/*

 * Copyright (c) 2013, 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 java.io.PrintStream;

import java.util.Comparator;

import java.util.HashMap;

import java.util.HashSet;

import java.util.List;

import java.util.Map;

import java.util.Objects;

import java.util.Set;

import java.util.stream.Collectors;

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

/**

 * Dependency Analyzer.

 */

public class Analyzer {

    /**

     * Type of the dependency analysis.  Appropriate level of data

     * will be stored.

     */

    public enum Type {

        SUMMARY,

        PACKAGE,

        CLASS,

        VERBOSE

    }

    /**

     * Filter to be applied when analyzing the dependencies from the given archives.

     * Only the accepted dependencies are recorded.

     */

    interface Filter {

        boolean accepts(Location origin, Archive originArchive, Location target, Archive targetArchive);

    }

    protected final Type type;

    protected final Filter filter;

    protected final Map<Archive, ArchiveDeps> results = new HashMap<>();

    protected final Map<Location, Archive> map = new HashMap<>();

    private static final Archive NOT_FOUND

        = new Archive(JdepsTask.getMessage("artifact.not.found"));

    /**

     * Constructs an Analyzer instance.

     *

     * @param type Type of the dependency analysis

     * @param filter

     */

    public Analyzer(Type type, Filter filter) {

        this.type = type;

        this.filter = filter;

    }

    /**

     * Performs the dependency analysis on the given archives.

     */

    public boolean run(List<Archive> archives) {

        // build a map from Location to Archive

        buildLocationArchiveMap(archives);

        // traverse and analyze all dependencies

        for (Archive archive : archives) {

            ArchiveDeps deps = new ArchiveDeps(archive, type);

            archive.visitDependences(deps);

            results.put(archive, deps);

        }

        return true;

    }

    protected void buildLocationArchiveMap(List<Archive> archives) {

        // build a map from Location to Archive

        for (Archive archive: archives) {

            for (Location l: archive.getClasses()) {

                if (!map.containsKey(l)) {

                    map.put(l, archive);

                } else {

                    // duplicated class warning?

                }

            }

        }

    }

    public boolean hasDependences(Archive archive) {

        if (results.containsKey(archive)) {

            return results.get(archive).dependencies().size() > 0;

        }

        return false;

    }

    public Set<String> dependences(Archive source) {

        ArchiveDeps result = results.get(source);

        return result.dependencies().stream()

                     .map(Dep::target)

                     .collect(Collectors.toSet());

    }

    public interface Visitor {

        /**

         * Visits a recorded dependency from origin to target which can be

         * a fully-qualified classname, a package name, a module or

         * archive name depending on the Analyzer's type.

         */

        public void visitDependence(String origin, Archive originArchive,

                                    String target, Archive targetArchive);

    }

    /**

     * Visit the dependencies of the given source.

     * If the requested level is SUMMARY, it will visit the required archives list.

     */

    public void visitDependences(Archive source, Visitor v, Type level) {

        if (level == Type.SUMMARY) {

            final ArchiveDeps result = results.get(source);

            result.requires().stream()

                  .sorted(Comparator.comparing(Archive::getName))

                  .forEach(archive -> {

                      Profile profile = result.getTargetProfile(archive);

                      v.visitDependence(source.getName(), source,

                                        profile != null ? profile.profileName() : archive.getName(), archive);

                  });

        } else {

            ArchiveDeps result = results.get(source);

            if (level != type) {

                // requesting different level of analysis

                result = new ArchiveDeps(source, level);

                source.visitDependences(result);

            }

            result.dependencies().stream()

                  .sorted(Comparator.comparing(Dep::origin)

                                    .thenComparing(Dep::target))

                  .forEach(d -> v.visitDependence(d.origin(), d.originArchive(), d.target(), d.targetArchive()));

        }

    }

    public void visitDependences(Archive source, Visitor v) {

        visitDependences(source, v, type);

    }

    /**

     * ArchiveDeps contains the dependencies for an Archive that can have one or

     * more classes.

     */

    class ArchiveDeps implements Archive.Visitor {

        protected final Archive archive;

        protected final Set<Archive> requires;

        protected final Set<Dep> deps;

        protected final Type level;

        private Profile profile;

        ArchiveDeps(Archive archive, Type level) {

            this.archive = archive;

            this.deps = new HashSet<>();

            this.requires = new HashSet<>();

            this.level = level;

        }

        Set<Dep> dependencies() {

            return deps;

        }

        Set<Archive> requires() {

            return requires;

        }

        Profile getTargetProfile(Archive target) {

            if (target instanceof Module) {

                return Profile.getProfile((Module) target);

            } else {

                return null;

            }

        }

        Archive findArchive(Location t) {

            Archive target = archive.getClasses().contains(t) ? archive : map.get(t);

            if (target == null) {

                map.put(t, target = NOT_FOUND);

            }

            return target;

        }

        // return classname or package name depedning on the level

        private String getLocationName(Location o) {

            if (level == Type.CLASS || level == Type.VERBOSE) {

                return o.getClassName();

            } else {

                String pkg = o.getPackageName();

                return pkg.isEmpty() ? "<unnamed>" : pkg;

            }

        }

        @Override

        public void visit(Location o, Location t) {

            Archive targetArchive = findArchive(t);

            if (filter.accepts(o, archive, t, targetArchive)) {

                addDep(o, t);

                if (!requires.contains(targetArchive)) {

                    requires.add(targetArchive);

                }

            }

            if (targetArchive instanceof Module) {

                Profile p = Profile.getProfile(t.getPackageName());

                if (profile == null || (p != null && p.compareTo(profile) > 0)) {

                    profile = p;

                }

            }

        }

        private Dep curDep;

        protected Dep addDep(Location o, Location t) {

            String origin = getLocationName(o);

            String target = getLocationName(t);

            Archive targetArchive = findArchive(t);

            if (curDep != null &&

                    curDep.origin().equals(origin) &&

                    curDep.originArchive() == archive &&

                    curDep.target().equals(target) &&

                    curDep.targetArchive() == targetArchive) {

                return curDep;

            }

            Dep e = new Dep(origin, archive, target, targetArchive);

            if (deps.contains(e)) {

                for (Dep e1 : deps) {

                    if (e.equals(e1)) {

                        curDep = e1;

                    }

                }

            } else {

                deps.add(e);

                curDep = e;

            }

            return curDep;

        }

    }

    /*

     * Class-level or package-level dependency

     */

    class Dep {

        final String origin;

        final Archive originArchive;

        final String target;

        final Archive targetArchive;

        Dep(String origin, Archive originArchive, String target, Archive targetArchive) {

            this.origin = origin;

            this.originArchive = originArchive;

            this.target = target;

            this.targetArchive = targetArchive;

        }

        String origin() {

            return origin;

        }

        Archive originArchive() {

            return originArchive;

        }

        String target() {

            return target;

        }

        Archive targetArchive() {

            return targetArchive;

        }

        @Override

        @SuppressWarnings("unchecked")

        public boolean equals(Object o) {

            if (o instanceof Dep) {

                Dep d = (Dep) o;

                return this.origin.equals(d.origin) &&

                        this.originArchive == d.originArchive &&

                        this.target.equals(d.target) &&

                        this.targetArchive == d.targetArchive;

            }

            return false;

        }

        @Override

        public int hashCode() {

            int hash = 7;

            hash = 67*hash + Objects.hashCode(this.origin)

                           + Objects.hashCode(this.originArchive)

                           + Objects.hashCode(this.target)

                           + Objects.hashCode(this.targetArchive);

            return hash;

        }

        public String toString() {

            return String.format("%s (%s) -> %s (%s)%n",

                    origin, originArchive.getName(),

                    target, targetArchive.getName());

        }

    }

    static Analyzer getExportedAPIsAnalyzer() {

        return new ModuleAccessAnalyzer(ModuleAccessAnalyzer.reexportsFilter, true);

    }

    static Analyzer getModuleAccessAnalyzer() {

        return new ModuleAccessAnalyzer(ModuleAccessAnalyzer.accessCheckFilter, false);

    }

    private static class ModuleAccessAnalyzer extends Analyzer {

        private final boolean apionly;

        ModuleAccessAnalyzer(Filter filter, boolean apionly) {

            super(Type.VERBOSE, filter);

            this.apionly = apionly;

        }

        /**

         * Verify module access

         */

        public boolean run(List<Archive> archives) {

            // build a map from Location to Archive

            buildLocationArchiveMap(archives);

            // traverse and analyze all dependencies

            int count = 0;

            for (Archive archive : archives) {

                ArchiveDeps checker = new ArchiveDeps(archive, type);

                archive.visitDependences(checker);

                count += checker.dependencies().size();

                // output if any error

                Module m = (Module)archive;

                printDependences(System.err, m, checker.dependencies());

                results.put(archive, checker);

            }

            return count == 0;

        }

        private void printDependences(PrintStream out, Module m, Set<Dep> deps) {

            if (deps.isEmpty())

                return;

            String msg = apionly ? "API reference:" : "inaccessible reference:";

            deps.stream().sorted(Comparator.comparing(Dep::origin)

                                           .thenComparing(Dep::target))

                .forEach(d -> out.format("%s %s (%s) -> %s (%s)%n", msg,

                                         d.origin(), d.originArchive().getName(),

                                         d.target(), d.targetArchive().getName()));

            if (apionly) {

                out.format("Dependences missing re-exports=\"true\" attribute:%n");

                deps.stream()

                        .map(Dep::targetArchive)

                        .map(Archive::getName)

                        .distinct()

                        .sorted()

                        .forEach(d -> out.format("  %s -> %s%n", m.name(), d));

            }

        }

        private static Module findModule(Archive archive) {

            if (Module.class.isInstance(archive)) {

                return (Module) archive;

            } else {

                return null;

            }

        }

        // returns true if target is accessible by origin

        private static boolean canAccess(Location o, Archive originArchive, Location t, Archive targetArchive) {

            Module origin = findModule(originArchive);

            Module target = findModule(targetArchive);

            if (targetArchive == Analyzer.NOT_FOUND) {

                return false;

            }

            // unnamed module

            // ## should check public type?

            if (target == null)

                return true;

            // module-private

            if (origin == target)

                return true;

            return target.isAccessibleTo(t.getClassName(), origin);

        }

        static final Filter accessCheckFilter = new Filter() {

            @Override

            public boolean accepts(Location o, Archive originArchive, Location t, Archive targetArchive) {

                return !canAccess(o, originArchive, t, targetArchive);

            }

        };

        static final Filter reexportsFilter = new Filter() {

            @Override

            public boolean accepts(Location o, Archive originArchive, Location t, Archive targetArchive) {

                Module origin = findModule(originArchive);

                Module target = findModule(targetArchive);

                if (!origin.isExportedPackage(o.getPackageName())) {

                    // filter non-exported classes

                    return false;

                }

                boolean accessible = canAccess(o, originArchive, t, targetArchive);

                if (!accessible)

                    return true;

                String mn = target.name();

                // skip checking re-exports for java.base

                if (origin == target || "java.base".equals(mn))

                    return false;

                assert origin.requires().containsKey(mn);  // otherwise, should not be accessible

                if (origin.requires().get(mn)) {

                    return false;

                }

                return true;

            }

        };

    }

}