/*========================================================================
        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
    MODIFICATIONS.
========================================================================*/

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;

using CLab.Exceptions;
using CLab.Data;

using Casper;
using Casper.Data;
using Casper.Exceptions;

using Iesi.Collections;

namespace CLab.CSP
{
    /// <summary>
    /// The main class for finding valid solutions with the CSP approach.
    /// The class is designed to be used by <see cref="T:CLab.Clab"></see>, which
    /// provides the data needed for this class to work. 
    /// </summary>
    public class ClabCSP
    {
        private CSPLayout layout;
        private CSPExpressionBuilder builder;
        private Csp csp;
        private Clab clab;
        private ValidDomains vDomains;
        private Hashtable cpVarToVDomainID;
        private Casper.CspVariableOrdering variableOrdering;
        private Boolean initialSearchIsRun = false;

        /// <summary>
        /// Initializes a new instance of the <see cref="T:ClabCSP"/> class.
        /// </summary>
        /// <param name="clab">The <see cref="T:CLab.Clab"></see> object.</param>
        /// <param name="cp">The <see cref="T:CLab.Data.CP"></see> object of the problem.</param>
        /// <param name="symbols">The <see cref="CLab.Data.Symbols"></see> object of the problem.</param>
        /// <exception cref="CLab.Exceptions.ClabException"/>
        public ClabCSP(Clab clab, CP cp, Symbols symbols)
        {
            this.clab = clab;
            clab.SetStatusUpdateCount(cp.Variables.Count);
            cpVarToVDomainID = new Hashtable();

            try
            {
                layout = new CSPLayout(cp);
                List<CasperVarDom> casperVarDoms = layout.MakeCasperVarDoms();
                builder = new CSPExpressionBuilder(layout, cp, symbols);
                CSPExpressions expressions = builder.BuildCSPExpressions();
                csp = new Csp(expressions, casperVarDoms);               
                csp.CGraph = builder.ConstraintGraph;
                CreateValidDomainsData();
                csp.SetVariableOrdering(variableOrdering);
            }
            catch (ClabInternalErrorException e)
            {
                throw new ClabException(e.Message, e);
            }
            catch (ClabInvalidExpressionException e)
            {
                throw new ClabException(e.Message, e);
            }
            catch (ClabSymbolException e)
            {
                throw new ClabException(e.Message, e);
            }
            catch (Exception e)
            {
                throw new ClabException(e.Message, e);
            }
        }

        /// <summary>
        /// Gets the <see cref="T:CSPLayout"></see> of the problem.
        /// </summary>
        /// <value>The CSP layout of the problem.</value>
        public CSPLayout Layout
        {
            get { return layout; }
        }

        /// <summary>
        /// Gets the <see cref="T:Casper.CSP"></see> object of the problem.
        /// </summary>
        /// <value>The CSP object.</value>
        public Csp Csp
        {
            get { return csp; }
        }

        /// <summary>
        /// Sets the variable ordering.
        /// </summary>
        /// <param name="variableOrder">The variable ordering.</param>
        public void SetVariableOrdering(Casper.CspVariableOrdering variableOrder)
        {
            this.variableOrdering = variableOrder;
            if (csp != null)
            {
                csp.SetVariableOrdering(variableOrdering);
            }
        }

        /// <summary>
        /// Creates the <see cref="T:CLab.ValidDomains"></see> instance for this problem.
        /// It is filled with the data of the problem, except for the domain information.
        /// A mapping from valid domain index to cp variable index is also created.
        /// </summary>
        private void CreateValidDomainsData()
        {
            vDomains = new ValidDomains();
            List<String> varIDToCPVar = layout.VarIDToCPVar;

            foreach (String cpVar in varIDToCPVar)
            {
                String typeName = layout.GetTypeName(cpVar);
                CPTypes TypeFormat = layout.GetTypeFormat(typeName);
                ValidDomain valid = new ValidDomain(cpVar, typeName, TypeFormat);
                int validId = vDomains.addValidDomain(valid);
                cpVarToVDomainID[cpVar] = validId;
            }
        }

        /// <summary>
        /// Updates the <see cref="T:CLab.ValidDomains"></see> instance with the domain information from 
        /// the current <see cref="T:Casper.CSP"></see> object. Before a search is run, all domain values
        /// are possible and returned.
        /// </summary>
        /// <returns>The valid domains.</returns>
        /// <exception cref="CLab.Exceptions.ClabException"/>
        public ValidDomains GetValidDomains()
        {
            List<CasperVarDom> casperVarDoms = csp.CasperVarDoms;

            if (casperVarDoms == null)
            {
                for (int i = 0; i < vDomains.ValidDoms.Count; i++)
                {
                    ValidDomain vd = vDomains.ValidDoms[i];
                    vd.EmptyValidDomain();
                }
                return vDomains;
            }
            for (int i = 0; i < casperVarDoms.Count; i++)
            {
                CasperVarDom varDom = casperVarDoms[i];
                String cpVar = layout.GetCPVarFromVarID(varDom.VarID);
                int validIndex = (int)cpVarToVDomainID[cpVar];
                ValidDomain vDomain = vDomains.ValidDoms[validIndex];
                vDomain.EmptyValidDomain();
                List<int> vDomainInts = varDom.DomainValues;
                for (int j = 0; j < vDomainInts.Count; j++)
                {
                    try
                    {
                        vDomain.AddValidDomain(layout.GetDomainStringFromDomainInt(cpVar, vDomainInts[j]));
                    }
                    catch (ClabException) { throw; }
                }
            }
            return vDomains;
        }

        /// <summary>
        /// Runs the CSP search with the expressions defined, and
        /// return the valid domaines for the problem.
        /// </summary>
        /// <exception cref="CLab.Exceptions.ClabException"/>
        public void RunCSPSearch()
        {
            csp.StatusChangedEvent -= new Csp.StatusChanged(this.ObserveStatusChanged);
            csp.StatusChangedEvent += new Csp.StatusChanged(this.ObserveStatusChanged);
            try
            {
                csp.ValidDomains();
                initialSearchIsRun = true;
            }
            catch (CasperException e)
            {
                throw new ClabException("CSP search could not be run", e);
            }
        }

        /// <summary>
        /// Runs the CSP search reduced with a user chosen domain value
        /// for a variable. Returns the valid domaines for the problem after
        /// this reduction.
        /// </summary>
        /// <param name="var">The chosen variable.</param>
        /// <param name="domVal">The chosen domain value.</param>
        /// <exception cref="CLab.Exceptions.ClabException"/>
        public void RunCSPSearchUserChoice(String var, String domVal)
        {
            if (!initialSearchIsRun) throw new ClabException("Initial CSP search not run");

            csp.StatusChangedEvent -= new Csp.StatusChanged(this.ObserveStatusChanged);
            csp.StatusChangedEvent += new Csp.StatusChanged(this.ObserveStatusChanged);
            int casperVarIndex = layout.GetCasperVarDomIndex(var);
            CasperVarDom vd = csp.CasperVarDoms[casperVarIndex];
            int chosenDomainInt = layout.GetDomainIntFromDomainString(var, domVal);
            csp.OmitTestOnSingleValuedDomains = true;
            try
            {
                csp.ValidDomainsUserChoice(vd, chosenDomainInt);
            }
            catch (CasperException e)
            {
                throw new ClabException("CSP search with user choice could not be run", e);
            }
        }

        /// <summary>
        /// Adds an extra rule to the problem. Does not run a search for
        /// valid solutions, this has to be done, to get the reduced valid domaines
        /// after adding the new expression.
        /// </summary>
        /// <param name="newExpr">The new expression.</param>
        /// <exception cref="CLab.Exceptions.ClabException"/>
        public void AddExtraRule(Expression newExpr)
        {
            try
            {
                CSPExprWrapper cspExprW = builder.BuildCSPExpression(newExpr);
                csp.Expressions.AddWrappedExpr(cspExprW);
            }
            catch (ClabInternalErrorException e)
            {
                throw new ClabException("Extra rule could not be added", e);
            }
        }

        /// <summary>
        /// Observes the status for changes, and updates the current
        /// <see cref="T:CLab.Clab"></see> instance. 
        /// </summary>
        /// <param name="currentlyRunVar">The currently run var.</param>
        public void ObserveStatusChanged(int currentlyRunVar)
        {
            clab.UpdateStatus(currentlyRunVar);
        }
    }
}