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/*
 *
 * Copyright 2017-2018 Nitrite author or authors.
 *
 * 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.dizitart.no2.internals;

import org.dizitart.no2.*;
import org.dizitart.no2.exceptions.InvalidOperationException;
import org.dizitart.no2.store.NitriteMap;
import org.dizitart.no2.util.Iterables;

import java.util.*;

import static org.dizitart.no2.exceptions.ErrorMessage.REMOVE_ON_DOCUMENT_ITERATOR_NOT_SUPPORTED;
import static org.dizitart.no2.util.EqualsUtils.deepEquals;

/**
 * @author Anindya Chatterjee.
 */
class JoinedDocumentIterable implements RecordIterable {
    private final Collection resultSet;
    private final NitriteMap underlyingMap;
    private boolean hasMore;
    private int totalCount;
    private Cursor foreignCursor;
    private Lookup lookup;

    JoinedDocumentIterable(FindResult findResult, Cursor foreignCursor, Lookup lookup) {
        this.foreignCursor = foreignCursor;
        this.lookup = lookup;
        if (findResult.getIdSet() != null) {
            resultSet = findResult.getIdSet();
        } else {
            resultSet = new TreeSet<>();
        }
        this.underlyingMap = findResult.getUnderlyingMap();
        this.hasMore = findResult.isHasMore();
        this.totalCount = findResult.getTotalCount();
    }

    @Override
    public boolean hasMore() {
        return hasMore;
    }

    @Override
    public int size() {
        return resultSet.size();
    }

    @Override
    public int totalCount() {
        return totalCount;
    }

    @Override
    public Document firstOrDefault() {
        return Iterables.firstOrDefault(this);
    }

    @Override
    public List toList() {
        return Iterables.toList(this);
    }

    @Override
    public Iterator iterator() {
        return new JoinedDocumentIterator();
    }

    @Override
    public String toString() {
        return toList().toString();
    }

    private class JoinedDocumentIterator implements Iterator {
        private Iterator iterator;

        JoinedDocumentIterator() {
            iterator = resultSet.iterator();
        }

        @Override
        public boolean hasNext() {
            return iterator.hasNext();
        }

        @Override
        public Document next() {
            NitriteId next = iterator.next();
            Document document = underlyingMap.get(next);
            if (document != null) {
                return join(new Document(document), foreignCursor, lookup);
            }
            return null;
        }

        @Override
        public void remove() {
            throw new InvalidOperationException(REMOVE_ON_DOCUMENT_ITERATOR_NOT_SUPPORTED);
        }

        private Document join(Document localDocument, Cursor foreignCursor, Lookup lookup) {
            Object localObject = localDocument.get(lookup.getLocalField());
            if (localObject == null) return localDocument;
            Document resultDocument = new Document(localDocument);
            Set target = new HashSet<>();

            for (Document foreignDocument: foreignCursor) {
                Object foreignObject = foreignDocument.get(lookup.getForeignField());
                if (foreignObject != null) {
                    if (deepEquals(foreignObject, localObject)) {
                        target.add(foreignDocument);
                    }
                }
            }
            if (!target.isEmpty()) {
                resultDocument.put(lookup.getTargetField(), target);
            }
            return resultDocument;
        }
    }
}