/*
 * 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
 *
 *      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.tomcat.util.file;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URL;
import java.net.URLConnection;

Abstracts configuration file storage. Allows Tomcat embedding using the regular
configuration style.
This abstraction aims to be very simple and does not cover resource listing,
which is usually used for dynamic deployments that are usually not used when
embedding, as well as resource writing.
/**
 * Abstracts configuration file storage. Allows Tomcat embedding using the regular
 * configuration style.
 * This abstraction aims to be very simple and does not cover resource listing,
 * which is usually used for dynamic deployments that are usually not used when
 * embedding, as well as resource writing.
 */
public interface ConfigurationSource {

    public static final ConfigurationSource DEFAULT = new ConfigurationSource() {
        protected final File userDir = new File(System.getProperty("user.dir"));
        protected final URI userDirUri = userDir.toURI();
        @Override
        public Resource getResource(String name) throws IOException {
            File f = new File(name);
            if (!f.isAbsolute()) {
                f = new File(userDir, name);
            }
            if (f.isFile()) {
                FileInputStream fis = new FileInputStream(f);
                return new Resource(fis, f.toURI());
            }
            URI uri = null;
            try {
                uri = getURI(name);
            } catch (IllegalArgumentException e) {
                throw new FileNotFoundException(name);
            }
            try {
                URL url = uri.toURL();
                return new Resource(url.openConnection().getInputStream(), uri);
            } catch (MalformedURLException e) {
                throw new FileNotFoundException(name);
            }
        }
        @Override
        public URI getURI(String name) {
            File f = new File(name);
            if (!f.isAbsolute()) {
                f = new File(userDir, name);
            }
            if (f.isFile()) {
                return f.toURI();
            }
            return userDirUri.resolve(name);
        }
    };

    
Represents a resource: a stream to the resource associated with
its URI.
/**
     * Represents a resource: a stream to the resource associated with
     * its URI.
     */
    public class Resource implements AutoCloseable {
        private final InputStream inputStream;
        private final URI uri;
        public Resource(InputStream inputStream, URI uri) {
            this.inputStream = inputStream;
            this.uri = uri;
        }
        public InputStream getInputStream() {
            return inputStream;
        }
        public URI getURI() {
            return uri;
        }
        public long getLastModified()
                throws MalformedURLException, IOException {
            URLConnection connection = null;
            try {
                connection = uri.toURL().openConnection();
                return connection.getLastModified();
            } finally {
                if (connection != null) {
                    connection.getInputStream().close();
                }
            }
        }
        @Override
        public void close() throws IOException {
            if (inputStream != null) {
                inputStream.close();
            }
        }
    }

    
Returns the contents of the main conf/server.xml file.
Throws:
IOException – if an error occurs or if the resource does not exist
Returns:
the server.xml as an InputStream/**
     * Returns the contents of the main conf/server.xml file.
     * @return the server.xml as an InputStream
     * @throws IOException if an error occurs or if the resource does not exist
     */
    public default Resource getServerXml()
            throws IOException {
        return getConfResource("server.xml");
    }

    
Returns the contents of the shared conf/web.xml file. This usually
contains the declaration of the default and JSP servlets.
Throws:
IOException – if an error occurs or if the resource does not exist
Returns:
the web.xml as an InputStream/**
     * Returns the contents of the shared conf/web.xml file. This usually
     * contains the declaration of the default and JSP servlets.
     * @return the web.xml as an InputStream
     * @throws IOException if an error occurs or if the resource does not exist
     */
    public default Resource getSharedWebXml()
            throws IOException {
        return getConfResource("web.xml");
    }

    
Get a resource, based on the conf path.
Params:
name – The resource name
Throws:
IOException – if an error occurs or if the resource does not exist
Returns:
the resource as an InputStream/**
     * Get a resource, based on the conf path.
     * @param name The resource name
     * @return the resource as an InputStream
     * @throws IOException if an error occurs or if the resource does not exist
     */
    public default Resource getConfResource(String name)
            throws IOException {
        String fullName = "conf/" + name;
        return getResource(fullName);
    }

    
Get a resource, not based on the conf path.
Params:
name – The resource name
Throws:
IOException – if an error occurs or if the resource does not exist
Returns:
the resource/**
     * Get a resource, not based on the conf path.
     * @param name The resource name
     * @return the resource
     * @throws IOException if an error occurs or if the resource does not exist
     */
    public Resource getResource(String name)
            throws IOException;

    
Get a URI to the given resource. Unlike getResource, this will also
return URIs to locations where no resource exists.
Params:
name – The resource name
Returns:
a URI representing the resource location/**
     * Get a URI to the given resource. Unlike getResource, this will also
     * return URIs to locations where no resource exists.
     * @param name The resource name
     * @return a URI representing the resource location
     */
    public URI getURI(String name);

}