// Copyright 2003-2004 The Apache Software Foundation
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
//     http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

namespace Apache.Avalon.Framework
{
	using System;

	/// <summary>
	/// An enumeration used to mark a dependency as optional or not.
	/// </summary>
	public enum Optional
	{
		/// <summary>
		/// Use "True" if the dependency is not required for the component
		/// to run properly.
		/// </summary>
		True,
		/// <summary>
		/// Use "False" if the component will not work without the dependnecy.
		/// </summary>
		False
	}

	///<summary>
	///  Attribute to mark the dependencies for a component.
	///</summary>
	[AttributeUsage(AttributeTargets.Class,AllowMultiple=true,Inherited=true)]
	public sealed class AvalonDependencyAttribute : Attribute
	{
		private Type m_type;
		private bool m_optional;
		private string m_name;

		///<summary>
		///  Constructor to initialize the dependency's name.
		///</summary>
		///<param name="type">The type for the dependency</param>
		///<param name="key">The dependency's lookup key</param>
		///<param name="optional">Whether or not the dependency is optional</param>
		///<exception cref="ArgumentException">If the "type" value is not an interface</exception>
		public AvalonDependencyAttribute(Type type, string key, Optional optional)
		{
			if (!type.IsInterface)
			{
				throw new ArgumentException(
					"The type passed in does not represent an interface",
					"type" );
			}

			m_name = (null == key) ? type.Name : key;
			m_optional = (optional == Optional.True);
			m_type = type;
		}

		///<summary>
		///  The lookup name of the dependency
		///</summary>
		public string Key
		{
			get
			{
				return m_name;
			}
		}

		///<summary>
		///  Is this dependency optional?
		///</summary>
		public bool IsOptional
		{
			get
			{
				return m_optional;
			}
		}

		/// <summary>
		///   The dependency type
		/// </summary>
		public Type DependencyType
		{
			get
			{
				return m_type;
			}
		}
	}
}