/*

 * Copyright (c) 2014, 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.  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.sjavac.comp;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.util.HashSet;

import java.util.Iterator;

import java.util.Set;

import javax.tools.JavaFileObject;

import com.sun.source.tree.CompilationUnitTree;

import com.sun.source.util.TaskEvent;

import com.sun.source.util.TaskListener;

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

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

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

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

import com.sun.tools.javac.util.DefinedBy.Api;

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

import com.sun.tools.sjavac.Log;

public class PathAndPackageVerifier implements TaskListener {

    // Stores the set of compilation units whose source file path does not

    // match the package declaration.

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

    @Override

    @DefinedBy(Api.COMPILER_TREE)

    public void finished(TaskEvent e) {

        if (e.getKind() == TaskEvent.Kind.ANALYZE) {

            CompilationUnitTree cu = e.getCompilationUnit();

            if (cu == null)

                return;

            JavaFileObject jfo = cu.getSourceFile();

            if (jfo == null)

                return; // No source file -> package doesn't matter

            JCTree pkg = (JCTree) cu.getPackageName();

            if (pkg == null)

                return; // Default package. See JDK-8048144.

            Path dir = Paths.get(jfo.toUri()).normalize().getParent();

            if (!checkPathAndPackage(dir, pkg))

                misplacedCompilationUnits.add(cu);

        }

        if (e.getKind() == TaskEvent.Kind.COMPILATION) {

            for (CompilationUnitTree cu : misplacedCompilationUnits) {

                Log.error("Misplaced compilation unit.");

                Log.error("    Directory: " + Paths.get(cu.getSourceFile().toUri()).getParent());

                Log.error("    Package:   " + cu.getPackageName());

            }

        }

    }

    public boolean errorsDiscovered() {

        return misplacedCompilationUnits.size() > 0;

    }

    /* Returns true if dir matches pkgName.

     *

     * Examples:

     *     (a/b/c, a.b.c) gives true

     *     (i/j/k, i.x.k) gives false

     *

     * Currently (x/a/b/c, a.b.c) also gives true. See JDK-8059598.

     */

    private boolean checkPathAndPackage(Path dir, JCTree pkgName) {

        Iterator<String> pathIter = new ParentIterator(dir);

        Iterator<String> pkgIter = new EnclosingPkgIterator(pkgName);

        while (pathIter.hasNext() && pkgIter.hasNext()) {

            if (!pathIter.next().equals(pkgIter.next()))

                return false;

        }

        return !pkgIter.hasNext(); /*&& !pathIter.hasNext() See JDK-8059598 */

    }

    /* Iterates over the names of the parents of the given path:

     * Example: dir1/dir2/dir3  results in  dir3 -> dir2 -> dir1

     */

    private static class ParentIterator implements Iterator<String> {

        Path next;

        ParentIterator(Path initial) {

            next = initial;

        }

        @Override

        public boolean hasNext() {

            return next != null;

        }

        @Override

        public String next() {

            String tmp = next.getFileName().toString();

            next = next.getParent();

            return tmp;

        }

    }

    /* Iterates over the names of the enclosing packages:

     * Example: pkg1.pkg2.pkg3  results in  pkg3 -> pkg2 -> pkg1

     */

    private static class EnclosingPkgIterator implements Iterator<String> {

        JCTree next;

        EnclosingPkgIterator(JCTree initial) {

            next = initial;

        }

        @Override

        public boolean hasNext() {

            return next != null;

        }

        @Override

        public String next() {

            Name name;

            if (next instanceof JCIdent) {

                name = ((JCIdent) next).name;

                next = null;

            } else {

                JCFieldAccess fa = (JCFieldAccess) next;

                name = fa.name;

                next = fa.selected;

            }

            return name.toString();

        }

    }

}