/*
 * Copyright (C) 2010, Sasa Zivkov <sasa.zivkov@sap.com> and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.eclipse.jgit.nls;

import java.util.Locale;
import java.util.concurrent.ConcurrentHashMap;

import org.eclipse.jgit.errors.TranslationBundleLoadingException;
import org.eclipse.jgit.errors.TranslationStringMissingException;

The purpose of this class is to provide NLS (National Language Support)
configurable per thread.
 The setLocale(Locale) method is used to configure locale for the calling thread. The locale setting is thread inheritable. This means that a child thread will have the same locale setting as its creator thread until it changes it explicitly. 

Example of usage:
NLS.setLocale(Locale.GERMAN);
TransportText t = NLS.getBundleFor(TransportText.class);

/**
 * The purpose of this class is to provide NLS (National Language Support)
 * configurable per thread.
 *
 * <p>
 * The {@link #setLocale(Locale)} method is used to configure locale for the
 * calling thread. The locale setting is thread inheritable. This means that a
 * child thread will have the same locale setting as its creator thread until it
 * changes it explicitly.
 *
 * <p>
 * Example of usage:
 *
 * <pre>
 * NLS.setLocale(Locale.GERMAN);
 * TransportText t = NLS.getBundleFor(TransportText.class);
 * </pre>
 */
public class NLS {
	
The root locale constant. It is defined here because the Locale.ROOT is
not defined in Java 5
/**
	 * The root locale constant. It is defined here because the Locale.ROOT is
	 * not defined in Java 5
	 */
	public static final Locale ROOT_LOCALE = new Locale("", "", ""); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$

	private static final InheritableThreadLocal<NLS> local = new InheritableThreadLocal<>();

	
Sets the locale for the calling thread.
 The getBundleFor(Class<TranslationBundle>) method will honor this setting if it is supported by the provided resource bundle property files. Otherwise, it will use a fall back locale as described in the TranslationBundle 
Params:
locale – 
           the preferred locale/**
	 * Sets the locale for the calling thread.
	 * <p>
	 * The {@link #getBundleFor(Class)} method will honor this setting if it
	 * is supported by the provided resource bundle property files. Otherwise,
	 * it will use a fall back locale as described in the
	 * {@link TranslationBundle}
	 *
	 * @param locale
	 *            the preferred locale
	 */
	public static void setLocale(Locale locale) {
		local.set(new NLS(locale));
	}

	
Sets the JVM default locale as the locale for the calling thread.

Semantically this is equivalent to
NLS.setLocale(Locale.getDefault()).
/**
	 * Sets the JVM default locale as the locale for the calling thread.
	 * <p>
	 * Semantically this is equivalent to
	 * <code>NLS.setLocale(Locale.getDefault())</code>.
	 */
	public static void useJVMDefaultLocale() {
		useJVMDefaultInternal();
	}

	// TODO(ms): change signature of public useJVMDefaultLocale() in 5.0 to get
	// rid of this internal method
	private static NLS useJVMDefaultInternal() {
		NLS b = new NLS(Locale.getDefault());
		local.set(b);
		return b;
	}

	
Returns an instance of the translation bundle of the required type. All public String fields of the bundle instance will get their values injected as described in the TranslationBundle. 
Params:
type – 
           required bundle type
Throws:
TranslationBundleLoadingException –  see TranslationBundleLoadingException
TranslationStringMissingException –  see TranslationStringMissingException
Returns:
an instance of the required bundle type/**
	 * Returns an instance of the translation bundle of the required type. All
	 * public String fields of the bundle instance will get their values
	 * injected as described in the
	 * {@link org.eclipse.jgit.nls.TranslationBundle}.
	 *
	 * @param type
	 *            required bundle type
	 * @return an instance of the required bundle type
	 * @exception TranslationBundleLoadingException
	 *                see
	 *                {@link org.eclipse.jgit.errors.TranslationBundleLoadingException}
	 * @exception TranslationStringMissingException
	 *                see
	 *                {@link org.eclipse.jgit.errors.TranslationStringMissingException}
	 */
	public static <T extends TranslationBundle> T getBundleFor(Class<T> type) {
		NLS b = local.get();
		if (b == null) {
			b = useJVMDefaultInternal();
		}
		return b.get(type);
	}

	
Release resources held by NLS
Since:
5.8/**
	 * Release resources held by NLS
	 * @since 5.8
	 */
	public static void clear() {
		local.remove();
		GlobalBundleCache.clear();
	}

	private final Locale locale;
	private final ConcurrentHashMap<Class, TranslationBundle> map = new ConcurrentHashMap<>();

	private NLS(Locale locale) {
		this.locale = locale;
	}

	@SuppressWarnings("unchecked")
	private <T extends TranslationBundle> T get(Class<T> type) {
		TranslationBundle bundle = map.get(type);
		if (bundle == null) {
			bundle = GlobalBundleCache.lookupBundle(locale, type);
			// There is a small opportunity for a race, which we may
			// lose. Accept defeat and return the winner's instance.
			TranslationBundle old = map.putIfAbsent(type, bundle);
			if (old != null)
				bundle = old;
		}
		return (T) bundle;
	}
}