Copyright (c) 2017 Till Brychcy 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:
    Till Brychcy - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2017 Till Brychcy 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:
 *     Till Brychcy - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.compiler.env;

import java.io.File;
import java.io.IOException;
import java.util.jar.JarFile;
import java.util.jar.Manifest;

public class AutomaticModuleNaming {

	private static final String AUTOMATIC_MODULE_NAME = "Automatic-Module-Name"; //$NON-NLS-1$

	
Determine the automatic module name of a given jar as specified in <a href=
	 * "http://download.java.net/java/jdk9/docs/api/java/lang/module/ModuleFinder.html#of-java.nio.file.Path...-">
	 * ModuleFinder.of</a> /**
	 * Determine the automatic module name of a given jar as specified in {@link <a href=
	 * "http://download.java.net/java/jdk9/docs/api/java/lang/module/ModuleFinder.html#of-java.nio.file.Path...-">
	 * ModuleFinder.of</a>}
	 */
	public static char[] determineAutomaticModuleName(final String jarFileName) {
		// "If the JAR file has the attribute "Automatic-Module-Name" in its main manifest then its value is the
		// module name."
		try (JarFile jar = new JarFile(jarFileName)) {
			Manifest manifest = jar.getManifest();
			if (manifest != null) {
				String automaticModuleName = manifest.getMainAttributes().getValue(AUTOMATIC_MODULE_NAME);
				if (automaticModuleName != null) {
					return automaticModuleName.toCharArray();
				}
			}
		} catch (IOException e) {
			// ignore
		}
		// The module name is otherwise derived from the name of the JAR file.
		return determineAutomaticModuleNameFromFileName(jarFileName, true, true);
	}

	
Determine the automatic module name of a given jar or project as specified in <a href=
	 * "http://download.java.net/java/jdk9/docs/api/java/lang/module/ModuleFinder.html#of-java.nio.file.Path...-">
	 * ModuleFinder.of</a> 
Params:
fileName – names either a jar file or a java project in the workspace
isFile – true indicates that fileName denotes a file, false must be used for projects
manifest – representation of the META-INF/MANIFEST.MF entry within the given source (jar or project), or null
Returns:
the derived module name or null/**
	 * Determine the automatic module name of a given jar or project as specified in {@link <a href=
	 * "http://download.java.net/java/jdk9/docs/api/java/lang/module/ModuleFinder.html#of-java.nio.file.Path...-">
	 * ModuleFinder.of</a>}
	 * @param fileName names either a jar file or a java project in the workspace
	 * @param isFile <code>true</code> indicates that fileName denotes a file, <code>false</code> must be used for projects
	 * @param manifest representation of the META-INF/MANIFEST.MF entry within the given source (jar or project), or <code>null</code>
	 * @return the derived module name or <code>null</code>
	 */
	public static char[] determineAutomaticModuleName(final String fileName, boolean isFile, Manifest manifest) {
		if (manifest != null) {
			String automaticModuleName = manifest.getMainAttributes().getValue(AUTOMATIC_MODULE_NAME);
			if (automaticModuleName != null) {
				return automaticModuleName.toCharArray();
			}
		}
		return determineAutomaticModuleNameFromFileName(fileName, true, isFile);
	}

	
Determine the automatic module name of a given jar or project as defined by an Automatic-Module-Name
header in its manifest.
Params:
manifest – representation of the META-INF/MANIFEST.MF entry within the given source (jar or project), or null
Returns:
the derived module name or null/**
	 * Determine the automatic module name of a given jar or project as defined by an Automatic-Module-Name
	 * header in its manifest.
	 * @param manifest representation of the META-INF/MANIFEST.MF entry within the given source (jar or project), or <code>null</code>
	 * @return the derived module name or <code>null</code>
	 */
	public static char[] determineAutomaticModuleNameFromManifest(Manifest manifest) {
		if (manifest != null) {
			String automaticModuleName = manifest.getMainAttributes().getValue(AUTOMATIC_MODULE_NAME);
			if (automaticModuleName != null) {
				return automaticModuleName.toCharArray();
			}
		}
		return null;
	}

	
Determine the automatic module name if no "Automatic-Module-Name" was found in the Manifest, as specified in <a href=
	 * "http://download.java.net/java/jdk9/docs/api/java/lang/module/ModuleFinder.html#of-java.nio.file.Path...-">ModuleFinder.of</a> 
Params:
name – 
           the filename (or directory name)
skipDirectory – 
           if true, parent directory names are skipped
removeExtension – 
           if true, the ".jar" extension is removed./**
	 * Determine the automatic module name if no "Automatic-Module-Name" was found in the Manifest, as specified in
	 * {@link <a href=
	 * "http://download.java.net/java/jdk9/docs/api/java/lang/module/ModuleFinder.html#of-java.nio.file.Path...-">ModuleFinder.of</a>}
	 * 
	 * @param name
	 *            the filename (or directory name)
	 * @param skipDirectory
	 *            if true, parent directory names are skipped
	 * @param removeExtension
	 *            if true, the ".jar" extension is removed.
	 */
	public static char[] determineAutomaticModuleNameFromFileName(String name, boolean skipDirectory,
			boolean removeExtension) {
		int index;
		int start = 0;
		int end = name.length();
		if (skipDirectory) {
			index = name.lastIndexOf(File.separatorChar);
			start = index + 1;
		}

		// "The ".jar" suffix is removed"
		if (removeExtension) {
			if (name.endsWith(".jar") || name.endsWith(".JAR")) { //$NON-NLS-1$//$NON-NLS-2$
				end -= 4;
			}
		}

		// "If the name matches the regular expression "-(\\d+(\\.|$))" then the module name will be derived from the
		// subsequence preceding the hyphen of the first occurrence. [...]"
		dashLoop: for (index = start; index < end - 1; index++) {
			if (name.charAt(index) == '-' && name.charAt(index + 1) >= '0' && name.charAt(index + 1) <= '9') {
				for (int index2 = index + 2; index2 < end; index2++) {
					final char c = name.charAt(index2);
					if (c == '.') {
						break;
					}
					if (c < '0' || c > '9') {
						continue dashLoop;
					}
				}
				end = index;
				break;
			}
		}

		// "All non-alphanumeric characters ([^A-Za-z0-9]) in the module name are replaced with a dot ("."), all
		// repeating dots are replaced with one dot, and all leading and trailing dots are removed."
		StringBuilder sb = new StringBuilder(end - start);
		boolean needDot = false;
		for (int i = start; i < end; i++) {
			char c = name.charAt(i);
			if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9')) {
				if (needDot) {
					sb.append('.');
					needDot = false;
				}
				sb.append(c);
			} else {
				if (sb.length() > 0) {
					needDot = true;
				}
			}
		}
		return sb.toString().toCharArray();
	}

}