNode)
        {
            node = node.next;
        }

        node.next = newNode;
    }

    public void AddAsNext(FightWorld.Fighter value)
    {
        // if first node
        if (currentNode == null)
        {
            AddAsLast(value);
            return;
        }

        var newNode = new Node { fighter = value, next = currentNode.next };
        currentNode.next = newNode;
    }

    public bool Remove(FightWorld.Fighter value)
    {
        if (currentNode == null) return false;

        // if only one node
        if (currentNode.next == currentNode)
        {
            if (currentNode.fighter == value)
            {
                currentNode = null;
                return true;
            }

            return false;
        }

        var node = currentNode;
        do
        {
            // next is the fighter to remove
            if (node.next.fighter == value)
            {
                // if removing current, keep current
                // it will be implicitly deleted on the next Next() call
                
                node.next = node.next.next;
                return true;
            }

            node = node.next;
        } while (node != currentNode);

        return false;
    }
}