/*

 * Copyright (c) 2010 Nokia Corporation and/or its subsidiary(-ies).

 * All rights reserved.

 * This component and the accompanying materials are made available

 * under the terms of "Eclipse Public License v1.0"

 * which accompanies this distribution, and is available

 * at the URL "http://www.eclipse.org/legal/epl-v10.html".

 *

 * Initial Contributors:

 * Nokia Corporation - initial contribution.

 *

 * Contributors:

 *

 * Description:  Definitions for the class ReadFile

 *

 */

package com.nokia.s60tools.analyzetool.engine;

import java.io.File;

import java.io.IOException;

import java.io.RandomAccessFile;

import java.util.AbstractList;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import com.nokia.s60tools.analyzetool.engine.statistic.AllocCallstack;

import com.nokia.s60tools.analyzetool.engine.statistic.BaseInfo;

import com.nokia.s60tools.analyzetool.engine.statistic.ProcessInfo;

/**

 * CallstackManager for reading of callstacks on demand by accessing the .dat

 * file after the initial parsing of the file has completed.

 * 

 */

public class DeferredCallstackManager implements ICallstackManager {

	/**

	 * Max number of lines to parse before giving up and forcing the callstack

	 * as complete. This helps to deal with corrupt files.

	 */

	private static final int BAIL_OUT_LIMIT = 100;

	/** Location of the .dat file */

	String fileLocation;

	/**

	 * list of processes for this file; this has to contain all DllLoads for

	 * each process

	 */

	private Map<Integer, ProcessInfo> processMap;

	/**

	 * Constructor

	 * 

	 * @param fileLocation

	 *            full path of the file to read callstacks from

	 */

	public DeferredCallstackManager(String fileLocation) {

		this.fileLocation = fileLocation;

	}

	/**

	 * Setter for all processes valid for this data file. This has to contain

	 * all DllInfo information for each of the processes

	 * 

	 * @param processes

	 *            List of processes for the file

	 */

	public void setProcesses(AbstractList<ProcessInfo> processes) {

		// make a copy

		if (processMap == null) {

			processMap = new HashMap<Integer, ProcessInfo>();

			for (ProcessInfo processInfo : processes) {

				processMap.put(processInfo.getProcessID(), processInfo);

			}

		}

	}

	/*

	 * (non-Javadoc)

	 * 

	 * @seecom.nokia.s60tools.analyzetool.engine.statistic.ICallstackManager#

	 * readCallstack(com.nokia.s60tools.analyzetool.engine.statistic.BaseInfo)

	 */

	public List<AllocCallstack> readCallstack(BaseInfo baseInfo)

			throws IOException {

		// Returns a fully resolved callstack file in .dat format.

		// The baseInfo's file position points to the beginning of a record

		// where the callstack information starts

		if (!hasCallstack(baseInfo)) {

			return null;

		}

		ProcessInfo p = processMap.get(baseInfo.getProcessID());

		if (p == null) {

			// no matching process found

			return new ArrayList<AllocCallstack>();

		}

		RandomAccessFile fileReader = null;

		List<AllocCallstack> ret = null;

		try {

			// Open .dat file for reading

			fileReader = new RandomAccessFile(new File(fileLocation), "r"); //$NON-NLS-1$

			// Parsing the ELF header to read the Program Header Offset

			// 'e_phoff' value

			fileReader.seek(baseInfo.getFilePos());

			CallstackDataParser parser = new CallstackDataParser(baseInfo, p);

			int lineCnt = 0;

			String line;

			while ((line = fileReader.readLine()) != null) {

				if (parser.parseLine(line)) {

					parser.finaliseCallstack();

					ret = parser.getCallstack();

					break;

				}

				// let's count the lines we parse and bail out after <n> lines

				// in case the file is corrupt

				lineCnt++;

				if (lineCnt == BAIL_OUT_LIMIT) {

					parser.forceComplete();

					ret = parser.getCallstack();

					break;

				}

			}

		} finally {

			if (fileReader != null) {

				fileReader.close();

			}

		}

		return ret == null ? new ArrayList<AllocCallstack>() : ret;

	}

	/*

	 * (non-Javadoc)

	 * 

	 * @seecom.nokia.s60tools.analyzetool.engine.statistic.ICallstackManager#

	 * hasCallstack(com.nokia.s60tools.analyzetool.engine.statistic.BaseInfo)

	 */

	public boolean hasCallstack(BaseInfo baseInfo) {

		return baseInfo.getFilePos() > -1;

	}

}