/*========================================================================
        Copyright (C) 2006 by Geir-Tore Lindsve, Torbjørn Meistad 
        and Yngve Raudberget, hereby refered to as "the authors".
                        All rights reserved

    Permission is hereby granted, without written agreement and without
    license or royalty fees, to use, reproduce, prepare derivative
    works, distribute, and display this software and its documentation
    for NONCOMMERCIAL RESEARCH AND EDUCATIONAL PURPOSES, provided 
    that (1) the above copyright notice and the following two paragraphs 
    appear in all copies of the source code and (2) redistributions, 
    including without limitation binaries, reproduce these notices in 
    the supporting documentation. 

    IN NO EVENT SHALL THE AUTHORS, OR DISTRIBUTORS OF THIS SOFTWARE 
    BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, 
    OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF THIS SOFTWARE 
    AND ITS DOCUMENTATION, EVEN IF THE AUTHORS OR ANY OF THE ABOVE 
    PARTIES HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    THE AUTHORS SPECIFICALLY DISCLAIM ANY WARRANTIES, INCLUDING,
    BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
    FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
    ON AN "AS IS" BASIS, AND THE AUTHORS AND DISTRIBUTORS HAVE NO
    OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR
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========================================================================*/

using System;
using System.Collections.Generic;
using System.Collections;
using System.Text;
using Casper.Exceptions;
using Casper.Data;
using Casper.Algorithm.VariableOrdering;
using Iesi.Collections;

namespace Casper.Algorithm
{
    /// <summary>
    /// Class storing the variables and domaines used by <see cref="T:GenerelizedLookahed"></see>.
    /// </summary>
    public class LookaheadVariables
    {
        private Hashtable varDoms;
        private IVariableOrdering varOrder;

        /// <summary>
        /// Initializes a new instance of the <see cref="T:LookaheadVariables"/> class.
        /// </summary>
        /// <param name="varOrderType">The variable ordering</param>
        /// <param name="cGraph">The constraint graph.</param>
        /// <exception cref="T:Casper.Exceptions.CasperException"></exception>
        public LookaheadVariables(CspVariableOrdering varOrderType, ConstraintGraph cGraph)
        {
            this.varDoms = new Hashtable();
            if (cGraph == null) this.varOrder = new StaticVarOrder();
            else
            {
                try
                {
                    this.varOrder = GenerateVarOrder(varOrderType, cGraph);
                }
                catch (CasperException) { throw; }
            }
       
        }

        /// <summary>
        /// Gets or sets the variables and domaines.
        /// </summary>
        /// <value>The variables/domaines</value>
        public Hashtable VarDoms
        {
            get { return varDoms; }
            set { varDoms = value; }
        }

        /// <summary>
        /// Gets or sets the variable ordering.
        /// </summary>
        /// <value>The var order.</value>
        public IVariableOrdering VarOrder
        {
            get { return varOrder; }
            set { varOrder = value; }
        }

        /// <summary>
        /// Gets the variable which belongs to number in queue.
        /// </summary>
        /// <param name="numberInQueue">The number in queue.</param>
        /// <returns>A variable and its domaines.</returns>
        public LookAheadVarDom GetVar(int numberInQueue)
        {
            if (numberInQueue >= varDoms.Count)
                    return null;
            else
            {
                LookAheadVarDom var = (LookAheadVarDom)varDoms[this.varOrder.GetNextVar(numberInQueue)];
                return var;
            }
        }

        /// <summary>
        /// Generetes the variable ordering. For internal use of this class.
        /// </summary>
        /// <param name="varOrderType">Chosen variable ordering</param>
        /// <param name="cGraph">The constraint graph.</param>
        /// <returns>The variable ordering class.</returns>
        /// <exception cref="T:Casper.Exceptions.CasperException"></exception>
        private IVariableOrdering GenerateVarOrder(CspVariableOrdering varOrderType, ConstraintGraph cGraph)
        {
            if(varOrderType == CspVariableOrdering.vo_static) return new StaticVarOrder();
            else if (varOrderType == CspVariableOrdering.vo_minwidth)
            {
                try
                {
                    return new MinimumWidthOrder(cGraph);
                }
                catch (CasperException) { throw; }
            }
            else return new StaticVarOrder();
        }
    }
}