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package org.imixs.workflow.documents;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;

import javax.ejb.Stateless;
import javax.enterprise.event.Observes;
import javax.inject.Inject;

import org.eclipse.microprofile.config.inject.ConfigProperty;
import org.imixs.workflow.FileData;
import org.imixs.workflow.ItemCollection;
import org.imixs.workflow.engine.ProcessingEvent;
import org.imixs.workflow.exceptions.PluginException;

/**
 * The TikaPlugin extracts the textual information from document attachments.
 * The plug-in sends each new attached document to an instance of an Apache Tika
 * Server to get the file content.
 * 

 * The plug-in expects the Environment Parameter 'TIKA_SERVICE_ENDPONT' to get
 * the Rest API end-point.
 * 

 * See also the project: https://github.com/imixs/imixs-docker/tree/master/tika
 * 
 * @version 1.0
 * @author rsoika
 */
@Stateless
public class TikaDocumentService {

	public static final String PLUGIN_ERROR = "PLUGIN_ERROR";
	public static final String ENV_TIKA_SERVICE_ENDPONT = "TIKA_SERVICE_ENDPONT";
	public static final String ENV_TIKA_SERVICE_MODE = "TIKA_SERVICE_MODE";

	private static Logger logger = Logger.getLogger(TikaDocumentService.class.getName());

	
	@Inject
	@ConfigProperty(name = ENV_TIKA_SERVICE_ENDPONT, defaultValue = "")
	String serviceEndpoint;
	
	@Inject
	@ConfigProperty(name = ENV_TIKA_SERVICE_MODE, defaultValue = "auto")
	String serviceMode;

	
	

	/**
	 * React on the ProcessingEvent This method sends the document content to the
	 * tika server and updates teh DMS information.
	 * 
	 * @throws PluginException
	 */
	public void onBeforeProcess(@Observes ProcessingEvent processingEvent) throws PluginException {
		
		if (serviceEndpoint == null || serviceEndpoint.isEmpty()) {
			return;
		}
		// read the Tika Service mode
		
		if ("auto".equalsIgnoreCase(serviceMode)) {
			if (processingEvent.getEventType() == ProcessingEvent.BEFORE_PROCESS) {
				// update the dms meta data
				extractText(processingEvent.getDocument());
			}
		}
	}

	/**
	 * Extracts the textual information from document attachments.
	 * 

	 * The method sends each new document to the tika server and updates the
	 * fileData attribute 'content'
	 * 
	 * @param workitem
	 * @throws PluginException
	 */
	public void extractText(ItemCollection workitem) throws PluginException {
		// read the Tika Service Enpoint
		
		if (serviceEndpoint == null || serviceEndpoint.isEmpty()) {
			return;
		}

		long l = System.currentTimeMillis();
		// List currentDmsList = DMSHandler.getDmsList(workitem);
		List files = workitem.getFileData();

		for (FileData fileData : files) {
			// We parse the file content if a new file content was added
			byte[] fileContent = fileData.getContent();
			// tesseract did not support any content type (e.g. application/octet-stream)
			if (acceptContentType(fileData.getContentType()) && fileContent != null && fileContent.length > 1) {
				// scan content...
				try {
					logger.info("...send " + fileData.getName() + " to tika server...");
					// RestClient restClient = new RestClient(serviceEndpoint);

					String result = put(serviceEndpoint, fileContent, fileData.getContentType(), "UTF-8");

					if (result != null && !result.isEmpty()) {
						List list = new ArrayList();
						list.add(result);
						fileData.setAttribute("content", list);
					}
				} catch (Exception e) {
					throw new PluginException(TikaDocumentService.class.getSimpleName(), PLUGIN_ERROR,
							"Unable to scan attached document '" + fileData.getName() + "'", e);
				}
			}

		}
		logger.fine("...extracted textual information in " + (System.currentTimeMillis() - l) + "ms");

	}

	/**
	 * Posts a String data object with a specific Content-Type to a Rest Service URI
	 * Endpoint. This method can be used to simulate different post scenarios.
	 * 
	 * @param uri
	 *            - Rest Endpoint RUI
	 * @param dataString
	 *            - content
	 * @return content
	 */
	public String put(String uri, byte[] dataString, String contentType, String encoding) throws Exception {
		PrintWriter printWriter = null;
		if (contentType == null || contentType.isEmpty()) {
			contentType = "application/xml";
		}

		HttpURLConnection urlConnection = null;
		try {

			urlConnection = (HttpURLConnection) new URL(uri).openConnection();
			urlConnection.setRequestMethod("PUT");
			urlConnection.setDoOutput(true);
			urlConnection.setDoInput(true);
			urlConnection.setAllowUserInteraction(false);

			/** * HEADER ** */
			urlConnection.setRequestProperty("Content-Type", contentType + "; charset=" + encoding);

			urlConnection.setRequestProperty("Accept", "text/plain");

			// compute length
			urlConnection.setRequestProperty("Content-Length", "" + Integer.valueOf(dataString.length));
			OutputStream output = urlConnection.getOutputStream();
			PrintWriter writer = new PrintWriter(new OutputStreamWriter(output, encoding), true);
			output.write(dataString);
			writer.flush();

			String sHTTPResponse = urlConnection.getHeaderField(0);
			int iLastHTTPResult = 0;

			try {
				iLastHTTPResult = Integer.parseInt(sHTTPResponse.substring(9, 12));
			} catch (Exception eNumber) {
				// eNumber.printStackTrace();
				return null;
			}

			if (iLastHTTPResult >= 200 && iLastHTTPResult <= 299) {
				return readResponse(urlConnection, encoding);
			}

			// no data!
			return null;

		} catch (Exception ioe) {
			// ioe.printStackTrace();
			throw ioe;
		} finally {
			// Release current connection
			if (printWriter != null)
				printWriter.close();
		}
	}

	/**
	 * Reads the response from a http request.
	 * 
	 * @param urlConnection
	 * @throws IOException
	 */
	private String readResponse(URLConnection urlConnection, String encoding) throws IOException {
		// get content of result
		logger.finest("......readResponse....");
		StringWriter writer = new StringWriter();
		BufferedReader in = null;
		try {
			// test if content encoding is provided
			String sContentEncoding = urlConnection.getContentEncoding();
			if (sContentEncoding == null || sContentEncoding.isEmpty()) {
				// no so lets see if the client has defined an encoding..
				if (encoding != null && !encoding.isEmpty())
					sContentEncoding = encoding;
			}

			// if an encoding is provided read stream with encoding.....
			if (sContentEncoding != null && !sContentEncoding.isEmpty())
				in = new BufferedReader(new InputStreamReader(urlConnection.getInputStream(), sContentEncoding));
			else
				in = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
			String inputLine;
			while ((inputLine = in.readLine()) != null) {
				logger.finest("......" + inputLine);
				writer.write(inputLine);
			}
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if (in != null)
				in.close();
		}

		return writer.toString();

	}

	

	/**
	 * Tika does not support any content type. So we filter some of them (e.g.
	 * application/octet-stream).
	 * 
	 * @param contentType
	 * @return
	 */
	private boolean acceptContentType(String contentType) {

		if (contentType==null || contentType.isEmpty()) {
			return false;
		}
		if ("application/octet-stream".equalsIgnoreCase(contentType)) {
			return false;
		}
		
		return true;
	}

}    

    

    

            

    

            



    
    






    
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