Copyright (c) 2003, 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) 2003, 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.internal.framework;

import java.io.*;
import java.nio.charset.StandardCharsets;
import java.util.*;
import java.util.Map.Entry;
import org.eclipse.osgi.internal.debug.Debug;
import org.eclipse.osgi.internal.util.Tokenizer;

This class maps aliases.
/**
 * This class maps aliases.
 */
public class AliasMapper {
	private static final Map<String, Collection<String>> processorAliasTable = new HashMap<>();
	private static final Map<String, String> processorCanonicalTable = new HashMap<>();
	private static final Map<String, Collection<String>> osnameAliasTable = new HashMap<>();
	private static final Map<String, String> osnameCanonicalTable = new HashMap<>();
	static {
		getTables("osname.aliases", osnameAliasTable, osnameCanonicalTable); //$NON-NLS-1$
		getTables("processor.aliases", processorAliasTable, processorCanonicalTable); //$NON-NLS-1$
	}

	private static void getTables(String resourceName, Map<String, Collection<String>> aliasTable, Map<String, String> canonicalTable) {
		InputStream in = AliasMapper.class.getResourceAsStream(resourceName);
		if (in != null) {
			try {
				initAliases(in, aliasTable, canonicalTable);
			} finally {
				try {
					in.close();
				} catch (IOException ee) {
					// nothing
				}
			}
		}
	}

	
Return the master alias for the processor.
Params:
processor – Input name
Returns:
aliased name (if any)/**
	 * Return the master alias for the processor.
	 *
	 * @param processor Input name
	 * @return aliased name (if any)
	 */
	public Collection<String> getProcessorAliases(String processor) {
		return getAlias(processor.toLowerCase(), processorAliasTable);
	}

	
Return the master alias for the osname.
Params:
osname – Input name
Returns:
aliased name (if any)/**
	 * Return the master alias for the osname.
	 *
	 * @param osname Input name
	 * @return aliased name (if any)
	 */
	public Collection<String> getOSNameAliases(String osname) {
		return getAlias(osname.toLowerCase(), osnameAliasTable);
	}

	public String getCanonicalOSName(String osname) {
		String lowerName = osname.toLowerCase();
		String result = osnameCanonicalTable.get(lowerName);
		if (result == null) {
			if (lowerName.startsWith("windows")) { //$NON-NLS-1$
				return "win32"; //$NON-NLS-1$
			}
		}
		return result == null ? osname : result;
	}

	public String getCanonicalProcessor(String processor) {
		String result = processorCanonicalTable.get(processor.toLowerCase());
		return result == null ? processor : result;
	}

	private Collection<String> getAlias(String name, Map<String, Collection<String>> aliasMap) {
		if (name == null) {
			return Collections.emptyList();
		}
		Collection<String> aliases = aliasMap == null ? null : aliasMap.get(name);
		if (aliases != null) {
			return Collections.unmodifiableCollection(aliases);
		}
		return Collections.singletonList(name.toLowerCase());
	}

	
Read alias data and populate a Map.
Params:
in – InputStream from which to read alias data.
Returns:
Map of aliases./**
	 * Read alias data and populate a Map.
	 *
	 * @param in InputStream from which to read alias data.
	 * @return Map of aliases.
	 */
	private static Map<String, Collection<String>> initAliases(InputStream in, Map<String, Collection<String>> aliasTable, Map<String, String> canonicalTable) {
		try {
			BufferedReader br = new BufferedReader(new InputStreamReader(in, StandardCharsets.UTF_8));
			Map<String, Set<String>> multiMaster = new HashMap<>();
			while (true) {
				String line = br.readLine();
				if (line == null) /* EOF */ {
					break; /* done */
				}
				Tokenizer tokenizer = new Tokenizer(line);
				String master = tokenizer.getString("# \t"); //$NON-NLS-1$
				if (master != null) {
					String masterLower = master.toLowerCase();
					canonicalTable.put(masterLower, master);
					Collection<String> aliasLine = new ArrayList<>(1);
					aliasLine.add(master);
					parseloop: while (true) {
						String alias = tokenizer.getString("# \t"); //$NON-NLS-1$
						if (alias == null) {
							break parseloop;
						}
						aliasLine.add(alias);
						String aliasLower = alias.toLowerCase();
						if (!canonicalTable.containsKey(aliasLower)) {
							canonicalTable.put(aliasLower, master);
						} else {
							// the alias has multiple masters just make its canonical name be the alias
							String existingMaster = canonicalTable.put(aliasLower, alias);
							Set<String> masters = multiMaster.get(aliasLower);
							if (masters == null) {
								masters = new HashSet<>();
								multiMaster.put(aliasLower, masters);
								masters.add(existingMaster.toLowerCase());
							}
							masters.add(masterLower);
						}
					}
					aliasTable.put(masterLower, aliasLine);
				}
			}
			Map<String, Set<String>> multiMasterAliases = new HashMap<>(multiMaster.size());
			for (Entry<String, Set<String>> entry : multiMaster.entrySet()) {
				Set<String> aliases = new HashSet<>();
				for (String master : entry.getValue()) {
					aliases.addAll(aliasTable.get(master));
				}
				multiMasterAliases.put(entry.getKey(), aliases);
			}
			aliasTable.putAll(multiMasterAliases);
		} catch (IOException e) {
			Debug.printStackTrace(e);
		}
		return aliasTable;
	}
}