/*

 * Copyright (c) 2012, 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.jdeps;

import com.sun.tools.classfile.AccessFlags;

import com.sun.tools.classfile.ClassFile;

import com.sun.tools.classfile.ConstantPoolException;

import com.sun.tools.classfile.Dependencies.ClassFileError;

import java.io.Closeable;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.InputStream;

import java.io.UncheckedIOException;

import java.nio.file.FileSystem;

import java.nio.file.FileSystems;

import java.nio.file.Files;

import java.nio.file.Path;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Enumeration;

import java.util.Iterator;

import java.util.List;

import java.util.NoSuchElementException;

import java.util.Set;

import java.util.jar.JarEntry;

import java.util.jar.JarFile;

import java.util.stream.Collectors;

import java.util.stream.Stream;

import java.util.zip.ZipFile;

/**

 * ClassFileReader reads ClassFile(s) of a given path that can be

 * a .class file, a directory, or a JAR file.

 */

public class ClassFileReader implements Closeable {

    /**

     * Returns a ClassFileReader instance of a given path.

     */

    public static ClassFileReader newInstance(Path path) throws IOException {

        return newInstance(path, null);

    }

    /**

     * Returns a ClassFileReader instance of a given path.

     */

    public static ClassFileReader newInstance(Path path, Runtime.Version version) throws IOException {

        if (Files.notExists(path)) {

            throw new FileNotFoundException(path.toString());

        }

        if (Files.isDirectory(path)) {

            return new DirectoryReader(path);

        } else if (path.getFileName().toString().endsWith(".jar")) {

            return new JarFileReader(path, version);

        } else {

            return new ClassFileReader(path);

        }

    }

    /**

     * Returns a ClassFileReader instance of a given FileSystem and path.

     *

     * This method is used for reading classes from jrtfs.

     */

    public static ClassFileReader newInstance(FileSystem fs, Path path) throws IOException {

        return new DirectoryReader(fs, path);

    }

    protected final Path path;

    protected final String baseFileName;

    protected Set<String> entries; // binary names

    protected final List<String> skippedEntries = new ArrayList<>();

    protected ClassFileReader(Path path) {

        this.path = path;

        this.baseFileName = path.getFileName() != null

                                ? path.getFileName().toString()

                                : path.toString();

    }

    public String getFileName() {

        return baseFileName;

    }

    public List<String> skippedEntries() {

        return skippedEntries;

    }

    /**

     * Returns all entries in this archive.

     */

    public Set<String> entries() {

        Set<String> es = this.entries;

        if (es == null) {

            // lazily scan the entries

            this.entries = scan();

        }

        return this.entries;

    }

    /**

     * Returns the ClassFile matching the given binary name

     * or a fully-qualified class name.

     */

    public ClassFile getClassFile(String name) throws IOException {

        if (name.indexOf('.') > 0) {

            int i = name.lastIndexOf('.');

            String pathname = name.replace('.', File.separatorChar) + ".class";

            if (baseFileName.equals(pathname) ||

                    baseFileName.equals(pathname.substring(0, i) + "$" +

                                        pathname.substring(i+1, pathname.length()))) {

                return readClassFile(path);

            }

        } else {

            if (baseFileName.equals(name.replace('/', File.separatorChar) + ".class")) {

                return readClassFile(path);

            }

        }

        return null;

    }

    public Iterable<ClassFile> getClassFiles() throws IOException {

        return FileIterator::new;

    }

    protected ClassFile readClassFile(Path p) throws IOException {

        InputStream is = null;

        try {

            is = Files.newInputStream(p);

            return ClassFile.read(is);

        } catch (ConstantPoolException e) {

            throw new ClassFileError(e);

        } finally {

            if (is != null) {

                is.close();

            }

        }

    }

    protected Set<String> scan() {

        try {

            ClassFile cf = ClassFile.read(path);

            String name = cf.access_flags.is(AccessFlags.ACC_MODULE)

                ? "module-info" : cf.getName();

            return Collections.singleton(name);

        } catch (ConstantPoolException|IOException e) {

            throw new ClassFileError(e);

        }

    }

    static boolean isClass(Path file) {

        String fn = file.getFileName().toString();

        return fn.endsWith(".class");

    }

    @Override

    public void close() throws IOException {

    }

    class FileIterator implements Iterator<ClassFile> {

        int count;

        FileIterator() {

            this.count = 0;

        }

        public boolean hasNext() {

            return count == 0 && baseFileName.endsWith(".class");

        }

        public ClassFile next() {

            if (!hasNext()) {

                throw new NoSuchElementException();

            }

            try {

                ClassFile cf = readClassFile(path);

                count++;

                return cf;

            } catch (IOException e) {

                throw new ClassFileError(e);

            }

        }

        public void remove() {

            throw new UnsupportedOperationException("Not supported yet.");

        }

    }

    public String toString() {

        return path.toString();

    }

    private static class DirectoryReader extends ClassFileReader {

        protected final String fsSep;

        DirectoryReader(Path path) throws IOException {

            this(FileSystems.getDefault(), path);

        }

        DirectoryReader(FileSystem fs, Path path) throws IOException {

            super(path);

            this.fsSep = fs.getSeparator();

        }

        protected Set<String> scan() {

            try (Stream<Path> stream = Files.walk(path, Integer.MAX_VALUE)) {

                return stream.filter(ClassFileReader::isClass)

                             .map(path::relativize)

                             .map(Path::toString)

                             .map(p -> p.replace(File.separatorChar, '/'))

                             .collect(Collectors.toSet());

            } catch (IOException e) {

                throw new UncheckedIOException(e);

            }

        }

        public ClassFile getClassFile(String name) throws IOException {

            if (name.indexOf('.') > 0) {

                int i = name.lastIndexOf('.');

                String pathname = name.replace(".", fsSep) + ".class";

                Path p = path.resolve(pathname);

                if (Files.notExists(p)) {

                    p = path.resolve(pathname.substring(0, i) + "$" +

                            pathname.substring(i+1, pathname.length()));

                }

                if (Files.exists(p)) {

                    return readClassFile(p);

                }

            } else {

                Path p = path.resolve(name + ".class");

                if (Files.exists(p)) {

                    return readClassFile(p);

                }

            }

            return null;

        }

        public Iterable<ClassFile> getClassFiles() throws IOException {

            final Iterator<ClassFile> iter = new DirectoryIterator();

            return () -> iter;

        }

        class DirectoryIterator implements Iterator<ClassFile> {

            private final List<Path> entries;

            private int index = 0;

            DirectoryIterator() throws IOException {

                List<Path> paths = null;

                try (Stream<Path> stream = Files.walk(path, Integer.MAX_VALUE)) {

                    paths = stream.filter(ClassFileReader::isClass)

                                  .collect(Collectors.toList());

                }

                this.entries = paths;

                this.index = 0;

            }

            public boolean hasNext() {

                return index != entries.size();

            }

            public ClassFile next() {

                if (!hasNext()) {

                    throw new NoSuchElementException();

                }

                Path path = entries.get(index++);

                try {

                    return readClassFile(path);

                } catch (IOException e) {

                    throw new ClassFileError(e);

                }

            }

            public void remove() {

                throw new UnsupportedOperationException("Not supported yet.");

            }

        }

    }

    static class JarFileReader extends ClassFileReader {

        private final JarFile jarfile;

        private final Runtime.Version version;

        JarFileReader(Path path, Runtime.Version version) throws IOException {

            this(path, openJarFile(path.toFile(), version), version);

        }

        JarFileReader(Path path, JarFile jf, Runtime.Version version) throws IOException {

            super(path);

            this.jarfile = jf;

            this.version = version;

        }

        @Override

        public void close() throws IOException {

            jarfile.close();

        }

        private static JarFile openJarFile(File f, Runtime.Version version)

                throws IOException {

            JarFile jf;

            if (version == null) {

                jf = new JarFile(f, false);

                if (jf.isMultiRelease()) {

                    throw new MultiReleaseException("err.multirelease.option.notfound", f.getName());

                }

            } else {

                jf = new JarFile(f, false, ZipFile.OPEN_READ, version);

                if (!jf.isMultiRelease()) {

                    throw new MultiReleaseException("err.multirelease.option.exists", f.getName());

                }

            }

            return jf;

        }

        protected Set<String> scan() {

            try (JarFile jf = openJarFile(path.toFile(), version)) {

                return jf.versionedStream().map(JarEntry::getName)

                         .filter(n -> n.endsWith(".class"))

                         .collect(Collectors.toSet());

            } catch (IOException e) {

                throw new UncheckedIOException(e);

            }

        }

        public ClassFile getClassFile(String name) throws IOException {

            if (name.indexOf('.') > 0) {

                int i = name.lastIndexOf('.');

                String entryName = name.replace('.', '/') + ".class";

                JarEntry e = jarfile.getJarEntry(entryName);

                if (e == null) {

                    e = jarfile.getJarEntry(entryName.substring(0, i) + "$"

                            + entryName.substring(i + 1, entryName.length()));

                }

                if (e != null) {

                    return readClassFile(jarfile, e);

                }

            } else {

                JarEntry e = jarfile.getJarEntry(name + ".class");

                if (e != null) {

                    return readClassFile(jarfile, e);

                }

            }

            return null;

        }

        protected ClassFile readClassFile(JarFile jarfile, JarEntry e) throws IOException {

            try (InputStream is = jarfile.getInputStream(e)) {

                ClassFile cf = ClassFile.read(is);

                if (jarfile.isMultiRelease()) {

                    VersionHelper.add(jarfile, e, cf);

                }

                return cf;

            } catch (ConstantPoolException ex) {

                throw new ClassFileError(ex);

            }

        }

        public Iterable<ClassFile> getClassFiles() throws IOException {

            final Iterator<ClassFile> iter = new JarFileIterator(this, jarfile);

            return () -> iter;

        }

    }

    class JarFileIterator implements Iterator<ClassFile> {

        protected final JarFileReader reader;

        protected Iterator<JarEntry> entries;

        protected JarFile jf;

        protected JarEntry nextEntry;

        protected ClassFile cf;

        JarFileIterator(JarFileReader reader) {

            this(reader, null);

        }

        JarFileIterator(JarFileReader reader, JarFile jarfile) {

            this.reader = reader;

            setJarFile(jarfile);

        }

        void setJarFile(JarFile jarfile) {

            if (jarfile == null) return;

            this.jf = jarfile;

            this.entries = jarfile.versionedStream().iterator();

            this.nextEntry = nextEntry();

        }

        public boolean hasNext() {

            if (nextEntry != null && cf != null) {

                return true;

            }

            while (nextEntry != null) {

                try {

                    cf = reader.readClassFile(jf, nextEntry);

                    return true;

                } catch (ClassFileError | IOException ex) {

                    skippedEntries.add(String.format("%s: %s (%s)",

                                                     ex.getMessage(),

                                                     nextEntry.getName(),

                                                     jf.getName()));

                }

                nextEntry = nextEntry();

            }

            return false;

        }

        public ClassFile next() {

            if (!hasNext()) {

                throw new NoSuchElementException();

            }

            ClassFile classFile = cf;

            cf = null;

            nextEntry = nextEntry();

            return classFile;

        }

        protected JarEntry nextEntry() {

            while (entries.hasNext()) {

                JarEntry e = entries.next();

                String name = e.getName();

                if (name.endsWith(".class")) {

                    return e;

                }

            }

            return null;

        }

        public void remove() {

            throw new UnsupportedOperationException("Not supported yet.");

        }

    }

    private static final String MODULE_INFO = "module-info.class";

}