/*
 * Copyright 2009-2012 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.btree.impls;

import java.io.File;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;

import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
import edu.uci.ics.hyracks.api.io.FileReference;
import edu.uci.ics.hyracks.api.io.IIOManager;
import edu.uci.ics.hyracks.api.io.IODeviceHandle;
import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndex;
import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
import edu.uci.ics.hyracks.storage.am.lsm.common.impls.AbstractLSMIndexFileManager;
import edu.uci.ics.hyracks.storage.am.lsm.common.impls.LSMComponentFileReferences;
import edu.uci.ics.hyracks.storage.am.lsm.common.impls.TreeIndexFactory;
import edu.uci.ics.hyracks.storage.common.file.IFileMapProvider;

public class LSMBTreeFileManager extends AbstractLSMIndexFileManager {
    private static final String BTREE_STRING = "b";

    private final TreeIndexFactory<? extends ITreeIndex> btreeFactory;

    public LSMBTreeFileManager(IIOManager ioManager, IFileMapProvider fileMapProvider, FileReference file,
            TreeIndexFactory<? extends ITreeIndex> btreeFactory, int startIODeviceIndex) {
        super(ioManager, fileMapProvider, file, null, startIODeviceIndex);
        this.btreeFactory = btreeFactory;
    }

    @Override
    public LSMComponentFileReferences getRelFlushFileReference() {
        Date date = new Date();
        String ts = formatter.format(date);
        String baseName = baseDir + ts + SPLIT_STRING + ts;
        // Begin timestamp and end timestamp are identical since it is a flush
        return new LSMComponentFileReferences(createFlushFile(baseName + SPLIT_STRING + BTREE_STRING), null,
                createFlushFile(baseName + SPLIT_STRING + BLOOM_FILTER_STRING));
    }

    @Override
    public LSMComponentFileReferences getRelMergeFileReference(String firstFileName, String lastFileName)
            throws HyracksDataException {
        String[] firstTimestampRange = firstFileName.split(SPLIT_STRING);
        String[] lastTimestampRange = lastFileName.split(SPLIT_STRING);

        String baseName = baseDir + firstTimestampRange[0] + SPLIT_STRING + lastTimestampRange[1];
        // Get the range of timestamps by taking the earliest and the latest timestamps
        return new LSMComponentFileReferences(createMergeFile(baseName + SPLIT_STRING + BTREE_STRING), null,
                createMergeFile(baseName + SPLIT_STRING + BLOOM_FILTER_STRING));
    }

    private static FilenameFilter btreeFilter = new FilenameFilter() {
        public boolean accept(File dir, String name) {
            return !name.startsWith(".") && name.endsWith(BTREE_STRING);
        }
    };

    @Override
    public List<LSMComponentFileReferences> cleanupAndGetValidFiles() throws HyracksDataException, IndexException {
        List<LSMComponentFileReferences> validFiles = new ArrayList<LSMComponentFileReferences>();
        ArrayList<ComparableFileName> allBTreeFiles = new ArrayList<ComparableFileName>();
        ArrayList<ComparableFileName> allBloomFilterFiles = new ArrayList<ComparableFileName>();

        // Gather files from all IODeviceHandles.
        for (IODeviceHandle dev : ioManager.getIODevices()) {
            // List of valid BTree files.
            cleanupAndGetValidFilesInternal(dev, btreeFilter, btreeFactory, allBTreeFiles);
            HashSet<String> btreeFilesSet = new HashSet<String>();
            for (ComparableFileName cmpFileName : allBTreeFiles) {
                int index = cmpFileName.fileName.lastIndexOf(SPLIT_STRING);
                btreeFilesSet.add(cmpFileName.fileName.substring(0, index));
            }
            validateFiles(dev, btreeFilesSet, allBloomFilterFiles, bloomFilterFilter, null);
        }

        // Sanity check.
        if (allBTreeFiles.size() != allBloomFilterFiles.size()) {
            throw new HyracksDataException(
                    "Unequal number of valid BTree and bloom filter files found. Aborting cleanup.");
        }

        // Trivial cases.
        if (allBTreeFiles.isEmpty() || allBloomFilterFiles.isEmpty()) {
            return validFiles;
        }

        if (allBTreeFiles.size() == 1 && allBloomFilterFiles.size() == 1) {
            validFiles.add(new LSMComponentFileReferences(allBTreeFiles.get(0).fileRef, null, allBloomFilterFiles
                    .get(0).fileRef));
            return validFiles;
        }

        // Sorts files names from earliest to latest timestamp.
        Collections.sort(allBTreeFiles);
        Collections.sort(allBloomFilterFiles);

        List<ComparableFileName> validComparableBTreeFiles = new ArrayList<ComparableFileName>();
        ComparableFileName lastBTree = allBTreeFiles.get(0);
        validComparableBTreeFiles.add(lastBTree);

        List<ComparableFileName> validComparableBloomFilterFiles = new ArrayList<ComparableFileName>();
        ComparableFileName lastBloomFilter = allBloomFilterFiles.get(0);
        validComparableBloomFilterFiles.add(lastBloomFilter);

        for (int i = 1; i < allBTreeFiles.size(); i++) {
            ComparableFileName currentBTree = allBTreeFiles.get(i);
            ComparableFileName currentBloomFilter = allBloomFilterFiles.get(i);
            // Current start timestamp is greater than last stop timestamp.
            if (currentBTree.interval[0].compareTo(lastBTree.interval[1]) > 0
                    && currentBloomFilter.interval[0].compareTo(lastBloomFilter.interval[1]) > 0) {
                validComparableBTreeFiles.add(currentBTree);
                validComparableBloomFilterFiles.add(currentBloomFilter);
                lastBTree = currentBTree;
                lastBloomFilter = currentBloomFilter;
            } else if (currentBTree.interval[0].compareTo(lastBTree.interval[0]) >= 0
                    && currentBTree.interval[1].compareTo(lastBTree.interval[1]) <= 0
                    && currentBloomFilter.interval[0].compareTo(lastBloomFilter.interval[0]) >= 0
                    && currentBloomFilter.interval[1].compareTo(lastBloomFilter.interval[1]) <= 0) {
                // Invalid files are completely contained in last interval.
                File invalidBTreeFile = new File(currentBTree.fullPath);
                invalidBTreeFile.delete();
                File invalidBloomFilterFile = new File(currentBloomFilter.fullPath);
                invalidBloomFilterFile.delete();
            } else {
                // This scenario should not be possible.
                throw new HyracksDataException("Found LSM files with overlapping but not contained timetamp intervals.");
            }
        }

        // Sort valid files in reverse lexicographical order, such that newer
        // files come first.
        Collections.sort(validComparableBTreeFiles, recencyCmp);
        Collections.sort(validComparableBloomFilterFiles, recencyCmp);

        Iterator<ComparableFileName> btreeFileIter = validComparableBTreeFiles.iterator();
        Iterator<ComparableFileName> bloomFilterFileIter = validComparableBloomFilterFiles.iterator();
        while (btreeFileIter.hasNext() && bloomFilterFileIter.hasNext()) {
            ComparableFileName cmpBTreeFileName = btreeFileIter.next();
            ComparableFileName cmpBloomFilterFileName = bloomFilterFileIter.next();
            validFiles.add(new LSMComponentFileReferences(cmpBTreeFileName.fileRef, null,
                    cmpBloomFilterFileName.fileRef));
        }

        return validFiles;
    }
}