/*

 * Copyright (c) 2009, 2014, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.tools.javac.nio;

import java.io.File;

import java.io.IOException;

import java.net.MalformedURLException;

import java.net.URL;

import java.nio.charset.Charset;

import java.nio.file.FileSystem;

import java.nio.file.FileSystems;

import java.nio.file.FileVisitOption;

import java.nio.file.FileVisitResult;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.SimpleFileVisitor;

import java.nio.file.attribute.BasicFileAttributes;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collection;

import java.util.Collections;

import java.util.EnumSet;

import java.util.HashMap;

import java.util.Iterator;

import java.util.LinkedHashSet;

import java.util.Map;

import java.util.Set;

import javax.lang.model.SourceVersion;

import javax.tools.FileObject;

import javax.tools.JavaFileManager;

import javax.tools.JavaFileObject;

import javax.tools.JavaFileObject.Kind;

import javax.tools.StandardLocation;

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

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

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

import com.sun.tools.javac.util.DefinedBy.Api;

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

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

import static java.nio.file.FileVisitOption.*;

import static javax.tools.StandardLocation.*;

import static com.sun.tools.javac.main.Option.*;

// NOTE the imports carefully for this compilation unit.

//

// Path:  java.nio.file.Path -- the new NIO type for which this file manager exists

//

// Paths: com.sun.tools.javac.file.Paths -- legacy javac type for handling path options

//      The other Paths (java.nio.file.Paths) is not used

// NOTE this and related classes depend on new API in JDK 7.

// This requires special handling while bootstrapping the JDK build,

// when these classes might not yet have been compiled. To workaround

// this, the build arranges to make stubs of these classes available

// when compiling this and related classes. The set of stub files

// is specified in make/build.properties.

/**

 *  Implementation of PathFileManager: a JavaFileManager based on the use

 *  of java.nio.file.Path.

 *

 *  <p>Just as a Path is somewhat analagous to a File, so too is this

 *  JavacPathFileManager analogous to JavacFileManager, as it relates to the

 *  support of FileObjects based on File objects (i.e. just RegularFileObject,

 *  not ZipFileObject and its variants.)

 *

 *  <p>The default values for the standard locations supported by this file

 *  manager are the same as the default values provided by JavacFileManager --

 *  i.e. as determined by the javac.file.Paths class. To override these values,

 *  call {@link #setLocation}.

 *

 *  <p>To reduce confusion with Path objects, the locations such as "class path",

 *  "source path", etc, are generically referred to here as "search paths".

 *

 *  <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 JavacPathFileManager extends BaseFileManager implements PathFileManager {

    protected FileSystem defaultFileSystem;

    /**

     * Create a JavacPathFileManager using a given context, optionally registering

     * it as the JavaFileManager for that context.

     */

    public JavacPathFileManager(Context context, boolean register, Charset charset) {

        super(charset);

        if (register)

            context.put(JavaFileManager.class, this);

        pathsForLocation = new HashMap<>();

        fileSystems = new HashMap<>();

        setContext(context);

    }

    /**

     * Set the context for JavacPathFileManager.

     */

    @Override

    public void setContext(Context context) {

        super.setContext(context);

    }

    @Override

    public FileSystem getDefaultFileSystem() {

        if (defaultFileSystem == null)

            defaultFileSystem = FileSystems.getDefault();

        return defaultFileSystem;

    }

    @Override

    public void setDefaultFileSystem(FileSystem fs) {

        defaultFileSystem = fs;

    }

    @Override @DefinedBy(Api.COMPILER)

    public void flush() throws IOException {

        contentCache.clear();

    }

    @Override @DefinedBy(Api.COMPILER)

    public void close() throws IOException {

        for (FileSystem fs: fileSystems.values())

            fs.close();

    }

    @Override @DefinedBy(Api.COMPILER)

    public ClassLoader getClassLoader(Location location) {

        nullCheck(location);

        Iterable<? extends Path> path = getLocation(location);

        if (path == null)

            return null;

        ListBuffer<URL> lb = new ListBuffer<>();

        for (Path p: path) {

            try {

                lb.append(p.toUri().toURL());

            } catch (MalformedURLException e) {

                throw new AssertionError(e);

            }

        }

        return getClassLoader(lb.toArray(new URL[lb.size()]));

    }

    // <editor-fold defaultstate="collapsed" desc="Location handling">

    @DefinedBy(Api.COMPILER)

    public boolean hasLocation(Location location) {

        return (getLocation(location) != null);

    }

    public Iterable<? extends Path> getLocation(Location location) {

        nullCheck(location);

        lazyInitSearchPaths();

        PathsForLocation path = pathsForLocation.get(location);

        if (path == null && !pathsForLocation.containsKey(location)) {

            setDefaultForLocation(location);

            path = pathsForLocation.get(location);

        }

        return path;

    }

    private Path getOutputLocation(Location location) {

        Iterable<? extends Path> paths = getLocation(location);

        return (paths == null ? null : paths.iterator().next());

    }

    public void setLocation(Location location, Iterable<? extends Path> searchPath)

            throws IOException

    {

        nullCheck(location);

        lazyInitSearchPaths();

        if (searchPath == null) {

            setDefaultForLocation(location);

        } else {

            if (location.isOutputLocation())

                checkOutputPath(searchPath);

            PathsForLocation pl = new PathsForLocation();

            for (Path p: searchPath)

                pl.add(p);  // TODO -Xlint:path warn if path not found

            pathsForLocation.put(location, pl);

        }

    }

    private void checkOutputPath(Iterable<? extends Path> searchPath) throws IOException {

        Iterator<? extends Path> pathIter = searchPath.iterator();

        if (!pathIter.hasNext())

            throw new IllegalArgumentException("empty path for directory");

        Path path = pathIter.next();

        if (pathIter.hasNext())

            throw new IllegalArgumentException("path too long for directory");

        if (!isDirectory(path))

            throw new IOException(path + ": not a directory");

    }

    private void setDefaultForLocation(Location locn) {

        Collection<Path> files = null;

        if (locn instanceof StandardLocation) {

            switch ((StandardLocation) locn) {

                case CLASS_PATH:

                    files = locations.userClassPath();

                    break;

                case PLATFORM_CLASS_PATH:

                    files = locations.bootClassPath();

                    break;

                case SOURCE_PATH:

                    files = locations.sourcePath();

                    break;

                case CLASS_OUTPUT: {

                    String arg = options.get(D);

                    files = (arg == null ? null : Collections.singleton(Paths.get(arg)));

                    break;

                }

                case SOURCE_OUTPUT: {

                    String arg = options.get(S);

                    files = (arg == null ? null : Collections.singleton(Paths.get(arg)));

                    break;

                }

            }

        }

        PathsForLocation pl = new PathsForLocation();

        if (files != null) {

            for (Path f: files)

                pl.add(f);

        }

        if (!pl.isEmpty())

            pathsForLocation.put(locn, pl);

    }

    private void lazyInitSearchPaths() {

        if (!inited) {

            setDefaultForLocation(PLATFORM_CLASS_PATH);

            setDefaultForLocation(CLASS_PATH);

            setDefaultForLocation(SOURCE_PATH);

            inited = true;

        }

    }

    // where

        private boolean inited = false;

    private Map<Location, PathsForLocation> pathsForLocation;

    private static class PathsForLocation extends LinkedHashSet<Path> {

        private static final long serialVersionUID = 6788510222394486733L;

    }

    // </editor-fold>

    // <editor-fold defaultstate="collapsed" desc="FileObject handling">

    @Override

    public Path getPath(FileObject fo) {

        nullCheck(fo);

        if (!(fo instanceof PathFileObject))

            throw new IllegalArgumentException();

        return ((PathFileObject) fo).getPath();

    }

    @Override @DefinedBy(Api.COMPILER)

    public boolean isSameFile(FileObject a, FileObject b) {

        nullCheck(a);

        nullCheck(b);

        if (!(a instanceof PathFileObject))

            throw new IllegalArgumentException("Not supported: " + a);

        if (!(b instanceof PathFileObject))

            throw new IllegalArgumentException("Not supported: " + b);

        return ((PathFileObject) a).isSameFile((PathFileObject) b);

    }

    @Override @DefinedBy(Api.COMPILER)

    public Iterable<JavaFileObject> list(Location location,

            String packageName, Set<Kind> kinds, boolean recurse)

            throws IOException {

        // validatePackageName(packageName);

        nullCheck(packageName);

        nullCheck(kinds);

        Iterable<? extends Path> paths = getLocation(location);

        if (paths == null)

            return List.nil();

        ListBuffer<JavaFileObject> results = new ListBuffer<>();

        for (Path path : paths)

            list(path, packageName, kinds, recurse, results);

        return results.toList();

    }

    private void list(Path path, String packageName, final Set<Kind> kinds,

            boolean recurse, final ListBuffer<JavaFileObject> results)

            throws IOException {

        if (!Files.exists(path))

            return;

        final Path pathDir;

        if (isDirectory(path))

            pathDir = path;

        else {

            FileSystem fs = getFileSystem(path);

            if (fs == null)

                return;

            pathDir = fs.getRootDirectories().iterator().next();

        }

        String sep = path.getFileSystem().getSeparator();

        Path packageDir = packageName.isEmpty() ? pathDir

                : pathDir.resolve(packageName.replace(".", sep));

        if (!Files.exists(packageDir))

            return;

/* Alternate impl of list, superceded by use of Files.walkFileTree */

//        Deque<Path> queue = new LinkedList<Path>();

//        queue.add(packageDir);

//

//        Path dir;

//        while ((dir = queue.poll()) != null) {

//            DirectoryStream<Path> ds = dir.newDirectoryStream();

//            try {

//                for (Path p: ds) {

//                    String name = p.getFileName().toString();

//                    if (isDirectory(p)) {

//                        if (recurse && SourceVersion.isIdentifier(name)) {

//                            queue.add(p);

//                        }

//                    } else {

//                        if (kinds.contains(getKind(name))) {

//                            JavaFileObject fe =

//                                PathFileObject.createDirectoryPathFileObject(this, p, pathDir);

//                            results.append(fe);

//                        }

//                    }

//                }

//            } finally {

//                ds.close();

//            }

//        }

        int maxDepth = (recurse ? Integer.MAX_VALUE : 1);

        Set<FileVisitOption> opts = EnumSet.of(FOLLOW_LINKS);

        Files.walkFileTree(packageDir, opts, maxDepth,

                new SimpleFileVisitor<Path>() {

            @Override

            public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {

                Path name = dir.getFileName();

                if (name == null || SourceVersion.isIdentifier(name.toString()))

                    return FileVisitResult.CONTINUE;

                else

                    return FileVisitResult.SKIP_SUBTREE;

            }

            @Override

            public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {

                if (attrs.isRegularFile() && kinds.contains(getKind(file.getFileName().toString()))) {

                    // WORKAROUND for .jimage files

                    if (!file.isAbsolute())

                        file = pathDir.resolve(file);

                    JavaFileObject fe =

                        PathFileObject.createDirectoryPathFileObject(

                            JavacPathFileManager.this, file, pathDir);

                    results.append(fe);

                }

                return FileVisitResult.CONTINUE;

            }

        });

    }

    @Override

    public Iterable<? extends JavaFileObject> getJavaFileObjectsFromPaths(

        Iterable<? extends Path> paths) {

        ArrayList<PathFileObject> result;

        if (paths instanceof Collection<?>)

            result = new ArrayList<>(((Collection<?>)paths).size());

        else

            result = new ArrayList<>();

        for (Path p: paths)

            result.add(PathFileObject.createSimplePathFileObject(this, nullCheck(p)));

        return result;

    }

    @Override

    public Iterable<? extends JavaFileObject> getJavaFileObjects(Path... paths) {

        return getJavaFileObjectsFromPaths(Arrays.asList(nullCheck(paths)));

    }

    @Override @DefinedBy(Api.COMPILER)

    public JavaFileObject getJavaFileForInput(Location location,

            String className, Kind kind) throws IOException {

        return getFileForInput(location, getRelativePath(className, kind));

    }

    @Override @DefinedBy(Api.COMPILER)

    public FileObject getFileForInput(Location location,

            String packageName, String relativeName) throws IOException {

        return getFileForInput(location, getRelativePath(packageName, relativeName));

    }

    private JavaFileObject getFileForInput(Location location, String relativePath)

            throws IOException {

        for (Path p: getLocation(location)) {

            if (isDirectory(p)) {

                Path f = resolve(p, relativePath);

                if (Files.exists(f))

                    return PathFileObject.createDirectoryPathFileObject(this, f, p);

            } else {

                FileSystem fs = getFileSystem(p);

                if (fs != null) {

                    Path file = getPath(fs, relativePath);

                    if (Files.exists(file))

                        return PathFileObject.createJarPathFileObject(this, file);

                }

            }

        }

        return null;

    }

    @Override @DefinedBy(Api.COMPILER)

    public JavaFileObject getJavaFileForOutput(Location location,

            String className, Kind kind, FileObject sibling) throws IOException {

        return getFileForOutput(location, getRelativePath(className, kind), sibling);

    }

    @Override @DefinedBy(Api.COMPILER)

    public FileObject getFileForOutput(Location location, String packageName,

            String relativeName, FileObject sibling)

            throws IOException {

        return getFileForOutput(location, getRelativePath(packageName, relativeName), sibling);

    }

    private JavaFileObject getFileForOutput(Location location,

            String relativePath, FileObject sibling) {

        Path dir = getOutputLocation(location);

        if (dir == null) {

            if (location == CLASS_OUTPUT) {

                Path siblingDir = null;

                if (sibling != null && sibling instanceof PathFileObject) {

                    siblingDir = ((PathFileObject) sibling).getPath().getParent();

                }

                return PathFileObject.createSiblingPathFileObject(this,

                        siblingDir.resolve(getBaseName(relativePath)),

                        relativePath);

            } else if (location == SOURCE_OUTPUT) {

                dir = getOutputLocation(CLASS_OUTPUT);

            }

        }

        Path file;

        if (dir != null) {

            file = resolve(dir, relativePath);

            return PathFileObject.createDirectoryPathFileObject(this, file, dir);

        } else {

            file = getPath(getDefaultFileSystem(), relativePath);

            return PathFileObject.createSimplePathFileObject(this, file);

        }

    }

    @Override @DefinedBy(Api.COMPILER)

    public String inferBinaryName(Location location, JavaFileObject fo) {

        nullCheck(fo);

        // Need to match the path semantics of list(location, ...)

        Iterable<? extends Path> paths = getLocation(location);

        if (paths == null) {

            return null;

        }

        if (!(fo instanceof PathFileObject))

            throw new IllegalArgumentException(fo.getClass().getName());

        return ((PathFileObject) fo).inferBinaryName(paths);

    }

    private FileSystem getFileSystem(Path p) throws IOException {

        FileSystem fs = fileSystems.get(p);

        if (fs == null) {

            fs = FileSystems.newFileSystem(p, null);

            fileSystems.put(p, fs);

        }

        return fs;

    }

    private Map<Path,FileSystem> fileSystems;

    // </editor-fold>

    // <editor-fold defaultstate="collapsed" desc="Utility methods">

    private static String getRelativePath(String className, Kind kind) {

        return className.replace(".", "/") + kind.extension;

    }