Copyright (c) 2005, 2016 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 - Initial API and implementation
/*******************************************************************************
 * Copyright (c) 2005, 2016 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 - Initial API and implementation
 *******************************************************************************/
package org.eclipse.osgi.util;

import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Properties;
import org.eclipse.osgi.framework.log.FrameworkLog;
import org.eclipse.osgi.framework.log.FrameworkLogEntry;
import org.eclipse.osgi.internal.util.SupplementDebug;

Common superclass for all message bundle classes.  Provides convenience
methods for manipulating messages.

The #bind methods perform string substitution and should be considered a
convenience and not a full substitute replacement for MessageFormat#format
method calls. 


Text appearing within curly braces in the given message, will be interpreted
as a numeric index to the corresponding substitution object in the given array. Calling
the #bind methods with text that does not map to an integer will result in an IllegalArgumentException. 

Text appearing within single quotes is treated as a literal. A single quote is escaped by
a preceeding single quote.


Clients who wish to use the full substitution power of the MessageFormat class should
call that class directly and not use these #bind methods.


Clients may subclass this type.

Since:
3.1/**
 * Common superclass for all message bundle classes.  Provides convenience
 * methods for manipulating messages.
 * <p>
 * The <code>#bind</code> methods perform string substitution and should be considered a
 * convenience and <em>not</em> a full substitute replacement for <code>MessageFormat#format</code>
 * method calls. 
 * </p>
 * <p>
 * Text appearing within curly braces in the given message, will be interpreted
 * as a numeric index to the corresponding substitution object in the given array. Calling
 * the <code>#bind</code> methods with text that does not map to an integer will result in an
 * {@link IllegalArgumentException}.
 * </p>
 * <p>
 * Text appearing within single quotes is treated as a literal. A single quote is escaped by
 * a preceeding single quote.
 * </p>
 * <p>
 * Clients who wish to use the full substitution power of the <code>MessageFormat</code> class should
 * call that class directly and not use these <code>#bind</code> methods.
 * </p>
 * <p>
 * Clients may subclass this type.
 * </p>
 * 
 * @since 3.1
 */
public abstract class NLS {

	private static final Object[] EMPTY_ARGS = new Object[0];
	private static final String EXTENSION = ".properties"; //$NON-NLS-1$
	private static String[] nlSuffixes;
	private static final String PROP_WARNINGS = "osgi.nls.warnings"; //$NON-NLS-1$
	private static final String IGNORE = "ignore"; //$NON-NLS-1$
	private static final boolean ignoreWarnings = AccessController.doPrivileged(new PrivilegedAction<Boolean>() {
		@Override
		public Boolean run() {
			return IGNORE.equals(System.getProperty(PROP_WARNINGS));
		}
	});

	/*
	 * NOTE do not change the name of this field; it is set by the Framework using reflection
	 */
	private static FrameworkLog frameworkLog;

	static final int SEVERITY_ERROR = 0x04;
	static final int SEVERITY_WARNING = 0x02;
	/*
	 * This object is assigned to the value of a field map to indicate
	 * that a translated message has already been assigned to that field.
	 */
	static final Object ASSIGNED = new Object();

	
Creates a new NLS instance.
/**
	 * Creates a new NLS instance.
	 */
	protected NLS() {
		super();
	}

	
Bind the given message's substitution locations with the given string value.
Params:
message – the message to be manipulated
binding – the object to be inserted into the message
Throws:
IllegalArgumentException – if the text appearing within curly braces in the given message does not map to an integer
Returns:
the manipulated String/**
	 * Bind the given message's substitution locations with the given string value.
	 * 
	 * @param message the message to be manipulated
	 * @param binding the object to be inserted into the message
	 * @return the manipulated String
	 * @throws IllegalArgumentException if the text appearing within curly braces in the given message does not map to an integer 
	 */
	public static String bind(String message, Object binding) {
		return internalBind(message, null, String.valueOf(binding), null);
	}

	
Bind the given message's substitution locations with the given string values.
Params:
message – the message to be manipulated
binding1 – An object to be inserted into the message
binding2 – A second object to be inserted into the message
Throws:
IllegalArgumentException – if the text appearing within curly braces in the given message does not map to an integer
Returns:
the manipulated String/**
	 * Bind the given message's substitution locations with the given string values.
	 * 
	 * @param message the message to be manipulated
	 * @param binding1 An object to be inserted into the message
	 * @param binding2 A second object to be inserted into the message
	 * @return the manipulated String
	 * @throws IllegalArgumentException if the text appearing within curly braces in the given message does not map to an integer
	 */
	public static String bind(String message, Object binding1, Object binding2) {
		return internalBind(message, null, String.valueOf(binding1), String.valueOf(binding2));
	}

	
Bind the given message's substitution locations with the given string values.
Params:
message – the message to be manipulated
bindings – An array of objects to be inserted into the message
Throws:
IllegalArgumentException – if the text appearing within curly braces in the given message does not map to an integer
Returns:
the manipulated String/**
	 * Bind the given message's substitution locations with the given string values.
	 * 
	 * @param message the message to be manipulated
	 * @param bindings An array of objects to be inserted into the message
	 * @return the manipulated String
	 * @throws IllegalArgumentException if the text appearing within curly braces in the given message does not map to an integer
	 */
	public static String bind(String message, Object[] bindings) {
		return internalBind(message, bindings, null, null);
	}

	
Initialize the given class with the values from the message properties specified by the
base name.  The base name specifies a fully qualified base name to a message properties file,
including the package where the message properties file is located.  The class loader of the 
specified class will be used to load the message properties resources.

For example, if the locale is set to en_US and org.eclipse.example.nls.messages
is used as the base name then the following resources will be searched using the class
loader of the specified class:

  org/eclipse/example/nls/messages_en_US.properties
  org/eclipse/example/nls/messages_en.properties
  org/eclipse/example/nls/messages.properties

Params:
baseName – the base name of a fully qualified message properties file.
clazz – the class where the constants will exist/**
	 * Initialize the given class with the values from the message properties specified by the
	 * base name.  The base name specifies a fully qualified base name to a message properties file,
	 * including the package where the message properties file is located.  The class loader of the 
	 * specified class will be used to load the message properties resources.
	 * <p>
	 * For example, if the locale is set to en_US and <code>org.eclipse.example.nls.messages</code>
	 * is used as the base name then the following resources will be searched using the class
	 * loader of the specified class:
	 * </p>
	 * <pre>
	 *   org/eclipse/example/nls/messages_en_US.properties
	 *   org/eclipse/example/nls/messages_en.properties
	 *   org/eclipse/example/nls/messages.properties
	 * </pre>
	 * 
	 * @param baseName the base name of a fully qualified message properties file.
	 * @param clazz the class where the constants will exist
	 */
	public static void initializeMessages(final String baseName, final Class<?> clazz) {
		if (System.getSecurityManager() == null) {
			load(baseName, clazz);
			return;
		}
		AccessController.doPrivileged(new PrivilegedAction<Void>() {
			@Override
			public Void run() {
				load(baseName, clazz);
				return null;
			}
		});
	}

	/*
	 * Perform the string substitution on the given message with the specified args.
	 * See the class comment for exact details.
	 */
	private static String internalBind(String message, Object[] args, String argZero, String argOne) {
		if (message == null)
			return "No message available."; //$NON-NLS-1$
		if (args == null || args.length == 0)
			args = EMPTY_ARGS;

		int length = message.length();
		//estimate correct size of string buffer to avoid growth
		int bufLen = length + (args.length * 5);
		if (argZero != null)
			bufLen += argZero.length() - 3;
		if (argOne != null)
			bufLen += argOne.length() - 3;
		StringBuilder buffer = new StringBuilder(bufLen < 0 ? 0 : bufLen);
		for (int i = 0; i < length; i++) {
			char c = message.charAt(i);
			switch (c) {
				case '{' :
					int index = message.indexOf('}', i);
					// if we don't have a matching closing brace then...
					if (index == -1) {
						buffer.append(c);
						break;
					}
					i++;
					if (i >= length) {
						buffer.append(c);
						break;
					}
					// look for a substitution
					int number = -1;
					try {
						number = Integer.parseInt(message.substring(i, index));
					} catch (NumberFormatException e) {
						throw new IllegalArgumentException(e);
					}
					if (number == 0 && argZero != null)
						buffer.append(argZero);
					else if (number == 1 && argOne != null)
						buffer.append(argOne);
					else {
						if (number >= args.length || number < 0) {
							buffer.append("<missing argument>"); //$NON-NLS-1$
							i = index;
							break;
						}
						buffer.append(args[number]);
					}
					i = index;
					break;
				case '\'' :
					// if a single quote is the last char on the line then skip it
					int nextIndex = i + 1;
					if (nextIndex >= length) {
						buffer.append(c);
						break;
					}
					char next = message.charAt(nextIndex);
					// if the next char is another single quote then write out one
					if (next == '\'') {
						i++;
						buffer.append(c);
						break;
					}
					// otherwise we want to read until we get to the next single quote
					index = message.indexOf('\'', nextIndex);
					// if there are no more in the string, then skip it
					if (index == -1) {
						buffer.append(c);
						break;
					}
					// otherwise write out the chars inside the quotes
					buffer.append(message, nextIndex, index);
					i = index;
					break;
				default :
					buffer.append(c);
			}
		}
		return buffer.toString();
	}

	/*
	 * Build an array of property files to search.  The returned array contains
	 * the property fields in order from most specific to most generic.
	 * So, in the FR_fr locale, it will return file_fr_FR.properties, then
	 * file_fr.properties, and finally file.properties.
	 */
	private static String[] buildVariants(String root) {
		if (nlSuffixes == null) {
			//build list of suffixes for loading resource bundles
			String nl = Locale.getDefault().toString();
			List<String> result = new ArrayList<>(4);
			int lastSeparator;
			while (true) {
				result.add('_' + nl + EXTENSION);
				lastSeparator = nl.lastIndexOf('_');
				if (lastSeparator == -1)
					break;
				nl = nl.substring(0, lastSeparator);
			}
			//add the empty suffix last (most general)
			result.add(EXTENSION);
			nlSuffixes = result.toArray(new String[result.size()]);
		}
		root = root.replace('.', '/');
		String[] variants = new String[nlSuffixes.length];
		for (int i = 0; i < variants.length; i++)
			variants[i] = root + nlSuffixes[i];
		return variants;
	}

	private static void computeMissingMessages(String bundleName, Class<?> clazz, Map<Object, Object> fieldMap, Field[] fieldArray, boolean isAccessible) {
		// iterate over the fields in the class to make sure that there aren't any empty ones
		final int MOD_EXPECTED = Modifier.PUBLIC | Modifier.STATIC;
		final int MOD_MASK = MOD_EXPECTED | Modifier.FINAL;
		final int numFields = fieldArray.length;
		for (int i = 0; i < numFields; i++) {
			Field field = fieldArray[i];
			if ((field.getModifiers() & MOD_MASK) != MOD_EXPECTED)
				continue;
			//if the field has a a value assigned, there is nothing to do
			if (fieldMap.get(field.getName()) == ASSIGNED)
				continue;
			try {
				// Set a value for this empty field. We should never get an exception here because
				// we know we have a public static non-final field. If we do get an exception, silently
				// log it and continue. This means that the field will (most likely) be un-initialized and
				// will fail later in the code and if so then we will see both the NPE and this error.
				String value = "NLS missing message: " + field.getName() + " in: " + bundleName; //$NON-NLS-1$ //$NON-NLS-2$
				if (SupplementDebug.STATIC_DEBUG_MESSAGE_BUNDLES)
					System.out.println(value);
				log(SEVERITY_WARNING, value, null);
				if (!isAccessible)
					field.setAccessible(true);
				field.set(null, value);
			} catch (Exception e) {
				log(SEVERITY_ERROR, "Error setting the missing message value for: " + field.getName(), e); //$NON-NLS-1$
			}
		}
	}

	/*
	 * Load the given resource bundle using the specified class loader.
	 */
	static void load(final String bundleName, Class<?> clazz) {
		long start = System.currentTimeMillis();
		final Field[] fieldArray = clazz.getDeclaredFields();
		ClassLoader loader = clazz.getClassLoader();

		boolean isAccessible = (clazz.getModifiers() & Modifier.PUBLIC) != 0;

		//build a map of field names to Field objects
		final int len = fieldArray.length;
		Map<Object, Object> fields = new HashMap<>(len * 2);
		for (int i = 0; i < len; i++)
			fields.put(fieldArray[i].getName(), fieldArray[i]);

		// search the variants from most specific to most general, since
		// the MessagesProperties.put method will mark assigned fields
		// to prevent them from being assigned twice
		final String[] variants = buildVariants(bundleName);
		for (String variant : variants) {
			// loader==null if we're launched off the Java boot classpath
			final InputStream input = loader == null ? ClassLoader.getSystemResourceAsStream(variant) : loader.getResourceAsStream(variant);
			if (input == null)
				continue;
			try {
				final MessagesProperties properties = new MessagesProperties(fields, bundleName, isAccessible);
				properties.load(input);
			} catch (IOException e) {
				log(SEVERITY_ERROR, "Error loading " + variant, e); //$NON-NLS-1$
			} finally {
				if (input != null)
					try {
						input.close();
					} catch (IOException e) {
						// ignore
					}
			}
		}
		computeMissingMessages(bundleName, clazz, fields, fieldArray, isAccessible);
		if (SupplementDebug.STATIC_DEBUG_MESSAGE_BUNDLES)
			System.out.println("Time to load message bundle: " + bundleName + " was " + (System.currentTimeMillis() - start) + "ms."); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
	}

	/*
	 * The method adds a log entry based on the error message and exception. 
	 * The output is written to the System.err.
	 * 
	 * This method is only expected to be called if there is a problem in
	 * the NLS mechanism. As a result, translation facility is not available 
	 * here and messages coming out of this log are generally not translated.
	 * 
	 * @param severity - severity of the message (SEVERITY_ERROR or SEVERITY_WARNING)
	 * @param message - message to log
	 * @param e - exception to log
	 */
	static void log(int severity, String message, Exception e) {
		if (severity == SEVERITY_WARNING && ignoreWarnings)
			return; // ignoring warnings; bug 292980
		if (frameworkLog != null) {
			frameworkLog.log(new FrameworkLogEntry("org.eclipse.osgi", severity, 1, message, 0, e, null)); //$NON-NLS-1$
			return;
		}
		String statusMsg;
		switch (severity) {
			case SEVERITY_ERROR :
				statusMsg = "Error: "; //$NON-NLS-1$
				break;
			case SEVERITY_WARNING :
				// intentionally fall through:
			default :
				statusMsg = "Warning: "; //$NON-NLS-1$
		}
		if (message != null)
			statusMsg += message;
		if (e != null)
			statusMsg += ": " + e.getMessage(); //$NON-NLS-1$
		System.err.println(statusMsg);
		if (e != null)
			e.printStackTrace();
	}

	/*
	 * Class which sub-classes java.util.Properties and uses the #put method
	 * to set field values rather than storing the values in the table.
	 */
	private static class MessagesProperties extends Properties {

		private static final int MOD_EXPECTED = Modifier.PUBLIC | Modifier.STATIC;
		private static final int MOD_MASK = MOD_EXPECTED | Modifier.FINAL;
		private static final long serialVersionUID = 1L;

		private final String bundleName;
		private final Map<Object, Object> fields;
		private final boolean isAccessible;

		public MessagesProperties(Map<Object, Object> fieldMap, String bundleName, boolean isAccessible) {
			super();
			this.fields = fieldMap;
			this.bundleName = bundleName;
			this.isAccessible = isAccessible;
		}

		/* (non-Javadoc)
		 * @see java.util.Hashtable#put(java.lang.Object, java.lang.Object)
		 */
		@Override
		public synchronized Object put(Object key, Object value) {
			Object fieldObject = fields.put(key, ASSIGNED);
			// if already assigned, there is nothing to do
			if (fieldObject == ASSIGNED)
				return null;
			if (fieldObject == null) {
				final String msg = "NLS unused message: " + key + " in: " + bundleName;//$NON-NLS-1$ //$NON-NLS-2$
				if (SupplementDebug.STATIC_DEBUG_MESSAGE_BUNDLES)
					System.out.println(msg);
				// keys with '.' are ignored by design (bug 433424)
				if (key instanceof String && ((String) key).indexOf('.') < 0) {
					log(SEVERITY_WARNING, msg, null);
				}
				return null;
			}
			final Field field = (Field) fieldObject;
			//can only set value of public static non-final fields
			if ((field.getModifiers() & MOD_MASK) != MOD_EXPECTED)
				return null;
			try {
				// Check to see if we are allowed to modify the field. If we aren't (for instance 
				// if the class is not public) then change the accessible attribute of the field
				// before trying to set the value.
				if (!isAccessible)
					field.setAccessible(true);
				// Set the value into the field. We should never get an exception here because
				// we know we have a public static non-final field. If we do get an exception, silently
				// log it and continue. This means that the field will (most likely) be un-initialized and
				// will fail later in the code and if so then we will see both the NPE and this error.

				// Extra care is taken to be sure we create a String with its own backing char[] (bug 287183)
				// This is to ensure we do not keep the key chars in memory.
				field.set(null, new String(((String) value).toCharArray()));
			} catch (Exception e) {
				log(SEVERITY_ERROR, "Exception setting field value.", e); //$NON-NLS-1$
			}
			return null;
		}
	}
}