src/main/java/org/apache/sling/feature/io/artifacts/ArtifactManager.java - sling-org-apache-sling-feature - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements. See the NOTICE file distributed with this
  * work for additional information regarding copyright ownership. The ASF
  * licenses this file to You 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 org.apache.sling.feature.io.artifacts;

 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.OutputStream;
 import java.io.Reader;
 import java.lang.ProcessBuilder.Redirect;
 import java.net.MalformedURLException;
 import java.net.URISyntaxException;
 import java.net.URL;
 import java.net.URLConnection;
 import java.nio.charset.Charset;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Base64;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.ServiceLoader;

 import org.apache.sling.feature.ArtifactId;
 import org.apache.sling.feature.Feature;
 import org.apache.sling.feature.builder.FeatureProvider;
 import org.apache.sling.feature.io.artifacts.spi.ArtifactProvider;
 import org.apache.sling.feature.io.artifacts.spi.ArtifactProviderContext;
 import org.apache.sling.feature.io.json.FeatureJSONReader;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

 /**
  * The artifact manager is the central service to get artifacts.
  * It uses {@link ArtifactProvider}s to get artifacts. The
  * providers are loaded using the service loader.
  */
 public class ArtifactManager
         implements AutoCloseable, org.apache.sling.feature.builder.ArtifactProvider {

     private final Logger logger = LoggerFactory.getLogger(this.getClass());

     /** The map of providers. */
     private final Map<String, ArtifactProvider> providers;

     /** The configuration */
     private final ArtifactManagerConfig config;

     /**
      * Get an artifact manager based on the configuration
      * @param config The configuration
      * @return The artifact manager
      * @throws IOException If the manager can't be initialized
      */
     public static ArtifactManager getArtifactManager(final ArtifactManagerConfig config) throws IOException {
         final ServiceLoader<ArtifactProvider> loader = ServiceLoader.load(ArtifactProvider.class);
         final Map<String, ArtifactProvider> providers = new HashMap<>();
         for(final ArtifactProvider provider : loader) {
             providers.put(provider.getProtocol(), provider);
         }

         final String[] repositoryURLs = new String[config.getRepositoryUrls().length];
         int index = 0;
         for(final String urlString : config.getRepositoryUrls()) {
             repositoryURLs[index] = urlString;
             index++;
         }
         // default
         if ( !providers.containsKey("*") ) {
             providers.put("*", new DefaultArtifactHandler());
         }

         return new ArtifactManager(config, providers);
     }

     /**
      * Internal constructor for the manager
      * @param config The configuration
      * @param providers The provider map
      * @throws IOException If the manager can't be initialized
      */
     ArtifactManager(final ArtifactManagerConfig config, final Map<String, ArtifactProvider> providers)
     throws IOException {
         this.config = config;
         this.providers = providers;
         try {
             for(final ArtifactProvider provider : this.providers.values()) {
                 provider.init(config);
             }
         } catch (final IOException io) {
             try {
                 close();
             } catch (IOException ioeDuringClose) {
                 io.addSuppressed(ioeDuringClose);
             }
             throw io;
         }
     }

     /**
      * Shutdown the artifact manager.
      * @deprecated Use {@link #close()} instead.
      */
     @Deprecated
     public void shutdown() {
         try {
             close();
         } catch (IOException e) {
             logger.warn("Error shutting down ArtifactManager", e);
         }
     }

     /**
      * Shutdown the artifact manager.
      * @throws IOException
      */
     @Override
     public void close() throws IOException {
         IOException e = null;
         for(final ArtifactProvider provider : this.providers.values()) {
             try {
                 provider.close();
             } catch (IOException ioe) {
                 if (e == null) {
                     e = new IOException("Could not close one or more providers. Look at suppressed exceptions for the underlying exceptions");
                 }
                 e.addSuppressed(ioe);
             }
         }
         this.providers.clear();
         if (e != null) {
             throw e;
         }
     }

     @Override
     public URL provide(final ArtifactId id) {
         try {
             final ArtifactHandler handler = this.getArtifactHandler(id.toMvnUrl());
             return handler.getLocalURL();
         } catch (final IOException e) {
             // ignore
             return null;
         }
     }

     /**
      * Return a feature provider based on this artifact manager
      *
      * @return A feature provider
      * @since 1.1.0
      */
     public FeatureProvider toFeatureProvider() {
         return (id -> {
             try {
                 final ArtifactHandler handler = this.getArtifactHandler(id.toMvnUrl());
                 try (final Reader r = new InputStreamReader(handler.getLocalURL().openStream(), "UTF-8")) {
                     final Feature f = FeatureJSONReader.read(r, handler.getUrl());
                     return f;
                 }
             } catch (final IOException e) {
                 // ignore
                 return null;
             }
         });
     }

     private final URL getArtifactFromProviders(final String url, final String relativeCachePath) throws IOException {
         final int pos = url.indexOf(":");
         final String scheme = url.substring(0, pos);

         ArtifactProvider provider = this.providers.get(scheme);
         if ( provider == null ) {
             provider = this.providers.get("*");
         }
         if ( provider == null ) {
             throw new IOException("No URL provider found for " + url);
         }
         return provider.getArtifact(url, relativeCachePath);
     }

     /**
      * Get the full artifact url and file for an artifact.
      *
      * @param url Artifact url or relative path.
      * @return Absolute url and file in the form of a handler.
      * @throws IOException If something goes wrong or the artifact can't be found.
      */
     public ArtifactHandler getArtifactHandler(final String url) throws IOException {
         logger.debug("Trying to get artifact for {}", url);

         final String path;

         ArtifactId artifactId = null;

         if ( url.startsWith("mvn:") ) {
             // mvn url
             try {
                 artifactId = ArtifactId.fromMvnUrl(url);
                 path = artifactId.toMvnPath();
             } catch (final IllegalArgumentException iae) {
                 throw new IOException(iae.getMessage(), iae);
             }
         } else if ( url.startsWith(":") ) {
             // repository path
             path = url.substring(1);

         } else if ( url.indexOf(":/") > 0 ) {

             // absolute URL
             int pos = url.indexOf(":/") + 2;
             while ( url.charAt(pos) == '/') {
                 pos++;
             }
             final URL file = this.getArtifactFromProviders(url, url.substring(pos));
             if ( file == null ) {
                 throw new IOException("Artifact " + url + " not found.");
             }
             return new ArtifactHandler(url, file);

         } else {
             // file (either relative or absolute)
             final File f = new File(url);
             if ( !f.exists()) {
                 throw new IOException("Artifact " + url + " not found.");
             }
             return new ArtifactHandler(f);
         }
         logger.debug("Querying repositories for {}", path);

         for(final String repoUrl : this.config.getRepositoryUrls()) {
             final StringBuilder builder = new StringBuilder();
             builder.append(repoUrl);
             builder.append('/');
             builder.append(path);

             final String artifactUrl = builder.toString();
             final int pos = artifactUrl.indexOf(":");
             final String scheme = artifactUrl.substring(0, pos);

             ArtifactProvider handler = this.providers.get(scheme);
             if ( handler == null ) {
                 handler = this.providers.get("*");
             }
             if ( handler == null ) {
                 throw new IOException("No URL handler found for " + artifactUrl);
             }

             logger.debug("Checking {} to get artifact from {}", handler, artifactUrl);

             final URL file = handler.getArtifact(artifactUrl, path);
             if ( file != null ) {
                 logger.debug("Found artifact {}", artifactUrl);
                 return new ArtifactHandler(artifactUrl, file);
             }

             // check for SNAPSHOT
             final int lastSlash = artifactUrl.lastIndexOf('/');
             final int startSnapshot = artifactUrl.indexOf("-SNAPSHOT", lastSlash + 1);

             if ( startSnapshot > -1 ) {
                 // special snapshot handling
                 final String metadataUrl = artifactUrl.substring(0, lastSlash) + "/maven-metadata.xml";
                 try {
                     final ArtifactHandler metadataHandler = this.getArtifactHandler(metadataUrl);

                     final String contents = getFileContents(metadataHandler);

                     final String latestVersion = getLatestSnapshot(contents);
                     if ( latestVersion != null ) {
                         final String name = artifactUrl.substring(lastSlash); // includes slash
                         final String fullURL = artifactUrl.substring(0, lastSlash) + name.replace("SNAPSHOT", latestVersion);
                         int pos2 = fullURL.indexOf(":/") + 2;
                         while ( fullURL.charAt(pos2) == '/') {
                             pos2++;
                         }
                         final URL file2 = this.getArtifactFromProviders(fullURL, path);
                         if ( file2 == null ) {
                             throw new IOException("Artifact " + fullURL + " not found.");
                         }
                         return new ArtifactHandler(artifactUrl, file2);
                     }
                 } catch ( final IOException ignore ) {
                     // we ignore this but report the original 404
                 }
             }
         }

         // if we have an artifact id and using mvn is enabled, we try this as a last
         // resort
         if (artifactId != null && this.config.isUseMvn()) {
             final File file = getArtifactFromMvn(artifactId);
             if (file != null) {
                 return new ArtifactHandler(file);
             }
         }
         throw new IOException("Artifact " + url + " not found in any repository.");
     }

     protected String getFileContents(final ArtifactHandler handler) throws IOException {
         final StringBuilder sb = new StringBuilder();
         try (BufferedReader reader = new BufferedReader(new InputStreamReader(handler.getLocalURL().openStream(), "UTF-8"))) {
             for(String line = reader.readLine(); line != null; line = reader.readLine()) {
                 sb.append(line).append('\n');
             }
         }

         return sb.toString();
     }

     public static String getValue(final String xml, final String[] xpath) {
         String value = null;
         int pos = 0;
         for(final String name : xpath) {
             final String element = '<' + name + '>';

             pos = xml.indexOf(element, pos);
             if ( pos == -1 ) {
                 final String elementWithAttributes = '<' + name + ' ';
                 pos = xml.indexOf(elementWithAttributes, pos);
                 if ( pos == -1 ) {
                     break;
                 }
             }
             pos = xml.indexOf('>', pos) + 1;
         }
         if ( pos != -1 ) {
             final int endPos = xml.indexOf("</", pos);
             if ( endPos != -1 ) {
                 value = xml.substring(pos, endPos).trim();
             }
         }
         return value;
     }

     public static String getLatestSnapshot(final String mavenMetadata) {
         final String timestamp = getValue(mavenMetadata, new String[] {"metadata", "versioning", "snapshot", "timestamp"});
         final String buildNumber = getValue(mavenMetadata, new String[] {"metadata", "versioning", "snapshot", "buildNumber"});

         if ( timestamp != null && buildNumber != null ) {
             return timestamp + '-' + buildNumber;
         }

         return null;
     }

     private static final class DefaultArtifactHandler implements ArtifactProvider {

         private final Logger logger = LoggerFactory.getLogger(this.getClass());

         private File cacheDir;

         private ArtifactProviderContext config;

         @Override
         public String getProtocol() {
             return "*";
         }

         @Override
         public void init(final ArtifactProviderContext config) throws IOException {
             this.cacheDir = config.getCacheDirectory();
             this.config = config;
         }

         @Override
         public void close() {
             this.config = null;
             this.cacheDir = null;
         }

         @Override
         public URL getArtifact(final String url, final String relativeCachePath) {
             logger.debug("Checking url to be local file {}", url);
             // check if this is already a local file
             try {
                 final File f = new File(new URL(url).toURI());
                 if (f.exists()) {
                     this.config.incLocalArtifacts();
                     return f.toURI().toURL();
                 }
                 return null;
             } catch ( final URISyntaxException ise) {
                 // ignore
             } catch ( final IllegalArgumentException iae) {
                 // ignore
             } catch ( final MalformedURLException mue) {
                 // ignore
             }
             logger.debug("Checking remote url {}", url);
             try {
                 // check for url
                 if ( url.indexOf(":") == -1 ) {
                     return null;
                 }

                 String adjustedRelativePath = relativeCachePath;
                 // For Windows we need to remove the drive name from the path
                 int pos = adjustedRelativePath.indexOf(":/");
                 if(pos >= 0) {
                     adjustedRelativePath = adjustedRelativePath.substring(pos + 2);
                 }
                 final String filePath = (this.cacheDir.getAbsolutePath() + File.separatorChar + adjustedRelativePath).replace('/', File.separatorChar);
                 final File cacheFile = new File(filePath);

                 if ( !cacheFile.exists() ) {
                     cacheFile.getParentFile().mkdirs();
                     final URL u = new URL(url);
                     final URLConnection con = u.openConnection();
                     final String userInfo = u.getUserInfo();
                     if (userInfo != null) {
                         con.addRequestProperty("Authorization", "Basic " + Base64.getEncoder().encodeToString(u.toURI().getUserInfo().getBytes("UTF-8")));
                     }
                     con.connect();

                     final InputStream readIS = con.getInputStream();
                     try {
                         copyFileContent(readIS, cacheFile, 32768);
                     } catch(IOException e) {
                         //TODO: Remove this logging statement when it settled down
                         logger.debug("Failed to copy file", e);
                         throw e;
                     }
                     this.config.incDownloadedArtifacts();
                 } else {
                     this.config.incCachedArtifacts();
                 }
                 return cacheFile.toURI().toURL();
             } catch ( final FileNotFoundException e) {
                 logger.trace("File not found here (keep on looking): '{}'", url);
                 // Do not report if the file does not exist as we cycle through the various sources
                 return null;
             } catch ( final Exception e) {
                 logger.info("Artifact not found in one repository", e);
                 // ignore for now
                 return null;
             }
         }

         @Override
         public String toString() {
             return "DefaultArtifactHandler";
         }

         private void copyFileContent(InputStream readIS, File cacheFile, int bufferSize) throws IOException {
             final byte[] buffer = new byte[bufferSize];
             int l;
             OutputStream os = null;
             try {
                 os = new FileOutputStream(cacheFile);
                 while ( (l = readIS.read(buffer)) >= 0 ) {
                     os.write(buffer, 0, l);
                 }
             } finally {
                 try {
                     readIS.close();
                 } catch ( final IOException ignore) {
                     // ignore
                 }
                 if ( os != null ) {
                     try {
                         os.close();
                     } catch ( final IOException ignore ) {
                         // ignore
                     }
                 }
             }
         }
     }

     private File getArtifactFromMvn(final ArtifactId artifactId) {
         final String filePath = this.config.getMvnHome()
                 .concat(artifactId.toMvnPath().replace('/', File.separatorChar));
         logger.debug("Trying to fetch artifact {} from local mvn repository {}", artifactId.toMvnId(), filePath);
         final File f = new File(filePath);
         if (!f.exists() || !f.isFile() || !f.canRead()) {
             logger.debug("Trying to download {}", artifactId.toMvnId());
             try {
                 this.downloadArtifact(artifactId);
             } catch (final IOException ioe) {
                 logger.debug("Error downloading file.", ioe);
             }
             if (!f.exists() || !f.isFile() || !f.canRead()) {
                 logger.info("Artifact not found {}", artifactId.toMvnId());

                 return null;
             }
         }
         return f;
     }

     /**
      * Download artifact from maven
      *
      * @throws IOException
      */
     private void downloadArtifact(final ArtifactId artifactId) throws IOException {
         // create fake pom
         final Path dir = Files.createTempDirectory(null);
         try {
             final List<String> lines = new ArrayList<String>();
             lines.add(
                     "<project xmlns=\"http://maven.apache.org/POM/4.0.0\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:schemaLocation=\"http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd\">");
             lines.add("    <modelVersion>4.0.0</modelVersion>");
             lines.add("    <groupId>org.apache.sling</groupId>");
             lines.add("    <artifactId>temp-artifact</artifactId>");
             lines.add("    <version>1-SNAPSHOT</version>");
             lines.add("    <dependencies>");
             lines.add("        <dependency>");
             lines.add("            <groupId>".concat(artifactId.getGroupId()).concat("</groupId>"));
             lines.add("            <artifactId>".concat(artifactId.getArtifactId()).concat("</artifactId>"));
             lines.add("            <version>".concat(artifactId.getVersion()).concat("</version>"));
             if (artifactId.getClassifier() != null) {
                 lines.add("            <classifier>".concat(artifactId.getClassifier()).concat("</classifier>"));
             }
             if (!"bundle".equals(artifactId.getType()) && !"jar".equals(artifactId.getType())) {
                 lines.add("            <type>".concat(artifactId.getType()).concat("</type>"));
             }
             lines.add("            <scope>provided</scope>");
             lines.add("        </dependency>");
             lines.add("    </dependencies>");
             lines.add("</project>");
             logger.debug("Writing pom to {}", dir);
             Files.write(dir.resolve("pom.xml"), lines, Charset.forName("UTF-8"));

             final File output = dir.resolve("output.txt").toFile();
             final File error = dir.resolve("error.txt").toFile();

             // invoke maven
             logger.debug("Invoking mvn...");
             final ProcessBuilder pb = new ProcessBuilder("mvn", "verify");
             pb.directory(dir.toFile());
             pb.redirectOutput(Redirect.to(output));
             pb.redirectError(Redirect.to(error));

             final Process p = pb.start();
             try {
                 p.waitFor();
             } catch (final InterruptedException e) {
                 Thread.currentThread().interrupt();
             }

         } finally {
             Files.walk(dir).sorted(Comparator.reverseOrder()).map(Path::toFile).forEach(File::delete);
         }
     }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with this
	* work for additional information regarding copyright ownership. The ASF
	* licenses this file to You 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 org.apache.sling.feature.io.artifacts;

	import java.io.BufferedReader;
	import java.io.File;
	import java.io.FileNotFoundException;
	import java.io.FileOutputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.InputStreamReader;
	import java.io.OutputStream;
	import java.io.Reader;
	import java.lang.ProcessBuilder.Redirect;
	import java.net.MalformedURLException;
	import java.net.URISyntaxException;
	import java.net.URL;
	import java.net.URLConnection;
	import java.nio.charset.Charset;
	import java.nio.file.Files;
	import java.nio.file.Path;
	import java.util.ArrayList;
	import java.util.Base64;
	import java.util.Comparator;
	import java.util.HashMap;
	import java.util.List;
	import java.util.Map;
	import java.util.ServiceLoader;

	import org.apache.sling.feature.ArtifactId;
	import org.apache.sling.feature.Feature;
	import org.apache.sling.feature.builder.FeatureProvider;
	import org.apache.sling.feature.io.artifacts.spi.ArtifactProvider;
	import org.apache.sling.feature.io.artifacts.spi.ArtifactProviderContext;
	import org.apache.sling.feature.io.json.FeatureJSONReader;
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;

	/**
	* The artifact manager is the central service to get artifacts.
	* It uses {@link ArtifactProvider}s to get artifacts. The
	* providers are loaded using the service loader.
	*/
	public class ArtifactManager
	implements AutoCloseable, org.apache.sling.feature.builder.ArtifactProvider {

	private final Logger logger = LoggerFactory.getLogger(this.getClass());

	/** The map of providers. */
	private final Map<String, ArtifactProvider> providers;

	/** The configuration */
	private final ArtifactManagerConfig config;

	/**
	* Get an artifact manager based on the configuration
	* @param config The configuration
	* @return The artifact manager
	* @throws IOException If the manager can't be initialized
	*/
	public static ArtifactManager getArtifactManager(final ArtifactManagerConfig config) throws IOException {
	final ServiceLoader<ArtifactProvider> loader = ServiceLoader.load(ArtifactProvider.class);
	final Map<String, ArtifactProvider> providers = new HashMap<>();
	for(final ArtifactProvider provider : loader) {
	providers.put(provider.getProtocol(), provider);
	}

	final String[] repositoryURLs = new String[config.getRepositoryUrls().length];
	int index = 0;
	for(final String urlString : config.getRepositoryUrls()) {
	repositoryURLs[index] = urlString;
	index++;
	}
	// default
	if ( !providers.containsKey("*") ) {
	providers.put("*", new DefaultArtifactHandler());
	}

	return new ArtifactManager(config, providers);
	}

	/**
	* Internal constructor for the manager
	* @param config The configuration
	* @param providers The provider map
	* @throws IOException If the manager can't be initialized
	*/
	ArtifactManager(final ArtifactManagerConfig config, final Map<String, ArtifactProvider> providers)
	throws IOException {
	this.config = config;
	this.providers = providers;
	try {
	for(final ArtifactProvider provider : this.providers.values()) {
	provider.init(config);
	}
	} catch (final IOException io) {
	try {
	close();
	} catch (IOException ioeDuringClose) {
	io.addSuppressed(ioeDuringClose);
	}
	throw io;
	}
	}

	/**
	* Shutdown the artifact manager.
	* @deprecated Use {@link #close()} instead.
	*/
	@Deprecated
	public void shutdown() {
	try {
	close();
	} catch (IOException e) {
	logger.warn("Error shutting down ArtifactManager", e);
	}
	}

	/**
	* Shutdown the artifact manager.
	* @throws IOException
	*/
	@Override
	public void close() throws IOException {
	IOException e = null;
	for(final ArtifactProvider provider : this.providers.values()) {
	try {
	provider.close();
	} catch (IOException ioe) {
	if (e == null) {
	e = new IOException("Could not close one or more providers. Look at suppressed exceptions for the underlying exceptions");
	}
	e.addSuppressed(ioe);
	}
	}
	this.providers.clear();
	if (e != null) {
	throw e;
	}
	}

	@Override
	public URL provide(final ArtifactId id) {
	try {
	final ArtifactHandler handler = this.getArtifactHandler(id.toMvnUrl());
	return handler.getLocalURL();
	} catch (final IOException e) {
	// ignore
	return null;
	}
	}

	/**
	* Return a feature provider based on this artifact manager
	*
	* @return A feature provider
	* @since 1.1.0
	*/
	public FeatureProvider toFeatureProvider() {
	return (id -> {
	try {
	final ArtifactHandler handler = this.getArtifactHandler(id.toMvnUrl());
	try (final Reader r = new InputStreamReader(handler.getLocalURL().openStream(), "UTF-8")) {
	final Feature f = FeatureJSONReader.read(r, handler.getUrl());
	return f;
	}
	} catch (final IOException e) {
	// ignore
	return null;
	}
	});
	}

	private final URL getArtifactFromProviders(final String url, final String relativeCachePath) throws IOException {
	final int pos = url.indexOf(":");
	final String scheme = url.substring(0, pos);

	ArtifactProvider provider = this.providers.get(scheme);
	if ( provider == null ) {
	provider = this.providers.get("*");
	}
	if ( provider == null ) {
	throw new IOException("No URL provider found for " + url);
	}
	return provider.getArtifact(url, relativeCachePath);
	}

	/**
	* Get the full artifact url and file for an artifact.
	*
	* @param url Artifact url or relative path.
	* @return Absolute url and file in the form of a handler.
	* @throws IOException If something goes wrong or the artifact can't be found.
	*/
	public ArtifactHandler getArtifactHandler(final String url) throws IOException {
	logger.debug("Trying to get artifact for {}", url);

	final String path;

	ArtifactId artifactId = null;

	if ( url.startsWith("mvn:") ) {
	// mvn url
	try {
	artifactId = ArtifactId.fromMvnUrl(url);
	path = artifactId.toMvnPath();
	} catch (final IllegalArgumentException iae) {
	throw new IOException(iae.getMessage(), iae);
	}
	} else if ( url.startsWith(":") ) {
	// repository path
	path = url.substring(1);

	} else if ( url.indexOf(":/") > 0 ) {

	// absolute URL
	int pos = url.indexOf(":/") + 2;
	while ( url.charAt(pos) == '/') {
	pos++;
	}
	final URL file = this.getArtifactFromProviders(url, url.substring(pos));
	if ( file == null ) {
	throw new IOException("Artifact " + url + " not found.");
	}
	return new ArtifactHandler(url, file);

	} else {
	// file (either relative or absolute)
	final File f = new File(url);
	if ( !f.exists()) {
	throw new IOException("Artifact " + url + " not found.");
	}
	return new ArtifactHandler(f);
	}
	logger.debug("Querying repositories for {}", path);

	for(final String repoUrl : this.config.getRepositoryUrls()) {
	final StringBuilder builder = new StringBuilder();
	builder.append(repoUrl);
	builder.append('/');
	builder.append(path);

	final String artifactUrl = builder.toString();
	final int pos = artifactUrl.indexOf(":");
	final String scheme = artifactUrl.substring(0, pos);

	ArtifactProvider handler = this.providers.get(scheme);
	if ( handler == null ) {
	handler = this.providers.get("*");
	}
	if ( handler == null ) {
	throw new IOException("No URL handler found for " + artifactUrl);
	}

	logger.debug("Checking {} to get artifact from {}", handler, artifactUrl);

	final URL file = handler.getArtifact(artifactUrl, path);
	if ( file != null ) {
	logger.debug("Found artifact {}", artifactUrl);
	return new ArtifactHandler(artifactUrl, file);
	}

	// check for SNAPSHOT
	final int lastSlash = artifactUrl.lastIndexOf('/');
	final int startSnapshot = artifactUrl.indexOf("-SNAPSHOT", lastSlash + 1);

	if ( startSnapshot > -1 ) {
	// special snapshot handling
	final String metadataUrl = artifactUrl.substring(0, lastSlash) + "/maven-metadata.xml";
	try {
	final ArtifactHandler metadataHandler = this.getArtifactHandler(metadataUrl);

	final String contents = getFileContents(metadataHandler);

	final String latestVersion = getLatestSnapshot(contents);
	if ( latestVersion != null ) {
	final String name = artifactUrl.substring(lastSlash); // includes slash
	final String fullURL = artifactUrl.substring(0, lastSlash) + name.replace("SNAPSHOT", latestVersion);
	int pos2 = fullURL.indexOf(":/") + 2;
	while ( fullURL.charAt(pos2) == '/') {
	pos2++;
	}
	final URL file2 = this.getArtifactFromProviders(fullURL, path);
	if ( file2 == null ) {
	throw new IOException("Artifact " + fullURL + " not found.");
	}
	return new ArtifactHandler(artifactUrl, file2);
	}
	} catch ( final IOException ignore ) {
	// we ignore this but report the original 404
	}
	}
	}

	// if we have an artifact id and using mvn is enabled, we try this as a last
	// resort
	if (artifactId != null && this.config.isUseMvn()) {
	final File file = getArtifactFromMvn(artifactId);
	if (file != null) {
	return new ArtifactHandler(file);
	}
	}
	throw new IOException("Artifact " + url + " not found in any repository.");
	}

	protected String getFileContents(final ArtifactHandler handler) throws IOException {
	final StringBuilder sb = new StringBuilder();
	try (BufferedReader reader = new BufferedReader(new InputStreamReader(handler.getLocalURL().openStream(), "UTF-8"))) {
	for(String line = reader.readLine(); line != null; line = reader.readLine()) {
	sb.append(line).append('\n');
	}
	}

	return sb.toString();
	}

	public static String getValue(final String xml, final String[] xpath) {
	String value = null;
	int pos = 0;
	for(final String name : xpath) {
	final String element = '<' + name + '>';

	pos = xml.indexOf(element, pos);
	if ( pos == -1 ) {
	final String elementWithAttributes = '<' + name + ' ';
	pos = xml.indexOf(elementWithAttributes, pos);
	if ( pos == -1 ) {
	break;
	}
	}
	pos = xml.indexOf('>', pos) + 1;
	}
	if ( pos != -1 ) {
	final int endPos = xml.indexOf("</", pos);
	if ( endPos != -1 ) {
	value = xml.substring(pos, endPos).trim();
	}
	}
	return value;
	}

	public static String getLatestSnapshot(final String mavenMetadata) {
	final String timestamp = getValue(mavenMetadata, new String[] {"metadata", "versioning", "snapshot", "timestamp"});
	final String buildNumber = getValue(mavenMetadata, new String[] {"metadata", "versioning", "snapshot", "buildNumber"});

	if ( timestamp != null && buildNumber != null ) {
	return timestamp + '-' + buildNumber;
	}

	return null;
	}

	private static final class DefaultArtifactHandler implements ArtifactProvider {

	private final Logger logger = LoggerFactory.getLogger(this.getClass());

	private File cacheDir;

	private ArtifactProviderContext config;

	@Override
	public String getProtocol() {
	return "*";
	}

	@Override
	public void init(final ArtifactProviderContext config) throws IOException {
	this.cacheDir = config.getCacheDirectory();
	this.config = config;
	}

	@Override
	public void close() {
	this.config = null;
	this.cacheDir = null;
	}

	@Override
	public URL getArtifact(final String url, final String relativeCachePath) {
	logger.debug("Checking url to be local file {}", url);
	// check if this is already a local file
	try {
	final File f = new File(new URL(url).toURI());
	if (f.exists()) {
	this.config.incLocalArtifacts();
	return f.toURI().toURL();
	}
	return null;
	} catch ( final URISyntaxException ise) {
	// ignore
	} catch ( final IllegalArgumentException iae) {
	// ignore
	} catch ( final MalformedURLException mue) {
	// ignore
	}
	logger.debug("Checking remote url {}", url);
	try {
	// check for url
	if ( url.indexOf(":") == -1 ) {
	return null;
	}

	String adjustedRelativePath = relativeCachePath;
	// For Windows we need to remove the drive name from the path
	int pos = adjustedRelativePath.indexOf(":/");
	if(pos >= 0) {
	adjustedRelativePath = adjustedRelativePath.substring(pos + 2);
	}
	final String filePath = (this.cacheDir.getAbsolutePath() + File.separatorChar + adjustedRelativePath).replace('/', File.separatorChar);
	final File cacheFile = new File(filePath);

	if ( !cacheFile.exists() ) {
	cacheFile.getParentFile().mkdirs();
	final URL u = new URL(url);
	final URLConnection con = u.openConnection();
	final String userInfo = u.getUserInfo();
	if (userInfo != null) {
	con.addRequestProperty("Authorization", "Basic " + Base64.getEncoder().encodeToString(u.toURI().getUserInfo().getBytes("UTF-8")));
	}
	con.connect();

	final InputStream readIS = con.getInputStream();
	try {
	copyFileContent(readIS, cacheFile, 32768);
	} catch(IOException e) {
	//TODO: Remove this logging statement when it settled down
	logger.debug("Failed to copy file", e);
	throw e;
	}
	this.config.incDownloadedArtifacts();
	} else {
	this.config.incCachedArtifacts();
	}
	return cacheFile.toURI().toURL();
	} catch ( final FileNotFoundException e) {
	logger.trace("File not found here (keep on looking): '{}'", url);
	// Do not report if the file does not exist as we cycle through the various sources
	return null;
	} catch ( final Exception e) {
	logger.info("Artifact not found in one repository", e);
	// ignore for now
	return null;
	}
	}

	@Override
	public String toString() {
	return "DefaultArtifactHandler";
	}

	private void copyFileContent(InputStream readIS, File cacheFile, int bufferSize) throws IOException {
	final byte[] buffer = new byte[bufferSize];
	int l;
	OutputStream os = null;
	try {
	os = new FileOutputStream(cacheFile);
	while ( (l = readIS.read(buffer)) >= 0 ) {
	os.write(buffer, 0, l);
	}
	} finally {
	try {
	readIS.close();
	} catch ( final IOException ignore) {
	// ignore
	}
	if ( os != null ) {
	try {
	os.close();
	} catch ( final IOException ignore ) {
	// ignore
	}
	}
	}
	}
	}

	private File getArtifactFromMvn(final ArtifactId artifactId) {
	final String filePath = this.config.getMvnHome()
	.concat(artifactId.toMvnPath().replace('/', File.separatorChar));
	logger.debug("Trying to fetch artifact {} from local mvn repository {}", artifactId.toMvnId(), filePath);
	final File f = new File(filePath);
	if (!f.exists() \|\| !f.isFile() \|\| !f.canRead()) {
	logger.debug("Trying to download {}", artifactId.toMvnId());
	try {
	this.downloadArtifact(artifactId);
	} catch (final IOException ioe) {
	logger.debug("Error downloading file.", ioe);
	}
	if (!f.exists() \|\| !f.isFile() \|\| !f.canRead()) {
	logger.info("Artifact not found {}", artifactId.toMvnId());

	return null;
	}
	}
	return f;
	}

	/**
	* Download artifact from maven
	*
	* @throws IOException
	*/
	private void downloadArtifact(final ArtifactId artifactId) throws IOException {
	// create fake pom
	final Path dir = Files.createTempDirectory(null);
	try {
	final List<String> lines = new ArrayList<String>();
	lines.add(
	"<project xmlns=\"http://maven.apache.org/POM/4.0.0\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:schemaLocation=\"http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd\">");
	lines.add(" <modelVersion>4.0.0</modelVersion>");
	lines.add(" <groupId>org.apache.sling</groupId>");
	lines.add(" <artifactId>temp-artifact</artifactId>");
	lines.add(" <version>1-SNAPSHOT</version>");
	lines.add(" <dependencies>");
	lines.add(" <dependency>");
	lines.add(" <groupId>".concat(artifactId.getGroupId()).concat("</groupId>"));
	lines.add(" <artifactId>".concat(artifactId.getArtifactId()).concat("</artifactId>"));
	lines.add(" <version>".concat(artifactId.getVersion()).concat("</version>"));
	if (artifactId.getClassifier() != null) {
	lines.add(" <classifier>".concat(artifactId.getClassifier()).concat("</classifier>"));
	}
	if (!"bundle".equals(artifactId.getType()) && !"jar".equals(artifactId.getType())) {
	lines.add(" <type>".concat(artifactId.getType()).concat("</type>"));
	}
	lines.add(" <scope>provided</scope>");
	lines.add(" </dependency>");
	lines.add(" </dependencies>");
	lines.add("</project>");
	logger.debug("Writing pom to {}", dir);
	Files.write(dir.resolve("pom.xml"), lines, Charset.forName("UTF-8"));

	final File output = dir.resolve("output.txt").toFile();
	final File error = dir.resolve("error.txt").toFile();

	// invoke maven
	logger.debug("Invoking mvn...");
	final ProcessBuilder pb = new ProcessBuilder("mvn", "verify");
	pb.directory(dir.toFile());
	pb.redirectOutput(Redirect.to(output));
	pb.redirectError(Redirect.to(error));

	final Process p = pb.start();
	try {
	p.waitFor();
	} catch (final InterruptedException e) {
	Thread.currentThread().interrupt();
	}

	} finally {
	Files.walk(dir).sorted(Comparator.reverseOrder()).map(Path::toFile).forEach(File::delete);
	}
	}
	}