/*

 * 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.

 *

 * 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 combo;

import com.sun.source.tree.ClassTree;

import com.sun.source.tree.CompilationUnitTree;

import com.sun.source.util.JavacTask;

import com.sun.source.util.TaskEvent;

import com.sun.source.util.TaskEvent.Kind;

import com.sun.source.util.TaskListener;

import com.sun.source.util.TreeScanner;

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

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

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

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

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

import com.sun.tools.javac.code.Type.ClassType;

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

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

import com.sun.tools.javac.comp.Check;

import com.sun.tools.javac.comp.CompileStates;

import com.sun.tools.javac.comp.Enter;

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

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

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

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

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

import javax.tools.Diagnostic;

import javax.tools.DiagnosticListener;

import javax.tools.JavaFileManager;

import javax.tools.JavaFileObject;

import java.util.HashSet;

import java.util.Set;

/**

 * A reusable context is a context that can be used safely across multiple compilation rounds

 * arising from execution of a combo test. It achieves reuse by replacing some components

 * (most notably JavaCompiler and Log) with reusable counterparts, and by exposing a method

 * to cleanup leftovers from previous compilation.

 * <p>

 * There are, however, situations in which reusing the context is not safe: (i) when different

 * compilations are using different sets of compiler options (as most option values are cached

 * inside components themselves) and (ii) when the compilation unit happens to redefine classes

 * in the java.* packages.

 */

class ReusableContext extends Context implements TaskListener {

    Set<CompilationUnitTree> roots = new HashSet<>();

    String opts;

    boolean polluted = false;

    ReusableContext() {

        super();

        put(Log.logKey, ReusableLog.factory);

        put(JavaCompiler.compilerKey, ReusableJavaCompiler.factory);

    }

    void clear() {

        drop(Arguments.argsKey);

        drop(DiagnosticListener.class);

        drop(Log.outKey);

        drop(JavaFileManager.class);

        drop(JavacTask.class);

        if (ht.get(Log.logKey) instanceof ReusableLog) {

            //log already inited - not first round

            ((ReusableLog)Log.instance(this)).clear();

            Enter.instance(this).newRound();

            ((ReusableJavaCompiler)ReusableJavaCompiler.instance(this)).clear();

            Types.instance(this).newRound();

            Check.instance(this).newRound();

            CompileStates.instance(this).clear();

            MultiTaskListener.instance(this).clear();

            //find if any of the roots have redefined java.* classes

            Symtab syms = Symtab.instance(this);

            pollutionScanner.scan(roots, syms);

            roots.clear();

        }

    }

    /**

     * This scanner detects as to whether the shared context has been polluted. This happens

     * whenever a compiled program redefines a core class (in 'java.*' package) or when

     * (typically because of cyclic inheritance) the symbol kind of a core class has been touched.

     */

    TreeScanner<Void, Symtab> pollutionScanner = new TreeScanner<Void, Symtab>() {

        @Override

        public Void visitClass(ClassTree node, Symtab syms) {

            Symbol sym = ((JCClassDecl)node).sym;

            if (sym != null) {

                syms.classes.remove(sym.flatName());

                Type sup = supertype(sym);

                if (isCoreClass(sym) ||

                        (sup != null && isCoreClass(sup.tsym) && sup.tsym.kind != Kinds.Kind.TYP)) {

                    polluted = true;

                }

            }

            return super.visitClass(node, syms);

        }

        private boolean isCoreClass(Symbol s) {

            return s.flatName().toString().startsWith("java.");

        }

        private Type supertype(Symbol s) {

            if (s.type == null ||

                    !s.type.hasTag(TypeTag.CLASS)) {

                return null;

            } else {

                ClassType ct = (ClassType)s.type;

                return ct.supertype_field;

            }

        }

    };

    @Override

    public void finished(TaskEvent e) {

        if (e.getKind() == Kind.PARSE) {

            roots.add(e.getCompilationUnit());

        }

    }

    @Override

    public void started(TaskEvent e) {

        //do nothing

    }

    <T> void drop(Key<T> k) {

        ht.remove(k);

    }

    <T> void drop(Class<T> c) {

        ht.remove(key(c));

    }

    /**

     * Reusable JavaCompiler; exposes a method to clean up the component from leftovers associated with

     * previous compilations.

     */

    static class ReusableJavaCompiler extends JavaCompiler {

        static Factory<JavaCompiler> factory = ReusableJavaCompiler::new;

        ReusableJavaCompiler(Context context) {

            super(context);

        }

        @Override

        public void close() {

            //do nothing

        }

        void clear() {

            newRound();

        }

        @Override

        protected void checkReusable() {

            //do nothing - it's ok to reuse the compiler

        }

    }

    /**

     * Reusable Log; exposes a method to clean up the component from leftovers associated with

     * previous compilations.

     */

    static class ReusableLog extends Log {

        static Factory<Log> factory = ReusableLog::new;

        Context context;

        ReusableLog(Context context) {

            super(context);

            this.context = context;

        }

        void clear() {

            recorded.clear();

            sourceMap.clear();

            nerrors = 0;

            nwarnings = 0;

            //Set a fake listener that will lazily lookup the context for the 'real' listener. Since

            //this field is never updated when a new task is created, we cannot simply reset the field

            //or keep old value. This is a hack to workaround the limitations in the current infrastructure.

            diagListener = new DiagnosticListener<JavaFileObject>() {

                DiagnosticListener<JavaFileObject> cachedListener;

                @Override

                @SuppressWarnings("unchecked")

                public void report(Diagnostic<? extends JavaFileObject> diagnostic) {

                    if (cachedListener == null) {

                        cachedListener = context.get(DiagnosticListener.class);

                    }

                    cachedListener.report(diagnostic);

                }

            };

        }

    }

}