/*
 * 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.bcel.util;

import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;

import org.apache.bcel.classfile.ClassParser;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Utility;

/**
 * The repository maintains information about which classes have been loaded.
 *
 * It loads its data from the ClassLoader implementation passed into its constructor.
 *
 * @see org.apache.bcel.Repository
 */
public class ClassLoaderRepository implements Repository {

    private final java.lang.ClassLoader loader;
    private final Map<String, JavaClass> loadedClasses = new HashMap<>(); // CLASSNAME X JAVACLASS

    /**
     * Constructs a ClassLoaderRepository.
     *
     * @param loader the class loader.
     */
    public ClassLoaderRepository(final java.lang.ClassLoader loader) {
        this.loader = loader;
    }

    /**
     * Clear all entries from cache.
     */
    @Override
    public void clear() {
        loadedClasses.clear();
    }

    /**
     * Find an already defined JavaClass.
     */
    @Override
    public JavaClass findClass(final String className) {
        return loadedClasses.get(className);
    }

    /*
     * @return null.
     */
    @Override
    public ClassPath getClassPath() {
        return null;
    }

    @Override
    public JavaClass loadClass(final Class<?> clazz) throws ClassNotFoundException {
        return loadClass(clazz.getName());
    }

    /**
     * Lookup a JavaClass object from the Class Name provided.
     */
    @Override
    public JavaClass loadClass(final String className) throws ClassNotFoundException {
        final String classFile = Utility.packageToPath(className);
        JavaClass RC = findClass(className);
        if (RC != null) {
            return RC;
        }
        try (InputStream is = loader.getResourceAsStream(classFile + JavaClass.EXTENSION)) {
            if (is == null) {
                throw new ClassNotFoundException(className + " not found.");
            }
            final ClassParser parser = new ClassParser(is, className);
            RC = parser.parse();
            storeClass(RC);
            return RC;
        } catch (final IOException e) {
            throw new ClassNotFoundException(className + " not found: " + e, e);
        }
    }

    /**
     * Remove class from repository
     */
    @Override
    public void removeClass(final JavaClass clazz) {
        loadedClasses.remove(clazz.getClassName());
    }

    /**
     * Store a new JavaClass into this Repository.
     */
    @Override
    public void storeClass(final JavaClass clazz) {
        loadedClasses.put(clazz.getClassName(), clazz);
        clazz.setRepository(this);
    }
}
