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Cristal-ise is a description-driven software platform originally developed to track the construction of the CMS ECAL detector of the LHC at CERN. This is its core library, known as the kernel, which manages business objects called Items. Items are entirely configured from data, called descriptions, held in other Items. Every change of a state in an Item is a consequence of an execution of an activity in that Item's lifecycle, meaning that Cristal-ise applications are completely traceable, even in their design. It also supports extensive versioning of Item description data, giving the system a high level of flexibility.

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/**
 * This file is part of the CRISTAL-iSE kernel.
 * Copyright (c) 2001-2015 The CRISTAL Consortium. All rights reserved.
 *
 * This library 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 3 of the License, or (at
 * your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; with out even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * http://www.fsf.org/licensing/licenses/lgpl.html
 */
package org.cristalise.kernel.process.resource;

import java.net.MalformedURLException;
import java.net.URL;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Hashtable;

import org.cristalise.kernel.common.InvalidDataException;
import org.cristalise.kernel.common.ObjectNotFoundException;
import org.cristalise.kernel.utils.FileStringUtility;
import org.cristalise.kernel.utils.Logger;

/**
 * Default implementation of ResourceLoader
 *
 */
public class Resource implements ResourceLoader {

    private final Hashtable txtCache = new Hashtable();
    private final URL baseURL;
    private final HashMap moduleBaseURLs = new HashMap();
    private final HashMap allBaseURLs = new HashMap();

    public Resource() throws InvalidDataException {
        baseURL = getURLorResURL("org/cristalise/kernel/utils/resources/");
        allBaseURLs.put(null, baseURL);
    }

    @Override
    public URL getKernelBaseURL() {
        return baseURL;
    }

    @Override
    public ClassLoader getClassLoader(String className) { 
        return Resource.class.getClassLoader();
    }

    @Override
    public Class getClassForName(String name) throws ClassNotFoundException {
        return Class.forName(name);
    }

    @Override
    public URL getKernelResourceURL(String resName) throws MalformedURLException {
        return new URL(baseURL, resName);
    }

    @Override
    public void addModuleBaseURL(String ns, URL newBaseURL) {
        moduleBaseURLs.put(ns, newBaseURL);
        allBaseURLs.put(ns, newBaseURL);
        Logger.msg("Adding resource URL for "+ns+": "+newBaseURL.toString());
    }

    @Override
    public void addModuleBaseURL(String ns, String newBaseURL) throws InvalidDataException {
        addModuleBaseURL(ns, getURLorResURL(newBaseURL));
    }

    @Override
    public HashMap getModuleBaseURLs() {
        return moduleBaseURLs;
    }

    private HashMap getAllBaseURLs() {
        return allBaseURLs;
    }

    @Override
    public URL getModuleResourceURL(String ns, String resName) throws MalformedURLException {
        if (!moduleBaseURLs.containsKey(ns)) throw new MalformedURLException("Could not locate resource. Namespace '"+ns+"' not registered.");
        return new URL(moduleBaseURLs.get(ns), resName);
    }

    static private URL getURLorResURL(String newURL) throws InvalidDataException {
        URL result;
        try {
            result = new URL(newURL);
        }
        catch (java.net.MalformedURLException ex) {
            //it is assumed that a 'wrong' URL denotes a directory of files resolvable from the CLASSPATH
            result = Resource.class.getClassLoader().getResource(newURL);
        }
        if (result == null) {
            Logger.error("URL "+newURL+" could not be found");
            throw new InvalidDataException();
        }
        return result;
    }

    @Override
    public String findTextResource(String resName) {
        for (String ns : getAllBaseURLs().keySet()) {
            try {
                return getTextResource(ns, resName);
            }
            catch (ObjectNotFoundException ex) { }
        }
        Logger.warning("Text resource '"+resName+"' not found.");
        return null;
    }

    @Override
    public HashMap getAllTextResources(String resName) {
        HashMap results = new HashMap();
        for (String ns : getAllBaseURLs().keySet()) {
            try {
                results.put(ns, getTextResource(ns, resName));
            }
            catch (ObjectNotFoundException ex) { }
        }
        return results;
    }

    @Override
    public String getTextResource(String ns, String resName) throws ObjectNotFoundException {
        Logger.msg(8, "Resource::getTextResource() - Getting resource from namespacce "+ns+": " + resName);

        if (txtCache.containsKey(ns+'/'+resName)) {
            return txtCache.get(ns+'/'+resName);
        }

        try {
            String newRes = null;
            URL loc;

            if (ns == null) // kernel
                loc = getKernelResourceURL(resName);
            else
                loc = getModuleResourceURL(ns, resName);

            Logger.msg(5, "Loading resource: "+loc.toString());
            newRes = FileStringUtility.url2String(loc);
            txtCache.put(ns+'/'+resName, newRes);
            return newRes;
        }
        catch (Exception e) {
            Logger.error(e);
            throw new ObjectNotFoundException(e.getMessage());
        }
    }

    @Override
    public Enumeration getModuleDefURLs() throws Exception {
        return getClassLoader("").getResources("META-INF/cristal/module.xml");
        //return ClassLoader.getSystemResources("META-INF/cristal/module.xml");
    }
}