/**
    * Oshi (https://github.com/dblock/oshi)
    * 
    * Copyright (c) 2010 - 2015 The Oshi Project Team
    * 
    * All rights reserved. This program and the accompanying materials
    * are made available under the terms of the Eclipse Public License v1.0
    * which accompanies this distribution, and is available at
    * http://www.eclipse.org/legal/epl-v10.html
   * 
   * Contributors:
   * dblock[at]dblock[dot]org
   * alessandro[at]perucchi[dot]org
   * widdis[at]gmail[dot]com
   * https://github.com/dblock/oshi/graphs/contributors
   */
  package oshi.software.os.linux.proc;
  
  import java.io.IOException;
  import java.lang.management.ManagementFactory;
  import java.util.List;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import oshi.hardware.Processor;
  import oshi.util.FileUtil;
  import oshi.util.ParseUtil;
  
  /**
   * A CPU as defined in Linux /proc.
   * 
   * @author alessandro[at]perucchi[dot]org
   * @author alessio.fachechi[at]gmail[dot]com
   * @author widdis[at]gmail[dot]com
   */
  @SuppressWarnings("restriction")
  public class CentralProcessor implements Processor {
  	// Determine whether MXBean supports Oracle JVM methods
  	private static final java.lang.management.OperatingSystemMXBean OS_MXBEAN = ManagementFactory
  			.getOperatingSystemMXBean();;
  	private static boolean sunMXBean;
  	static {
  		try {
  			Class.forName("com.sun.management.OperatingSystemMXBean");
  			// Initialize CPU usage
  			((com.sun.management.OperatingSystemMXBean) OS_MXBEAN)
  					.getSystemCpuLoad();
  			sunMXBean = true;
  		} catch (ClassNotFoundException e) {
  			sunMXBean = false;
  		}
  	}
  	// Maintain two sets of previous ticks to be used for calculating usage
  	// between them.
  	// System ticks (static)
  	private static long tickTime = System.currentTimeMillis();
  	private static long[] prevTicks = new long[4];
  	private static long[] curTicks = new long[4];
  	static {
  		updateSystemTicks();
  		System.arraycopy(curTicks, 0, prevTicks, 0, curTicks.length);
  	}
  
  	// Maintain similar arrays for per-processor ticks (class variables)
  	private long procTickTime = System.currentTimeMillis();
  	private long[] prevProcTicks = new long[4];
  	private long[] curProcTicks = new long[4];
  
  	// Initialize numCPU
  	private static int numCPU = 0;
  	static {
  		try {
  			List<String> procCpu = FileUtil.readFile("/proc/cpuinfo");
  			for (String cpu : procCpu) {
  				if (cpu.startsWith("core id")) {
  					numCPU++;
  				}
  			}
  		} catch (IOException e) {
  			System.err.println("Problem with: /proc/cpuinfo");
  			System.err.println(e.getMessage());
  		}
  	}
  	// Set up array to maintain current ticks for rapid reference. This array
  	// will be updated in place and used as a cache to avoid rereading file
  	// while iterating processors
  	private static long[][] allProcessorTicks = new long[numCPU][4];
  	private static long allProcTickTime = 0;
  
  	private int processorNumber;
  	private String cpuVendor;
  	private String cpuName;
  	private String cpuIdentifier = null;
  	private String cpuStepping;
  	private String cpuModel;
  	private String cpuFamily;
  	private Long cpuVendorFreq = null;
  	private Boolean cpu64;
  
 	/**
 	 * Create a Processor with the given number
 	 * 
 	 * @param procNo
 	 */
 	public CentralProcessor(int procNo) {
 		if (procNo >= numCPU)
 			throw new IllegalArgumentException("Processor number (" + procNo
 					+ ") must be less than the number of CPUs: " + numCPU);
 		this.processorNumber = procNo;
 		updateProcessorTicks();
 		System.arraycopy(allProcessorTicks[processorNumber], 0, curProcTicks,
 				0, curProcTicks.length);
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	@Override
 	public int getProcessorNumber() {
 		return processorNumber;
 	}
 
 	/**
 	 * Vendor identifier, eg. GenuineIntel.
 	 * 
 	 * @return Processor vendor.
 	 */
 	@Override
 	public String getVendor() {
 		return this.cpuVendor;
 	}
 
 	/**
 	 * Set processor vendor.
 	 * 
 	 * @param vendor
 	 *            Vendor.
 	 */
 	@Override
 	public void setVendor(String vendor) {
 		this.cpuVendor = vendor;
 	}
 
 	/**
 	 * Name, eg. Intel(R) Core(TM)2 Duo CPU T7300 @ 2.00GHz
 	 * 
 	 * @return Processor name.
 	 */
 	@Override
 	public String getName() {
 		return this.cpuName;
 	}
 
 	/**
 	 * Set processor name.
 	 * 
 	 * @param name
 	 *            Name.
 	 */
 	@Override
 	public void setName(String name) {
 		this.cpuName = name;
 	}
 
 	/**
 	 * Vendor frequency (in Hz), eg. for processor named Intel(R) Core(TM)2 Duo
 	 * CPU T7300 @ 2.00GHz the vendor frequency is 2000000000.
 	 * 
 	 * @return Processor frequency or -1 if unknown.
 	 */
 	@Override
 	public long getVendorFreq() {
 		if (this.cpuVendorFreq == null) {
 			Pattern pattern = Pattern.compile("@ (.*)$");
 			Matcher matcher = pattern.matcher(getName());
 
 			if (matcher.find()) {
 				String unit = matcher.group(1);
 				this.cpuVendorFreq = Long.valueOf(ParseUtil.parseHertz(unit));
 			} else {
 				this.cpuVendorFreq = Long.valueOf(-1L);
 			}
 		}
 
 		return this.cpuVendorFreq.longValue();
 	}
 
 	/**
 	 * Set vendor frequency.
 	 * 
 	 * @param freq
 	 *            Frequency.
 	 */
 	@Override
 	public void setVendorFreq(long freq) {
 		this.cpuVendorFreq = Long.valueOf(freq);
 	}
 
 	/**
 	 * Identifier, eg. x86 Family 6 Model 15 Stepping 10.
 	 * 
 	 * @return Processor identifier.
 	 */
 	@Override
 	public String getIdentifier() {
 		if (this.cpuIdentifier == null) {
 			StringBuilder sb = new StringBuilder();
 			if (getVendor().contentEquals("GenuineIntel"))
 				sb.append(isCpu64bit() ? "Intel64" : "x86");
 			else
 				sb.append(getVendor());
 			sb.append(" Family ");
 			sb.append(getFamily());
 			sb.append(" Model ");
 			sb.append(getModel());
 			sb.append(" Stepping ");
 			sb.append(getStepping());
 			this.cpuIdentifier = sb.toString();
 		}
 		return this.cpuIdentifier;
 	}
 
 	/**
 	 * Set processor identifier.
 	 * 
 	 * @param identifier
 	 *            Identifier.
 	 */
 	@Override
 	public void setIdentifier(String identifier) {
 		this.cpuIdentifier = identifier;
 	}
 
 	/**
 	 * Is CPU 64bit?
 	 * 
 	 * @return True if cpu is 64bit.
 	 */
 	@Override
 	public boolean isCpu64bit() {
 		return this.cpu64.booleanValue();
 	}
 
 	/**
 	 * Set flag is cpu is 64bit.
 	 * 
 	 * @param cpu64
 	 *            True if cpu is 64.
 	 */
 	@Override
 	public void setCpu64(boolean cpu64) {
 		this.cpu64 = Boolean.valueOf(cpu64);
 	}
 
 	/**
 	 * @return the stepping
 	 */
 	@Override
 	public String getStepping() {
 		return this.cpuStepping;
 	}
 
 	/**
 	 * @param stepping
 	 *            the stepping to set
 	 */
 	@Override
 	public void setStepping(String stepping) {
 		this.cpuStepping = stepping;
 	}
 
 	/**
 	 * @return the model
 	 */
 	@Override
 	public String getModel() {
 		return this.cpuModel;
 	}
 
 	/**
 	 * @param model
 	 *            the model to set
 	 */
 	@Override
 	public void setModel(String model) {
 		this.cpuModel = model;
 	}
 
 	/**
 	 * @return the family
 	 */
 	@Override
 	public String getFamily() {
 		return this.cpuFamily;
 	}
 
 	/**
 	 * @param family
 	 *            the family to set
 	 */
 	@Override
 	public void setFamily(String family) {
 		this.cpuFamily = family;
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	@Override
 	@Deprecated
 	public float getLoad() {
 		// TODO Remove in 2.0
 		return (float) getSystemCpuLoadBetweenTicks() * 100;
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	@Override
 	public double getSystemCpuLoadBetweenTicks() {
 		// Check if > ~ 0.95 seconds since last tick count.
 		long now = System.currentTimeMillis();
 		boolean update = (now - tickTime > 950);
 		if (update) {
 			// Enough time has elapsed.
 			// Update latest
 			updateSystemTicks();
 			tickTime = now;
 		}
 		// Calculate total
 		long total = 0;
 		for (int i = 0; i < curTicks.length; i++) {
 			total += (curTicks[i] - prevTicks[i]);
 		}
 		// Calculate idle from last field [3]
 		long idle = curTicks[3] - prevTicks[3];
 
 		// Copy latest ticks to earlier position for next call
 		if (update) {
 			System.arraycopy(curTicks, 0, prevTicks, 0, curTicks.length);
 		}
 
 		// return
 		if (total > 0 && idle >= 0) {
 			return (double) (total - idle) / total;
 		}
 		return 0d;
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	@Override
 	public long[] getSystemCpuLoadTicks() {
 		updateSystemTicks();
 		// Make a copy
 		long[] ticks = new long[curTicks.length];
 		System.arraycopy(curTicks, 0, ticks, 0, curTicks.length);
 		return ticks;
 	}
 
 	/**
 	 * Updates system tick information from parsing /proc/stat. Array with four
 	 * elements representing clock ticks or milliseconds (platform dependent)
 	 * spent in User (0), Nice (1), System (2), and Idle (3) states. By
 	 * measuring the difference between ticks across a time interval, CPU load
 	 * over that interval may be calculated.
 	 * 
 	 * @return An array of 4 long values representing time spent in User,
 	 *         Nice(if applicable), System, and Idle states.
 	 */
 	private static void updateSystemTicks() {
 		// /proc/stat expected format
 		// first line is overall user,nice,system,idle, etc.
 		// cpu 3357 0 4313 1362393 ...
 		String tickStr = "";
 		try {
 			List<String> procStat = FileUtil.readFile("/proc/stat");
 			if (!procStat.isEmpty())
 				tickStr = procStat.get(0);
 		} catch (IOException e) {
 			System.err.println("Problem with: /proc/stat");
 			System.err.println(e.getMessage());
 			return;
 		}
 		String[] tickArr = tickStr.split("\\s+");
 		if (tickArr.length < 5)
 			return;
 		for (int i = 0; i < 4; i++) {
 			curTicks[i] = Long.parseLong(tickArr[i + 1]);
 		}
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	@Override
 	public double getSystemCpuLoad() {
 		if (sunMXBean) {
 			return ((com.sun.management.OperatingSystemMXBean) OS_MXBEAN)
 					.getSystemCpuLoad();
 		}
 		return getSystemCpuLoadBetweenTicks();
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	@Override
 	public double getSystemLoadAverage() {
 		return OS_MXBEAN.getSystemLoadAverage();
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	@Override
 	public double getProcessorCpuLoadBetweenTicks() {
 		// Check if > ~ 0.95 seconds since last tick count.
 		long now = System.currentTimeMillis();
 		if (now - procTickTime > 950) {
 			// Enough time has elapsed. Update array in place
 			updateProcessorTicks();
 			// Copy arrays in place
 			System.arraycopy(curProcTicks, 0, prevProcTicks, 0,
 					curProcTicks.length);
 			System.arraycopy(allProcessorTicks[processorNumber], 0,
 					curProcTicks, 0, curProcTicks.length);
 			procTickTime = now;
 		}
 		long total = 0;
 		for (int i = 0; i < curProcTicks.length; i++) {
 			total += (curProcTicks[i] - prevProcTicks[i]);
 		}
 		// Calculate idle from last field [3]
 		long idle = curProcTicks[3] - prevProcTicks[3];
 		// update
 		return (total > 0 && idle >= 0) ? (double) (total - idle) / total : 0d;
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public long[] getProcessorCpuLoadTicks() {
 		updateProcessorTicks();
 		return allProcessorTicks[processorNumber];
 	}
 
 	/**
 	 * Updates the tick array for all processors if more than 100ms has elapsed
 	 * since the last update. This permits using the allProcessorTicks as a
 	 * cache when iterating over processors so that the /proc/stat file is only
 	 * read once
 	 */
 	private static void updateProcessorTicks() {
 		// Update no more frequently than 100ms so this is only triggered once
 		// during iteration over Processors
 		long now = System.currentTimeMillis();
 		if (now - allProcTickTime < 100)
 			return;
 
 		// /proc/stat expected format
 		// first line is overall user,nice,system,idle, etc.
 		// cpu 3357 0 4313 1362393 ...
 		// per-processor subsequent lines for cpu0, cpu1, etc.
 		try {
 			int cpu = 0;
 			List<String> procStat = FileUtil.readFile("/proc/stat");
 			for (String stat : procStat) {
 				if (stat.startsWith("cpu") && !stat.startsWith("cpu ")) {
 					String[] tickArr = stat.split("\\s+");
 					if (tickArr.length < 5)
 						break;
 					for (int i = 0; i < 4; i++) {
 						allProcessorTicks[cpu][i] = Long
 								.parseLong(tickArr[i + 1]);
 					}
 					if (++cpu >= numCPU)
 						break;
 				}
 			}
 		} catch (IOException e) {
 			System.err.println("Problem with: /proc/stat");
 			System.err.println(e.getMessage());
 		}
 		allProcTickTime = now;
 	}
 
 	@Override
 	public String toString() {
 		return getName();
 	}
 }