namespace Einstein.MSBRE
{
    using System;

    /// <summary>
    /// Attribute-Value-House triplet.   Used as an internal fact type for 
    /// candidate decisions.
    /// </summary>
    public class AVH
    {
        /// <summary>
        /// Attribute-Value pair.
        /// </summary>
        private AV attributeValue;

        /// <summary>
        /// House position.
        /// </summary>
        public int House;

        /// <summary>
        /// Constructor.
        /// </summary>
        /// <param name="attrValue">Attribute-Value pair.</param>
        /// <param name="house">House position.</param>
        public AVH(AV attrValue, int house)
        {
            attributeValue = attrValue;
            House = house;
        }

        /// <summary>
        /// Helper method that returns the attribute value.  Although not strictly
        /// necessary for this puzzle, the attribute name is passed in and tested,
        /// and  an empty string is passed back if the attribute name does not
        /// match the attribute nae of the pair.  This would prevent incorrect 
        /// selection of this fact in situations where two distinct AV pairs have
        /// the same string value (NB, this situation does not arise in the
        /// Einstein puzzle).
        /// </summary>
        /// <param name="attrName">Name of attribute.</param>
        /// <returns>Vaue of attribute.</returns>
        public string ValueOf(string attrName)
        {
            if (attrName == attributeValue.Attribute) return attributeValue.Value;
            return String.Empty;
        }

        /// <summary>
        /// Attribute name.
        /// </summary>
        public string Attribute
        {
            get
            {
                return attributeValue.Attribute;
            }
        }

        /// <summary>
        /// Attribute value.
        /// </summary>
        public string Value
        {
            get
            {
                return attributeValue.Value;
            }
        }
    }
}