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/**
 * Original work: copyright 1999-2004 The Apache Software Foundation
 * (http://www.apache.org/)
 *
 * This project is based on the work 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.
 *
 * Modified work: copyright 2013-2022 Valery Silaev (http://vsilaev.com)
 *
 * Licensed 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 org.apache.commons.javaflow.spi;

import java.io.IOException;
import java.io.InputStream;
import java.lang.ref.Reference;
import java.lang.ref.WeakReference;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

public class ClasspathResourceLoader implements VetoableResourceLoader {

    private final Reference classLoaderRef;
    
    public ClasspathResourceLoader(ClassLoader classLoader) {
        this.classLoaderRef = new WeakReference(classLoader);
    }

    public boolean hasResource(String name) {
        ClassLoader classLoader = classLoaderRef.get();
        return null != classLoader && null != classLoader.getResource(name);
    }
    
    public InputStream getResourceAsStream(String name) throws IOException {
        ClassLoader classLoader = classLoaderRef.get();
        if (null == classLoader) {
            throw new IOException("Underlying class loader was evicted from memory, this resource loader is unusable");
        }
        
        InputStream result = classLoader.getResourceAsStream(name);
        if (null == result) {
            throw new IOException("Unable to find resource " + name);
        }
        return result;
    }
    
    public ClassMatcher createVeto() throws IOException {
        return getVetoStrategy().bind(this);
    }
    
    public ClassMatchStrategy getVetoStrategy() throws IOException {
        List strategies = new ArrayList();
        ClassLoader classLoader = classLoaderRef.get();
        if (null == classLoader) {
            return ClassMatchStrategies.MATCH_NONE;
        }
        Enumeration allResources = classLoader.getResources("META-INF/net.tascalate.javaflow.veto.cmf");
        ClassMatchStrategyFileParser parser = new ClassMatchStrategyFileParser();
        while (allResources.hasMoreElements()) {
            URL resource = allResources.nextElement();
            ClassMatchStrategy strategy = parser.parse(resource);
            if (null != strategy && ClassMatchStrategies.MATCH_NONE != strategy) {
                strategies.add(strategy);
            }
        }
        return strategies.isEmpty() ? ClassMatchStrategies.MATCH_NONE : ClassMatchStrategies.whenAny(strategies);
    }
}