webcommon/javascript.cdnjs/src/org/netbeans/modules/javascript/cdnjs/LibraryProvider.java - netbeans - 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.netbeans.modules.javascript.cdnjs;

 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.OutputStream;
 import java.io.UnsupportedEncodingException;
 import java.lang.ref.WeakReference;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLConnection;
 import java.net.URLEncoder;
 import java.text.MessageFormat;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Objects;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import org.json.simple.JSONArray;
 import org.json.simple.JSONObject;
 import org.json.simple.parser.JSONParser;
 import org.json.simple.parser.ParseException;
 import org.openide.filesystems.FileUtil;
 import org.openide.util.Pair;

 /**
  * CDNJS library provider, i.e., provider of the libraries available
  * on https://cdnjs.com/ server.
  *
  * The clients of this provider are expected to use {@link #findLibraries}
  * method to search libraries matching given search term. The search
  * for the libraries is performed asynchronously. Hence, this method
  * returns {@code null} when it is called for the first time for the given
  * search term. The clients should register property change listeners
  * on the provider to be notified when the result of the search is available.
  * The property change events fired by the provider will have the property
  * name set to the search term and the new value to the result of the search.
  * The new value may be set to {@code null} when the search failed for
  * some reason (the new value is set to an empty array when the result
  * of the search is empty).
  *
  * @author Jan Stola
  */
 public final class LibraryProvider {
     /** Name of the 'versions' property. */
     private static final String PROPERTY_VERSIONS = "assets"; // NOI18N
     /** Name of the 'version name' property. */
     private static final String PROPERTY_VERSION_NAME = "version"; // NOI18N
     /** Name of the 'files' property. */
     private static final String PROPERTY_FILES = "files"; // NOI18N
     /** Name of the 'file name' property. */
     private static final String PROPERTY_FILE_NAME = "name"; // NOI18N
     /** Name of the 'result' property. */
     private static final String PROPERTY_RESULT = "results"; // NOI18N
     /** Name of the 'name' property. */
     private static final String PROPERTY_NAME = "name"; // NOI18N
     /** Name of the 'description' property. */
     private static final String PROPERTY_DESCRIPTION = "description"; // NOI18N
     /** Name of the 'homepage' property. */
     private static final String PROPERTY_HOMEPAGE = "homepage"; // NOI18N

     /** The only instance of this provider. */
     private static final LibraryProvider INSTANCE = new LibraryProvider();
     /** Cache of the search results. It maps the search term to the search result. */
     private final Map<String,WeakReference<Library[]>> cache =
             Collections.synchronizedMap(new HashMap<>());
     private final Map<String,WeakReference<Library>> entryCache =
             Collections.synchronizedMap(new HashMap<>());

     /**
      * Creates a new {@code LibraryProvider}.
      */
     private LibraryProvider() {
     }

     /**
      * Returns the only instance of this class.
      *
      * @return (the only) instance of this class.
      */
     public static LibraryProvider getInstance() {
         return INSTANCE;
     }

     /**
      * Finds the libraries matching the given search term. The resulting
      * {@code Library} instances potentially don't have the versions property
      * set. If that is the case the Library needs to be updated with the
      * {@link #updateLibraryVersions} call.
      *
      * @param searchTerm search term.
      * otherwise.
      */
     public Library[] findLibraries(String searchTerm) {
         WeakReference<Library[]> reference = cache.get(searchTerm);
         Library[] result = null;
         if (reference != null) {
             result = reference.get();
         }
         if (result == null) {
             String searchURL = getSearchURL(searchTerm);
             String urlContent = readUrl(searchURL);
             Library[] libraries = null;
             if (urlContent != null) {
                 libraries = parse(urlContent);
             }
             cache.put(searchTerm, new WeakReference<>(libraries));
             result = libraries;
         }
         return result;
     }

     /**
      * Update a library returned by {@link #findLibraries(java.lang.String)}.
      * The full library data is fetched and the {@code versions} property is
      * filled.
      *
      * @param library to be updated
      */
     public void updateLibraryVersions(Library library) {
         Objects.nonNull(library);
         if(library.getVersions() != null && library.getVersions().length > 0) {
             return;
         }
         Library cachedLibrary = getCachedLibrary(library.getName());
         if(cachedLibrary != null) {
             library.setVersions(cachedLibrary.getVersions());
             return;
         }
         String data = readUrl(getLibraryDataUrl(library.getName()));
         if(data != null) {
             try {
                 JSONParser parser = new JSONParser();
                 JSONObject libraryData = (JSONObject)parser.parse(data);
                 updateLibrary(library, libraryData);
                 entryCache.put(library.getName(), new WeakReference<>(library));
             } catch (ParseException ex) {
                 Logger.getLogger(LibraryProvider.class.getName()).log(Level.INFO, null, ex);
             }
         }
     }

     /**
      * Load the full data for the supplied library. All fields are populated,
      * including the {@code versions} property.
      *
      * @param libraryName
      * @return
      */
     public Library loadLibrary(String libraryName) {
         Library cachedLibrary = getCachedLibrary(libraryName);
         if(cachedLibrary != null) {
             return cachedLibrary;
         }
         String data = readUrl(getLibraryDataUrl(libraryName));
         if (data != null) {
             try {
                 JSONParser parser = new JSONParser();
                 JSONObject libraryData = (JSONObject) parser.parse(data);
                 Library library = createLibrary(libraryData);
                 entryCache.put(library.getName(), new WeakReference<>(library));
                 return library;
             } catch (ParseException ex) {
                 Logger.getLogger(LibraryProvider.class.getName()).log(Level.INFO, null, ex);
             }
         }
         return null;
     }

     private Library getCachedLibrary(String name) {
         WeakReference<Library> cachedEntry = entryCache.get(name);
         if (cachedEntry != null) {
             return cachedEntry.get();
         } else {
             return null;
         }
     }

     private String getLibraryDataUrl(String libraryName) {
         String encodedLibraryName;
         try {
             encodedLibraryName = URLEncoder.encode(libraryName, "UTF-8"); // NOI18N
         } catch (UnsupportedEncodingException ueex) {
             // Should not happen, UTF-8 should be supported everywhere
             Logger.getLogger(LibraryProvider.class.getName()).log(Level.SEVERE, null, ueex);
             encodedLibraryName = libraryName;
         }
         return String.format(ASSET_URL_PATTERN, encodedLibraryName);
     }

     /**
      * URL pattern for library files.
      * {0} library name
      * {1} version name
      * {2} file name
      */
     private static final String LIBRARY_FILE_URL_PATTERN = System.getProperty(
             "netbeans.cdnjs.downloadurl", // NOI18N
             "https://cdnjs.cloudflare.com/ajax/libs/{0}/{1}/{2}"); // NOI18N

     /**
      * Downloads the specified file of the given library version. The data are saved
      * into a temporary file that is returned.
      *
      * @param version library version whose file should be downloaded
      * (only libraries/versions returned by this provider can be downloaded).
      * @param fileIndex 0-based index of the file (in the version's list of files).
      * @return downloaded (temporary) file.
      * @throws IOException when the downloading of the file failed.
      */
     public File downloadLibraryFile(Library.Version version, int fileIndex) throws IOException {
         String libraryName = version.getLibrary().getName();
         String versionName = version.getName();
         String[] fileNames = version.getFiles();
         String fileName = fileNames[fileIndex];
         String url = MessageFormat.format(LIBRARY_FILE_URL_PATTERN, libraryName, versionName, fileName);
         URL urlObject = new URL(url);
         URLConnection urlConnection = urlObject.openConnection();
         try (InputStream input = urlConnection.getInputStream()) {
             int index = fileName.lastIndexOf('.');
             String prefix = (index == -1) ? fileName : fileName.substring(0,index);
             if (prefix.length() < 3) {
                 prefix = "tmp" + prefix; // NOI18N
             }
             String suffix = (index == -1) ? "" : fileName.substring(index);
             File file = File.createTempFile(prefix, suffix);
             try (OutputStream output = new FileOutputStream(file)) {
                 FileUtil.copy(input, output);
                 return file;
             }
         }
     }

     /** URL of the search web service. */
     static final String SEARCH_URL_PREFIX =
             System.getProperty("netbeans.cdnjs.searchurl", // NOI18N
             "https://api.cdnjs.com/libraries?fields=description,homepage,assets&search="); // NOI18N
     /** URL to fetch asset data */
     static final String ASSET_URL_PATTERN =
             System.getProperty("netbeans.cdnjs.asseturlpattern", // NOI18N
             "https://api.cdnjs.com/libraries/%1$s?fields=name,description,homepage,assets"); // NOI18N

     /**
      * Comparator that helps to sort library versions.
      */
     static final Comparator<Pair<Library.Version, Version>> VERSION_COMPARATOR = new Comparator<Pair<Library.Version, Version>>() {
         @Override
         public int compare(Pair<Library.Version, Version> pair1, Pair<Library.Version, Version> pair2) {
             return Version.Comparator.getInstance(false).compare(pair1.second(), pair2.second());
         }
     };

     private static void extractVersionInformation(JSONObject data, Library library) {
         JSONArray versionsData = (JSONArray) data.get(PROPERTY_VERSIONS);
         if (versionsData != null) {
             Library.Version[] versions = new Library.Version[versionsData.size()];
             for (int i = 0; i < versions.length; i++) {
                 JSONObject versionData = (JSONObject) versionsData.get(i);
                 versions[i] = createVersion(library, versionData);
             }
             sort(versions);
             library.setVersions(versions);
         } else {
             library.setVersions(new Library.Version[0]);
         }
     }

     /**
      * Sorts the library versions (in a descending order).
      *
      * @param versions versions to sort.
      */
     private static void sort(Library.Version[] versions) {
         Pair<Library.Version, Version>[] pairs = new Pair[versions.length];
         for (int i = 0; i < versions.length; i++) {
             Library.Version libraryVersion = versions[i];
             Version version = Version.parse(libraryVersion.getName());
             pairs[i] = Pair.of(libraryVersion, version);
         }
         Arrays.sort(pairs, VERSION_COMPARATOR);
         for (int i = 0; i < versions.length; i++) {
             versions[i] = pairs[i].first();
         }
     }

     /**
      * Creates a library version for the given JSON data.
      *
      * @param library owning library.
      * @param data    JSON data describing the library version.
      *
      * @return library version that corresponds to the given JSON data.
      */
     private static Library.Version createVersion(Library library, JSONObject data) {
         Library.Version version = new Library.Version(library, false);

         String versionName = (String) data.get(PROPERTY_VERSION_NAME);
         version.setName(versionName);

         JSONArray filesData = (JSONArray) data.get(PROPERTY_FILES);
         String[] files = new String[filesData.size()];
         for (int i = 0; i < files.length; i++) {
             Object fileInfo = filesData.get(i);
             String fileName;
             if (fileInfo instanceof JSONObject) {
                 JSONObject fileData = (JSONObject) fileInfo;
                 fileName = (String) fileData.get(PROPERTY_FILE_NAME);
             } else {
                 fileName = fileInfo.toString();
             }
             files[i] = fileName;
         }
         version.setFileInfo(files, null);

         return version;
     }

     /**
      * Reads the content of the given URL.
      *
      * @param url URL whose content should be read.
      *
      * @return content of the given URL.
      */
     static String readUrl(String url) {
         String urlContent = null;
         try {
             URL urlObject = new URL(url);
             URLConnection urlConnection = urlObject.openConnection();
             StringBuilder content = new StringBuilder();
             try (BufferedReader reader = new BufferedReader(new InputStreamReader(
                 urlConnection.getInputStream(), "UTF-8"))) { // NOI18N
                 String line;
                 while ((line = reader.readLine()) != null) {
                     content.append(line).append('\n');
                 }
             }
             urlContent = content.toString();
         } catch (MalformedURLException muex) {
             Logger.getLogger(LibraryProvider.class.getName()).log(Level.INFO, null, muex);
         } catch (IOException ioex) {
             Logger.getLogger(LibraryProvider.class.getName()).log(Level.INFO, null, ioex);
         }
         return urlContent;
     }

     String getSearchURL(String searchTerm) {
         String encodedSearchTerm;
         try {
             encodedSearchTerm = URLEncoder.encode(searchTerm, "UTF-8"); // NOI18N
         } catch (UnsupportedEncodingException ueex) {
             // Should not happen, UTF-8 should be supported everywhere
             Logger.getLogger(LibraryProvider.class.getName()).log(Level.SEVERE, null, ueex);
             encodedSearchTerm = searchTerm;
         }
         return SEARCH_URL_PREFIX + encodedSearchTerm;
     }

     /**
      * Parses the given JSON result of the search.
      *
      * @param data search result.
      *
      * @return libraries returned in the search result.
      */
     Library[] parse(String data) {
         Library[] libraries = null;
         try {
             JSONParser parser = new JSONParser();
             JSONObject searchResult = (JSONObject) parser.parse(data);
             JSONArray libraryArray = (JSONArray) searchResult.get(PROPERTY_RESULT);
             libraries = new Library[libraryArray.size()];
             for (int i = 0; i < libraries.length; i++) {
                 JSONObject libraryData = (JSONObject) libraryArray.get(i);
                 libraries[i] = createLibrary(libraryData);
             }
         } catch (ParseException pex) {
             Logger.getLogger(LibraryProvider.class.getName()).log(Level.INFO, null, pex);
         }
         return libraries;
     }

     /**
      * Creates a library for the given JSON data.
      *
      * @param data JSON data describing the library.
      *
      * @return library that corresponds to the given JSON data.
      */
     Library createLibrary(JSONObject data) {
         Library library = new Library();

         updateLibrary(library, data);

         return library;
     }

     void updateLibrary(Library library, JSONObject data) {
         String name = (String) data.get(PROPERTY_NAME);
         library.setName(name);

         String description = (String) data.get(PROPERTY_DESCRIPTION);
         library.setDescription(description);

         String homepage = (String) data.get(PROPERTY_HOMEPAGE);
         library.setHomePage(homepage);

         extractVersionInformation(data, library);
     }
 }
	/*
	* 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.netbeans.modules.javascript.cdnjs;

	import java.io.BufferedReader;
	import java.io.File;
	import java.io.FileOutputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.InputStreamReader;
	import java.io.OutputStream;
	import java.io.UnsupportedEncodingException;
	import java.lang.ref.WeakReference;
	import java.net.MalformedURLException;
	import java.net.URL;
	import java.net.URLConnection;
	import java.net.URLEncoder;
	import java.text.MessageFormat;
	import java.util.Arrays;
	import java.util.Collections;
	import java.util.Comparator;
	import java.util.HashMap;
	import java.util.Map;
	import java.util.Objects;
	import java.util.logging.Level;
	import java.util.logging.Logger;
	import org.json.simple.JSONArray;
	import org.json.simple.JSONObject;
	import org.json.simple.parser.JSONParser;
	import org.json.simple.parser.ParseException;
	import org.openide.filesystems.FileUtil;
	import org.openide.util.Pair;

	/**
	* CDNJS library provider, i.e., provider of the libraries available
	* on https://cdnjs.com/ server.
	*
	* The clients of this provider are expected to use {@link #findLibraries}
	* method to search libraries matching given search term. The search
	* for the libraries is performed asynchronously. Hence, this method
	* returns {@code null} when it is called for the first time for the given
	* search term. The clients should register property change listeners
	* on the provider to be notified when the result of the search is available.
	* The property change events fired by the provider will have the property
	* name set to the search term and the new value to the result of the search.
	* The new value may be set to {@code null} when the search failed for
	* some reason (the new value is set to an empty array when the result
	* of the search is empty).
	*
	* @author Jan Stola
	*/
	public final class LibraryProvider {
	/** Name of the 'versions' property. */
	private static final String PROPERTY_VERSIONS = "assets"; // NOI18N
	/** Name of the 'version name' property. */
	private static final String PROPERTY_VERSION_NAME = "version"; // NOI18N
	/** Name of the 'files' property. */
	private static final String PROPERTY_FILES = "files"; // NOI18N
	/** Name of the 'file name' property. */
	private static final String PROPERTY_FILE_NAME = "name"; // NOI18N
	/** Name of the 'result' property. */
	private static final String PROPERTY_RESULT = "results"; // NOI18N
	/** Name of the 'name' property. */
	private static final String PROPERTY_NAME = "name"; // NOI18N
	/** Name of the 'description' property. */
	private static final String PROPERTY_DESCRIPTION = "description"; // NOI18N
	/** Name of the 'homepage' property. */
	private static final String PROPERTY_HOMEPAGE = "homepage"; // NOI18N

	/** The only instance of this provider. */
	private static final LibraryProvider INSTANCE = new LibraryProvider();
	/** Cache of the search results. It maps the search term to the search result. */
	private final Map<String,WeakReference<Library[]>> cache =
	Collections.synchronizedMap(new HashMap<>());
	private final Map<String,WeakReference<Library>> entryCache =
	Collections.synchronizedMap(new HashMap<>());

	/**
	* Creates a new {@code LibraryProvider}.
	*/
	private LibraryProvider() {
	}

	/**
	* Returns the only instance of this class.
	*
	* @return (the only) instance of this class.
	*/
	public static LibraryProvider getInstance() {
	return INSTANCE;
	}

	/**
	* Finds the libraries matching the given search term. The resulting
	* {@code Library} instances potentially don't have the versions property
	* set. If that is the case the Library needs to be updated with the
	* {@link #updateLibraryVersions} call.
	*
	* @param searchTerm search term.
	* otherwise.
	*/
	public Library[] findLibraries(String searchTerm) {
	WeakReference<Library[]> reference = cache.get(searchTerm);
	Library[] result = null;
	if (reference != null) {
	result = reference.get();
	}
	if (result == null) {
	String searchURL = getSearchURL(searchTerm);
	String urlContent = readUrl(searchURL);
	Library[] libraries = null;
	if (urlContent != null) {
	libraries = parse(urlContent);
	}
	cache.put(searchTerm, new WeakReference<>(libraries));
	result = libraries;
	}
	return result;
	}

	/**
	* Update a library returned by {@link #findLibraries(java.lang.String)}.
	* The full library data is fetched and the {@code versions} property is
	* filled.
	*
	* @param library to be updated
	*/
	public void updateLibraryVersions(Library library) {
	Objects.nonNull(library);
	if(library.getVersions() != null && library.getVersions().length > 0) {
	return;
	}
	Library cachedLibrary = getCachedLibrary(library.getName());
	if(cachedLibrary != null) {
	library.setVersions(cachedLibrary.getVersions());
	return;
	}
	String data = readUrl(getLibraryDataUrl(library.getName()));
	if(data != null) {
	try {
	JSONParser parser = new JSONParser();
	JSONObject libraryData = (JSONObject)parser.parse(data);
	updateLibrary(library, libraryData);
	entryCache.put(library.getName(), new WeakReference<>(library));
	} catch (ParseException ex) {
	Logger.getLogger(LibraryProvider.class.getName()).log(Level.INFO, null, ex);
	}
	}
	}

	/**
	* Load the full data for the supplied library. All fields are populated,
	* including the {@code versions} property.
	*
	* @param libraryName
	* @return
	*/
	public Library loadLibrary(String libraryName) {
	Library cachedLibrary = getCachedLibrary(libraryName);
	if(cachedLibrary != null) {
	return cachedLibrary;
	}
	String data = readUrl(getLibraryDataUrl(libraryName));
	if (data != null) {
	try {
	JSONParser parser = new JSONParser();
	JSONObject libraryData = (JSONObject) parser.parse(data);
	Library library = createLibrary(libraryData);
	entryCache.put(library.getName(), new WeakReference<>(library));
	return library;
	} catch (ParseException ex) {
	Logger.getLogger(LibraryProvider.class.getName()).log(Level.INFO, null, ex);
	}
	}
	return null;
	}

	private Library getCachedLibrary(String name) {
	WeakReference<Library> cachedEntry = entryCache.get(name);
	if (cachedEntry != null) {
	return cachedEntry.get();
	} else {
	return null;
	}
	}

	private String getLibraryDataUrl(String libraryName) {
	String encodedLibraryName;
	try {
	encodedLibraryName = URLEncoder.encode(libraryName, "UTF-8"); // NOI18N
	} catch (UnsupportedEncodingException ueex) {
	// Should not happen, UTF-8 should be supported everywhere
	Logger.getLogger(LibraryProvider.class.getName()).log(Level.SEVERE, null, ueex);
	encodedLibraryName = libraryName;
	}
	return String.format(ASSET_URL_PATTERN, encodedLibraryName);
	}

	/**
	* URL pattern for library files.
	* {0} library name
	* {1} version name
	* {2} file name
	*/
	private static final String LIBRARY_FILE_URL_PATTERN = System.getProperty(
	"netbeans.cdnjs.downloadurl", // NOI18N
	"https://cdnjs.cloudflare.com/ajax/libs/{0}/{1}/{2}"); // NOI18N

	/**
	* Downloads the specified file of the given library version. The data are saved
	* into a temporary file that is returned.
	*
	* @param version library version whose file should be downloaded
	* (only libraries/versions returned by this provider can be downloaded).
	* @param fileIndex 0-based index of the file (in the version's list of files).
	* @return downloaded (temporary) file.
	* @throws IOException when the downloading of the file failed.
	*/
	public File downloadLibraryFile(Library.Version version, int fileIndex) throws IOException {
	String libraryName = version.getLibrary().getName();
	String versionName = version.getName();
	String[] fileNames = version.getFiles();
	String fileName = fileNames[fileIndex];
	String url = MessageFormat.format(LIBRARY_FILE_URL_PATTERN, libraryName, versionName, fileName);
	URL urlObject = new URL(url);
	URLConnection urlConnection = urlObject.openConnection();
	try (InputStream input = urlConnection.getInputStream()) {
	int index = fileName.lastIndexOf('.');
	String prefix = (index == -1) ? fileName : fileName.substring(0,index);
	if (prefix.length() < 3) {
	prefix = "tmp" + prefix; // NOI18N
	}
	String suffix = (index == -1) ? "" : fileName.substring(index);
	File file = File.createTempFile(prefix, suffix);
	try (OutputStream output = new FileOutputStream(file)) {
	FileUtil.copy(input, output);
	return file;
	}
	}
	}

	/** URL of the search web service. */
	static final String SEARCH_URL_PREFIX =
	System.getProperty("netbeans.cdnjs.searchurl", // NOI18N
	"https://api.cdnjs.com/libraries?fields=description,homepage,assets&search="); // NOI18N
	/** URL to fetch asset data */
	static final String ASSET_URL_PATTERN =
	System.getProperty("netbeans.cdnjs.asseturlpattern", // NOI18N
	"https://api.cdnjs.com/libraries/%1$s?fields=name,description,homepage,assets"); // NOI18N

	/**
	* Comparator that helps to sort library versions.
	*/
	static final Comparator<Pair<Library.Version, Version>> VERSION_COMPARATOR = new Comparator<Pair<Library.Version, Version>>() {
	@Override
	public int compare(Pair<Library.Version, Version> pair1, Pair<Library.Version, Version> pair2) {
	return Version.Comparator.getInstance(false).compare(pair1.second(), pair2.second());
	}
	};

	private static void extractVersionInformation(JSONObject data, Library library) {
	JSONArray versionsData = (JSONArray) data.get(PROPERTY_VERSIONS);
	if (versionsData != null) {
	Library.Version[] versions = new Library.Version[versionsData.size()];
	for (int i = 0; i < versions.length; i++) {
	JSONObject versionData = (JSONObject) versionsData.get(i);
	versions[i] = createVersion(library, versionData);
	}
	sort(versions);
	library.setVersions(versions);
	} else {
	library.setVersions(new Library.Version[0]);
	}
	}

	/**
	* Sorts the library versions (in a descending order).
	*
	* @param versions versions to sort.
	*/
	private static void sort(Library.Version[] versions) {
	Pair<Library.Version, Version>[] pairs = new Pair[versions.length];
	for (int i = 0; i < versions.length; i++) {
	Library.Version libraryVersion = versions[i];
	Version version = Version.parse(libraryVersion.getName());
	pairs[i] = Pair.of(libraryVersion, version);
	}
	Arrays.sort(pairs, VERSION_COMPARATOR);
	for (int i = 0; i < versions.length; i++) {
	versions[i] = pairs[i].first();
	}
	}

	/**
	* Creates a library version for the given JSON data.
	*
	* @param library owning library.
	* @param data JSON data describing the library version.
	*
	* @return library version that corresponds to the given JSON data.
	*/
	private static Library.Version createVersion(Library library, JSONObject data) {
	Library.Version version = new Library.Version(library, false);

	String versionName = (String) data.get(PROPERTY_VERSION_NAME);
	version.setName(versionName);

	JSONArray filesData = (JSONArray) data.get(PROPERTY_FILES);
	String[] files = new String[filesData.size()];
	for (int i = 0; i < files.length; i++) {
	Object fileInfo = filesData.get(i);
	String fileName;
	if (fileInfo instanceof JSONObject) {
	JSONObject fileData = (JSONObject) fileInfo;
	fileName = (String) fileData.get(PROPERTY_FILE_NAME);
	} else {
	fileName = fileInfo.toString();
	}
	files[i] = fileName;
	}
	version.setFileInfo(files, null);

	return version;
	}

	/**
	* Reads the content of the given URL.
	*
	* @param url URL whose content should be read.
	*
	* @return content of the given URL.
	*/
	static String readUrl(String url) {
	String urlContent = null;
	try {
	URL urlObject = new URL(url);
	URLConnection urlConnection = urlObject.openConnection();
	StringBuilder content = new StringBuilder();
	try (BufferedReader reader = new BufferedReader(new InputStreamReader(
	urlConnection.getInputStream(), "UTF-8"))) { // NOI18N
	String line;
	while ((line = reader.readLine()) != null) {
	content.append(line).append('\n');
	}
	}
	urlContent = content.toString();
	} catch (MalformedURLException muex) {
	Logger.getLogger(LibraryProvider.class.getName()).log(Level.INFO, null, muex);
	} catch (IOException ioex) {
	Logger.getLogger(LibraryProvider.class.getName()).log(Level.INFO, null, ioex);
	}
	return urlContent;
	}

	String getSearchURL(String searchTerm) {
	String encodedSearchTerm;
	try {
	encodedSearchTerm = URLEncoder.encode(searchTerm, "UTF-8"); // NOI18N
	} catch (UnsupportedEncodingException ueex) {
	// Should not happen, UTF-8 should be supported everywhere
	Logger.getLogger(LibraryProvider.class.getName()).log(Level.SEVERE, null, ueex);
	encodedSearchTerm = searchTerm;
	}
	return SEARCH_URL_PREFIX + encodedSearchTerm;
	}

	/**
	* Parses the given JSON result of the search.
	*
	* @param data search result.
	*
	* @return libraries returned in the search result.
	*/
	Library[] parse(String data) {
	Library[] libraries = null;
	try {
	JSONParser parser = new JSONParser();
	JSONObject searchResult = (JSONObject) parser.parse(data);
	JSONArray libraryArray = (JSONArray) searchResult.get(PROPERTY_RESULT);
	libraries = new Library[libraryArray.size()];
	for (int i = 0; i < libraries.length; i++) {
	JSONObject libraryData = (JSONObject) libraryArray.get(i);
	libraries[i] = createLibrary(libraryData);
	}
	} catch (ParseException pex) {
	Logger.getLogger(LibraryProvider.class.getName()).log(Level.INFO, null, pex);
	}
	return libraries;
	}

	/**
	* Creates a library for the given JSON data.
	*
	* @param data JSON data describing the library.
	*
	* @return library that corresponds to the given JSON data.
	*/
	Library createLibrary(JSONObject data) {
	Library library = new Library();

	updateLibrary(library, data);

	return library;
	}

	void updateLibrary(Library library, JSONObject data) {
	String name = (String) data.get(PROPERTY_NAME);
	library.setName(name);

	String description = (String) data.get(PROPERTY_DESCRIPTION);
	library.setDescription(description);

	String homepage = (String) data.get(PROPERTY_HOMEPAGE);
	library.setHomePage(homepage);

	extractVersionInformation(data, library);
	}
	}