/*

 * Copyright (c) 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

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 */

package com.sun.tools.jdeps;

import static com.sun.tools.jdeps.Module.*;

import static com.sun.tools.jdeps.Analyzer.NOT_FOUND;

import static java.util.stream.Collectors.*;

import com.sun.tools.classfile.AccessFlags;

import com.sun.tools.classfile.ClassFile;

import com.sun.tools.classfile.ConstantPoolException;

import com.sun.tools.classfile.Dependencies;

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

import com.sun.tools.classfile.Dependency;

import com.sun.tools.classfile.Dependency.Location;

import java.io.IOException;

import java.io.UncheckedIOException;

import java.util.Collections;

import java.util.Deque;

import java.util.HashMap;

import java.util.HashSet;

import java.util.Map;

import java.util.Optional;

import java.util.Set;

import java.util.concurrent.Callable;

import java.util.concurrent.ConcurrentHashMap;

import java.util.concurrent.ConcurrentLinkedDeque;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.FutureTask;

import java.util.stream.Stream;

/**

 * Parses class files and finds dependences

 */

class DependencyFinder {

    private static Finder API_FINDER = new Finder(true);

    private static Finder CLASS_FINDER = new Finder(false);

    private final JdepsConfiguration configuration;

    private final JdepsFilter filter;

    private final Map<Finder, Deque<Archive>> parsedArchives = new ConcurrentHashMap<>();

    private final Map<Location, Archive> parsedClasses = new ConcurrentHashMap<>();

    private final ExecutorService pool = Executors.newFixedThreadPool(2);

    private final Deque<FutureTask<Set<Location>>> tasks = new ConcurrentLinkedDeque<>();

    DependencyFinder(JdepsConfiguration configuration,

                     JdepsFilter filter) {

        this.configuration = configuration;

        this.filter = filter;

        this.parsedArchives.put(API_FINDER, new ConcurrentLinkedDeque<>());

        this.parsedArchives.put(CLASS_FINDER, new ConcurrentLinkedDeque<>());

    }

    Map<Location, Archive> locationToArchive() {

        return parsedClasses;

    }

    /**

     * Returns the modules of all dependencies found

     */

    Stream<Archive> getDependences(Archive source) {

        return source.getDependencies()

                     .map(this::locationToArchive)

                     .filter(a -> a != source);

    }

    /**

     * Returns the location to archive map; or NOT_FOUND.

     *

     * Location represents a parsed class.

     */

    Archive locationToArchive(Location location) {

        return parsedClasses.containsKey(location)

            ? parsedClasses.get(location)

            : configuration.findClass(location).orElse(NOT_FOUND);

    }

    /**

     * Returns a map from an archive to its required archives

     */

    Map<Archive, Set<Archive>> dependences() {

        Map<Archive, Set<Archive>> map = new HashMap<>();

        parsedArchives.values().stream()

            .flatMap(Deque::stream)

            .filter(a -> !a.isEmpty())

            .forEach(source -> {

                Set<Archive> deps = getDependences(source).collect(toSet());

                if (!deps.isEmpty()) {

                    map.put(source, deps);

                }

        });

        return map;

    }

    boolean isParsed(Location location) {

        return parsedClasses.containsKey(location);

    }

    /**

     * Parses all class files from the given archive stream and returns

     * all target locations.

     */

    public Set<Location> parse(Stream<? extends Archive> archiveStream) {

        archiveStream.forEach(archive -> parse(archive, CLASS_FINDER));

        return waitForTasksCompleted();

    }

    /**

     * Parses the exported API class files from the given archive stream and

     * returns all target locations.

     */

    public Set<Location> parseExportedAPIs(Stream<? extends Archive> archiveStream) {

        archiveStream.forEach(archive -> parse(archive, API_FINDER));

        return waitForTasksCompleted();

    }

    /**

     * Parses the named class from the given archive and

     * returns all target locations the named class references.

     */

    public Set<Location> parse(Archive archive, String name) {

        try {

            return parse(archive, CLASS_FINDER, name);

        } catch (IOException e) {

            throw new UncheckedIOException(e);

        }

    }

    /**

     * Parses the exported API of the named class from the given archive and

     * returns all target locations the named class references.

     */

    public Set<Location> parseExportedAPIs(Archive archive, String name)

    {

        try {

            return parse(archive, API_FINDER, name);

        } catch (IOException e) {

            throw new UncheckedIOException(e);

        }

    }

    private Optional<FutureTask<Set<Location>>> parse(Archive archive, Finder finder) {

        if (parsedArchives.get(finder).contains(archive))

            return Optional.empty();

        parsedArchives.get(finder).add(archive);

        trace("parsing %s %s%n", archive.getName(), archive.path());

        FutureTask<Set<Location>> task = new FutureTask<>(() -> {

            Set<Location> targets = new HashSet<>();

            for (ClassFile cf : archive.reader().getClassFiles()) {

                if (cf.access_flags.is(AccessFlags.ACC_MODULE))

                    continue;

                String classFileName;

                try {

                    classFileName = cf.getName();

                } catch (ConstantPoolException e) {

                    throw new ClassFileError(e);

                }

                // filter source class/archive

                String cn = classFileName.replace('/', '.');

                if (!finder.accept(archive, cn, cf.access_flags))

                    continue;

                // tests if this class matches the -include

                if (!filter.matches(cn))

                    continue;

                for (Dependency d : finder.findDependencies(cf)) {

                    if (filter.accepts(d)) {

                        archive.addClass(d.getOrigin(), d.getTarget());

                        targets.add(d.getTarget());

                    } else {

                        // ensure that the parsed class is added the archive

                        archive.addClass(d.getOrigin());

                    }

                    parsedClasses.putIfAbsent(d.getOrigin(), archive);

                }

            }

            return targets;

        });

        tasks.add(task);

        pool.submit(task);

        return Optional.of(task);

    }

    private Set<Location> parse(Archive archive, Finder finder, String name)

        throws IOException

    {

        ClassFile cf = archive.reader().getClassFile(name);

        if (cf == null) {

            throw new IllegalArgumentException(archive.getName() +

                " does not contain " + name);

        }

        if (cf.access_flags.is(AccessFlags.ACC_MODULE))

            return Collections.emptySet();

        Set<Location> targets = new HashSet<>();

        String cn;

        try {

            cn =  cf.getName().replace('/', '.');

        } catch (ConstantPoolException e) {

            throw new Dependencies.ClassFileError(e);

        }

        if (!finder.accept(archive, cn, cf.access_flags))

            return targets;

        // tests if this class matches the -include

        if (!filter.matches(cn))

            return targets;

        // skip checking filter.matches

        for (Dependency d : finder.findDependencies(cf)) {

            if (filter.accepts(d)) {

                targets.add(d.getTarget());

                archive.addClass(d.getOrigin(), d.getTarget());

            } else {

                // ensure that the parsed class is added the archive

                archive.addClass(d.getOrigin());

            }

            parsedClasses.putIfAbsent(d.getOrigin(), archive);

        }

        return targets;

    }

    /*

     * Waits until all submitted tasks are completed.

     */

    private Set<Location> waitForTasksCompleted() {

        try {

            Set<Location> targets = new HashSet<>();

            FutureTask<Set<Location>> task;

            while ((task = tasks.poll()) != null) {

                // wait for completion

                if (!task.isDone())

                    targets.addAll(task.get());

            }

            return targets;

        } catch (InterruptedException|ExecutionException e) {

            throw new Error(e);

        }

    }

    /*

     * Shutdown the executor service.

     */

    void shutdown() {

        pool.shutdown();

    }

    private interface SourceFilter {

        boolean accept(Archive archive, String cn, AccessFlags accessFlags);

    }

    private static class Finder implements Dependency.Finder, SourceFilter {

        private final Dependency.Finder finder;

        private final boolean apiOnly;

        Finder(boolean apiOnly) {

            this.apiOnly = apiOnly;

            this.finder = apiOnly

                ? Dependencies.getAPIFinder(AccessFlags.ACC_PROTECTED)

                : Dependencies.getClassDependencyFinder();

        }

        @Override

        public boolean accept(Archive archive, String cn, AccessFlags accessFlags) {

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

            String pn = i > 0 ? cn.substring(0, i) : "";

            // if -apionly is specified, analyze only exported and public types

            // All packages are exported in unnamed module.

            return apiOnly ? archive.getModule().isExported(pn) &&

                                 accessFlags.is(AccessFlags.ACC_PUBLIC)

                           : true;

        }

        @Override

        public Iterable<? extends Dependency> findDependencies(ClassFile classfile) {

            return finder.findDependencies(classfile);

        }

    }

}