/*
 * Copyright (c) 2011-2015 EPFL DATA Laboratory
 * Copyright (c) 2014-2015 The Squall Collaboration (see NOTICE)
 *
 * All rights reserved.
 *
 * 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 ch.epfl.data.squall.storage;

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;
import java.io.Serializable;
import java.util.ArrayList;

import org.apache.log4j.Logger;

/* R denotes the type of objects you expect the store to return at a access or update call */
public abstract class BasicStore<R> implements Serializable {
    private static Logger LOG = Logger.getLogger(BasicStore.class);

    private final String _uniqId;
    private PrintStream _ps;
    protected String _objRemId;
    private static int _uniqIdCounter = 0;
    // protected MemoryManager _memoryManager;
    // protected StorageManager _storageManager;
    private ByteArrayOutputStream _baos = null;
    private static final long serialVersionUID = 1L;
    private static final String _uniqIdPrefix = "Store#";

    public BasicStore(int storesizemb) {
	_uniqIdCounter++;
	this._uniqId = BasicStore._uniqIdPrefix
		+ Integer.toString(BasicStore._uniqIdCounter);
	LOG.info("SquallStorage: Initializing store of size " + storesizemb
		+ " MB with UniqStoreId: " + _uniqId);
    }

    public abstract ArrayList<R> access(Object... data);

    public abstract R update(Object... data);

    public abstract boolean contains(Object... data);

    public abstract boolean equals(BasicStore store);

    public String getContent() {
	String str = null;
	if (this._baos == null) {
	    this._baos = new ByteArrayOutputStream();
	    this._ps = new PrintStream(this._baos);
	} else
	    this._baos.reset();
	this.printStore(this._ps, true);
	str = this._baos.toString();
	return str.equals("") ? null : str;
    }

    public String getUniqId() {
	return this._uniqId;
    }

    public void insert(Object... obj) {
	this.onInsert(obj);
	/*
	 * Check if store has exceeded it's maximum space, and if yes, removes
	 * some elements from it and writes them to stable storage.
	 */
	// while (this._memoryManager.hasExceededMaxSpace() == true) {
	// final Object remObj = this.onRemove();
	// _storageManager.write(_objRemId, remObj);
	// }
    }

    /* Functions to be implemented by all stores */
    public abstract void onInsert(Object... data);

    /* must set _objRemId */
    // public abstract Object onRemove();

    public abstract void printStore(PrintStream stream, boolean printStorage);

    public abstract void reset();

    public abstract void setSingleEntry(boolean singleEntry);

}