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Concourse is a self-tuning database that is designed for both ad hoc analytics and high volume transactions at scale. Developers use Concourse to quickly build mission critical software while also benefiting from real time insight into their most important data. With Concourse, end-to-end data management requires no extra infrastructure, no prior configuration and no additional coding–all of which greatly reduce costs and allow developers to focus on core business problems.

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/*
 * Copyright (c) 2013-2019 Cinchapi Inc.
 *
 * 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 com.cinchapi.concourse.util;

import java.io.File;
import java.io.IOException;
import java.net.URISyntaxException;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import java.util.Map;

import com.cinchapi.common.base.CheckedExceptions;
import com.google.common.collect.Maps;

/**
 * Utilities to handle getting resources in a standard and portable way.
 * 
 * @author Jeff Nelson
 */
public class Resources {

    /**
     * Collection which maps a resource name with its URL.
     */
    private static Map map = Maps.newHashMap();

    /**
     * Finds a resource with a given name. The rules for searching resources
     * associated with a given class are implemented by the defining
     * {@linkplain ClassLoader class loader} of the class. This method
     * delegates to this object's class loader. If this object was loaded by
     * the bootstrap class loader, the method delegates to
     * {@link ClassLoader#getSystemResourceAsStream}.
     * 
     * 
     * Before delegation, an absolute resource name is constructed from the
     * given resource name using this algorithm:
     * 
     * 

     * 
     * If the {@code name} begins with a {@code '/'} ('\u002f'
     * ), then the absolute name of the resource is the portion of the
     * {@code name} following the {@code '/'}.
     * 
     * 
Otherwise, the absolute name is of the following form:
     * 
     *  {@code modified_package_name/name} 
     * 
     * 
     * Where the {@code modified_package_name} is the package name of this
     * object with {@code '/'} substituted for {@code '.'} (
     * '\u002e').
     * 
     * 
     * 
     * @param name name of the desired resource
     * @return A {@link java.io.InputStream} object or {@code null} if
     *         no resource with this name is found
     * @throws NullPointerException If {@code name} is {@code null}
     * @since JDK1.1
     */
    public static URL get(final String name) {
        File temp;
        try {
            URL url = map.get(name);
            if(url == null) {
                temp = File.createTempFile("java-resource", ".tmp");
                Path path = Paths.get(temp.getAbsolutePath());
                Files.copy(Resources.class.getResourceAsStream(name), path,
                        StandardCopyOption.REPLACE_EXISTING);
                url = temp.toURI().toURL();
                map.put(name, url);
                return url;
            }
            else {
                return url;
            }
        }
        catch (IOException e) {
            throw CheckedExceptions.wrapAsRuntimeException(e);
        }
    }

    /**
     * Find a resource with a given {@code name} and return an absolute file
     * path to access that resource using File path based APIs.
     * 
     * @param name
     * @return the file path
     */
    public static String getAbsolutePath(final String name) {
        try {
            return new File(Resources.get(name).toURI()).getAbsolutePath();
        }
        catch (URISyntaxException e) {
            throw CheckedExceptions.wrapAsRuntimeException(e);
        }
    }

}