/*
 * Copyright 2002-2016 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.core.io;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URI;
import java.net.URL;

import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

/**
 * {@link Resource} implementation for {@code java.io.File} handles.
 * Supports resolution as a {@code File} and also as a {@code URL}.
 * Implements the extended {@link WritableResource} interface.
 *
 * @author Juergen Hoeller
 * @since 28.12.2003
 * @see java.io.File
 */
public class FileSystemResource extends AbstractResource implements WritableResource {

        private final File file;

        private final String path;


        /**
         * Create a new {@code FileSystemResource} from a {@link File} handle.
         * <p>Note: When building relative resources via {@link #createRelative},
         * the relative path will apply <i>at the same directory level</i>:
         * e.g. new File("C:/dir1"), relative path "dir2" -> "C:/dir2"!
         * If you prefer to have relative paths built underneath the given root
         * directory, use the {@link #FileSystemResource(String) constructor with a file path}
         * to append a trailing slash to the root path: "C:/dir1/", which
         * indicates this directory as root for all relative paths.
         * @param file a File handle
         */
        public FileSystemResource(File file) {
                Assert.notNull(file, "File must not be null");
                this.file = file;
                this.path = StringUtils.cleanPath(file.getPath());
        }

        /**
         * Create a new {@code FileSystemResource} from a file path.
         * <p>Note: When building relative resources via {@link #createRelative},
         * it makes a difference whether the specified resource base path here
         * ends with a slash or not. In the case of "C:/dir1/", relative paths
         * will be built underneath that root: e.g. relative path "dir2" ->
         * "C:/dir1/dir2". In the case of "C:/dir1", relative paths will apply
         * at the same directory level: relative path "dir2" -> "C:/dir2".
         * @param path a file path
         */
        public FileSystemResource(String path) {
                Assert.notNull(path, "Path must not be null");
                this.file = new File(path);
                this.path = StringUtils.cleanPath(path);
        }


        /**
         * Return the file path for this resource.
         */
        public final String getPath() {
                return this.path;
        }

        /**
         * This implementation returns whether the underlying file exists.
         * @see java.io.File#exists()
         */
        @Override
        public boolean exists() {
                return this.file.exists();
        }

        /**
         * This implementation checks whether the underlying file is marked as readable
         * (and corresponds to an actual file with content, not to a directory).
         * @see java.io.File#canRead()
         * @see java.io.File#isDirectory()
         */
        @Override
        public boolean isReadable() {
                return (this.file.canRead() && !this.file.isDirectory());
        }

        /**
         * This implementation opens a FileInputStream for the underlying file.
         * @see java.io.FileInputStream
         */
        @Override
        public InputStream getInputStream() throws IOException {
                return new FileInputStream(this.file);
        }

        /**
         * This implementation checks whether the underlying file is marked as writable
         * (and corresponds to an actual file with content, not to a directory).
         * @see java.io.File#canWrite()
         * @see java.io.File#isDirectory()
         */
        @Override
        public boolean isWritable() {
                return (this.file.canWrite() && !this.file.isDirectory());
        }

        /**
         * This implementation opens a FileOutputStream for the underlying file.
         * @see java.io.FileOutputStream
         */
        @Override
        public OutputStream getOutputStream() throws IOException {
                return new FileOutputStream(this.file);
        }

        /**
         * This implementation returns a URL for the underlying file.
         * @see java.io.File#toURI()
         */
        @Override
        public URL getURL() throws IOException {
                return this.file.toURI().toURL();
        }

        /**
         * This implementation returns a URI for the underlying file.
         * @see java.io.File#toURI()
         */
        @Override
        public URI getURI() throws IOException {
                return this.file.toURI();
        }

        /**
         * This implementation returns the underlying File reference.
         */
        @Override
        public File getFile() {
                return this.file;
        }

        /**
         * This implementation returns the underlying File's length.
         */
        @Override
        public long contentLength() throws IOException {
                return this.file.length();
        }

        /**
         * This implementation creates a FileSystemResource, applying the given path
         * relative to the path of the underlying file of this resource descriptor.
         * @see org.springframework.util.StringUtils#applyRelativePath(String, String)
         */
        @Override
        public Resource createRelative(String relativePath) {
                String pathToUse = StringUtils.applyRelativePath(this.path, relativePath);
                return new FileSystemResource(pathToUse);
        }

        /**
         * This implementation returns the name of the file.
         * @see java.io.File#getName()
         */
        @Override
        public String getFilename() {
                return this.file.getName();
        }

        /**
         * This implementation returns a description that includes the absolute
         * path of the file.
         * @see java.io.File#getAbsolutePath()
         */
        @Override
        public String getDescription() {
                return "file [" + this.file.getAbsolutePath() + "]";
        }


        /**
         * This implementation compares the underlying File references.
         */
        @Override
        public boolean equals(Object obj) {
                return (obj == this ||
                        (obj instanceof FileSystemResource && this.path.equals(((FileSystemResource) obj).path)));
        }

        /**
         * This implementation returns the hash code of the underlying File reference.
         */
        @Override
        public int hashCode() {
                return this.path.hashCode();
        }

}