/*
 * Copyright 2005 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.drools.core;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.NoSuchElementException;
import java.util.Set;

import org.drools.core.base.ClassFieldReader;
import org.drools.core.base.QueryRowWithSubruleIndex;
import org.drools.core.base.ValueType;
import org.drools.core.rule.Declaration;
import org.drools.core.spi.InternalReadAccessor;
import org.kie.api.runtime.rule.QueryResults;
import org.kie.api.runtime.rule.QueryResultsRow;

/**
 * Returned QueryResults instance for a requested named query. from here you can iterate the returned data, or
 * get a specific row. All the available Declarations used in the query can also be accessed.
 */
public class QueryResultsImpl
    implements
    QueryResults {

    private Map<String, Declaration>[]        declarations;

    protected List<QueryRowWithSubruleIndex>  results;
    protected WorkingMemory                   workingMemory;
    protected Declaration[] parameters;

    private String[] identifiers;

    public QueryResultsImpl(final List<QueryRowWithSubruleIndex> results,
                            final Map<String, Declaration>[] declarations,
                            final WorkingMemory workingMemory,
                            final Declaration[] parameters) {
        this.results = results;
        this.workingMemory = workingMemory;
        this.declarations = declarations;
        this.parameters = parameters;

    }

    public Map<String, Declaration>[] getDeclarations() {
        return this.declarations;
    }

    public Declaration[] getParameters() {
        return this.parameters;
    }

    public Map<String, Declaration> getDeclarations(int subruleIndex) {
        if ( this.declarations == null || this.declarations.length == 0 ) {
            return Collections.<String, Declaration>emptyMap();
        } else {
            return this.declarations[subruleIndex];
        }
    }

    public QueryResultsRowImpl get(final int i) {
        if ( i > this.results.size() ) {
            throw new NoSuchElementException();
        }
        return new QueryResultsRowImpl( this.results.get( i ),
                                this.workingMemory,
                                this );
    }

    public int size() {
        return this.results.size();
    }

    public String[] getIdentifiers() {
        if ( identifiers != null ) {
            return identifiers;
        }
        Declaration[] parameters = getParameters();

        Set<String> idSet  = new HashSet<String>();
        for ( Declaration declr : parameters ) {
            idSet.add( declr.getIdentifier() );
        }

        for ( Declaration declr : getDeclarations(0).values() ) {
            if ( ! idSet.contains( declr.getIdentifier() ) ) {
                idSet.add(declr.getIdentifier());
            }
        }

        identifiers = idSet.toArray(new String[idSet.size()]);
        return identifiers;
    }

    public Iterator<QueryResultsRow> iterator() {
        return new QueryResultsIterator( results.iterator() );
    }

    private class QueryResultsIterator
        implements
        Iterator<QueryResultsRow> {
        private Iterator<QueryRowWithSubruleIndex> iterator;

        public QueryResultsIterator(final Iterator<QueryRowWithSubruleIndex> iterator) {
            this.iterator = iterator;
        }

        public boolean hasNext() {
            return this.iterator.hasNext();
        }

        public QueryResultsRow next() {
            return new QueryResultsRowImpl( this.iterator.next(),
                                    QueryResultsImpl.this.workingMemory,
                                    QueryResultsImpl.this );
        }

        public void remove() {
            this.iterator.remove();
        }

    }
}