using System;
using System.Collections.Generic;
using System.Collections;
using System.Text;

namespace Sunweaver.VM
{
    /// <summary>
    /// A stack of integers
    /// </summary>
    public class IntStack : IEnumerable<Int64>
    {
        Stack<Int64> stack = new Stack<Int64>();

        // 15 digits is the largest number that you can store in a double precision float's 53 bit mantissa.
        public static Int64 Max =  (Int64)1E15 - 1;
        public static Int64 Min = -Max;

        public Int64 Pop()
        {
            if (stack.Count > 0)
                return stack.Pop();
            else
                return 0;
        }

        public static long Mod(long val)
        {
            if (val >= 0)
                val = val % (Max + 1);
            else
                val = val % (Min - 1);
            return val;
        }

        /// <summary>
        /// Pushes the value onto the stack, modding it first down to 9 digits
        /// </summary>
        /// <param name="val">Value to push onto the stack</param>
        public void Push(long val)
        {
            stack.Push(Mod(val));
        }

        public Int32 Count
        {
            get
            {
                return stack.Count;
            }
        }

        public void Clear()
        {
            stack.Clear();
        }

        public override string ToString()
        {
            string returnme = "";
            foreach (int x in stack)
                returnme += " " + x;

            returnme = returnme.Trim();

            return returnme;
        }

        public IEnumerator<Int64> GetEnumerator()
        {
            foreach (var level in stack)
            {
                yield return level;
            }
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            foreach (var level in stack)
            {
                yield return level;
            }
        }
    }
}