/*

 * Copyright (c) 2009, 2013, 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 genstubs;

import java.io.*;

import java.util.*;

import javax.tools.JavaFileObject;

import javax.tools.StandardJavaFileManager;

import javax.tools.StandardLocation;

import com.sun.source.tree.CompilationUnitTree;

import com.sun.source.util.JavacTask;

import com.sun.tools.javac.api.JavacTool;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

import com.sun.tools.javac.util.Context;

import com.sun.tools.javac.util.ListBuffer;

import com.sun.tools.javac.util.Name;

import javax.tools.JavaFileManager;

/**

 * Generate stub source files by removing implementation details from input files.

 *

 * This is a special purpose stub generator, specific to the needs of generating

 * stub files for JDK 7 API that are needed to compile langtools files that depend

 * on that API. The stub generator works by removing as much of the API source code

 * as possible without affecting the public signature, in order to reduce the

 * transitive closure of the API being referenced. The resulting stubs can be

 * put on the langtools sourcepath with -implicit:none to compile the langtools

 * files that depend on the JDK 7 API.

 *

 * Usage:

 *  genstubs -s <outdir> -sourcepath <path> <classnames>

 *

 * The specified class names are looked up on the sourcepath, and corresponding

 * stubs are written to the source output directory.

 *

 * Classes are parsed into javac ASTs, then processed with a javac TreeTranslator

 * to remove implementation details, and written out in the source output directory.

 * Documentation comments and annotations are removed. Method bodies are removed

 * and methods are marked native. Private and package-private field definitions

 * have their initializers replace with 0, 0.0, false, null as appropriate.

 */

public class GenStubs {

    static class Fault extends Exception {

        private static final long serialVersionUID = 0;

        Fault(String message) {

            super(message);

        }

        Fault(String message, Throwable cause) {

            super(message);

            initCause(cause);

        }

    }

    public static void main(String[] args) {

        boolean ok = new GenStubs().run(args);

        if (!ok)

            System.exit(1);

    }

    public boolean run(String... args) {

        File outdir = null;

        String sourcepath = null;

        List<String> classes = new ArrayList<String>();

        for (ListIterator<String> iter = Arrays.asList(args).listIterator(); iter.hasNext(); ) {

            String arg = iter.next();

            if (arg.equals("-s") && iter.hasNext())

                outdir = new File(iter.next());

            else if (arg.equals("-sourcepath") && iter.hasNext())

                sourcepath = iter.next();

            else if (arg.startsWith("-"))

                throw new IllegalArgumentException(arg);

            else {

                classes.add(arg);

                while (iter.hasNext())

                    classes.add(iter.next());

            }

        }

        return run(sourcepath, outdir, classes);

    }

    public boolean run(String sourcepath, File outdir, List<String> classes) {

        //System.err.println("run: sourcepath:" + sourcepath + " outdir:" + outdir + " classes:" + classes);

        if (sourcepath == null)

            throw new IllegalArgumentException("sourcepath not set");

        if (outdir == null)

            throw new IllegalArgumentException("source output dir not set");

        JavacTool tool = JavacTool.create();

        StandardJavaFileManager fm = tool.getStandardFileManager(null, null, null);

        try {

            fm.setLocation(StandardLocation.SOURCE_OUTPUT, Collections.singleton(outdir));

            fm.setLocation(StandardLocation.SOURCE_PATH, splitPath(sourcepath));

            List<JavaFileObject> files = new ArrayList<JavaFileObject>();

            for (String c: classes) {

                JavaFileObject fo = fm.getJavaFileForInput(

                        StandardLocation.SOURCE_PATH, c, JavaFileObject.Kind.SOURCE);

                if (fo == null)

                    error("class not found: " + c);

                else

                    files.add(fo);

            }

            JavacTask t = tool.getTask(null, fm, null, null, null, files);

            Iterable<? extends CompilationUnitTree> trees = t.parse();

            for (CompilationUnitTree tree: trees) {

                makeStub(fm, tree);

            }

        } catch (IOException e) {

            error("IO error " + e, e);

        }

        return (errors == 0);

    }

    void makeStub(StandardJavaFileManager fm, CompilationUnitTree tree) throws IOException {

        CompilationUnitTree tree2 = new StubMaker().translate(tree);

        CompilationUnitTree tree3 = new ImportCleaner(fm).removeRedundantImports(tree2);

        String className = fm.inferBinaryName(StandardLocation.SOURCE_PATH, tree.getSourceFile());

        JavaFileObject fo = fm.getJavaFileForOutput(StandardLocation.SOURCE_OUTPUT,

                className, JavaFileObject.Kind.SOURCE, null);

        // System.err.println("Writing " + className + " to " + fo.getName());

        Writer out = fo.openWriter();

        try {

            new Pretty(out, true).printExpr((JCTree) tree3);

        } finally {

            out.close();

        }

    }

    List<File> splitPath(String path) {

        List<File> list = new ArrayList<File>();

        for (String p: path.split(File.pathSeparator)) {

            if (p.length() > 0)

                list.add(new File(p));

        }

        return list;

    }

    void error(String message) {

        System.err.println(message);

        errors++;

    }

    void error(String message, Throwable cause) {

        error(message);

    }

    int errors;

    class StubMaker extends TreeTranslator {

        CompilationUnitTree translate(CompilationUnitTree tree) {

            return super.translate((JCCompilationUnit) tree);

        }

        /**

         * compilation units: remove javadoc comments

         * -- required, in order to remove @deprecated tags, since we

         * (separately) remove all annotations, including @Deprecated

         */

        public void visitTopLevel(JCCompilationUnit tree) {

            super.visitTopLevel(tree);

            tree.docComments = null;

        }

        /**

         * methods: remove method bodies, make methods native

         */

        @Override

        public void visitClassDef(JCClassDecl tree) {

            long prevClassMods = currClassMods;

            currClassMods = tree.mods.flags;

            try {

                super.visitClassDef(tree);;

            } finally {

                currClassMods = prevClassMods;

            }

        }

        private long currClassMods = 0;

        /**

         * methods: remove method bodies, make methods native

         */

        @Override

        public void visitMethodDef(JCMethodDecl tree) {

            tree.mods = translate(tree.mods);

            tree.restype = translate(tree.restype);

            tree.typarams = translateTypeParams(tree.typarams);

            tree.params = translateVarDefs(tree.params);

            tree.thrown = translate(tree.thrown);

            if (tree.body != null) {

                if ((currClassMods & Flags.INTERFACE) != 0) {

                    tree.mods.flags &= ~(Flags.DEFAULT | Flags.STATIC);

                } else {

                    tree.mods.flags |= Flags.NATIVE;

                }

                tree.body = null;

            }

            result = tree;

        }

        /**

         * modifiers: remove annotations

         */

        @Override

        public void visitModifiers(JCModifiers tree) {

            tree.annotations = com.sun.tools.javac.util.List.nil();

            result = tree;

        }

        /**

         * field definitions: replace initializers with 0, 0.0, false etc

         * when possible -- i.e. leave public, protected initializers alone

         */

        @Override

        public void visitVarDef(JCVariableDecl tree) {

            tree.mods = translate(tree.mods);

            tree.vartype = translate(tree.vartype);

            if (tree.init != null) {

                if ((tree.mods.flags & (Flags.PUBLIC | Flags.PROTECTED)) != 0)

                    tree.init = translate(tree.init);

                else {

                    String t = tree.vartype.toString();

                    if (t.equals("boolean"))

                        tree.init = new JCLiteral(TypeTag.BOOLEAN, 0) { };

                    else if (t.equals("byte"))

                        tree.init = new JCLiteral(TypeTag.BYTE, 0) { };

                    else if (t.equals("char"))

                        tree.init = new JCLiteral(TypeTag.CHAR, 0) { };

                    else if (t.equals("double"))

                        tree.init = new JCLiteral(TypeTag.DOUBLE, 0.d) { };

                    else if (t.equals("float"))

                        tree.init = new JCLiteral(TypeTag.FLOAT, 0.f) { };

                    else if (t.equals("int"))

                        tree.init = new JCLiteral(TypeTag.INT, 0) { };

                    else if (t.equals("long"))

                        tree.init = new JCLiteral(TypeTag.LONG, 0) { };

                    else if (t.equals("short"))

                        tree.init = new JCLiteral(TypeTag.SHORT, 0) { };

                    else

                        tree.init = new JCLiteral(TypeTag.BOT, null) { };

                }

            }

            result = tree;

        }

    }

    class ImportCleaner extends TreeScanner {

        private Set<Name> names = new HashSet<Name>();

        private TreeMaker m;

        ImportCleaner(JavaFileManager fm) {

            // ImportCleaner itself doesn't require a filemanager, but instantiating

            // a TreeMaker does, indirectly (via ClassReader, sigh)

            Context c = new Context();

            c.put(JavaFileManager.class, fm);

            m = TreeMaker.instance(c);

        }

        CompilationUnitTree removeRedundantImports(CompilationUnitTree t) {

            JCCompilationUnit tree = (JCCompilationUnit) t;

            tree.accept(this);

            ListBuffer<JCTree> defs = new ListBuffer<JCTree>();

            for (JCTree def: tree.defs) {

                if (def.getTag() == JCTree.Tag.IMPORT) {

                    JCImport imp = (JCImport) def;

                    if (imp.qualid.getTag() == JCTree.Tag.SELECT) {

                        JCFieldAccess qualid = (JCFieldAccess) imp.qualid;

                        if (!qualid.name.toString().equals("*")

                                && !names.contains(qualid.name)) {

                            continue;

                        }

                    }

                }

                defs.add(def);

            }

            return m.TopLevel(tree.packageAnnotations, tree.pid, defs.toList());

        }

        @Override

        public void visitImport(JCImport tree) { } // ignore names found in imports

        @Override

        public void visitIdent(JCIdent tree) {

            names.add(tree.name);

        }

        @Override

        public void visitSelect(JCFieldAccess tree) {

            super.visitSelect(tree);

            names.add(tree.name);

        }

    }

}