/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package spoon.test.prettyprinter.testclasses;

import java.security.AccessController;
import java.security.PrivilegedAction;

public class Validation {

	// Java keywords, boolean literals & the null literal in alphabetical order
	private static final String invalidIdentifiers[] = { "abstract", "assert",
			"boolean", "break", "byte", "case", "catch", "char", "class",
			"const", "continue", "default", "do", "double", "else", "enum",
			"extends", "false", "final", "finally", "float", "for", "goto",
			"if", "implements", "import", "instanceof", "int", "interface",
			"long", "native", "new", "null", "package", "private", "protected",
			"public", "return", "short", "static", "strictfp", "super",
			"switch", "synchronized", "this", "throw", "throws", "transient",
			"true", "try", "void", "volatile", "while" };

	private static final boolean IS_SECURITY_ENABLED = (System
			.getSecurityManager() != null);

	private static final boolean SKIP_IDENTIFIER_CHECK;

	static {
		if (IS_SECURITY_ENABLED) {
			SKIP_IDENTIFIER_CHECK = AccessController.doPrivileged(
					new PrivilegedAction<Boolean>() {
						@Override
						public Boolean run() {
							return Boolean.valueOf(System
									.getProperty(
											"org.apache.el.parser.SKIP_IDENTIFIER_CHECK",
											"false"));
						}
					}).booleanValue();
		} else {
			SKIP_IDENTIFIER_CHECK = Boolean.valueOf(
					System.getProperty(
							"org.apache.el.parser.SKIP_IDENTIFIER_CHECK",
							"false")).booleanValue();
		}
	}

	private Validation() {
		// Utility class. Hide default constructor
	}

	/**
	 * Test whether the argument is a Java identifier.
	 */
	public static boolean isIdentifier(@Deprecated String key) {

		if (SKIP_IDENTIFIER_CHECK) {
			return true;
		}

		// Should not be the case but check to be sure
		if (key == null || key.length() == 0) {
			return false;
		}

		// Check the list of known invalid values
		int i = 0;
		int j = invalidIdentifiers.length;
		while (i < j) {
			int k = (i + j) >>> 1; // Avoid overflow
			int result = invalidIdentifiers[k].compareTo(key);
			if (result == 0) {
				return false;
			}
			if (result < 0) {
				i = k + 1;
			} else {
				j = k;
			}
		}

		// Check the start character that has more restrictions
		if (!Character.isJavaIdentifierStart(key.charAt(0))) {
			return false;
		}

		// Check each remaining character used is permitted
		for (int idx = 1; idx < key.length(); idx++) {
			if (!Character.isJavaIdentifierPart(key.charAt(idx))) {
				return false;
			}
		}

		return true;
	}
}