Copyright (c) 2004, 2017 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2004, 2017 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.osgi.storage;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Dictionary;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.List;
import java.util.Locale;
import java.util.Map.Entry;
import java.util.MissingResourceException;
import java.util.PropertyResourceBundle;
import java.util.ResourceBundle;
import org.eclipse.osgi.container.Module;
import org.eclipse.osgi.container.ModuleWire;
import org.eclipse.osgi.container.ModuleWiring;
import org.eclipse.osgi.framework.util.CaseInsensitiveDictionaryMap;
import org.eclipse.osgi.storage.BundleInfo.Generation;
import org.osgi.framework.Constants;
import org.osgi.framework.namespace.HostNamespace;
import org.osgi.framework.wiring.BundleRevision;

This class is used to localize manifest headers for a revision.
/**
 * This class is used to localize manifest headers for a revision.
 */
public class ManifestLocalization {
	final String defaultRoot;
	private final Generation generation;
	private final Dictionary<String, String> rawHeaders;
	private volatile Dictionary<String, String> defaultLocaleHeaders = null;
	private final Hashtable<String, BundleResourceBundle> cache = new Hashtable<>(5);

	public ManifestLocalization(Generation generation, Dictionary<String, String> rawHeaders, String defaultRoot) {
		this.generation = generation;
		this.rawHeaders = rawHeaders;
		this.defaultRoot = defaultRoot;
	}

	public void clearCache() {
		synchronized (cache) {
			cache.clear();
			defaultLocaleHeaders = null;
		}
	}

	Dictionary<String, String> getHeaders(String localeString) {
		if (localeString == null)
			localeString = Locale.getDefault().toString();
		if (localeString.length() == 0)
			return rawHeaders;
		boolean isDefaultLocale = localeString.equals(Locale.getDefault().toString());
		Dictionary<String, String> currentDefault = defaultLocaleHeaders;
		if (isDefaultLocale && currentDefault != null) {
			return currentDefault;
		}
		if (generation.getRevision().getRevisions().getModule().getState().equals(Module.State.UNINSTALLED)) {
			// defaultLocaleHeaders should have been initialized on uninstall
			if (currentDefault != null)
				return currentDefault;
			return rawHeaders;
		}
		ResourceBundle localeProperties = getResourceBundle(localeString, isDefaultLocale);
		CaseInsensitiveDictionaryMap<String, String> localeHeaders = new CaseInsensitiveDictionaryMap<>(this.rawHeaders);
		for (Entry<String, String> entry : localeHeaders.entrySet()) {
			String value = entry.getValue();
			if (value.startsWith("%") && (value.length() > 1)) { //$NON-NLS-1$
				String propertiesKey = value.substring(1);
				try {
					value = localeProperties == null ? propertiesKey : (String) localeProperties.getObject(propertiesKey);
				} catch (MissingResourceException ex) {
					value = propertiesKey;
				}
				entry.setValue(value);
			}
		}
		Dictionary<String, String> result = localeHeaders.asUnmodifiableDictionary();
		if (isDefaultLocale) {
			defaultLocaleHeaders = result;
		}
		return result;
	}

	private String[] buildNLVariants(String nl) {
		List<String> result = new ArrayList<>();
		while (nl.length() > 0) {
			result.add(nl);
			int i = nl.lastIndexOf('_');
			nl = (i < 0) ? "" : nl.substring(0, i); //$NON-NLS-1$
		}
		result.add(""); //$NON-NLS-1$
		return result.toArray(new String[result.size()]);
	}

	/*
	 * This method find the appropriate Manifest Localization file inside the
	 * bundle. If not found, return null.
	 */
	ResourceBundle getResourceBundle(String localeString, boolean isDefaultLocale) {
		BundleResourceBundle resourceBundle = lookupResourceBundle(localeString);
		if (isDefaultLocale)
			return (ResourceBundle) resourceBundle;
		// need to determine if this is resource bundle is an empty stem
		// if it is then the default locale should be used
		if (resourceBundle == null || resourceBundle.isStemEmpty())
			return (ResourceBundle) lookupResourceBundle(Locale.getDefault().toString());
		return (ResourceBundle) resourceBundle;
	}

	private BundleResourceBundle lookupResourceBundle(String localeString) {
		// get the localization header as late as possible to avoid accessing the raw headers
		// getting the first value from the raw headers forces the manifest to be parsed (bug 332039)
		String localizationHeader = rawHeaders.get(Constants.BUNDLE_LOCALIZATION);
		if (localizationHeader == null)
			localizationHeader = Constants.BUNDLE_LOCALIZATION_DEFAULT_BASENAME;

		BundleResourceBundle result = cache.get(localeString);
		if (result != null)
			return result.isEmpty() ? null : result;

		// Collect all the necessary inputstreams to create the resource bundle without
		// holding any locks.  Finding resources and inputstreams from the wirings requires a
		// read lock on the module database.  We must not hold the cache lock while doing this;
		// otherwise out of order locks will be possible when the resolver needs to clear the cache
		String[] nlVarients = buildNLVariants(localeString);
		InputStream[] nlStreams = new InputStream[nlVarients.length];
		for (int i = nlVarients.length - 1; i >= 0; i--) {

			URL url = findResource(localizationHeader + (nlVarients[i].equals("") ? nlVarients[i] : '_' + nlVarients[i]) + ".properties"); //$NON-NLS-1$ //$NON-NLS-2$
			if (url != null) {
				try {
					nlStreams[i] = url.openStream();
				} catch (IOException e) {
					// ignore
				}
			}
		}

		synchronized (cache) {
			BundleResourceBundle parent = null;
			for (int i = nlVarients.length - 1; i >= 0; i--) {
				BundleResourceBundle varientBundle = null;
				InputStream varientStream = nlStreams[i];
				if (varientStream == null) {
					varientBundle = cache.get(nlVarients[i]);
				} else {
					try {
						varientBundle = new LocalizationResourceBundle(varientStream);
					} catch (IOException e) {
						// ignore and continue
					} finally {
						if (varientStream != null) {
							try {
								varientStream.close();
							} catch (IOException e3) {
								//Ignore exception
							}
						}
					}
				}

				if (varientBundle == null) {
					varientBundle = new EmptyResouceBundle(nlVarients[i]);
				}
				if (parent != null)
					varientBundle.setParent((ResourceBundle) parent);
				cache.put(nlVarients[i], varientBundle);
				parent = varientBundle;
			}
			result = cache.get(localeString);
			return result.isEmpty() ? null : result;
		}
	}

	private URL findResource(String resource) {
		ModuleWiring searchWiring = generation.getRevision().getWiring();
		if (searchWiring != null) {
			if ((generation.getRevision().getTypes() & BundleRevision.TYPE_FRAGMENT) != 0) {
				List<ModuleWire> hostWires = searchWiring.getRequiredModuleWires(HostNamespace.HOST_NAMESPACE);
				searchWiring = null;
				Long lowestHost = Long.MAX_VALUE;
				if (hostWires != null) {
					// search for the host with the highest ID
					for (ModuleWire hostWire : hostWires) {
						Long hostID = hostWire.getProvider().getRevisions().getModule().getId();
						if (hostID.compareTo(lowestHost) <= 0) {
							lowestHost = hostID;
							searchWiring = hostWire.getProviderWiring();
						}
					}
				}
			}
		}
		if (searchWiring != null) {
			int lastSlash = resource.lastIndexOf('/');
			String path = lastSlash > 0 ? resource.substring(0, lastSlash) : "/"; //$NON-NLS-1$
			String fileName = lastSlash != -1 ? resource.substring(lastSlash + 1) : resource;
			List<URL> result = searchWiring.findEntries(path, fileName, 0);
			return (result == null || result.isEmpty()) ? null : result.get(0);
		}
		// search the raw bundle file for the generation
		return generation.getEntry(resource);
	}

	private interface BundleResourceBundle {
		void setParent(ResourceBundle parent);

		boolean isEmpty();

		boolean isStemEmpty();
	}

	private class LocalizationResourceBundle extends PropertyResourceBundle implements BundleResourceBundle {
		public LocalizationResourceBundle(InputStream in) throws IOException {
			super(in);
		}

		@Override
		public void setParent(ResourceBundle parent) {
			super.setParent(parent);
		}

		@Override
		public boolean isEmpty() {
			return false;
		}

		@Override
		public boolean isStemEmpty() {
			return parent == null;
		}
	}

	class EmptyResouceBundle extends ResourceBundle implements BundleResourceBundle {
		private final String localeString;

		public EmptyResouceBundle(String locale) {
			super();
			this.localeString = locale;
		}

		@SuppressWarnings("unchecked")
		@Override
		public Enumeration<String> getKeys() {
			return Collections.enumeration(Collections.EMPTY_LIST);
		}

		@Override
		protected Object handleGetObject(String arg0) throws MissingResourceException {
			return null;
		}

		@Override
		public void setParent(ResourceBundle parent) {
			super.setParent(parent);
		}

		@Override
		public boolean isEmpty() {
			if (parent == null)
				return true;
			return ((BundleResourceBundle) parent).isEmpty();
		}

		@Override
		public boolean isStemEmpty() {
			if (defaultRoot.equals(localeString))
				return false;
			if (parent == null)
				return true;
			return ((BundleResourceBundle) parent).isStemEmpty();
		}
	}
}