Param.NET - An Automated Command-line Parameter Parser

using System;
using System.Collections;
using System.Text.RegularExpressions;
using System.Xml;

namespace Params
{
	public class Param
	{
		protected string longName;
		protected string shortName;
		protected string description;
		protected ParamType type;
		protected bool isOptional;
		protected bool isDefault;
		protected bool allowMultipleValues;
		protected object value;
		protected object defaultValue;
		protected ArrayList values;

		public string Name
		{
			get
			{
				if(longName != null)
					return longName;
				else
					return shortName;
			}
		}
		
		public string ShortName
		{
			get
			{
				return this.shortName;
			}
		}

		public string LongName
		{
			get
			{
				return this.longName;
			}
		}

		public string Description
		{
			get 
			{
				return this.description;
			}
		}
		
		public ParamType Type
		{
			get
			{
				return this.type;
			}
		}
		
		public bool IsOptional
		{
			get
			{
				return this.isOptional;
			}
		}

		public bool IsDefault
		{
			get
			{
				return this.isDefault;
			}
		}

		public bool AllowMultipleValues
		{
			get
			{
				return this.allowMultipleValues;
			}
		}
			
		public object DefaultValue
		{
			get
			{
				return this.defaultValue;
			}
		}

		public object Value
		{
			get
			{
				if(this.allowMultipleValues)
				{
					if(this.values.Count > 0)
					{
						return this.values[0];
					}
					else
					{
						return null;
					}
				}
				else
				{
					return this.value;
				}
			}
		}

		internal void SetValue(object value)
		{
			if(this.allowMultipleValues)
			{
				this.values.Clear();
				this.values.Add(Cast(value));
			}
			else
			{
				this.value = Cast(value);
			}
		}

		internal void AddValue(object value)
		{
			if(this.allowMultipleValues)
			{
				this.values.Add(Cast(value));
			}
			else
			{
				this.value = Cast(value);
			}
		}

		public ArrayList Values
		{
			get 
			{
				if(this.allowMultipleValues)
				{
					return this.values;
				}
				else
				{
					ArrayList a = new ArrayList(1);
					a.Add(this.value);
					return a;
				}
			}
		}

		protected object Cast(object o)
		{
			object result;

			if(o is string && ((string)o) == string.Empty)
				o = null;

			switch(this.Type)
			{
				case ParamType.String:
					result = (o == null) ? null : (o.ToString());
					break;
				case ParamType.Integer:
					result = (o == null) ? null : (object)Convert.ToInt32(o);
					break;
				case ParamType.TimeSpan:
					if(o is String)
					{
						result = TimeSpan.Parse((string)o);
					}
					else //assume it is TimeSpan, don't catch the exception to show the user that something went wrong
					{
						result = (TimeSpan)o;
					}
					break;
				case ParamType.Float:
					result = (o == null) ? null : (object)Convert.ToSingle(o);
					break;
				case ParamType.Bool:
					result = (o == null) ? null : (object)Convert.ToBoolean(o);
					break;
				default:
					throw new NotImplementedException();
			}

			return result;
		}

		internal Param()
		{
			this.isOptional = true;
			this.allowMultipleValues = false;
		}

		internal Param(string name, object value) : this()
		{
			this.longName = name;
			this.value = value;
		}
		
		internal Param(string name, object value, ParamCollection col)
		{
			this.longName = name;
			this.value = value;
			this.isOptional = col.DefaultIsOptional;
			this.allowMultipleValues = col.DefaultAllowMultipleValues;

			if(allowMultipleValues)
				this.values = new ArrayList();
		}				
		
		internal Param(string name, object value, bool allowMultipleValues, bool isDefault)
		{
			this.longName = name;
			this.value = value;
			this.allowMultipleValues = allowMultipleValues;
			this.isDefault = isDefault;

			if(allowMultipleValues)
				this.values = new ArrayList();
		}		
		
		internal Param(XmlNode node, ParamCollection col)
		{
			this.longName = Helper.GetString(node.Attributes, "longName", null);
			this.shortName = Helper.GetString(node.Attributes, "shortName", null);
			this.description = Helper.GetString(node.Attributes, "description", null);

			this.type = (ParamType)Helper.GetEnum(node.Attributes, "type", col.DefaultType, typeof(ParamType));

			this.defaultValue = Cast(Helper.GetValue(node.Attributes, "defaultValue", null));
     
			this.isOptional = Helper.GetBool(node.Attributes, "optional", col.DefaultIsOptional);
			this.allowMultipleValues = Helper.GetBool(node.Attributes, "allowMultiple", col.DefaultAllowMultipleValues);
            			
			if(allowMultipleValues)
				this.values = new ArrayList();

			SetValue(Cast(node.InnerText));
		}

		public bool IsNamed(string name)
		{
            if(name == this.ShortName || name == this.LongName)
				return true;
			else
				return false;
		}
	}
}