/*

 * Copyright (c) 2014, 2015, 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 jdk.jshell;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.net.URI;

import java.nio.file.FileSystems;

import java.nio.file.Files;

import java.nio.file.Path;

import java.util.Collection;

import java.util.Iterator;

import java.util.Map;

import java.util.NoSuchElementException;

import java.util.Set;

import java.util.TreeMap;

import javax.tools.JavaFileObject.Kind;

import static javax.tools.StandardLocation.CLASS_PATH;

import javax.tools.FileObject;

import javax.tools.JavaFileManager;

import javax.tools.JavaFileObject;

import javax.tools.SimpleJavaFileObject;

import javax.tools.StandardJavaFileManager;

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

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

import static jdk.internal.jshell.debug.InternalDebugControl.DBG_FMGR;

/**

 * File manager for the compiler API.  Reads from memory (Strings) and writes

 * class files to memory (cached OutputMemoryJavaFileObject).

 *

 * @author Robert Field

 */

class MemoryFileManager implements JavaFileManager {

    private final StandardJavaFileManager stdFileManager;

    private final Map<String, OutputMemoryJavaFileObject> classObjects = new TreeMap<>();

    private ClassFileCreationListener classListener = null;

    private final ClassLoader loader = new REPLClassLoader();

    private final JShell proc;

    // Upcoming Jigsaw

    private Method inferModuleNameMethod = null;

    private Method listModuleLocationsMethod = null;

    static abstract class MemoryJavaFileObject extends SimpleJavaFileObject {

        public MemoryJavaFileObject(String name, JavaFileObject.Kind kind) {

            super(URI.create("string:///" + name.replace('.', '/')

                    + kind.extension), kind);

        }

    }

    class SourceMemoryJavaFileObject extends MemoryJavaFileObject {

        private final String src;

        private final Object origin;

        SourceMemoryJavaFileObject(Object origin, String className, String code) {

            super(className, JavaFileObject.Kind.SOURCE);

            this.origin = origin;

            this.src = code;

        }

        public Object getOrigin() {

            return origin;

        }

        @Override @DefinedBy(Api.COMPILER)

        public CharSequence getCharContent(boolean ignoreEncodingErrors) {

            return src;

        }

    }

    static class OutputMemoryJavaFileObject extends MemoryJavaFileObject {

        /**

         * Byte code created by the compiler will be stored in this

         * ByteArrayOutputStream.

         */

        private ByteArrayOutputStream bos = new ByteArrayOutputStream();

        private byte[] bytes = null;

        private final String className;

        public OutputMemoryJavaFileObject(String name, JavaFileObject.Kind kind) {

            super(name, kind);

            this.className = name;

        }

        public byte[] getBytes() {

            if (bytes == null) {

                bytes = bos.toByteArray();

                bos = null;

            }

            return bytes;

        }

        public void dump() {

            try {

                Path dumpDir = FileSystems.getDefault().getPath("dump");

                if (Files.notExists(dumpDir)) {

                    Files.createDirectory(dumpDir);

                }

                Path file = FileSystems.getDefault().getPath("dump", getName() + ".class");

                Files.write(file, getBytes());

            } catch (IOException ex) {

                throw new RuntimeException(ex);

            }

        }

        @Override @DefinedBy(Api.COMPILER)

        public String getName() {

            return className;

        }

        /**

         * Will provide the compiler with an output stream that leads to our

         * byte array.

         */

        @Override @DefinedBy(Api.COMPILER)

        public OutputStream openOutputStream() throws IOException {

            return bos;

        }

        @Override @DefinedBy(Api.COMPILER)

        public InputStream openInputStream() throws IOException {

            return new ByteArrayInputStream(getBytes());

        }

    }

    // For restoring process-local execution support

    class REPLClassLoader extends ClassLoader {

        @Override

        protected Class<?> findClass(String name) throws ClassNotFoundException {

            OutputMemoryJavaFileObject fo = classObjects.get(name);

            proc.debug(DBG_FMGR, "findClass %s = %s\n", name, fo);

            if (fo == null) {

                throw new ClassNotFoundException("Not ours");

            }

            byte[] b = fo.getBytes();

            return super.defineClass(name, b, 0, b.length, null);

        }

    }

    public MemoryFileManager(StandardJavaFileManager standardManager, JShell proc) {

        this.stdFileManager = standardManager;

        this.proc = proc;

    }

    private Collection<OutputMemoryJavaFileObject> generatedClasses() {

        return classObjects.values();

    }

    // For debugging dumps

    public void dumpClasses() {

        for (OutputMemoryJavaFileObject co : generatedClasses()) {

            co.dump();

        }

    }

    // For restoring process-local execution support

    public Class<?> findGeneratedClass(String genClassFullName) throws ClassNotFoundException {

        for (OutputMemoryJavaFileObject co : generatedClasses()) {

            if (co.className.equals(genClassFullName)) {

                Class<?> klass = loadClass(co.className);

                proc.debug(DBG_FMGR, "Loaded %s\n", klass);

                return klass;

            }

        }

        return null;

    }

    // For restoring process-local execution support

    public byte[] findGeneratedBytes(String genClassFullName) throws ClassNotFoundException {

        for (OutputMemoryJavaFileObject co : generatedClasses()) {

            if (co.className.equals(genClassFullName)) {

                return co.getBytes();

            }

        }

        return null;

    }

    // For restoring process-local execution support

    public Class<?> loadClass(String name) throws ClassNotFoundException {

        return getClassLoader(null).loadClass(name);

    }

    public JavaFileObject createSourceFileObject(Object origin, String name, String code) {

        return new SourceMemoryJavaFileObject(origin, name, code);

    }

    // Make compatible with Jigsaw

    public String inferModuleName(Location location) {

        try {

            if (inferModuleNameMethod == null) {

                inferModuleNameMethod = JavaFileManager.class.getDeclaredMethod("inferModuleName", Location.class);

            }

            @SuppressWarnings("unchecked")

            String result = (String) inferModuleNameMethod.invoke(stdFileManager, location);

            return result;

        } catch (NoSuchMethodException | SecurityException ex) {

            throw new InternalError("Cannot lookup JavaFileManager method", ex);

        } catch (IllegalAccessException |

                IllegalArgumentException |

                InvocationTargetException ex) {

            throw new InternalError("Cannot invoke JavaFileManager method", ex);

        }

    }

    // Make compatible with Jigsaw

    public Iterable<Set<Location>> listModuleLocations(Location location) throws IOException {

        try {

            if (listModuleLocationsMethod == null) {

                listModuleLocationsMethod = JavaFileManager.class.getDeclaredMethod("listModuleLocations", Location.class);

            }

            @SuppressWarnings("unchecked")

            Iterable<Set<Location>> result = (Iterable<Set<Location>>) listModuleLocationsMethod.invoke(stdFileManager, location);

            return result;

        } catch (NoSuchMethodException | SecurityException ex) {

            throw new InternalError("Cannot lookup JavaFileManager method", ex);

        } catch (IllegalAccessException |

                IllegalArgumentException |

                InvocationTargetException ex) {

            throw new InternalError("Cannot invoke JavaFileManager method", ex);

        }

    }

    /**

     * Returns a class loader for loading plug-ins from the given location. For

     * example, to load annotation processors, a compiler will request a class

     * loader for the {@link

     * StandardLocation#ANNOTATION_PROCESSOR_PATH

     * ANNOTATION_PROCESSOR_PATH} location.

     *

     * @param location a location

     * @return a class loader for the given location; or {@code null}

     * if loading plug-ins from the given location is disabled or if

     * the location is not known

     * @throws SecurityException if a class loader can not be created

     * in the current security context

     * @throws IllegalStateException if {@link #close} has been called

     * and this file manager cannot be reopened

     */

    @Override @DefinedBy(Api.COMPILER)

    public ClassLoader getClassLoader(JavaFileManager.Location location) {

        proc.debug(DBG_FMGR, "getClassLoader: location\n", location);

        return loader;

    }

    /**

     * Lists all file objects matching the given criteria in the given

     * location.  List file objects in "subpackages" if recurse is

     * true.

     *

     * <p>Note: even if the given location is unknown to this file

     * manager, it may not return {@code null}.  Also, an unknown

     * location may not cause an exception.

     *

     * @param location     a location

     * @param packageName  a package name

     * @param kinds        return objects only of these kinds

     * @param recurse      if true include "subpackages"

     * @return an Iterable of file objects matching the given criteria

     * @throws IOException if an I/O error occurred, or if {@link

     * #close} has been called and this file manager cannot be

     * reopened

     * @throws IllegalStateException if {@link #close} has been called

     * and this file manager cannot be reopened

     */

    @Override @DefinedBy(Api.COMPILER)

    public Iterable<JavaFileObject> list(JavaFileManager.Location location,

            String packageName,

            Set<JavaFileObject.Kind> kinds,

            boolean recurse)

            throws IOException {

        Iterable<JavaFileObject> stdList = stdFileManager.list(location, packageName, kinds, recurse);

        if (location==CLASS_PATH && packageName.equals("REPL")) {

            // if the desired list is for our JShell package, lazily iterate over

            // first the standard list then any generated classes.

            return () -> new Iterator<JavaFileObject>() {

                boolean stdDone = false;

                Iterator<? extends JavaFileObject> it;

                @Override

                public boolean hasNext() {

                    if (it == null) {

                        it = stdList.iterator();

                    }

                    if (it.hasNext()) {

                        return true;

                    }

                    if (stdDone) {

                        return false;

                    } else {

                        stdDone = true;

                        it = generatedClasses().iterator();

                        return it.hasNext();

                    }

                }

                @Override

                public JavaFileObject next() {

                    if (!hasNext()) {

                        throw new NoSuchElementException();

                    }

                    return it.next();

                }

            };

        } else {

            return stdList;

        }

    }

    /**

     * Infers a binary name of a file object based on a location.  The

     * binary name returned might not be a valid binary name according to

     * <cite>The Java&trade {        throw new UnsupportedOperationException("Not supported yet.");  } Language Specification</cite>.

     *

     * @param location a location

     * @param file a file object

     * @return a binary name or {@code null} the file object is not

     * found in the given location

     * @throws IllegalStateException if {@link #close} has been called

     * and this file manager cannot be reopened

     */

    @Override @DefinedBy(Api.COMPILER)

    public String inferBinaryName(JavaFileManager.Location location, JavaFileObject file) {

        if (file instanceof OutputMemoryJavaFileObject) {

            OutputMemoryJavaFileObject ofo = (OutputMemoryJavaFileObject) file;

            proc.debug(DBG_FMGR, "inferBinaryName %s => %s\n", file, ofo.getName());

            return ofo.getName();

        } else {

            return stdFileManager.inferBinaryName(location, file);

        }

    }

    /**

     * Compares two file objects and return true if they represent the

     * same underlying object.

     *

     * @param a a file object

     * @param b a file object

     * @return true if the given file objects represent the same

     * underlying object

     *

     * @throws IllegalArgumentException if either of the arguments

     * were created with another file manager and this file manager

     * does not support foreign file objects

     */

    @Override @DefinedBy(Api.COMPILER)

    public boolean isSameFile(FileObject a, FileObject b) {

        return stdFileManager.isSameFile(b, b);

    }

    /**

     * Determines if the given option is supported and if so, the

     * number of arguments the option takes.

     *

     * @param option an option

     * @return the number of arguments the given option takes or -1 if

     * the option is not supported

     */

    @Override @DefinedBy(Api.COMPILER)

    public int isSupportedOption(String option) {

        proc.debug(DBG_FMGR, "isSupportedOption: %s\n", option);

        return stdFileManager.isSupportedOption(option);

    }

    /**

     * Handles one option.  If {@code current} is an option to this

     * file manager it will consume any arguments to that option from

     * {@code remaining} and return true, otherwise return false.

     *

     * @param current current option

     * @param remaining remaining options

     * @return true if this option was handled by this file manager,

     * false otherwise

     * @throws IllegalArgumentException if this option to this file

     * manager is used incorrectly

     * @throws IllegalStateException if {@link #close} has been called

     * and this file manager cannot be reopened

     */

    @Override @DefinedBy(Api.COMPILER)

    public boolean handleOption(String current, Iterator<String> remaining) {

        proc.debug(DBG_FMGR, "handleOption: current: %s\n", current +

                ", remaining: " + remaining);

        return stdFileManager.handleOption(current, remaining);

    }

    /**

     * Determines if a location is known to this file manager.

     *

     * @param location a location

     * @return true if the location is known

     */

    @Override @DefinedBy(Api.COMPILER)

    public boolean hasLocation(JavaFileManager.Location location) {

        proc.debug(DBG_FMGR, "hasLocation: location: %s\n", location);

        return stdFileManager.hasLocation(location);

    }

    interface ClassFileCreationListener {

        void newClassFile(OutputMemoryJavaFileObject jfo, JavaFileManager.Location location,

                String className, Kind kind, FileObject sibling);

    }

    void registerClassFileCreationListener(ClassFileCreationListener listen) {

        this.classListener = listen;

    }

    /**

     * Returns a {@linkplain JavaFileObject file object} for input

     * representing the specified class of the specified kind in the

     * given location.

     *

     * @param location a location

     * @param className the name of a class

     * @param kind the kind of file, must be one of {@link

     * JavaFileObject.Kind#SOURCE SOURCE} or {@link

     * JavaFileObject.Kind#CLASS CLASS}

     * @return a file object, might return {@code null} if the

     * file does not exist

     * @throws IllegalArgumentException if the location is not known

     * to this file manager and the file manager does not support

     * unknown locations, or if the kind is not valid

     * @throws IOException if an I/O error occurred, or if {@link

     * #close} has been called and this file manager cannot be

     * reopened

     * @throws IllegalStateException if {@link #close} has been called

     * and this file manager cannot be reopened

     */

    @Override @DefinedBy(Api.COMPILER)

    public JavaFileObject getJavaFileForInput(JavaFileManager.Location location,

            String className,

            JavaFileObject.Kind kind)

            throws IOException {

        return stdFileManager.getJavaFileForInput(location, className, kind);

    }

    /**

     * Returns a {@linkplain JavaFileObject file object} for output

     * representing the specified class of the specified kind in the

     * given location.

     *

     * <p>Optionally, this file manager might consider the sibling as

     * a hint for where to place the output.  The exact semantics of

     * this hint is unspecified.  The JDK compiler, javac, for

     * example, will place class files in the same directories as

     * originating source files unless a class file output directory

     * is provided.  To facilitate this behavior, javac might provide

     * the originating source file as sibling when calling this

     * method.

     *

     * @param location a location

     * @param className the name of a class

     * @param kind the kind of file, must be one of {@link

     * JavaFileObject.Kind#SOURCE SOURCE} or {@link

     * JavaFileObject.Kind#CLASS CLASS}

     * @param sibling a file object to be used as hint for placement;

     * might be {@code null}

     * @return a file object for output

     * @throws IllegalArgumentException if sibling is not known to

     * this file manager, or if the location is not known to this file

     * manager and the file manager does not support unknown

     * locations, or if the kind is not valid

     * @throws IOException if an I/O error occurred, or if {@link

     * #close} has been called and this file manager cannot be

     * reopened

     * @throws IllegalStateException {@link #close} has been called

     * and this file manager cannot be reopened

     */

    @Override @DefinedBy(Api.COMPILER)

    public JavaFileObject getJavaFileForOutput(JavaFileManager.Location location,

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

        OutputMemoryJavaFileObject fo;

        fo = new OutputMemoryJavaFileObject(className, kind);

        classObjects.put(className, fo);

        proc.debug(DBG_FMGR, "Set out file: %s = %s\n", className, fo);

        if (classListener != null) {

            classListener.newClassFile(fo, location, className, kind, sibling);

        }

        return fo;

    }