using System;
namespace PingPong.GameEngine
{

	public class GameCondition
	{
		#region Members
			
		/// <summary>
		/// The expression.
		/// </summary>
		private Lazy<string> expression;
		
		#endregion
		
		#region Properties
		
		/// <summary>
		/// Gets the expression.
		/// </summary>
		/// <value>
		/// The expression.
		/// </value>
		public string Expression
		{
			get
			{
				return this.expression.Value;
			}
		}
		
		#endregion
		
		#region Constructors
		
		/// <summary>
		/// Initializes a new instance of the <see cref="PingPong.GameEngine.GameCondition"/> class.
		/// </summary>
		public GameCondition()
		{
			this.expression = new Lazy<string>(() => string.Empty);
		}
		
		#endregion
		
		#region Methods
		
		/// <summary>
		/// Evaluate this instance.
		/// </summary>
		public bool Evaluate()
		{
			Engine.ExpressionParser.Interpret(this.Expression);
			return Engine.ExpressionParser.Output.Equals(
				bool.TrueString,
				StringComparison.OrdinalIgnoreCase
			);
		}
		
		/// <summary>
		/// Sets the expression.
		/// </summary>
		/// <returns>
		/// The expression.
		/// </returns>
		/// <param name='expression'>
		/// Expression.
		/// </param>
		public GameCondition SetExpression(string expression)
		{
			this.expression = new Lazy<string>(() => expression);
			return this;
		}
		
		#endregion
	}
}