/*

 * Copyright (c) 2010, 2017, 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.nashorn.internal.runtime;

import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOError;

import java.io.IOException;

import java.io.InputStream;

import java.io.PrintWriter;

import java.io.Reader;

import java.lang.ref.WeakReference;

import java.net.MalformedURLException;

import java.net.URI;

import java.net.URISyntaxException;

import java.net.URL;

import java.net.URLConnection;

import java.nio.charset.Charset;

import java.nio.charset.StandardCharsets;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

import java.time.LocalDateTime;

import java.util.Arrays;

import java.util.Base64;

import java.util.Objects;

import java.util.WeakHashMap;

import jdk.nashorn.api.scripting.URLReader;

import jdk.nashorn.internal.parser.Token;

import jdk.nashorn.internal.runtime.logging.DebugLogger;

import jdk.nashorn.internal.runtime.logging.Loggable;

import jdk.nashorn.internal.runtime.logging.Logger;

/**

 * Source objects track the origin of JavaScript entities.

 */

@Logger(name="source")

public final class Source implements Loggable {

    private static final int BUF_SIZE = 8 * 1024;

    private static final Cache CACHE = new Cache();

    // Message digest to file name encoder

    private final static Base64.Encoder BASE64 = Base64.getUrlEncoder().withoutPadding();

    /**

     * Descriptive name of the source as supplied by the user. Used for error

     * reporting to the user. For example, SyntaxError will use this to print message.

     * Used to implement __FILE__. Also used for SourceFile in .class for debugger usage.

     */

    private final String name;

    /**

     * Base path or URL of this source. Used to implement __DIR__, which can be

     * used to load scripts relative to the location of the current script.

     * This will be null when it can't be computed.

     */

    private final String base;

    /** Source content */

    private final Data data;

    /** Cached hash code */

    private int hash;

    /** Base64-encoded SHA1 digest of this source object */

    private volatile byte[] digest;

    /** source URL set via //@ sourceURL or //# sourceURL directive */

    private String explicitURL;

    // Do *not* make this public, ever! Trusts the URL and content.

    private Source(final String name, final String base, final Data data) {

        this.name = name;

        this.base = base;

        this.data = data;

    }

    private static synchronized Source sourceFor(final String name, final String base, final URLData data) throws IOException {

        try {

            final Source newSource = new Source(name, base, data);

            final Source existingSource = CACHE.get(newSource);

            if (existingSource != null) {

                // Force any access errors

                data.checkPermissionAndClose();

                return existingSource;

            }

            // All sources in cache must be fully loaded

            data.load();

            CACHE.put(newSource, newSource);

            return newSource;

        } catch (final RuntimeException e) {

            final Throwable cause = e.getCause();

            if (cause instanceof IOException) {

                throw (IOException) cause;

            }

            throw e;

        }

    }

    private static class Cache extends WeakHashMap<Source, WeakReference<Source>> {

        public Source get(final Source key) {

            final WeakReference<Source> ref = super.get(key);

            return ref == null ? null : ref.get();

        }

        public void put(final Source key, final Source value) {

            assert !(value.data instanceof RawData);

            put(key, new WeakReference<>(value));

        }

    }

    /* package-private */

    DebuggerSupport.SourceInfo getSourceInfo() {

        return new DebuggerSupport.SourceInfo(getName(), data.hashCode(),  data.url(), data.array());

    }

    // Wrapper to manage lazy loading

    private static interface Data {

        URL url();

        int length();

        long lastModified();

        char[] array();

        boolean isEvalCode();

    }

    private static class RawData implements Data {

        private final char[] array;

        private final boolean evalCode;

        private int hash;

        private RawData(final char[] array, final boolean evalCode) {

            this.array = Objects.requireNonNull(array);

            this.evalCode = evalCode;

        }

        private RawData(final String source, final boolean evalCode) {

            this.array = Objects.requireNonNull(source).toCharArray();

            this.evalCode = evalCode;

        }

        private RawData(final Reader reader) throws IOException {

            this(readFully(reader), false);

        }

        @Override

        public int hashCode() {

            int h = hash;

            if (h == 0) {

                h = hash = Arrays.hashCode(array) ^ (evalCode? 1 : 0);

            }

            return h;

        }

        @Override

        public boolean equals(final Object obj) {

            if (this == obj) {

                return true;

            }

            if (obj instanceof RawData) {

                final RawData other = (RawData)obj;

                return Arrays.equals(array, other.array) && evalCode == other.evalCode;

            }

            return false;

        }

        @Override

        public String toString() {

            return new String(array());

        }

        @Override

        public URL url() {

            return null;

        }

        @Override

        public int length() {

            return array.length;

        }

        @Override

        public long lastModified() {

            return 0;

        }

        @Override

        public char[] array() {

            return array;

        }

        @Override

        public boolean isEvalCode() {

            return evalCode;

        }

    }

    private static class URLData implements Data {

        private final URL url;

        protected final Charset cs;

        private int hash;

        protected char[] array;

        protected int length;

        protected long lastModified;

        private URLData(final URL url, final Charset cs) {

            this.url = Objects.requireNonNull(url);

            this.cs = cs;

        }

        @Override

        public int hashCode() {

            int h = hash;

            if (h == 0) {

                h = hash = url.hashCode();

            }

            return h;

        }

        @Override

        public boolean equals(final Object other) {

            if (this == other) {

                return true;

            }

            if (!(other instanceof URLData)) {

                return false;

            }

            final URLData otherData = (URLData) other;

            if (url.equals(otherData.url)) {

                // Make sure both have meta data loaded

                try {

                    if (isDeferred()) {

                        // Data in cache is always loaded, and we only compare to cached data.

                        assert !otherData.isDeferred();

                        loadMeta();

                    } else if (otherData.isDeferred()) {

                        otherData.loadMeta();

                    }

                } catch (final IOException e) {

                    throw new RuntimeException(e);

                }

                // Compare meta data

                return this.length == otherData.length && this.lastModified == otherData.lastModified;

            }

            return false;

        }

        @Override

        public String toString() {

            return new String(array());

        }

        @Override

        public URL url() {

            return url;

        }

        @Override

        public int length() {

            return length;

        }

        @Override

        public long lastModified() {

            return lastModified;

        }

        @Override

        public char[] array() {

            assert !isDeferred();

            return array;

        }

        @Override

        public boolean isEvalCode() {

            return false;

        }

        boolean isDeferred() {

            return array == null;

        }

        @SuppressWarnings("try")

        protected void checkPermissionAndClose() throws IOException {

            try (InputStream in = url.openStream()) {

                // empty

            }

            debug("permission checked for ", url);

        }

        protected void load() throws IOException {

            if (array == null) {

                final URLConnection c = url.openConnection();

                try (InputStream in = c.getInputStream()) {

                    array = cs == null ? readFully(in) : readFully(in, cs);

                    length = array.length;

                    lastModified = c.getLastModified();

                    debug("loaded content for ", url);

                }

            }

        }

        protected void loadMeta() throws IOException {

            if (length == 0 && lastModified == 0) {

                final URLConnection c = url.openConnection();

                try (InputStream in = c.getInputStream()) {

                    length = c.getContentLength();

                    lastModified = c.getLastModified();

                    debug("loaded metadata for ", url);

                }

            }

        }

    }

    private static class FileData extends URLData {

        private final File file;

        private FileData(final File file, final Charset cs) {

            super(getURLFromFile(file), cs);

            this.file = file;

        }

        @Override

        protected void checkPermissionAndClose() throws IOException {

            if (!file.canRead()) {

                throw new FileNotFoundException(file + " (Permission Denied)");

            }

            debug("permission checked for ", file);

        }

        @Override

        protected void loadMeta() {

            if (length == 0 && lastModified == 0) {

                length = (int) file.length();

                lastModified = file.lastModified();

                debug("loaded metadata for ", file);

            }

        }

        @Override

        protected void load() throws IOException {

            if (array == null) {

                array = cs == null ? readFully(file) : readFully(file, cs);

                length = array.length;

                lastModified = file.lastModified();

                debug("loaded content for ", file);

            }

        }

    }

    private static void debug(final Object... msg) {

        final DebugLogger logger = getLoggerStatic();

        if (logger != null) {

            logger.info(msg);

        }

    }

    private char[] data() {

        return data.array();

    }

    /**

     * Returns a Source instance

     *

     * @param name    source name

     * @param content contents as char array

     * @param isEval does this represent code from 'eval' call?

     * @return source instance

     */

    public static Source sourceFor(final String name, final char[] content, final boolean isEval) {

        return new Source(name, baseName(name), new RawData(content, isEval));

    }

    /**

     * Returns a Source instance

     *

     * @param name    source name

     * @param content contents as char array

     *

     * @return source instance

     */

    public static Source sourceFor(final String name, final char[] content) {

        return sourceFor(name, content, false);

    }

    /**

     * Returns a Source instance

     *

     * @param name    source name

     * @param content contents as string

     * @param isEval does this represent code from 'eval' call?

     * @return source instance

     */

    public static Source sourceFor(final String name, final String content, final boolean isEval) {

        return new Source(name, baseName(name), new RawData(content, isEval));

    }

    /**

     * Returns a Source instance

     *

     * @param name    source name

     * @param content contents as string

     * @return source instance

     */

    public static Source sourceFor(final String name, final String content) {

        return sourceFor(name, content, false);

    }

    /**

     * Constructor

     *

     * @param name  source name

     * @param url   url from which source can be loaded

     *

     * @return source instance

     *

     * @throws IOException if source cannot be loaded

     */

    public static Source sourceFor(final String name, final URL url) throws IOException {

        return sourceFor(name, url, null);

    }

    /**

     * Constructor

     *

     * @param name  source name

     * @param url   url from which source can be loaded

     * @param cs    Charset used to convert bytes to chars

     *

     * @return source instance

     *

     * @throws IOException if source cannot be loaded

     */

    public static Source sourceFor(final String name, final URL url, final Charset cs) throws IOException {

        return sourceFor(name, baseURL(url), new URLData(url, cs));

    }

    /**

     * Constructor

     *

     * @param name  source name

     * @param file  file from which source can be loaded

     *

     * @return source instance

     *

     * @throws IOException if source cannot be loaded

     */

    public static Source sourceFor(final String name, final File file) throws IOException {

        return sourceFor(name, file, null);

    }

    /**

     * Constructor

     *

     * @param name  source name

     * @param path  path from which source can be loaded

     *

     * @return source instance