/*

 * Copyright (c) 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.javac.util;

import com.sun.tools.javac.code.Symbol;

import com.sun.tools.javac.code.Symbol.ClassSymbol;

import com.sun.tools.javac.code.Symbol.Completer;

import com.sun.tools.javac.code.Symbol.CompletionFailure;

import com.sun.tools.javac.main.JavaCompiler;

import com.sun.tools.javac.tree.JCTree;

import com.sun.tools.javac.util.GraphUtils.DotVisitor;

import com.sun.tools.javac.util.GraphUtils.NodeVisitor;

import java.io.Closeable;

import java.io.FileWriter;

import java.io.IOException;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collection;

import java.util.EnumMap;

import java.util.EnumSet;

import java.util.HashSet;

import java.util.LinkedHashMap;

import java.util.List;

import java.util.Map;

import java.util.Properties;

import java.util.Set;

import java.util.Stack;

import javax.tools.JavaFileObject;

/**

 *  This class is used to track dependencies in the javac symbol completion process.

 *

 *  <p><b>This is NOT part of any supported API.

 *  If you write code that depends on this, you do so at your own risk.

 *  This code and its internal interfaces are subject to change or

 *  deletion without notice.</b>

 */

public abstract class Dependencies {

    protected static final Context.Key<Dependencies> dependenciesKey = new Context.Key<>();

    public static Dependencies instance(Context context) {

        Dependencies instance = context.get(dependenciesKey);

        if (instance == null) {

            //use a do-nothing implementation in case no other implementation has been set by preRegister

            instance = new DummyDependencies(context);

        }

        return instance;

    }

        context.put(dependenciesKey, this);

    }

    /**

     * This enum models different kinds of attribution actions triggered during

     * symbol completion.

     */

    public enum AttributionKind {

        /**

         * Attribution of superclass (i.e. @{code extends} clause).

         */

        EXTENDS {

            @Override

            String format(JCTree tree) {

                return "extends " + super.format(tree);

            }

        },

        /**

         * Attribution of superinterface (i.e. an type in the @{code interface} clause).

         */

        IMPLEMENTS {

            @Override

            String format(JCTree tree) {

                return "implements " + super.format(tree);

            }

        },

        /**

         * Attribution of an import statement

         */

        IMPORT,

        /**

         * Attribution of type-variable bound

         */

        TVAR {

            @Override

            String format(JCTree tree) {

                return "<" + super.format(tree) + ">";

            }

        };

        String format(JCTree tree) {

            return tree.toString();

        }

    }

    /**

     * Push a new completion node on the stack.

     */

    /**

     * Push a new attribution node on the stack.

     */

    abstract public void push(AttributionKind ak, JCTree t);

    /**

     * Remove current dependency node from the stack.

     */

    abstract public void pop();

    /**

     * This class creates a graph of all dependencies as symbols are completed;

     * when compilation finishes, the resulting dependecy graph is then dumped

     * onto a dot file. Several options are provided to customise the output of the graph.

     */

    public static class GraphDependencies extends Dependencies implements Closeable, Completer {

        /**

         * set of enabled dependencies modes

         */

        private EnumSet<DependenciesMode> dependenciesModes;

        /**

         * file in which the dependency graph should be written

         */

        private String dependenciesFile;

        /**

         * Register a Context.Factory to create a Dependencies.

         */

        public static void preRegister(final Context context) {

            context.put(dependenciesKey, new Context.Factory<Dependencies>() {

                public Dependencies make(Context c) {

                    Dependencies deps = new GraphDependencies(context);

                    return deps;

                }

            });

        }

        /**

         * Build a Dependencies instance.

         */

        GraphDependencies(Context context) {

            super(context);

            Options options = Options.instance(context);

            //fetch filename

            String[] modes = options.get("completionDeps").split(",");

            for (String mode : modes) {

                if (mode.startsWith("file=")) {

                    dependenciesFile = mode.substring(5);

                }

            }

            //parse modes

            dependenciesModes = DependenciesMode.getDependenciesModes(modes);

            //add to closeables

            JavaCompiler compiler = JavaCompiler.instance(context);

            compiler.closeables = compiler.closeables.prepend(this);

        }

        enum DependenciesMode {

            SOURCE("source"),

            CLASS("class"),

            REDUNDANT("redundant"),

            SIDE_EFFECTS("side-effects");

            final String opt;

            private DependenciesMode(String opt) {

                this.opt = opt;

            }

            /**

             * This method is used to parse the {@code completionDeps} option.

             * Possible modes are separated by colon; a mode can be excluded by

             * prepending '-' to its name. Finally, the special mode 'all' can be used to

             * add all modes to the resulting enum.

             */

            static EnumSet<DependenciesMode> getDependenciesModes(String[] modes) {

                EnumSet<DependenciesMode> res = EnumSet.noneOf(DependenciesMode.class);

                Collection<String> args = Arrays.asList(modes);

                if (args.contains("all")) {

                    res = EnumSet.allOf(DependenciesMode.class);

                }

                for (DependenciesMode mode : values()) {

                    if (args.contains(mode.opt)) {

                        res.add(mode);

                    } else if (args.contains("-" + mode.opt)) {

                        res.remove(mode);

                    }

                }

                return res;

            }

        }

        /**

         * Class representing a node in the dependency graph. Nodes are of two main

         * kinds: (i) symbol nodes, corresponding to symbol completion requests

         * (either from source or classfile); (ii) attribution nodes, corresponding to

         * attribution actions triggered during (source) completion.

         */

        static abstract class Node extends GraphUtils.AbstractNode<String, Node>

                implements GraphUtils.DottableNode<String, Node> {

            /**

             * Model the dependencies between nodes.

             */

            enum DependencyKind implements GraphUtils.DependencyKind {

                /**

                 * standard dependency - i.e. completion of the source node depends

                 * on completion of the sink node.

                 */

                REQUIRES("solid"),

                /**

                 * soft dependencies - i.e. completion of the source node depends

                 * on side-effects of the source node. These dependencies are meant

                 * to capture the order in which javac processes all dependants of a given node.

                 */

                SIDE_EFFECTS("dashed");

                final String dotStyle;

                DependencyKind(String dotStyle) {

                    this.dotStyle = dotStyle;

                }

            }

            /**

             * dependant nodes grouped by kind

             */

            EnumMap<DependencyKind, List<Node>> depsByKind;

            Node(String value) {

                super(value);

                this.depsByKind = new EnumMap<>(DependencyKind.class);

                for (DependencyKind depKind : DependencyKind.values()) {

                    depsByKind.put(depKind, new ArrayList<Node>());

                }

            }

            void addDependency(DependencyKind depKind, Node dep) {

                List<Node> deps = depsByKind.get(depKind);

                if (!deps.contains(dep)) {

                    deps.add(dep);

                }

            }

            @Override

            public boolean equals(Object obj) {

                return obj instanceof Node &&

                        data.equals(((Node) obj).data);

            }

            @Override

            public int hashCode() {

                return data.hashCode();

            }

            @Override

            public GraphUtils.DependencyKind[] getSupportedDependencyKinds() {

                return DependencyKind.values();

            }

            @Override

            public java.util.Collection<? extends Node> getDependenciesByKind(GraphUtils.DependencyKind dk) {

                List<Node> deps = depsByKind.get(dk);

                if (dk == DependencyKind.REQUIRES) {

                    return deps;

                } else {

                    Set<Node> temp = new HashSet<>(deps);

                    temp.removeAll(depsByKind.get(DependencyKind.REQUIRES));

                    return temp;

                }

            }

            @Override

            public Properties nodeAttributes() {

                Properties p = new Properties();

                p.put("label", DotVisitor.wrap(toString()));

                return p;

            }

            @Override

            public Properties dependencyAttributes(Node to, GraphUtils.DependencyKind dk) {

                Properties p = new Properties();

                p.put("style", ((DependencyKind) dk).dotStyle);

                return p;

            }

        }

        /**

         * This is a dependency node used to model symbol completion requests.

         * Completion requests can come from either source or class.

         */

        static class CompletionNode extends Node {

            /**

             * Completion kind (source vs. classfile)

             */

            enum Kind {

                /**

                 * Source completion request

                 */

                SOURCE("solid"),

                /**

                 * Classfile completion request

                 */

                CLASS("dotted");

                final String dotStyle;

                Kind(String dotStyle) {

                    this.dotStyle = dotStyle;

                }

            }

            final Kind ck;

            CompletionNode(ClassSymbol sym) {

                super(sym.getQualifiedName().toString());

                //infer completion kind by looking at the symbol fields

                boolean fromClass = (sym.classfile == null && sym.sourcefile == null) ||

                        (sym.classfile != null && sym.classfile.getKind() == JavaFileObject.Kind.CLASS);

                ck = fromClass ?

                        CompletionNode.Kind.CLASS :

                        CompletionNode.Kind.SOURCE;

            }

            @Override

            public Properties nodeAttributes() {

                Properties p = super.nodeAttributes();

                p.put("style", ck.dotStyle);

                p.put("shape", "ellipse");

                return p;

            }

        }

        /**

         * This is a dependency node used to model attribution actions triggered during

         * source symbol completion. The possible kinds of attribution actions are

         * captured in {@link AttributionNode}.

         */

        static class AttributionNode extends Node {

            AttributionNode(AttributionKind ak, JCTree tree) {

                super(ak.format(tree));

            }

            @Override

            public Properties nodeAttributes() {

                Properties p = super.nodeAttributes();

                p.put("shape", "box");

                p.put("style", "solid");

                return p;

            }

        }

        /**

         * stack of dependency nodes currently being processed

         */

        Stack<Node> nodeStack = new Stack<>();

        /**

         * map containing all dependency nodes seen so far

         */

        Map<String, Node> dependencyNodeMap = new LinkedHashMap<>();

        @Override

            Node n = new CompletionNode(s);

            if (n == push(n)) {

                s.completer = this;

            }

        }

        @Override

        public void push(AttributionKind ak, JCTree t) {

            push(new AttributionNode(ak, t));

        }

        /**

         * Push a new dependency on the stack.

         */

        protected Node push(Node newNode) {

            Node cachedNode = dependencyNodeMap.get(newNode.data);

            if (cachedNode == null) {

                dependencyNodeMap.put(newNode.data, newNode);

            } else {

                newNode = cachedNode;

            }

            if (!nodeStack.isEmpty()) {

                Node currentNode = nodeStack.peek();

                currentNode.addDependency(Node.DependencyKind.REQUIRES, newNode);

            }

            nodeStack.push(newNode);

            return newNode;

        }

        @Override

        public void pop() {

            nodeStack.pop();

        }

        @Override

        public void close() throws IOException {

            if (dependenciesFile != null) {

                if (!dependenciesModes.contains(DependenciesMode.REDUNDANT)) {

                    //prune spurious edges

                    new PruneVisitor().visit(dependencyNodeMap.values(), null);

                }

                if (!dependenciesModes.contains(DependenciesMode.CLASS)) {

                    //filter class completions

                    new FilterVisitor(CompletionNode.Kind.SOURCE).visit(dependencyNodeMap.values(), null);

                }

                if (!dependenciesModes.contains(DependenciesMode.SOURCE)) {

                    //filter source completions

                    new FilterVisitor(CompletionNode.Kind.CLASS).visit(dependencyNodeMap.values(), null);

                }

                if (dependenciesModes.contains(DependenciesMode.SIDE_EFFECTS)) {

                    //add side-effects edges

                    new SideEffectVisitor().visit(dependencyNodeMap.values(), null);

                }

                //write to file

                try (FileWriter fw = new FileWriter(dependenciesFile)) {

                    fw.append(GraphUtils.toDot(dependencyNodeMap.values(), "CompletionDeps", ""));

                }

            }

        }

        @Override

        public void complete(Symbol sym) throws CompletionFailure {

            pop();

            sym.completer = this;

        }

        /**

         * This visitor is used to generate the special side-effect dependencies

         * given a graph containing only standard dependencies.

         */

        private static class SideEffectVisitor extends NodeVisitor<String, Node, Void> {

            @Override

            public void visitNode(Node node, Void arg) {

                //do nothing

            }

            @Override

            public void visitDependency(GraphUtils.DependencyKind dk, Node from, Node to, Void arg) {

                //if we are adding multiple dependencies to same node

                //make order explicit via special 'side-effect' dependencies

                List<Node> deps = from.depsByKind.get(dk);

                int pos = deps.indexOf(to);

                if (dk == Node.DependencyKind.REQUIRES && pos > 0) {

                    to.addDependency(Node.DependencyKind.SIDE_EFFECTS, deps.get(pos - 1));

                }

            }

        }

        /**

         * This visitor is used to prune the graph from spurious edges using some heuristics.

         */

        private static class PruneVisitor extends NodeVisitor<String, Node, Void> {

            @Override

            public void visitNode(Node node, Void arg) {

                //do nothing

            }

            @Override

            public void visitDependency(GraphUtils.DependencyKind dk, Node from, Node to, Void arg) {

                //heuristic - skips dependencies that are likely to be fake

                if (from.equals(to) ||

                        from.depsByKind.get(Node.DependencyKind.REQUIRES).contains(to)) {

                    to.depsByKind.get(dk).remove(from);

                }

            }

        }

        /**

         * This visitor is used to retain only completion nodes with given kind.

         */

        private class FilterVisitor extends NodeVisitor<String, Node, Void> {

            CompletionNode.Kind ck;

            private FilterVisitor(CompletionNode.Kind ck) {

                this.ck = ck;

            }

            @Override

            public void visitNode(Node node, Void arg) {

                if (node instanceof CompletionNode) {

                    if (((CompletionNode) node).ck != ck) {

                        dependencyNodeMap.remove(node.data);