#region Apache License
//
// Licensed to the Apache Software Foundation (ASF) under one or more 
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership. 
// The ASF licenses this file to you 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.
//
#endregion

using System;

using log4net;

namespace log4net.Core
{
	/// <summary>
	/// An evaluator that triggers at a threshold level
	/// </summary>
	/// <remarks>
	/// <para>
	/// This evaluator will trigger if the level of the event
	/// passed to <see cref="M:IsTriggeringEvent(LoggingEvent)"/>
	/// is equal to or greater than the <see cref="Threshold"/>
	/// level.
	/// </para>
	/// </remarks>
	/// <author>Nicko Cadell</author>
	public class LevelEvaluator : ITriggeringEventEvaluator 
	{
		/// <summary>
		/// The threshold for triggering
		/// </summary>
		private Level m_threshold;

		/// <summary>
		/// Create a new evaluator using the <see cref="Level.Off"/> threshold.
		/// </summary>
		/// <remarks>
		/// <para>
		/// Create a new evaluator using the <see cref="Level.Off"/> threshold.
		/// </para>
		/// <para>
		/// This evaluator will trigger if the level of the event
		/// passed to <see cref="M:IsTriggeringEvent(LoggingEvent)"/>
		/// is equal to or greater than the <see cref="Threshold"/>
		/// level.
		/// </para>
		/// </remarks>
		public LevelEvaluator() : this(Level.Off)
		{
		}

		/// <summary>
		/// Create a new evaluator using the specified <see cref="Level"/> threshold.
		/// </summary>
		/// <param name="threshold">the threshold to trigger at</param>
		/// <remarks>
		/// <para>
		/// Create a new evaluator using the specified <see cref="Level"/> threshold.
		/// </para>
		/// <para>
		/// This evaluator will trigger if the level of the event
		/// passed to <see cref="M:IsTriggeringEvent(LoggingEvent)"/>
		/// is equal to or greater than the <see cref="Threshold"/>
		/// level.
		/// </para>
		/// </remarks>
		public LevelEvaluator(Level threshold)
		{
			if (threshold == null)
			{
				throw new ArgumentNullException("threshold");
			}

			m_threshold = threshold;
		}

		/// <summary>
		/// the threshold to trigger at
		/// </summary>
		/// <value>
		/// The <see cref="Level"/> that will cause this evaluator to trigger
		/// </value>
		/// <remarks>
		/// <para>
		/// This evaluator will trigger if the level of the event
		/// passed to <see cref="M:IsTriggeringEvent(LoggingEvent)"/>
		/// is equal to or greater than the <see cref="Threshold"/>
		/// level.
		/// </para>
		/// </remarks>
		public Level Threshold
		{
			get { return m_threshold; }
			set { m_threshold = value; }
		}

		/// <summary>
		/// Is this <paramref name="loggingEvent"/> the triggering event?
		/// </summary>
		/// <param name="loggingEvent">The event to check</param>
		/// <returns>This method returns <c>true</c>, if the event level
		/// is equal or higher than the <see cref="Threshold"/>. 
		/// Otherwise it returns <c>false</c></returns>
		/// <remarks>
		/// <para>
		/// This evaluator will trigger if the level of the event
		/// passed to <see cref="M:IsTriggeringEvent(LoggingEvent)"/>
		/// is equal to or greater than the <see cref="Threshold"/>
		/// level.
		/// </para>
		/// </remarks>
		public bool IsTriggeringEvent(LoggingEvent loggingEvent) 
		{
			if (loggingEvent == null)
			{
				throw new ArgumentNullException("loggingEvent");
			}

			return (loggingEvent.Level >= m_threshold); 
		}
	}
}