/*
 *  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
 *
 *      https://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 org.apache.tools.ant.util.depend;
import java.io.File;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Vector;
import java.util.zip.ZipFile;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.types.Path;
import org.apache.tools.ant.util.VectorSet;

An abstract implementation of the analyzer interface providing support
for the bulk of interface methods.
/**
 * An abstract implementation of the analyzer interface providing support
 * for the bulk of interface methods.
 *
 */
public abstract class AbstractAnalyzer implements DependencyAnalyzer {
    
Maximum number of loops for looking for indirect dependencies. /** Maximum number of loops for looking for indirect dependencies. */
    public static final int MAX_LOOPS = 1000;

    
The source path for the source files /** The source path for the source files */
    private Path sourcePath = new Path(null);

    
The classpath containing dirs and jars of class files /** The classpath containing dirs and jars of class files */
    private Path classPath = new Path(null);

    
The list of root classes /** The list of root classes */
    private final Vector<String> rootClasses = new VectorSet<>();

    
true if dependencies have been determined /** true if dependencies have been determined */
    private boolean determined = false;

    
the list of File objects that the root classes depend upon /** the list of File objects that the root classes depend upon */
    private Vector<File> fileDependencies;
    
the list of java classes the root classes depend upon /** the list of java classes the root classes depend upon */
    private Vector<String> classDependencies;

    
true if indirect dependencies should be gathered /** true if indirect dependencies should be gathered */
    private boolean closure = true;

    
Setup the analyzer /** Setup the analyzer */
    protected AbstractAnalyzer() {
        reset();
    }

    
Set the closure flag. If this flag is true the analyzer will traverse
all class relationships until it has collected the entire set of
direct and indirect dependencies
Params:
closure – true if dependencies should be traversed to determine
     indirect dependencies./**
     * Set the closure flag. If this flag is true the analyzer will traverse
     * all class relationships until it has collected the entire set of
     * direct and indirect dependencies
     *
     * @param closure true if dependencies should be traversed to determine
     *      indirect dependencies.
     */
    @Override
    public void setClosure(boolean closure) {
        this.closure = closure;
    }

    
Get the list of files in the file system upon which the root classes
depend. The files will be either the classfiles or jar files upon
which the root classes depend.
Returns:
an enumeration of File instances./**
     * Get the list of files in the file system upon which the root classes
     * depend. The files will be either the classfiles or jar files upon
     * which the root classes depend.
     *
     * @return an enumeration of File instances.
     */
    @Override
    public Enumeration<File> getFileDependencies() {
        if (!supportsFileDependencies()) {
            throw new BuildException(
                "File dependencies are not supported by this analyzer");
        }
        if (!determined) {
            determineDependencies(fileDependencies, classDependencies);
        }
        return fileDependencies.elements();
    }

    
Get the list of classes upon which root classes depend. This is a
list of Java classnames in dot notation.
Returns:
an enumeration of Strings, each being the name of a Java
     class in dot notation./**
     * Get the list of classes upon which root classes depend. This is a
     * list of Java classnames in dot notation.
     *
     * @return an enumeration of Strings, each being the name of a Java
     *      class in dot notation.
     */
    @Override
    public Enumeration<String> getClassDependencies() {
        if (!determined) {
            determineDependencies(fileDependencies, classDependencies);
        }
        return classDependencies.elements();
    }

    
Get the file that contains the class definition
Params:
classname – the name of the required class
Throws:
IOException – if the files in the classpath cannot be read.
Returns:
the file instance, zip or class, containing the
        class or null if the class could not be found./**
     * Get the file that contains the class definition
     *
     * @param classname the name of the required class
     * @return the file instance, zip or class, containing the
     *         class or null if the class could not be found.
     * @exception IOException if the files in the classpath cannot be read.
     */
    @Override
    public File getClassContainer(String classname) throws IOException {
        String classLocation = classname.replace('.', '/') + ".class";
        // we look through the classpath elements. If the element is a dir
        // we look for the file. IF it is a zip, we look for the zip entry
        return getResourceContainer(classLocation, classPath.list());
    }

    
Get the file that contains the class source.
Params:
classname – the name of the required class
Throws:
IOException – if the files in the sourcepath cannot be read.
Returns:
the file instance, zip or java, containing the
        source or null if the source for the class could not be found./**
     * Get the file that contains the class source.
     *
     * @param classname the name of the required class
     * @return the file instance, zip or java, containing the
     *         source or null if the source for the class could not be found.
     * @exception IOException if the files in the sourcepath cannot be read.
     */
    @Override
    public File getSourceContainer(String classname) throws IOException {
        String sourceLocation = classname.replace('.', '/') + ".java";

        // we look through the source path elements. If the element is a dir
        // we look for the file. If it is a zip, we look for the zip entry.
        // This isn't normal for source paths but we get it for free
        return getResourceContainer(sourceLocation, sourcePath.list());
    }

    
Add a source path to the source path used by this analyzer. The
elements in the given path contain the source files for the classes
being analyzed. Not all analyzers will use this information.
Params:
sourcePath – The Path instance specifying the source path
     elements./**
     * Add a source path to the source path used by this analyzer. The
     * elements in the given path contain the source files for the classes
     * being analyzed. Not all analyzers will use this information.
     *
     * @param sourcePath The Path instance specifying the source path
     *      elements.
     */
    @Override
    public void addSourcePath(Path sourcePath) {
        if (sourcePath == null) {
            return;
        }
        this.sourcePath.append(sourcePath);
        this.sourcePath.setProject(sourcePath.getProject());
    }

    
Add a classpath to the classpath being used by the analyzer. The
classpath contains the binary classfiles for the classes being
analyzed The elements may either be the directories or jar files.Not
all analyzers will use this information.
Params:
classPath – the Path instance specifying the classpath elements/**
     * Add a classpath to the classpath being used by the analyzer. The
     * classpath contains the binary classfiles for the classes being
     * analyzed The elements may either be the directories or jar files.Not
     * all analyzers will use this information.
     *
     * @param classPath the Path instance specifying the classpath elements
     */
    @Override
    public void addClassPath(Path classPath) {
        if (classPath == null) {
            return;
        }

        this.classPath.append(classPath);
        this.classPath.setProject(classPath.getProject());
    }

    
Add a root class. The root classes are used to drive the
determination of dependency information. The analyzer will start at
the root classes and add dependencies from there.
Params:
className – the name of the class in Java dot notation./**
     * Add a root class. The root classes are used to drive the
     * determination of dependency information. The analyzer will start at
     * the root classes and add dependencies from there.
     *
     * @param className the name of the class in Java dot notation.
     */
    @Override
    public void addRootClass(String className) {
        if (className == null) {
            return;
        }
        if (!rootClasses.contains(className)) {
            rootClasses.addElement(className);
        }
    }

    
Configure an aspect of the analyzer. The set of aspects that are
supported is specific to each analyzer instance.
Params:
name – the name of the aspect being configured
info – the configuration info./**
     * Configure an aspect of the analyzer. The set of aspects that are
     * supported is specific to each analyzer instance.
     *
     * @param name the name of the aspect being configured
     * @param info the configuration info.
     */
    @Override
    public void config(String name, Object info) {
        // do nothing by default
    }

    
Reset the dependency list. This will reset the determined
dependencies and the also list of root classes.
/**
     * Reset the dependency list. This will reset the determined
     * dependencies and the also list of root classes.
     */
    @Override
    public void reset() {
        rootClasses.removeAllElements();
        determined = false;
        fileDependencies = new Vector<>();
        classDependencies = new Vector<>();
    }

    
Get an enumeration of the root classes
Returns:
an enumeration of Strings, each of which is a class name
        for a root class./**
     * Get an enumeration of the root classes
     *
     * @return an enumeration of Strings, each of which is a class name
     *         for a root class.
     */
    protected Enumeration<String> getRootClasses() {
        return rootClasses.elements();
    }

    
Indicate if the analyzer is required to follow
indirect class relationships.
Returns:
true if indirect relationships should be followed./**
     * Indicate if the analyzer is required to follow
     * indirect class relationships.
     *
     * @return true if indirect relationships should be followed.
     */
    protected boolean isClosureRequired() {
        return closure;
    }

    
Determine the dependencies of the current set of root classes
Params:
files – a vector into which Files upon which the root classes
     depend should be placed.
classes – a vector of Strings into which the names of classes
     upon which the root classes depend should be placed./**
     * Determine the dependencies of the current set of root classes
     *
     * @param files a vector into which Files upon which the root classes
     *      depend should be placed.
     * @param classes a vector of Strings into which the names of classes
     *      upon which the root classes depend should be placed.
     */
    protected abstract void determineDependencies(Vector<File> files, Vector<String> classes);

    
Indicate if the particular subclass supports file dependency
information.
Returns:
true if file dependencies are supported./**
     * Indicate if the particular subclass supports file dependency
     * information.
     *
     * @return true if file dependencies are supported.
     */
    protected abstract boolean supportsFileDependencies();

    
Get the file that contains the resource
Params:
resourceLocation – the name of the required resource.
paths – the paths which will be searched for the resource.
Throws:
IOException – if the files in the given paths cannot be read.
Returns:
the file instance, zip or class, containing the
        class or null if the class could not be found./**
     * Get the file that contains the resource
     *
     * @param resourceLocation the name of the required resource.
     * @param paths the paths which will be searched for the resource.
     * @return the file instance, zip or class, containing the
     *         class or null if the class could not be found.
     * @exception IOException if the files in the given paths cannot be read.
     */
    private File getResourceContainer(String resourceLocation, String[] paths)
         throws IOException {
        for (String path : paths) {
            File element = new File(path);
            if (!element.exists()) {
                continue;
            }
            if (element.isDirectory()) {
                File resource = new File(element, resourceLocation);
                if (resource.exists()) {
                    return resource;
                }
            } else {
                // must be a zip of some sort
                try (ZipFile zipFile = new ZipFile(element)) {
                    if (zipFile.getEntry(resourceLocation) != null) {
                        return element;
                    }
                }
            }
        }
        return null;
    }
}