/*

 * Copyright (c) 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 com.sun.tools.jdeps;

import static java.lang.module.ModuleDescriptor.Requires.Modifier.*;

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

import java.io.BufferedWriter;

import java.io.IOException;

import java.io.PrintWriter;

import java.lang.module.Configuration;

import java.lang.module.ModuleDescriptor;

import java.lang.module.ModuleFinder;

import java.lang.module.ModuleReference;

import java.lang.module.ResolvedModule;

import java.nio.file.Files;

import java.nio.file.Path;

import java.util.ArrayDeque;

import java.util.ArrayList;

import java.util.Deque;

import java.util.HashSet;

import java.util.List;

import java.util.Map;

import java.util.Objects;

import java.util.Set;

import java.util.TreeSet;

import java.util.function.Function;

import java.util.stream.Collectors;

import java.util.stream.Stream;

/**

 * Generate dot graph for modules

 */

public class ModuleDotGraph {

    private final Map<String, Configuration> configurations;

    private final boolean apiOnly;

    public ModuleDotGraph(JdepsConfiguration config, boolean apiOnly) {

        this(config.rootModules().stream()

                   .map(Module::name)

                   .sorted()

                   .collect(toMap(Function.identity(), mn -> config.resolve(Set.of(mn)))),

             apiOnly);

    }

    public ModuleDotGraph(Map<String, Configuration> configurations, boolean apiOnly) {

        this.configurations = configurations;

        this.apiOnly = apiOnly;

    }

    /**

     * Generate dotfile for all modules

     *

     * @param dir output directory

     */

    public boolean genDotFiles(Path dir) throws IOException {

        Files.createDirectories(dir);

        for (String mn : configurations.keySet()) {

            Path path = dir.resolve(mn + ".dot");

        }

        return true;

    }

    /**

     * Generate dotfile of the given path

     */

        throws IOException

    {

        // transitive reduction

        Graph<String> graph = apiOnly

                ? requiresTransitiveGraph(configuration, Set.of(name))

                : gengraph(configuration);

                         DotGraphBuilder.JAVA_SE_SUBGRAPH)

                         DotGraphBuilder.JDK_SUBGRAPH)

                                 .map(mn -> configuration.findModule(mn).get()

                                                .reference().descriptor()));

        // build dot file

        builder.build(path);

    }

    /**

     * Returns a Graph of the given Configuration after transitive reduction.

     *

     * Transitive reduction of requires transitive edge and requires edge have

     * to be applied separately to prevent the requires transitive edges

     * (e.g. U -> V) from being reduced by a path (U -> X -> Y -> V)

     * in which  V would not be re-exported from U.

     */

    private Graph<String> gengraph(Configuration cf) {

        Graph.Builder<String> builder = new Graph.Builder<>();

        cf.modules().stream()

                builder.addNode(mn);

            });

        Graph<String> rpg = requiresTransitiveGraph(cf, builder.nodes);

        return builder.build().reduce(rpg);

    }

    /**

     * Returns a Graph containing only requires transitive edges

     * with transitive reduction.

     */

    public Graph<String> requiresTransitiveGraph(Configuration cf,

                                                 Set<String> roots)

    {

        Deque<String> deque = new ArrayDeque<>(roots);

        Set<String> visited = new HashSet<>();

        Graph.Builder<String> builder = new Graph.Builder<>();

        while (deque.peek() != null) {

            String mn = deque.pop();

            if (visited.contains(mn))

                continue;

            visited.add(mn);

            builder.addNode(mn);

                                || d.name().equals("java.base"))

        }

        return builder.build().reduce();

    }

        static final Set<String> JAVA_SE_SUBGRAPH = javaSE();

        static final Set<String> JDK_SUBGRAPH = jdk();

        private static Set<String> javaSE() {

            String root = "java.se.ee";

            ModuleFinder system = ModuleFinder.ofSystem();

            if (system.find(root).isPresent()) {

                return Stream.concat(Stream.of(root),

                                     Configuration.empty().resolve(system,

                                                                   ModuleFinder.of(),

                                                                   Set.of(root))

                                                  .findModule(root).get()

                                                  .reads().stream()

                                                  .map(ResolvedModule::name))

                             .collect(toSet());

            } else {

                // approximation

                return system.findAll().stream()

                    .map(ModuleReference::descriptor)

                    .map(ModuleDescriptor::name)

                    .filter(name -> name.startsWith("java.") &&

                                        !name.equals("java.smartcardio"))

                    .collect(Collectors.toSet());

            }

        }

        private static Set<String> jdk() {

            return ModuleFinder.ofSystem().findAll().stream()

                    .map(ModuleReference::descriptor)

                    .map(ModuleDescriptor::name)

                    .filter(name -> !JAVA_SE_SUBGRAPH.contains(name) &&

                                        (name.startsWith("java.") ||

                                            name.startsWith("jdk.") ||

                                            name.startsWith("javafx.")))

                    .collect(Collectors.toSet());

        }

        static class SubGraph {

            final String name;

            final String group;

            final String color;

            final Set<String> nodes;

            SubGraph(String name, String group, String color, Set<String> nodes) {

                this.name = Objects.requireNonNull(name);

                this.group = Objects.requireNonNull(group);

                this.color = Objects.requireNonNull(color);

                this.nodes = Objects.requireNonNull(nodes);

            }

        }

        private final String name;

        private final Graph<String> graph;

        private final Set<ModuleDescriptor> descriptors = new TreeSet<>();

        private final List<SubGraph> subgraphs = new ArrayList<>();

            this.name = name;

            this.graph = graph;

        }

            descriptors.forEach(this.descriptors::add);

            return this;

        }

        public void build(Path filename) throws IOException {

            try (BufferedWriter writer = Files.newBufferedWriter(filename);

                 PrintWriter out = new PrintWriter(writer)) {

                out.format("digraph \"%s\" {%n", name);

                out.format("  nodesep=.5;%n");

                out.format("  pencolor=transparent;%n");

                // same RANKS

                                        .map(ModuleDescriptor::name)

                                        .filter(nodes::contains)

                                        .map(mn -> "\"" + mn + "\"")

                                        .collect(joining(",")))

                subgraphs.forEach(subgraph -> {

                    out.format("  subgraph %s {%n", subgraph.name);

                    descriptors.stream()

                        .map(ModuleDescriptor::name)

                        .filter(subgraph.nodes::contains)

                        .forEach(mn -> printNode(out, mn, subgraph.color, subgraph.group));

                    out.format("  }%n");

                });

                descriptors.stream()

                    .filter(md -> graph.contains(md.name()) &&

                                    !graph.adjacentNodes(md.name()).isEmpty())

                    .forEach(md -> printNode(out, md, graph.adjacentNodes(md.name())));

                out.println("}");

            }

        }

        public DotGraphBuilder subgraph(String name, String group, String color,

                                 Set<String> nodes) {

            subgraphs.add(new SubGraph(name, group, color, nodes));

            return this;

        }

        public void printNode(PrintWriter out, String node, String color, String group) {

            out.format("  \"%s\" [fontcolor=\"%s\", group=%s];%n",

                       node, color, group);

        }

        public void printNode(PrintWriter out, ModuleDescriptor md, Set<String> edges) {

            Set<String> requiresTransitive = md.requires().stream()

                .filter(d -> d.modifiers().contains(TRANSITIVE))

                .map(d -> d.name())

                .collect(toSet());

            String mn = md.name();

            edges.stream().forEach(dn -> {

                if (w > 1) {

                    if (!attr.isEmpty())

                        attr += ", ";

                    attr += "weight=" + w;

                }

                out.format("  \"%s\" -> \"%s\" [%s];%n", mn, dn, attr);

            });

        }

    }

}