// This Source Code is in the Public Domain per: http://litesoft.org/License.txt
package org.litesoft.bo.views;

import org.litesoft.bo.*;
import org.litesoft.commonfoundation.typeutils.*;
import org.litesoft.core.simpletypes.*;

import org.litesoft.commonfoundation.typeutils.Objects;
import java.util.*;

public class FilterUtil
{
    private enum MapForm
    {
        ALL
                {
                    public Boolean wouldImplicitlyProducesSuperSet( MapForm pCurrent )
                    {
                        return false; // We are ALL!  Nothing can produce more than us!
                    }
                },
        REGULAR
                {
                    public Boolean wouldImplicitlyProducesSuperSet( MapForm pCurrent )
                    {
                        switch ( pCurrent )
                        {
                            case ALL:
                                return true;
                            case REGULAR:
                                return null; // Indeterminate
                            case EQUALS:
                                return true; // Too different, assume the worst!
                            case NONE:
                                return false;
                        }
                        return true;  // Assume the worst!
                    }
                },
        EQUALS
                {
                    public Boolean wouldImplicitlyProducesSuperSet( MapForm pCurrent )
                    {
                        switch ( pCurrent )
                        {
                            case ALL:
                                return true;
                            case REGULAR:
                                return true; // Too different, assume the worst!
                            case EQUALS:
                                return null; // Indeterminate
                            case NONE:
                                return false;
                        }
                        return true;  // Assume the worst!
                    }
                },
        NONE
                {
                    public Boolean wouldImplicitlyProducesSuperSet( MapForm pCurrent )
                    {
                        return NONE != pCurrent; // if we are None then anything other than NONE can produce more than us!
                    }
                };

        abstract public Boolean wouldImplicitlyProducesSuperSet( MapForm pCurrent );
    }

    /**
     * Tests if the <code>pCurrent</code> filter would NOT produce a sub-set of the set that <code>pBase</code> would produce.
     *
     * @param pMetaData non-null. The meta data for the view object being filtered.
     * @param pBase     non-null
     * @param pCurrent  non-null
     *
     * @return <code>true</code> if the <code>pCurrent</code> filter would NOT produce a sub-set of the set that <code>pBase</code> would produce.
     */
    @SuppressWarnings({"SimplifiableIfStatement"})
    public static boolean needsRefresh( BoMetaData pMetaData, BoAccessorFilters pBase, BoAccessorFilters pCurrent )
    {
        Objects.assertNotNull( "pMetaData", pMetaData );
        Objects.assertNotNull( "pBase", pBase );
        Objects.assertNotNull( "pCurrent", pCurrent );

        return (!pBase.isUniqueEmpty() && pCurrent.isUniqueEmpty()) || //
               needsRefresh( pMetaData, pBase.getFilters(), pCurrent.getFilters() );
    }

    private static MapForm determineForm( SSMap pFilters )
    {
        if ( pFilters instanceof NoRowsMatchingFilterMap )
        {
            return MapForm.NONE;
        }
        if ( (pFilters == null) || pFilters.isEmpty() )
        {
            return MapForm.ALL;
        }
        return (pFilters instanceof EqualsMatchingFilterMap) ? MapForm.EQUALS : MapForm.REGULAR;
    }

    /**
     * Tests if the <code>pCurrentFilters</code> filter would NOT produce a sub-set of the set that <code>pBaseFilters</code> would produce.
     * <p/>
     * Note: two special types of SSMap: NoRowsMatchingFilterMap & EqualsMatchingFilterMap
     *
     * @param pMetaData       non-null. The meta data for the view object being filtered.
     * @param pBaseFilters    null / empty means ALL
     * @param pCurrentFilters null / empty means ALL
     *
     * @return <code>true</code> if the <code>pCurrentFilters</code> filter would NOT produce a sub-set of the set that <code>pBaseFilters</code> would produce.
     */
    public static boolean needsRefresh( BoMetaData pMetaData, SSMap pBaseFilters, SSMap pCurrentFilters )
    {
        MapForm zBaseForm = determineForm( pBaseFilters );

        Boolean zWouldImplicitlyProducesSuperSet = zBaseForm.wouldImplicitlyProducesSuperSet( determineForm( pCurrentFilters ) );

        if ( zWouldImplicitlyProducesSuperSet != null )
        {
            return zWouldImplicitlyProducesSuperSet;
        }

        if ( pBaseFilters.size() > pCurrentFilters.size() )
        {
            return true;
        }

        boolean zEquals = MapForm.EQUALS == zBaseForm;

        /*
         * Iterate over the base filter set, checking that a filter exists in
         * the current set which is the same or more restrictive.
         */
        for ( String zAttributeName : pBaseFilters.keySet() )
        {
            BoAttribute zAttribute;
            try
            {
                zAttribute = pMetaData.getBoAttribute( zAttributeName ); // todo: Custom Fields
            }
            catch ( NoSuchElementException e )
            {
                return true; // This is a simple coding Error!
            }
            String zBaseValue = pBaseFilters.get( zAttributeName );
            String zCurrentValue = pCurrentFilters.get( zAttributeName );
            if ( (zCurrentValue == null) && !pCurrentFilters.containsKey( zAttributeName ) ) // support 'null' values!
            {
                return true;
            }

            if ( isCurrentLessRestrictive( zEquals, zAttribute, zBaseValue, zCurrentValue ) )
            {
                return true;
            }
        }
        return false;
    }

    public static Filter createFilter( BoMetaData pMetaData, SSMap[] pORed_ANDFiltersNotNullNotEmpty )
    {
        if ( pORed_ANDFiltersNotNullNotEmpty.length == 0 )
        {
            return Filter.ALL;
        }
        Filter result = Filter.NONE;
        for ( SSMap zMap : pORed_ANDFiltersNotNullNotEmpty )
        {
            result = Filter.Or( result, createFilter( pMetaData, zMap ) );
            if ( result.getType() == Filter.Type.ALL )
            {
                break;
            }
        }
        return result;
    }

    public static Filter createFilter( BoMetaData pMetaData, SSMap pFilters )
    {
        if ( pFilters instanceof NoRowsMatchingFilterMap )
        {
            return Filter.NONE;
        }
        Filter result = Filter.ALL;
        if ( (pFilters != null) && !pFilters.isEmpty() )
        {
            boolean zEquals = (pFilters instanceof EqualsMatchingFilterMap);
            for ( String zAttributeName : pFilters.keySet() )
            {
                BoAttribute zAttribute;
                try
                {
                    zAttribute = pMetaData.getBoAttribute( zAttributeName ); // todo: Custom Fields
                }
                catch ( NoSuchElementException e )
                {
                    return Filter.NONE;
                }
                Filter zFilter = createFilter( zEquals, zAttribute, Strings.noEmpty( pFilters.get( zAttributeName ) ) ); // != Filter.Type.NONE
                result = Filter.And( result, zFilter );
            }
        }
        return result;
    }

    private static Filter createFilter( boolean pEquals, BoAttribute pAttribute, String pAttributeValue )
    {
        Filter result;
        if ( pEquals || pAttribute.getType() != BoAttribute.AttributeType.String ) // todo: Custom Fields
        {
            result = new Filter.ValueEqualsFilter( pAttribute.getName(), pAttributeValue );
        }
        else
        {
            result = new Filter.StringExpressionFilter( pAttribute.getName(), pAttributeValue, false ); // Case Sensitive
        }
        return result;
    }

    private static boolean isCurrentLessRestrictive( boolean pEquals, BoAttribute pAttribute, String pBaseValue, String pCurrentValue )
    {
        if ( Objects.areNonArraysEqual( pBaseValue, pCurrentValue ) ) // handle both null
        {
            return false; // equal implicitly means NOT Less Restrictive
        }
        if ( pEquals || pAttribute.getType() != BoAttribute.AttributeType.String ) // todo: Custom Fields
        {
            return true; // !equal means different, which means implicitly Less Restrictive
        }
        // Wild Carding...
        if ( (pBaseValue == null) || (pCurrentValue == null) )
        {
            return true; // if one is null then won't produce same results, which means implicitly Less Restrictive
        }
        String[] zBaseParts = createParts( pBaseValue );
        String[] zCurrentParts = createParts( pCurrentValue );

        int zBaseLast = zBaseParts.length - 1;
        int zCurrentLast = zCurrentParts.length - 1;

        if ( zBaseLast > zCurrentLast )
        {
            return true; // Current can NOT produce a sub-set
        }

        if ( !zCurrentParts[0].startsWith( zBaseParts[0] ) || //. . . . . . . . StartsWith
             !zCurrentParts[zCurrentLast].endsWith( zBaseParts[zBaseLast] ) )// EndsWith
        {
            return true;
        }

        int zCurrentIndex = 1;
        for ( int zBaseIndex = 1; zBaseIndex < zBaseLast; zBaseIndex++ )
        {
            String zBasePart = zBaseParts[zBaseIndex];
            do
            {
                if ( zCurrentIndex == zCurrentLast )
                {
                    return true; // Current did not contain a Base part, therefor it potentially wil produce a super-set
                }
            }
            while ( !zCurrentParts[zCurrentIndex++].contains( zBasePart ) );
        }
        return false;
    }

    private static String[] createParts( String pValue )
    {
        if ( pValue.indexOf( '*' ) == -1 )
        {
            pValue += '*';
        }
        return Strings.parseChar( pValue.toLowerCase(), '*' );
    }
}