/*
 * Copyright 2009-2010 by The Regents of the University of California
 * 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 from
 * 
 *     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 edu.uci.ics.hyracks.storage.am.lsm.rtree.impls;

import edu.uci.ics.hyracks.api.dataflow.value.ILinearizeComparator;
import edu.uci.ics.hyracks.api.dataflow.value.ILinearizeComparatorFactory;
import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
import edu.uci.ics.hyracks.storage.am.common.api.ICursorInitialState;
import edu.uci.ics.hyracks.storage.am.common.api.ISearchPredicate;
import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexCursor;
import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;

public class LSMRTreeSortedCursor extends LSMRTreeAbstractCursor implements ITreeIndexCursor {

    private ILinearizeComparator linearizeCmp;
    private boolean[] depletedRtreeCursors;
    private int foundIn = -1;

    public LSMRTreeSortedCursor(ILSMIndexOperationContext opCtx, ILinearizeComparatorFactory linearizer)
            throws HyracksDataException {
        super(opCtx);
        this.linearizeCmp = linearizer.createBinaryComparator();
        reset();
    }

    @Override
    public void reset() throws HyracksDataException {
        depletedRtreeCursors = new boolean[numberOfTrees];
        foundNext = false;
        try {
            for (int i = 0; i < numberOfTrees; i++) {
                rtreeCursors[i].reset();
                try {
                    diskRTreeAccessors[i].search(rtreeCursors[i], rtreeSearchPredicate);
                } catch (IndexException e) {
                    throw new HyracksDataException(e);
                }
                if (rtreeCursors[i].hasNext()) {
                    rtreeCursors[i].next();
                } else {
                    depletedRtreeCursors[i] = true;
                }
            }
        } finally {
            if (open) {
                lsmHarness.endSearch(opCtx);
            }
        }
    }

    @Override
    public boolean hasNext() throws HyracksDataException {
        while (!foundNext) {
            frameTuple = null;

            if (foundIn != -1) {
                if (rtreeCursors[foundIn].hasNext()) {
                    rtreeCursors[foundIn].next();
                } else {
                    depletedRtreeCursors[foundIn] = true;
                }
            }

            foundIn = -1;
            for (int i = 0; i < numberOfTrees; i++) {
                if (depletedRtreeCursors[i])
                    continue;

                if (frameTuple == null) {
                    frameTuple = rtreeCursors[i].getTuple();
                    foundIn = i;
                    continue;
                }

                if (linearizeCmp.compare(frameTuple.getFieldData(0), frameTuple.getFieldStart(0),
                        frameTuple.getFieldLength(0) * linearizeCmp.getDimensions(), rtreeCursors[i].getTuple()
                                .getFieldData(0), rtreeCursors[i].getTuple().getFieldStart(0), rtreeCursors[i]
                                .getTuple().getFieldLength(0) * linearizeCmp.getDimensions()) <= 0) {
                    frameTuple = rtreeCursors[i].getTuple();
                    foundIn = i;
                }
            }

            if (foundIn == -1)
                return false;

            boolean killed = false;
            for (int i = 0; i < foundIn; i++) {
                try {
                    btreeCursors[i].reset();
                    btreeRangePredicate.setHighKey(frameTuple, true);
                    btreeRangePredicate.setLowKey(frameTuple, true);
                    diskBTreeAccessors[i].search(btreeCursors[i], btreeRangePredicate);
                } catch (IndexException e) {
                    throw new HyracksDataException(e);
                }
                try {
                    if (btreeCursors[i].hasNext()) {
                        killed = true;
                        break;
                    }
                } finally {
                    btreeCursors[i].close();
                }
            }
            if (!killed) {
                foundNext = true;
            }
        }

        return true;
    }

    @Override
    public void next() throws HyracksDataException {
        foundNext = false;
    }

    @Override
    public void open(ICursorInitialState initialState, ISearchPredicate searchPred) throws HyracksDataException {
        super.open(initialState, searchPred);

        depletedRtreeCursors = new boolean[numberOfTrees];
        foundNext = false;
        for (int i = 0; i < numberOfTrees; i++) {
            rtreeCursors[i].reset();
            try {
                diskRTreeAccessors[i].search(rtreeCursors[i], rtreeSearchPredicate);
            } catch (IndexException e) {
                throw new HyracksDataException(e);
            }
            if (rtreeCursors[i].hasNext()) {
                rtreeCursors[i].next();
            } else {
                depletedRtreeCursors[i] = true;
            }
        }
    }
}