/*
 * Copyright (c) 2008, 2019, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */

package com.sun.tools.javac.file;

import java.io.IOError;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URISyntaxException;
import java.net.URL;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.InvalidPathException;
import java.nio.file.Path;
import java.nio.file.spi.FileSystemProvider;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.StringTokenizer;
import java.util.jar.Attributes;
import java.util.jar.JarFile;
import java.util.jar.Manifest;

import com.sun.tools.javac.util.Context;

Get meta-info about files. Default direct (non-caching) implementation.
See Also:
This is NOT part of any supported API.
If you write code that depends on this, you do so at your own risk.
This code and its internal interfaces are subject to change or
deletion without notice./**
 * Get meta-info about files. Default direct (non-caching) implementation.
 * @see CacheFSInfo
 *
 * <p><b>This is NOT part of any supported API.
 * If you write code that depends on this, you do so at your own risk.
 * This code and its internal interfaces are subject to change or
 * deletion without notice.</b>
 */
public class FSInfo {

    
Get the FSInfo instance for this context.
 @param context the context
 @return the Paths instance for this context
/** Get the FSInfo instance for this context.
     *  @param context the context
     *  @return the Paths instance for this context
     */
    public static FSInfo instance(Context context) {
        FSInfo instance = context.get(FSInfo.class);
        if (instance == null)
            instance = new FSInfo();
        return instance;
    }

    protected FSInfo() {
    }

    protected FSInfo(Context context) {
        context.put(FSInfo.class, this);
    }

    public Path getCanonicalFile(Path file) {
        try {
            return file.toRealPath();
        } catch (IOException e) {
            return file.toAbsolutePath().normalize();
        }
    }

    public boolean exists(Path file) {
        return Files.exists(file);
    }

    public boolean isDirectory(Path file) {
        return Files.isDirectory(file);
    }

    public boolean isFile(Path file) {
        return Files.isRegularFile(file);
    }

    public List<Path> getJarClassPath(Path file) throws IOException {
        try (JarFile jarFile = new JarFile(file.toFile())) {
            Manifest man = jarFile.getManifest();
            if (man == null)
                return Collections.emptyList();

            Attributes attr = man.getMainAttributes();
            if (attr == null)
                return Collections.emptyList();

            String path = attr.getValue(Attributes.Name.CLASS_PATH);
            if (path == null)
                return Collections.emptyList();

            List<Path> list = new ArrayList<>();
            URL base = file.toUri().toURL();

            for (StringTokenizer st = new StringTokenizer(path);
                 st.hasMoreTokens(); ) {
                String elt = st.nextToken();
                try {
                    URL url = tryResolveFile(base, elt);
                    if (url != null) {
                        list.add(Path.of(url.toURI()));
                    }
                } catch (URISyntaxException ex) {
                    throw new IOException(ex);
                }
            }

            return list;
        }
    }

    
Attempt to return a file URL by resolving input against a base file
URL.
Throws:
MalformedURLException – 
Returns:
the resolved URL or null if the input is an absolute URL with
        a scheme other than file (ignoring case)/**
     * Attempt to return a file URL by resolving input against a base file
     * URL.
     *
     * @return the resolved URL or null if the input is an absolute URL with
     *         a scheme other than file (ignoring case)
     * @throws MalformedURLException
     */
    static URL tryResolveFile(URL base, String input) throws MalformedURLException {
        URL retVal = new URL(base, input);
        if (input.indexOf(':') >= 0 && !"file".equalsIgnoreCase(retVal.getProtocol())) {
            // 'input' contains a ':', which might be a scheme, or might be
            // a Windows drive letter.  If the resolved file has a protocol
            // that isn't "file:", it should be ignored.
            return null;
        }
        return retVal;
    }

    private FileSystemProvider jarFSProvider;

    public synchronized FileSystemProvider getJarFSProvider() {
        if (jarFSProvider != null) {
            return jarFSProvider;
        }
        for (FileSystemProvider provider: FileSystemProvider.installedProviders()) {
            if (provider.getScheme().equals("jar")) {
                return (jarFSProvider = provider);
            }
        }
        return null;
    }

}