/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.core;

import java.util.StringTokenizer;

import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IWorkspace;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.jdt.core.compiler.*;
import org.eclipse.jdt.core.compiler.InvalidInputException;
import org.eclipse.jdt.internal.compiler.parser.Scanner;
import org.eclipse.jdt.internal.compiler.parser.TerminalTokens;
import org.eclipse.jdt.internal.compiler.util.SuffixConstants;
import org.eclipse.jdt.internal.core.*;
import org.eclipse.jdt.internal.core.JavaModelStatus;
import org.eclipse.jdt.internal.core.util.Util;

/**
 * Provides methods for checking Java-specific conventions such as name syntax.
 * <p>
 * This class provides static methods and constants only; it is not intended to be
 * instantiated or subclassed by clients.
 * </p>
 */
public final class JavaConventions {

	private final static char DOT= '.';
	private final static Scanner SCANNER = new Scanner();

	private JavaConventions() {
		// Not instantiable
	}

	/**
	 * Returns whether the given package fragment root paths are considered
	 * to overlap.
	 * <p>
	 * Two root paths overlap if one is a prefix of the other, or they point to
	 * the same location. However, a JAR is allowed to be nested in a root.
	 *
	 * @param rootPath1 the first root path
	 * @param rootPath2 the second root path
	 * @return true if the given package fragment root paths are considered to overlap, false otherwise
	 * @deprecated Overlapping roots are allowed in 2.1
	 */
	public static boolean isOverlappingRoots(IPath rootPath1, IPath rootPath2) {
		if (rootPath1 == null || rootPath2 == null) {
			return false;
		}
		String extension1 = rootPath1.getFileExtension();
		String extension2 = rootPath2.getFileExtension();
		if (extension1 != null && (extension1.equalsIgnoreCase(SuffixConstants.EXTENSION_JAR) || extension1.equalsIgnoreCase(SuffixConstants.EXTENSION_ZIP))) {
			return false;
		} 
		if (extension2 != null && (extension2.equalsIgnoreCase(SuffixConstants.EXTENSION_JAR) || extension2.equalsIgnoreCase(SuffixConstants.EXTENSION_ZIP))) {
			return false;
		}
		return rootPath1.isPrefixOf(rootPath2) || rootPath2.isPrefixOf(rootPath1);
	}

	/*
	 * Returns the current identifier extracted by the scanner (without unicode
	 * escapes) from the given id.
	 * Returns <code>null</code> if the id was not valid
	 */
	private static synchronized char[] scannedIdentifier(String id) {
		if (id == null) {
			return null;
		}
		String trimmed = id.trim();
		if (!trimmed.equals(id)) {
			return null;
		}
		try {
			SCANNER.setSource(id.toCharArray());
			int token = SCANNER.getNextToken();
			char[] currentIdentifier;
			try {
				currentIdentifier = SCANNER.getCurrentIdentifierSource();
			} catch (ArrayIndexOutOfBoundsException e) {
				return null;
			}
			int nextToken= SCANNER.getNextToken();
			if (token == TerminalTokens.TokenNameIdentifier 
				&& nextToken == TerminalTokens.TokenNameEOF
				&& SCANNER.startPosition == SCANNER.source.length) { // to handle case where we had an ArrayIndexOutOfBoundsException 
																     // while reading the last token
				return currentIdentifier;
			} else {
				return null;
			}
		}
		catch (InvalidInputException e) {
			return null;
		}
	}

	/**
	 * Validate the given compilation unit name.
	 * A compilation unit name must obey the following rules:
	 * <ul>
	 * <li> it must not be null
	 * <li> it must include the <code>".java"</code> suffix
	 * <li> its prefix must be a valid identifier
	 * <li> it must not contain any characters or substrings that are not valid 
	 *		   on the file system on which workspace root is located.
	 * </ul>
	 * </p>
	 * @param name the name of a compilation unit
	 * @return a status object with code <code>IStatus.OK</code> if
	 *		the given name is valid as a compilation unit name, otherwise a status 
	 *		object indicating what is wrong with the name
	 */
	public static IStatus validateCompilationUnitName(String name) {
		if (name == null) {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.unit.nullName"), null); //$NON-NLS-1$
		}
		if (!org.eclipse.jdt.internal.compiler.util.Util.isJavaFileName(name)) {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.unit.notJavaName"), null); //$NON-NLS-1$
		}
		String identifier;
		int index;
		index = name.lastIndexOf('.');
		if (index == -1) {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.unit.notJavaName"), null); //$NON-NLS-1$
		}
		identifier = name.substring(0, index);
		// JSR-175 metadata strongly recommends "package-info.java" as the
		// file in which to store package annotations and
		// the package-level spec (replaces package.html)
		if (!identifier.equals("package-info")) { //$NON-NLS-1$
			IStatus status = validateIdentifier(identifier);
			if (!status.isOK()) {
				return status;
			}
		}
		IStatus status = ResourcesPlugin.getWorkspace().validateName(name, IResource.FILE);
		if (!status.isOK()) {
			return status;
		}
		return JavaModelStatus.VERIFIED_OK;
	}

	/**
	 * Validate the given .class file name.
	 * A .class file name must obey the following rules:
	 * <ul>
	 * <li> it must not be null
	 * <li> it must include the <code>".class"</code> suffix
	 * <li> its prefix must be a valid identifier
	 * <li> it must not contain any characters or substrings that are not valid 
	 *		   on the file system on which workspace root is located.
	 * </ul>
	 * </p>
	 * @param name the name of a .class file
	 * @return a status object with code <code>IStatus.OK</code> if
	 *		the given name is valid as a .class file name, otherwise a status 
	 *		object indicating what is wrong with the name
	 * @since 2.0
	 */
	public static IStatus validateClassFileName(String name) {
		if (name == null) {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.classFile.nullName"), null); //$NON-NLS-1$
		}
		if (!org.eclipse.jdt.internal.compiler.util.Util.isClassFileName(name)) {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.classFile.notClassFileName"), null); //$NON-NLS-1$
		}
		String identifier;
		int index;
		index = name.lastIndexOf('.');
		if (index == -1) {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.classFile.notClassFileName"), null); //$NON-NLS-1$
		}
		identifier = name.substring(0, index);
		IStatus status = validateIdentifier(identifier);
		if (!status.isOK()) {
			return status;
		}
		status = ResourcesPlugin.getWorkspace().validateName(name, IResource.FILE);
		if (!status.isOK()) {
			return status;
		}
		return JavaModelStatus.VERIFIED_OK;
	}

	/**
	 * Validate the given field name.
	 * <p>
	 * Syntax of a field name corresponds to VariableDeclaratorId (JLS2 8.3).
	 * For example, <code>"x"</code>.
	 *
	 * @param name the name of a field
	 * @return a status object with code <code>IStatus.OK</code> if
	 *		the given name is valid as a field name, otherwise a status 
	 *		object indicating what is wrong with the name
	 */
	public static IStatus validateFieldName(String name) {
		return validateIdentifier(name);
	}

	/**
	 * Validate the given Java identifier.
	 * The identifier must not have the same spelling as a Java keyword,
	 * boolean literal (<code>"true"</code>, <code>"false"</code>), or null literal (<code>"null"</code>).
	 * See section 3.8 of the <em>Java Language Specification, Second Edition</em> (JLS2).
	 * A valid identifier can act as a simple type name, method name or field name.
	 *
	 * @param id the Java identifier
	 * @return a status object with code <code>IStatus.OK</code> if
	 *		the given identifier is a valid Java identifier, otherwise a status 
	 *		object indicating what is wrong with the identifier
	 */
	public static IStatus validateIdentifier(String id) {
		if (scannedIdentifier(id) != null) {
			return JavaModelStatus.VERIFIED_OK;
		} else {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.illegalIdentifier", id), null); //$NON-NLS-1$
		}
	}

	/**
	 * Validate the given import declaration name.
	 * <p>
	 * The name of an import corresponds to a fully qualified type name
	 * or an on-demand package name as defined by ImportDeclaration (JLS2 7.5).
	 * For example, <code>"java.util.*"</code> or <code>"java.util.Hashtable"</code>.
	 *
	 * @param name the import declaration
	 * @return a status object with code <code>IStatus.OK</code> if
	 *		the given name is valid as an import declaration, otherwise a status 
	 *		object indicating what is wrong with the name
	 */
	public static IStatus validateImportDeclaration(String name) {
		if (name == null || name.length() == 0) {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.import.nullImport"), null); //$NON-NLS-1$
		} 
		if (name.charAt(name.length() - 1) == '*') {
			if (name.charAt(name.length() - 2) == '.') {
				return validatePackageName(name.substring(0, name.length() - 2));
			} else {
				return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.import.unqualifiedImport"), null); //$NON-NLS-1$
			}
		}
		return validatePackageName(name);
	}

	/**
	 * Validate the given Java type name, either simple or qualified.
	 * For example, <code>"java.lang.Object"</code>, or <code>"Object"</code>.
	 * <p>
	 *
	 * @param name the name of a type
	 * @return a status object with code <code>IStatus.OK</code> if
	 *		the given name is valid as a Java type name, 
	 *      a status with code <code>IStatus.WARNING</code>
	 *		indicating why the given name is discouraged, 
	 *      otherwise a status object indicating what is wrong with 
	 *      the name
	 */
	public static IStatus validateJavaTypeName(String name) {
		if (name == null) {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.type.nullName"), null); //$NON-NLS-1$
		}
		String trimmed = name.trim();
		if (!name.equals(trimmed)) {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.type.nameWithBlanks"), null); //$NON-NLS-1$
		}
		int index = name.lastIndexOf('.');
		char[] scannedID;
		if (index == -1) {
			// simple name
			scannedID = scannedIdentifier(name);
		} else {
			// qualified name
			String pkg = name.substring(0, index).trim();
			IStatus status = validatePackageName(pkg);
			if (!status.isOK()) {
				return status;
			}
			String type = name.substring(index + 1).trim();
			scannedID = scannedIdentifier(type);
		}
	
		if (scannedID != null) {
			IStatus status = ResourcesPlugin.getWorkspace().validateName(new String(scannedID), IResource.FILE);
			if (!status.isOK()) {
				return status;
			}
			if (CharOperation.contains('$', scannedID)) {
				return new Status(IStatus.WARNING, JavaCore.PLUGIN_ID, -1, Util.bind("convention.type.dollarName"), null); //$NON-NLS-1$
			}
			if ((scannedID.length > 0 && Character.isLowerCase(scannedID[0]))) {
				return new Status(IStatus.WARNING, JavaCore.PLUGIN_ID, -1, Util.bind("convention.type.lowercaseName"), null); //$NON-NLS-1$
			}
			return JavaModelStatus.VERIFIED_OK;
		} else {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.type.invalidName", name), null); //$NON-NLS-1$
		}
	}

	/**
	 * Validate the given method name.
	 * The special names "&lt;init&gt;" and "&lt;clinit&gt;" are not valid.
	 * <p>
	 * The syntax for a method  name is defined by Identifier
	 * of MethodDeclarator (JLS2 8.4). For example "println".
	 *
	 * @param name the name of a method
	 * @return a status object with code <code>IStatus.OK</code> if
	 *		the given name is valid as a method name, otherwise a status 
	 *		object indicating what is wrong with the name
	 */
	public static IStatus validateMethodName(String name) {

		return validateIdentifier(name);
	}

	/**
	 * Validate the given package name.
	 * <p>
	 * The syntax of a package name corresponds to PackageName as
	 * defined by PackageDeclaration (JLS2 7.4). For example, <code>"java.lang"</code>.
	 * <p>
	 * Note that the given name must be a non-empty package name (that is, attempting to
	 * validate the default package will return an error status.)
	 * Also it must not contain any characters or substrings that are not valid 
	 * on the file system on which workspace root is located.
	 *
	 * @param name the name of a package
	 * @return a status object with code <code>IStatus.OK</code> if
	 *		the given name is valid as a package name, otherwise a status 
	 *		object indicating what is wrong with the name
	 */
	public static IStatus validatePackageName(String name) {

		if (name == null) {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.package.nullName"), null); //$NON-NLS-1$
		}
		int length;
		if ((length = name.length()) == 0) {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.package.emptyName"), null); //$NON-NLS-1$
		}
		if (name.charAt(0) == DOT || name.charAt(length-1) == DOT) {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.package.dotName"), null); //$NON-NLS-1$
		}
		if (CharOperation.isWhitespace(name.charAt(0)) || CharOperation.isWhitespace(name.charAt(name.length() - 1))) {
			return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.package.nameWithBlanks"), null); //$NON-NLS-1$
		}
		int dot = 0;
		while (dot != -1 && dot < length-1) {
			if ((dot = name.indexOf(DOT, dot+1)) != -1 && dot < length-1 && name.charAt(dot+1) == DOT) {
				return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.package.consecutiveDotsName"), null); //$NON-NLS-1$
				}
		}
		IWorkspace workspace = ResourcesPlugin.getWorkspace();
		StringTokenizer st = new StringTokenizer(name, new String(new char[] {DOT}));
		boolean firstToken = true;
		while (st.hasMoreTokens()) {
			String typeName = st.nextToken();
			typeName = typeName.trim(); // grammar allows spaces
			char[] scannedID = scannedIdentifier(typeName);
			if (scannedID == null) {
				return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, -1, Util.bind("convention.illegalIdentifier", typeName), null); //$NON-NLS-1$
			}
			IStatus status = workspace.validateName(new String(scannedID), IResource.FOLDER);
			if (!status.isOK()) {
				return status;
			}
			if (firstToken && scannedID.length > 0 && Character.isUpperCase(scannedID[0])) {
				return new Status(IStatus.WARNING, JavaCore.PLUGIN_ID, -1, Util.bind("convention.package.uppercaseName"), null); //$NON-NLS-1$
			}
			firstToken = false;
		}
		return JavaModelStatus.VERIFIED_OK;
	}
	
	/**
	 * Validate a given classpath and output location for a project, using the following rules:
	 * <ul>
	 *   <li> Classpath entries cannot collide with each other; that is, all entry paths must be unique.
	 *   <li> The project output location path cannot be null, must be absolute and located inside the project.
	 *   <li> Specific output locations (specified on source entries) can be null, if not they must be located inside the project,
	 *   <li> A project entry cannot refer to itself directly (that is, a project cannot prerequisite itself).
     *   <li> Classpath entries or output locations cannot coincidate or be nested in each other, except for the following scenarii listed below:
	 *      <ul><li> A source folder can coincidate with its own output location, in which case this output can then contain library archives. 
	 *                     However, a specific output location cannot coincidate with any library or a distinct source folder than the one referring to it. </li> 
	 *              <li> A source/library folder can be nested in any source folder as long as the nested folder is excluded from the enclosing one. </li>
	 * 			<li> An output location can be nested in a source folder, if the source folder coincidates with the project itself, or if the output
	 * 					location is excluded from the source folder.
	 *      </ul>
	 * </ul>
	 * 
	 *  Note that the classpath entries are not validated automatically. Only bound variables or containers are considered 
	 *  in the checking process (this allows to perform a consistency check on a classpath which has references to
	 *  yet non existing projects, folders, ...).
	 *  <p>
	 *  This validation is intended to anticipate classpath issues prior to assigning it to a project. In particular, it will automatically
	 *  be performed during the classpath setting operation (if validation fails, the classpath setting will not complete).
	 *  <p>
	 * @param javaProject the given java project
	 * @param rawClasspath the given classpath
	 * @param projectOutputLocation the given output location
	 * @return a status object with code <code>IStatus.OK</code> if
	 *		the given classpath and output location are compatible, otherwise a status 
	 *		object indicating what is wrong with the classpath or output location
	 * @since 2.0
	 */
	public static IJavaModelStatus validateClasspath(IJavaProject javaProject, IClasspathEntry[] rawClasspath, IPath projectOutputLocation) {

		return ClasspathEntry.validateClasspath(javaProject, rawClasspath, projectOutputLocation);
	}
	
	/**
	 * Returns a Java model status describing the problem related to this classpath entry if any, 
	 * a status object with code <code>IStatus.OK</code> if the entry is fine (that is, if the
	 * given classpath entry denotes a valid element to be referenced onto a classpath).
	 * 
	 * @param project the given java project
	 * @param entry the given classpath entry
	 * @param checkSourceAttachment a flag to determine if source attachement should be checked
	 * @return a java model status describing the problem related to this classpath entry if any, a status object with code <code>IStatus.OK</code> if the entry is fine
	 * @since 2.0
	 */
	public static IJavaModelStatus validateClasspathEntry(IJavaProject project, IClasspathEntry entry, boolean checkSourceAttachment){
		return ClasspathEntry.validateClasspathEntry(project, entry, checkSourceAttachment, true/*recurse in container*/);
	}
}