/**
    * HBaseWriterProcessor
    *
    * $Id$
    *
    * Created on June 23rd, 2007
    *
    * This file is part of the Heritrix web crawler (crawler.archive.org).
    *
   * Heritrix is free software; you can redistribute it and/or modify
   * it under the terms of the GNU Lesser Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * any later version.
   *
   * Heritrix is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU Lesser Public License for more details.
   *
   * You should have received a copy of the GNU Lesser Public License
   * along with Heritrix; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  package com.powerset.heritrix.writer;
  
  import java.io.Closeable;
  import java.io.IOException;
  import java.io.InputStream;
  
  import org.apache.hadoop.hbase.client.Get;
  import org.apache.hadoop.hbase.client.HTable;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.hbase.util.Keying;
  import org.apache.log4j.Logger;
  import org.archive.io.ReplayInputStream;
  import org.archive.io.WriterPool;
  import org.archive.io.WriterPoolMember;
  import org.archive.modules.ModuleAttributeConstants;
  import org.archive.modules.ProcessResult;
  import org.archive.modules.Processor;
  import org.archive.modules.ProcessorURI;
  import org.archive.modules.fetcher.FetchStatusCodes;
  import org.archive.modules.net.CrawlHost;
  import org.archive.modules.net.ServerCache;
  import org.archive.modules.net.ServerCacheUtil;
  import org.archive.state.Expert;
  import org.archive.state.Immutable;
  import org.archive.state.Initializable;
  import org.archive.state.Key;
  import org.archive.state.KeyManager;
  import org.archive.state.StateProvider;
  import org.archive.util.IoUtils;
  
  /**
   * An <a href="http://crawler.archive.org">heritrix2</a> processor that writes
   * to <a href="http://hbase.org">Hadoop HBase</a>.
   */
  public class HBaseWriterProcessor extends Processor implements Initializable, Closeable {
  	
  	/** The Constant serialVersionUID. */
  	private static final long serialVersionUID = 7166781798179114353L;
  
  	/** The LOG. */
  	private final Logger LOG = Logger.getLogger(this.getClass().getName());
  
  	/** Commas-seperated list of Hostnames in the zookeeper quorum. */
  	@Immutable
  	public static final Key<String> ZKQUORUM = Key.make("localhost");
  
  	/** The port that clients should connect on to contact their zk quorum hsots. */
  	@Immutable
  	public static final Key<Integer> ZKCLIENTPORT = Key.make(2181);
  	
  	/** HBase tableName to crawl into. */
  	@Immutable
  	public static final Key<String> TABLE = Key.make("crawl");
  
  	/** 
  	 * If set to true, then only write urls that are new rowkey records. Default is false, which will write all urls to the HBase table.  
  	 * Heritrix is good about not hitting the same url twice, so this feature is to ensure that you can run multiple sessions 
  	 * of the same crawl configuration and not write the same url more than once to the same hbase table. You may just want to crawl a site to 
  	 * see what new urls have been added over time, or continue where you left off on a terminated crawl.  Heritrix itself does support this
  	 * functionalty by supporting "Checkpoints" during a crawl session, so this may not be a necessary option. 
  	 */
  	@Immutable
  	public static final Key<Boolean> WRITE_ONLY_NEW_RECORDS = Key.make(false);
  	
  	/** 
  	 * If set to true, then only process urls that are new rowkey records. Default is false, which will process all urls to the HBase table.  
  	 * In this mode, Heritrix wont even fetch and parse the content served at the url if it already exists as a rowkey in the HBase table. 
  	 */
  	@Immutable
  	public static final Key<Boolean> PROCESS_ONLY_NEW_RECORDS = Key.make(false);
  
  	/** Maximum active files in pool. This setting cannot be varied over the life of a crawl. */
  	@Immutable
  	final public static Key<Integer> POOL_MAX_ACTIVE = Key.make(WriterPool.DEFAULT_MAX_ACTIVE);
  
  	/** Maximum time to wait on pool element (milliseconds). This setting cannot be varied over the life of a crawl. */
 	@Immutable
 	final public static Key<Integer> POOL_MAX_WAIT = Key.make(WriterPool.DEFAULT_MAXIMUM_WAIT);
 
 	/** The Constant SERVER_CACHE. */
 	@Immutable
 	final public static Key<ServerCache> SERVER_CACHE = Key.makeAuto(ServerCache.class);
 
 	/** Maximum allowable content size. */
 	@Immutable
 	final public static Key<Integer> CONTENT_MAX_SIZE = Key.make(20 * 1024 * 1024);
 
 	/** Total file bytes to write to disk. Once the size of all files on disk has exceeded this limit, this processor will stop the crawler. A value of zero means no upper limit. */
 	@Immutable
 	@Expert
 	final public static Key<Long> TOTAL_BYTES_TO_WRITE = Key.make(0L);
 
 	/** Reference to pool. */
 	private transient WriterPool pool = null;
 	
 	/** The server cache. */
 	private ServerCache serverCache;
 	
 	/** The max active. */
 	private int maxActive;
 	
 	/** The max wait. */
 	private int maxWait;
 	
 	/** The max content size. */
 	private int maxContentSize;
 	
 	/** The comma seperated string of hostnames that make up the zookeeper quorum. */
 	private String zkQuorum;
 	
 	/** The port that zk clients should connect to for information. */
 	private int zkClientPort;
 	
 	/** The hbase table name. */
 	private String tableName;
 	
 	/** The only write new records turnable. */
 	private boolean onlyWriteNewRecords;
 	
 	/** The only process new records turnable. */
 	private boolean onlyProcessNewRecords;
 
 	/** The total bytes written to disk. */
 	private long totalBytesWritten = 0;
 
 	static {
 		KeyManager.addKeys(HBaseWriterProcessor.class);
 	}
 
 	/**
 	 * Instantiates a new HBaseWriterProcessor.
 	 */
 	public HBaseWriterProcessor() {
 		super();
 	}
 
 	/* (non-Javadoc)
 	 * @see org.archive.state.Initializable#initialTasks(org.archive.state.StateProvider)
 	 */
 	public synchronized void initialTasks(StateProvider context) {
 		this.serverCache = context.get(this, SERVER_CACHE);
 		this.maxActive = context.get(this, POOL_MAX_ACTIVE).intValue();
 		this.maxWait = context.get(this, POOL_MAX_WAIT).intValue();
 		this.zkQuorum = context.get(this, ZKQUORUM);
 		this.zkClientPort = context.get(this, ZKCLIENTPORT);
 		this.tableName = context.get(this, TABLE);
 		this.onlyWriteNewRecords = context.get(this, WRITE_ONLY_NEW_RECORDS).booleanValue();
 		this.onlyProcessNewRecords = context.get(this, PROCESS_ONLY_NEW_RECORDS).booleanValue();
 		this.maxContentSize = context.get(this, CONTENT_MAX_SIZE).intValue();
 		setupPool();
 	}
 
 	/* (non-Javadoc)
 	 * @see org.archive.modules.Processor#innerProcessResult(org.archive.modules.ProcessorURI)
 	 */
 	protected ProcessResult innerProcessResult(final ProcessorURI puri) {
 		ProcessorURI curi = puri;
 		long recordLength = getRecordedSize(curi);
 		ReplayInputStream ris = null;
 		try {
 			if (shouldWrite(curi)) {
 				ris = curi.getRecorder().getRecordedInput().getReplayInputStream();
 				return write(curi, recordLength, ris, getHostAddress(curi));
 			}
 			LOG.info("does not write " + curi.toString());
 		} catch (IOException e) {
 			curi.getNonFatalFailures().add(e);
 			LOG.error("Failed write of Record: " + curi.toString(), e);
 		} finally {
 			IoUtils.close(ris);
 		}
 		return ProcessResult.PROCEED;
 	}
 
 	/**
 	 * Return IP address of given URI suitable for recording (as in a classic
 	 * ARC 5-field header line).
 	 * 
 	 * @param curi ProcessorURI
 	 * 
 	 * @return String of IP address
 	 */
 	protected String getHostAddress(ProcessorURI curi) {
 		// special handling for DNS URIs: want address of DNS server
 		if (curi.getUURI().getScheme().toLowerCase().equals("dns")) {
 			return (String) curi.getData().get(
 					ModuleAttributeConstants.A_DNS_SERVER_IP_LABEL);
 		}
 		// otherwise, host referenced in URI
 		CrawlHost crawlHost = ServerCacheUtil.getHostFor(serverCache, curi.getUURI());
 		if (crawlHost == null) {
 			throw new NullPointerException("Crawlhost is null for " + curi + " " + curi.getVia());
 		}
 		// check if the ip address was looked up.
 		if (crawlHost.getIP() == null) {
 			throw new NullPointerException(
 					"Address is null for "
 							+ curi
 							+ " "
 							+ curi.getVia()
 							+ ". Address "
 							+ ((crawlHost.getIpFetched() == CrawlHost.IP_NEVER_LOOKED_UP) ? "was never looked up."
 									: (System.currentTimeMillis() - crawlHost.getIpFetched()) 
 							+ " ms ago."));
 		}
 		return crawlHost.getIP().getHostAddress();
 	}
 
 	/* (non-Javadoc)
 	 * @see org.archive.modules.Processor#shouldProcess(org.archive.modules.ProcessorURI)
 	 */
 	@Override
 	protected boolean shouldProcess(ProcessorURI uri) {
 		ProcessorURI curi = uri;
 		// If failure, or we haven't fetched the resource yet, return
 		if (curi.getFetchStatus() <= 0) {
 			return false;
 		}
 
 		// If no recorded content at all, don't write record.
 		long recordLength = curi.getContentSize();
 		if (recordLength <= 0) {
 			// getContentSize() should be > 0 if any material (even just
 			// HTTP headers with zero-length body is available.
 			return false;
 		}
 		
 		// If onlyProcessNewRecords is enabled and the given rowkey has cell data,
 		// don't write the record.
 		if (this.onlyProcessNewRecords) {
 			return this.isRecordNew(curi);
 		}
 		// If we make it here, then we passed all our checks and we can assume
 		// we should write the record.
 		return true;
 	}
 	
 	/**
 	 * Whether the given ProcessorURI should be written to archive files.
 	 * Annotates ProcessorURI with a reason for any negative answer.
 	 * 
 	 * @param curi ProcessorURI
 	 * 
 	 * @return true if URI should be written; false otherwise
 	 */
 	protected boolean shouldWrite(ProcessorURI curi) {
 		boolean retVal;
 		String scheme = curi.getUURI().getScheme().toLowerCase();
 		// determine the return value of the uri request
 		if (scheme.equals("dns")) {
 			retVal = curi.getFetchStatus() == FetchStatusCodes.S_DNS_SUCCESS;
 		} else if (scheme.equals("http") || scheme.equals("https")) {
 			retVal = curi.getFetchStatus() > 0 && curi.getHttpMethod() != null;
 		} else if (scheme.equals("ftp")) {
 			retVal = curi.getFetchStatus() == 200;
 		} else {
 			curi.getAnnotations().add("unwritten:scheme");
 			return false;
 		}
 
 		if (retVal == false) {
 			// status not deserving writing
 			curi.getAnnotations().add("unwritten:status");
 			return false;
 		}
 
 		// If the content exceeds the maxContentSize, then dont write.
 		if (curi.getContentSize() > this.maxContentSize) {
 			// content size is too large
 			curi.getAnnotations().add("unwritten:size");
 			LOG.warn("content size for " + curi.getUURI() + " is too large ("
 					+ curi.getContentSize() + ") - maximum content size is: "
 					+ this.maxContentSize);
 			return false;
 		}
 
 		// If onlyWriteNewRecords is enabled and the given rowkey has cell data,
 		// don't write the record.
 		if (this.onlyWriteNewRecords) {
 			return this.isRecordNew(curi);
 		}
 		// all tests pass, return true to write the content locally.
 		return true;
 	}
 	
 	/**
 	 * Determine if the given uri exists as a rowkey in the configured hbase table.
 	 * 
 	 * @param curi the curi
 	 * 
 	 * @return true, if checks if is record new
 	 */
 	private boolean isRecordNew(ProcessorURI curi) {
 		WriterPoolMember writerPoolMember;
 		try {
 			writerPoolMember = getPool().borrowFile();
 		} catch (IOException e1) {
 			LOG.error("No writer could be borrowed from the pool: " + getPool().toString() 
 							+ " - exception is: \n" + e1.getMessage());
 			return false;
 		}
 		HTable hbaseTable = ((HBaseWriter) writerPoolMember).getClient();
 		// Here we can generate the rowkey for this uri ...
 		String url = curi.toString();
 		String row = Keying.createKey(url);
 		try {
 			// and look it up to see if it already exists...
 			Get rowToGet = new Get(Bytes.toBytes(row));
 			if (hbaseTable.get(rowToGet) != null && !hbaseTable.get(rowToGet).isEmpty()) {
 				if (LOG.isDebugEnabled()) {
 					LOG.debug("Not A NEW Record - Url: "
 								+ url
 								+ " has the existing rowkey: "
 								+ row.toString()
 								+ " and has cell data.");
 				}
 				return false;
 			}
 		} catch (IOException e) {
 			LOG.error("Failed to determine if record: "
 							+ row.toString()
 							+ " is a new record due to IOExecption.  Deciding the record is already existing for now. \n"
 							+ e.getMessage());
 			return false;
 		} finally {
 			try {
 				getPool().returnFile(writerPoolMember);
 			} catch (IOException e) {
 				LOG.error("Failed to add back writer to the pool after checking if a rowkey is new or existing: "
 								+ row.toString() + "\n" + e.getMessage());
 				return false;
 			}
 		}
 		return true;
 	}
 
 	/**
 	 * Write.
 	 * 
 	 * @param curi the curi
 	 * @param recordLength the record length
 	 * @param in the in
 	 * @param ip the ip
 	 * 
 	 * @return the process result
 	 * 
 	 * @throws IOException Signals that an I/O exception has occurred.
 	 */
 	protected ProcessResult write(final ProcessorURI curi, long recordLength, InputStream in, String ip) throws IOException {
 		WriterPoolMember writerPoolMember = getPool().borrowFile();
 		long writerPoolMemberPosition = writerPoolMember.getPosition();
 		HBaseWriter hbaseWriter = (HBaseWriter) writerPoolMember;
 		try {
 			hbaseWriter.write(curi, getHostAddress(curi), curi.getRecorder().getRecordedOutput(), curi.getRecorder().getRecordedInput());
 		} finally {
 			setTotalBytesWritten(getTotalBytesWritten() + (writerPoolMember.getPosition() - writerPoolMemberPosition));
 			getPool().returnFile(writerPoolMember);
 		}
 		return checkBytesWritten(curi);
 	}
 
 	/**
 	 * Check bytes written.
 	 * 
 	 * @param context the context
 	 * 
 	 * @return the process result
 	 */
 	protected ProcessResult checkBytesWritten(StateProvider context) {
 		long max = context.get(this, TOTAL_BYTES_TO_WRITE).longValue();
 		if (max <= 0) {
 			return ProcessResult.PROCEED;
 		}
 		if (max <= this.totalBytesWritten) {
 			return ProcessResult.FINISH; // FIXME: Specify reason
 			// controller.requestCrawlStop(CrawlStatus.FINISHED_WRITE_LIMIT);
 		}
 		return ProcessResult.PROCEED;
 	}
 
 	/**
 	 * Setup pool.
 	 */
 	protected void setupPool() {
 		setPool(new HBaseWriterPool(getZKQuorum(), getZKClientPort(), getTable(), getMaxActive(), getMaxWait()));
 	}
 
 	/**
 	 * Gets the zookeeper quorum.
 	 * 
 	 * @return the zkQuorum
 	 */
 	protected String getZKQuorum() {
 		return this.zkQuorum;
 	}
 
 	/**
 	 * Gets the zookeeper client port.
 	 * 
 	 * @return the zlClientPort
 	 */
 	protected int getZKClientPort() {
 		return this.zkClientPort;
 	}
 
 	
 	/**
 	 * Gets the table.
 	 * 
 	 * @return the table
 	 */
 	protected String getTable() {
 		return this.tableName;
 	}
 
 	
 	/**
 	 * Gets the max active.
 	 * 
 	 * @return the max active
 	 */
 	protected int getMaxActive() {
 		return maxActive;
 	}
 
 	/**
 	 * Gets the max wait.
 	 * 
 	 * @return the max wait
 	 */
 	protected int getMaxWait() {
 		return maxWait;
 	}
 
 	/**
 	 * Sets the pool.
 	 * 
 	 * @param pool the new pool
 	 */
 	protected void setPool(WriterPool pool) {
 		this.pool = pool;
 	}
 
 	/**
 	 * Gets the pool.
 	 * 
 	 * @return the pool
 	 */
 	protected WriterPool getPool() {
 		return this.pool;
 	}
 
 	/**
 	 * Gets the total bytes written.
 	 * 
 	 * @return the total bytes written
 	 */
 	protected long getTotalBytesWritten() {
 		return this.totalBytesWritten;
 	}
 
 	/**
 	 * Sets the total bytes written.
 	 * 
 	 * @param b the new total bytes written
 	 */
 	protected void setTotalBytesWritten(final long b) {
 		this.totalBytesWritten = b;
 	}
 	
 	/* (non-Javadoc)
 	 * @see org.archive.modules.Processor#innerProcess(org.archive.modules.ProcessorURI)
 	 */
 	protected void innerProcess(ProcessorURI puri) {
 		throw new AssertionError();
 	}
 
 	/* (non-Javadoc)
 	 * @see java.io.Closeable#close()
 	 */
 	public void close() {
 		this.pool.close();
 	}
 
 }