// ****************************************************************
// Copyright 2007, Charlie Poole
// This is free software licensed under the NUnit license. You may
// obtain a copy of the license at http://nunit.org/?p=license&r=2.4
// ****************************************************************

using System;

namespace NUnit.Framework.Constraints
{
	// TODO Needs tests
	/// <summary>
	/// ContainsConstraint tests a whether a string contains a substring
	/// or a collection contains an object. It postpones the decision of
	/// which test to use until the type of the actual argument is known.
	/// This allows testing whether a string is contained in a collection
	/// or as a substring of another string using the same syntax.
	/// </summary>
	public class ContainsConstraint : Constraint
	{
		object expected;
		Constraint realConstraint;

		private Constraint RealConstraint
		{
			get 
			{
				if ( realConstraint == null )
				{
					if ( actual is string )
						this.realConstraint = new SubstringConstraint( (string)expected );
					else
						this.realConstraint = new CollectionContainsConstraint( expected );
				}

				return realConstraint;
			}
			set 
			{ 
				realConstraint = value; 
			}
		}

        /// <summary>
        /// Initializes a new instance of the <see cref="T:ContainsConstraint"/> class.
        /// </summary>
        /// <param name="expected">The expected.</param>
		public ContainsConstraint( object expected )
		{
			this.expected = expected;
		}

        /// <summary>
        /// Test whether the constraint is satisfied by a given value
        /// </summary>
        /// <param name="actual">The value to be tested</param>
        /// <returns>True for success, false for failure</returns>
		public override bool Matches(object actual)
		{
			this.actual = actual;

			if ( this.caseInsensitive )
				this.RealConstraint = RealConstraint.IgnoreCase;

			return this.RealConstraint.Matches( actual );
		}

        /// <summary>
        /// Write the constraint description to a MessageWriter
        /// </summary>
        /// <param name="writer">The writer on which the description is displayed</param>
		public override void WriteDescriptionTo(MessageWriter writer)
		{
			this.RealConstraint.WriteDescriptionTo(writer);
		}
	}
}