using System.Security.Cryptography;
using System.Text.RegularExpressions;

namespace Dungeoneer {

	public static class Util {

		public static int Roll(int sides) {
			return RandomNumberGenerator.GetInt32(sides) + 1;
		}

	}

	public class RollExpression {
		private IList<string> Parts;
		public string Print { get; private set; }
		public string Expression { get; private set; }
		public dynamic Result {
			get {
				try { return Scripting.Expr($"eval('{Expression}')"); }
				catch { return null; }
			}
		}

		private const string DieFormat = "\x1b[34;1m";
		private static readonly Regex DiePattern = new Regex(@"(\d+)d(\d+)");

		public RollExpression(IList<string> parts) {
			this.Parts = parts;
			this.Print = "";
			this.Expression = "";

			//	build expression from string parts
			foreach(string piece in Parts) {
				//	die expression substitution
				var dieCheck = DiePattern.Match(piece);
				if(dieCheck.Success) {
					//	get /(d+)/ capture group values
					var count = int.Parse(dieCheck.Groups[1].Value);
					var sides = int.Parse(dieCheck.Groups[2].Value);

					//	and build roll outcomes
					this.Print += $"{DieFormat}( ";
					this.Expression += "( ";
					for(int i = 0; i < count; i++) {
						var roll = Util.Roll(sides);
						if(i < count - 1) {
							this.Print += $"{roll}, ";
							this.Expression += $"{roll} + ";
						} else {
							var part = $"{roll} ";
							this.Print += $"{roll} ){Format.Reset} ";
							this.Expression += $"{roll} ) ";
						}
					}
				} else {
					var part = $"{piece} ";
					this.Expression += part;
					this.Print += part;
				}
			}
		}

	}

}