/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.jena.tdb.index;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import org.apache.jena.atlas.lib.Bytes;
import org.apache.jena.tdb.base.record.Record;
import org.apache.jena.tdb.base.record.RecordFactory;

public class IndexMap implements Index {
    private final Map<ByteArray, ByteArray> index = new HashMap<>();
    private final RecordFactory recordFactory;

    public IndexMap(RecordFactory recordFactory) {
        this.recordFactory = recordFactory;
    }

    @Override
    public Record find(Record record) {
        ByteArray k = wrap(record.getKey());
        ByteArray v = index.get(k);
        if ( v == null )
            return null;
        return record(k, v);
    }

    @Override
    public boolean contains(Record record) {
        Record r = find(record);
        if ( r == null )
            return false;
        if ( !recordFactory.hasValue() )
            return true;
        return Bytes.compare(record.getValue(), r.getValue()) == 0;
    }

    @Override
    public boolean add(Record record) {
        Record r = find(record);
        if ( r != null && r.equals(record) )
            return false;
        index.put(wrap(record.getKey()), wrap(record.getValue()));
        return true;
    }

    @Override
    public boolean delete(Record record) {
        ByteArray x = index.remove(wrap(record.getKey()));
        if ( x == null )
            return false;
        return true;
    }

    @Override
    public Iterator<Record> iterator() {
        return new Iterator<Record>() {

            Iterator<Map.Entry<ByteArray, ByteArray>> iter = index.entrySet().iterator();

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

            @Override
            public Record next() {
                Map.Entry<ByteArray, ByteArray> e = iter.next();
                return record(e.getKey(), e.getValue());
            }
        };
    }

    @Override
    public RecordFactory getRecordFactory() {
        return recordFactory;
    }

    @Override
    public boolean isEmpty() {
        return index.isEmpty();
    }

    @Override
    public void clear() {
        index.clear();
    }

    @Override
    public void check() {}

    @Override
    public long size() {
        return index.size();
    }

    @Override
    public void sync() {}

    @Override
    public void close() {}

    private static ByteArray wrap(byte[] b) {
        return new ByteArray(b);
    }

    private Record record(ByteArray k, ByteArray v) {
        return recordFactory.create(k.bytes, v.bytes);
    }

    private static class ByteArray {
        byte[] bytes;
        ByteArray(byte[] bytes) {
            this.bytes = bytes;
        }

        @Override
        public int hashCode() {
            final int prime = 31;
            int result = 1;
            result = prime * result + Arrays.hashCode(bytes);
            return result;
        }

        @Override
        public boolean equals(Object obj) {
            if ( this == obj )
                return true;
            if ( obj == null )
                return false;
            if ( getClass() != obj.getClass() )
                return false;
            ByteArray other = (ByteArray)obj;
            if ( !Arrays.equals(bytes, other.bytes) )
                return false;
            return true;
        }
    }

}
