using System;
using System.Diagnostics.Contracts;

namespace DominionBase.Currencies
{
	[Serializable]
	public sealed class Debt : CurrencyBase
	{
		public Debt() { }

		public Debt(int value) : base(value) { }

		public Debt(Debt value) : base(value.Value) { }

		public new static string Sign => "⌂";

	    public static Debt operator +(Debt x, Debt y)
		{
			Contract.Requires(x != default(Potion), "x cannot be null");
			Contract.Requires(y != default(Potion), "y cannot be null");
			Debt newDebt = new Debt(x.Value);
			newDebt.Value += y.Value;
			if (newDebt.Value < 0)
				newDebt.Value = 0;
			return newDebt;
		}

		public static Debt operator +(Debt x, int y)
		{
			Contract.Requires(x != default(Potion), "x cannot be null");
			Debt newDebt = new Debt(x.Value);
			newDebt.Value += y;
			if (newDebt.Value < 0)
				newDebt.Value = 0;
			return newDebt;
		}

		public static Debt Add(Debt left, Debt right) { return left + right; }

		public static Debt operator -(Debt x, Debt y)
		{
			Contract.Requires(x != default(Potion), "x cannot be null");
			Contract.Requires(y != default(Potion), "y cannot be null");
			Debt newDebt = new Debt(x.Value);
			newDebt.Value -= y.Value;
			if (newDebt.Value < 0)
				newDebt.Value = 0;
			return newDebt;
		}

		public static Debt operator -(Debt x, int y)
		{
			return x + -y;
		}

		public static Debt Subtract(Debt left, Debt right) { return left - right; }

		public static Debt operator -(Debt c)
		{
			Contract.Requires(c != default(Potion), "c cannot be null");
			return new Debt { Value = -c.Value, IsVariable = c.IsVariable };
		}

		public static Debt Negate(Debt item) { return -item; }

		public override string ToString()
		{
			return $"<debt>{base.ToString()}</debt>";
		}
	}
}