/*

 * Copyright (c) 2009, 2016, 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.file;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStreamWriter;

import java.lang.ref.SoftReference;

import java.lang.reflect.Constructor;

import java.net.URL;

import java.net.URLClassLoader;

import java.nio.ByteBuffer;

import java.nio.CharBuffer;

import java.nio.charset.Charset;

import java.nio.charset.CharsetDecoder;

import java.nio.charset.CoderResult;

import java.nio.charset.CodingErrorAction;

import java.nio.charset.IllegalCharsetNameException;

import java.nio.charset.UnsupportedCharsetException;

import java.nio.file.Path;

import java.util.Collection;

import java.util.HashMap;

import java.util.Iterator;

import java.util.Map;

import java.util.Objects;

import java.util.Set;

import javax.tools.JavaFileManager;

import javax.tools.JavaFileObject;

import javax.tools.JavaFileObject.Kind;

import com.sun.tools.javac.code.Lint;

import com.sun.tools.javac.code.Source;

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

import com.sun.tools.javac.main.OptionHelper;

import com.sun.tools.javac.main.OptionHelper.GrumpyHelper;

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.JCDiagnostic.SimpleDiagnosticPosition;

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

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

/**

 * Utility methods for building a filemanager.

 * There are no references here to file-system specific objects such as

 * java.io.File or java.nio.file.Path.

 */

public abstract class BaseFileManager implements JavaFileManager {

    protected BaseFileManager(Charset charset) {

        this.charset = charset;

        byteBufferCache = new ByteBufferCache();

        locations = createLocations();

    }

    /**

     * Set the context for JavacPathFileManager.

     * @param context the context containing items to be associated with the file manager

     */

    public void setContext(Context context) {

        log = Log.instance(context);

        options = Options.instance(context);

        classLoaderClass = options.get("procloader");

        locations.update(log, Lint.instance(context), FSInfo.instance(context));

        // Setting this option is an indication that close() should defer actually closing

        // the file manager until after a specified period of inactivity.

        // This is to accomodate clients which save references to Symbols created for use

        // within doclets or annotation processors, and which then attempt to use those

        // references after the tool exits, having closed any internally managed file manager.

        // Ideally, such clients should run the tool via the javax.tools API, providing their

        // own file manager, which can be closed by the client when all use of that file

        // manager is complete.

        // If the option has a numeric value, it will be interpreted as the duration,

        // in seconds, of the period of inactivity to wait for, before the file manager

        // is actually closed.

        // See also deferredClose().

        String s = options.get("fileManager.deferClose");

        if (s != null) {

            try {

                deferredCloseTimeout = (int) (Float.parseFloat(s) * 1000);

            } catch (NumberFormatException e) {

                deferredCloseTimeout = 60 * 1000;  // default: one minute, in millis

            }

        }

    }

    protected Locations createLocations() {

        return new Locations();

    }

    /**

     * The log to be used for error reporting.

     */

    public Log log;

    /**

     * User provided charset (through javax.tools).

     */

    protected Charset charset;

    protected Options options;

    protected String classLoaderClass;

    protected Locations locations;

    /**

     * A flag for clients to use to indicate that this file manager should

     * be closed when it is no longer required.

     */

    public boolean autoClose;

    /**

     * Wait for a period of inactivity before calling close().

     * The length of the period of inactivity is given by {@code deferredCloseTimeout}

     */

    protected void deferredClose() {

        Thread t = new Thread(getClass().getName() + " DeferredClose") {

            @Override

            public void run() {

                try {

                    synchronized (BaseFileManager.this) {

                        long now = System.currentTimeMillis();

                        while (now < lastUsedTime + deferredCloseTimeout) {

                            BaseFileManager.this.wait(lastUsedTime + deferredCloseTimeout - now);

                            now = System.currentTimeMillis();

                        }

                        deferredCloseTimeout = 0;

                        close();

                    }

                } catch (InterruptedException e) {

                } catch (IOException e) {

                }

            }

        };

        t.setDaemon(true);

        t.start();

    }

    synchronized void updateLastUsedTime() {

        if (deferredCloseTimeout > 0) { // avoid updating the time unnecessarily

            lastUsedTime = System.currentTimeMillis();

        }

    }

    private long lastUsedTime = System.currentTimeMillis();

    protected long deferredCloseTimeout = 0;

    protected Source getSource() {

        String sourceName = options.get(Option.SOURCE);

        Source source = null;

        if (sourceName != null)

            source = Source.lookup(sourceName);

        return (source != null ? source : Source.DEFAULT);

    }

    protected ClassLoader getClassLoader(URL[] urls) {

        ClassLoader thisClassLoader = getClass().getClassLoader();

        // Allow the following to specify a closeable classloader

        // other than URLClassLoader.

        // 1: Allow client to specify the class to use via hidden option

        if (classLoaderClass != null) {

            try {

                Class<? extends ClassLoader> loader =

                        Class.forName(classLoaderClass).asSubclass(ClassLoader.class);

                Class<?>[] constrArgTypes = { URL[].class, ClassLoader.class };

                Constructor<? extends ClassLoader> constr = loader.getConstructor(constrArgTypes);

                return constr.newInstance(urls, thisClassLoader);

            } catch (ReflectiveOperationException t) {

                // ignore errors loading user-provided class loader, fall through

            }

        }

        return new URLClassLoader(urls, thisClassLoader);

    }

    public boolean isDefaultBootClassPath() {

        return locations.isDefaultBootClassPath();

    }

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

    @Override @DefinedBy(Api.COMPILER)

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

        OptionHelper helper = new GrumpyHelper(log) {

            @Override

            public String get(Option option) {

                return options.get(option.getText());

            }

            @Override

            public void put(String name, String value) {

                options.put(name, value);

            }

            @Override

            public void remove(String name) {

                options.remove(name);

            }

            @Override

            public boolean handleFileManagerOption(Option option, String value) {

                return handleOption(option, value);

            }

        };

        for (Option o: javacFileManagerOptions) {

            if (o.matches(current))  {

                if (o.hasArg()) {

                    if (remaining.hasNext()) {

                        if (!o.process(helper, current, remaining.next()))

                            return true;

                    }

                } else {

                    if (!o.process(helper, current))

                        return true;

                }

                // operand missing, or process returned true

                throw new IllegalArgumentException(current);

            }

        }

        return false;

    }

    // where

        private static final Set<Option> javacFileManagerOptions =

            Option.getJavacFileManagerOptions();

    @Override @DefinedBy(Api.COMPILER)

    public int isSupportedOption(String option) {

        for (Option o : javacFileManagerOptions) {

            if (o.matches(option))

                return o.hasArg() ? 1 : 0;

        }

        return -1;

    }

    /**

     * Common back end for OptionHelper handleFileManagerOption.

     * @param option the option whose value to be set

     * @param value the value for the option

     * @return true if successful, and false otherwise

     */

    public boolean handleOption(Option option, String value) {

    }

    /**

     * Call handleOption for collection of options and corresponding values.

     * @param map a collection of options and corresponding values

     * @return true if all the calls are successful

     */

    public boolean handleOptions(Map<Option, String> map) {

        boolean ok = true;

        for (Map.Entry<Option, String> e: map.entrySet())

            ok = ok & handleOption(e.getKey(), e.getValue());

        return ok;

    }

    // </editor-fold>

    // <editor-fold defaultstate="collapsed" desc="Encoding">

    private String defaultEncodingName;

    private String getDefaultEncodingName() {

        if (defaultEncodingName == null) {

            defaultEncodingName =

                new OutputStreamWriter(new ByteArrayOutputStream()).getEncoding();

        }

        return defaultEncodingName;

    }

    public String getEncodingName() {

    }

    @SuppressWarnings("cast")

    public CharBuffer decode(ByteBuffer inbuf, boolean ignoreEncodingErrors) {

        String encodingName = getEncodingName();

        CharsetDecoder decoder;

        try {

            decoder = getDecoder(encodingName, ignoreEncodingErrors);

        } catch (IllegalCharsetNameException | UnsupportedCharsetException e) {

            log.error("unsupported.encoding", encodingName);

            return (CharBuffer)CharBuffer.allocate(1).flip();

        }

        // slightly overestimate the buffer size to avoid reallocation.

        float factor =

            decoder.averageCharsPerByte() * 0.8f +

            decoder.maxCharsPerByte() * 0.2f;

        CharBuffer dest = CharBuffer.

            allocate(10 + (int)(inbuf.remaining()*factor));

        while (true) {

            CoderResult result = decoder.decode(inbuf, dest, true);

            dest.flip();

            if (result.isUnderflow()) { // done reading

                // make sure there is at least one extra character

                if (dest.limit() == dest.capacity()) {

                    dest = CharBuffer.allocate(dest.capacity()+1).put(dest);

                    dest.flip();

                }

                return dest;

            } else if (result.isOverflow()) { // buffer too small; expand

                int newCapacity =

                    10 + dest.capacity() +

                    (int)(inbuf.remaining()*decoder.maxCharsPerByte());

                dest = CharBuffer.allocate(newCapacity).put(dest);

            } else if (result.isMalformed() || result.isUnmappable()) {

                // bad character in input

                log.error(new SimpleDiagnosticPosition(dest.limit()),

                          "illegal.char.for.encoding",

                          charset == null ? encodingName : charset.name());

                // skip past the coding error

                inbuf.position(inbuf.position() + result.length());

                // undo the flip() to prepare the output buffer

                // for more translation

                dest.position(dest.limit());

                dest.limit(dest.capacity());

                dest.put((char)0xfffd); // backward compatible

            } else {

                throw new AssertionError(result);

            }

        }

        // unreached

    }

    public CharsetDecoder getDecoder(String encodingName, boolean ignoreEncodingErrors) {

        Charset cs = (this.charset == null)

            ? Charset.forName(encodingName)

            : this.charset;

        CharsetDecoder decoder = cs.newDecoder();

        CodingErrorAction action;

        if (ignoreEncodingErrors)

            action = CodingErrorAction.REPLACE;

        else

            action = CodingErrorAction.REPORT;

        return decoder

            .onMalformedInput(action)

            .onUnmappableCharacter(action);

    }

    // </editor-fold>

    // <editor-fold defaultstate="collapsed" desc="ByteBuffers">

    /**

     * Make a byte buffer from an input stream.

     * @param in the stream

     * @return a byte buffer containing the contents of the stream

     * @throws IOException if an error occurred while reading the stream

     */

    @SuppressWarnings("cast")

    public ByteBuffer makeByteBuffer(InputStream in)

        throws IOException {

        int limit = in.available();

        if (limit < 1024) limit = 1024;

        ByteBuffer result = byteBufferCache.get(limit);

        int position = 0;

        while (in.available() != 0) {

            if (position >= limit)

                // expand buffer

                result = ByteBuffer.

                    allocate(limit <<= 1).

                    put((ByteBuffer)result.flip());

            int count = in.read(result.array(),

                position,

                limit - position);

            if (count < 0) break;

            result.position(position += count);

        }

        return (ByteBuffer)result.flip();

    }

    public void recycleByteBuffer(ByteBuffer bb) {

        byteBufferCache.put(bb);

    }

    /**

     * A single-element cache of direct byte buffers.

     */

    @SuppressWarnings("cast")

    private static class ByteBufferCache {

        private ByteBuffer cached;

        ByteBuffer get(int capacity) {

            if (capacity < 20480) capacity = 20480;

            ByteBuffer result =

                (cached != null && cached.capacity() >= capacity)

                ? (ByteBuffer)cached.clear()

                : ByteBuffer.allocate(capacity + capacity>>1);

            cached = null;

            return result;

        }

        void put(ByteBuffer x) {

            cached = x;

        }

    }

    private final ByteBufferCache byteBufferCache;

    // </editor-fold>

    // <editor-fold defaultstate="collapsed" desc="Content cache">

    public CharBuffer getCachedContent(JavaFileObject file) {

        ContentCacheEntry e = contentCache.get(file);

        if (e == null)

            return null;

        if (!e.isValid(file)) {

            contentCache.remove(file);

            return null;

        }

        return e.getValue();

    }

    public void cache(JavaFileObject file, CharBuffer cb) {

        contentCache.put(file, new ContentCacheEntry(file, cb));

    }

    public void flushCache(JavaFileObject file) {

        contentCache.remove(file);

    }

    protected final Map<JavaFileObject, ContentCacheEntry> contentCache = new HashMap<>();

    protected static class ContentCacheEntry {

        final long timestamp;

        final SoftReference<CharBuffer> ref;

        ContentCacheEntry(JavaFileObject file, CharBuffer cb) {

            this.timestamp = file.getLastModified();

            this.ref = new SoftReference<>(cb);

        }

        boolean isValid(JavaFileObject file) {

            return timestamp == file.getLastModified();

        }

        CharBuffer getValue() {

            return ref.get();

        }

    }

    // </editor-fold>

    public static Kind getKind(Path path) {

        return getKind(path.getFileName().toString());

    }

    public static Kind getKind(String name) {

        if (name.endsWith(Kind.CLASS.extension))

            return Kind.CLASS;

        else if (name.endsWith(Kind.SOURCE.extension))

            return Kind.SOURCE;

        else if (name.endsWith(Kind.HTML.extension))

            return Kind.HTML;

        else

            return Kind.OTHER;

    }

    protected static <T> T nullCheck(T o) {

        return Objects.requireNonNull(o);

    }

    protected static <T> Collection<T> nullCheck(Collection<T> it) {

        for (T t : it)

            Objects.requireNonNull(t);

        return it;

    }

}