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/*
 * Copyright 2000,2005 wingS development team.
 *
 * This file is part of wingS (http://wingsframework.org).
 *
 * wingS is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1
 * of the License, or (at your option) any later version.
 *
 * Please see COPYING for the complete licence.
 */
package org.wings.resource;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.wings.externalizer.ExternalizeManager;
import org.wings.session.SessionManager;

import java.io.IOException;
import java.io.InputStream;

/**
 * A ClassPathStylesheetResource is a static resource whose content is
 * read from a classloader. It is special for its handling of occurences
 * of "url([classPath])" strings. These are read from classPath and 
 * externalized.
 *
 * @author ole
 * @version $$
 */
public class ClassPathStylesheetResource
        extends ClassPathResource {
    private final transient static Logger log = LoggerFactory.getLogger(ClassPathStylesheetResource.class);
    /**
     * The default max size for the buffer. since we do some replacement every time we
     * read the input stream, we want this to be high, so we can cache the
     * interpreted style sheet.
     */
    private static final int MAX_BUFFER_SIZE = 24 * 1024; // 24kb

    private transient ExternalizeManager extManager;

    /**
     * A static css resource that is obtained from the default classpath.
     */
    public ClassPathStylesheetResource(String resourceFileName) {
        this(Thread.currentThread().getContextClassLoader(), resourceFileName, "unkonwn");
    }

    /**
     * A static css resource that is obtained from the default classpath.
     */
    public ClassPathStylesheetResource(String resourceFileName, String mimeType) {
        this(Thread.currentThread().getContextClassLoader(), resourceFileName, mimeType);
    }

    /**
     * A static css resource that is obtained from the specified class loader
     *
     * @param classLoader      the classLoader from which the resource is obtained
     * @param resourceFileName the css resource relative to the baseClass
     */
    public ClassPathStylesheetResource(ClassLoader classLoader, String resourceFileName) {
        this(classLoader, resourceFileName, "unknown");
    }

    /**
     * A static css resource that is obtained from the specified class loader
     *
     * @param classLoader      the classLoader from which the resource is obtained
     * @param resourceFileName the css resource relative to the baseClass
     * @param mimeType         the mimetype of the resource
     */
    public ClassPathStylesheetResource(ClassLoader classLoader, String resourceFileName, String mimeType) {
        this(classLoader, resourceFileName, mimeType, MAX_BUFFER_SIZE);
    }

    /**
     * A static css resource that is obtained from the specified class loader
     *
     * @param classLoader      the classLoader from which the resource is obtained
     * @param resourceFileName the css resource relative to the baseClass
     * @param mimeType         the mimetype of the resource
     * @param maxBufferSize    the maximum buffer size for the style sheet. If
     *                         big enough, stylesheet is cached, else parsed again. 
     */
    public ClassPathStylesheetResource(ClassLoader classLoader, String resourceFileName, String mimeType, int maxBufferSize) {
        super(classLoader, resourceFileName, mimeType);
        // need to set it here, because at this moment there is a session in the sessionManager
        extManager = SessionManager.getSession().getExternalizeManager();
        // we need a bigger buffer, so that the parsing only happens once
        setMaxBufferSize(maxBufferSize);
    }

    /* (non-Javadoc)
     * @see org.wings.StaticResource#getResourceStream()
     */
    @Override
    protected final InputStream getResourceStream() throws ResourceNotFoundException {
        InputStream in = getClassLoader().getResourceAsStream(resourceFileName);
        if (in != null) {
            return new CssUrlFilterInputStream(in, getExtManager());
        } else {
            throw new ResourceNotFoundException("Unable to find classpath resource "+resourceFileName);
        }
    }

    /*
     * the equal() and hashCode() method make sure, that the same resources
     * get the same name in the SystemExternalizer.
     */

    /**
     * Two ClassPathStylesheetResource are equal if both of them are instances
     * of ClassPathStylesheetResource and the equals method of ClassPathResource
     * is true.
     *
     * @return true if the two instances are equal.
     */
    public boolean equals(Object o) {
        if (o instanceof ClassPathStylesheetResource) {
            if (super.equals(o)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Simple hascode implementation
     */
    public int hashCode() {
        return super.hashCode();
    }

    /* (non-Javadoc)
     * @see org.wings.StaticResource#bufferResource()
     */
    @Override
    protected LimitedBuffer bufferResource() throws IOException, ResourceNotFoundException {
        try {
            return super.bufferResource();
        } catch (IOException e) {
            log.error("Unable to retrieve css file from classpath: '"+resourceFileName); 
            throw e; 
        }
    }

    private ExternalizeManager getExtManager() {
        if (extManager == null)
            // need to set it here, because at this moment there is a session in the sessionManager
            extManager = SessionManager.getSession().getExternalizeManager();
        return extManager;
    }
}