/*

 * 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.

 *

 * 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.

 */

/*

 * @test

 * @summary Tests which path is used to represent an implicit type given

 * various xprefer arguments and multiple .class / .java files involved.

 * @bug 8028196

 */

import java.io.File;

import java.io.FileWriter;

import java.io.IOException;

import java.io.PrintWriter;

import java.io.StringWriter;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collection;

import java.util.Iterator;

import java.util.List;

import java.util.ListIterator;

import java.util.NoSuchElementException;

import java.util.Scanner;

import javax.tools.JavaCompiler;

import javax.tools.JavaCompiler.CompilationTask;

import javax.tools.ToolProvider;

public class XPreferTest {

    enum Dir {

        SOURCE_PATH("src"),

        CLASS_PATH("cp"),

        BOOT_PATH("boot");

        File file;

        Dir(String dir) {

            this.file = new File(dir);

        }

    }

    enum ImplicitOption {

        XPREFER_SOURCE("-Xprefer:source"),

        XPREFER_NEWER("-Xprefer:newer"),

        XXUSERPATHSFIRST("-XXuserPathsFirst");

        final String optionString;

        private ImplicitOption(String optionString) {

            this.optionString = optionString;

        }

    }

    final static JavaCompiler comp = ToolProvider.getSystemJavaCompiler();

    final static File OUTPUT_DIR = new File("out");

    public static void main(String... args) throws Exception {

        // Initialize test-directories

        OUTPUT_DIR.mkdir();

        for (Dir dir : Dir.values())

            dir.file.mkdir();

        int testCaseCounter = 0;

        for (List<Dir> dirSubset : SubseqIter.subseqsOf(Dir.values())) {

            if (dirSubset.isEmpty())

                continue;

            for (ImplicitOption policy : ImplicitOption.values()) {

                for (List<Dir> dirOrder : PermutationIterator.permutationsOf(dirSubset)) {

                    new TestCase(dirOrder, policy, testCaseCounter++).run();

                }

            }

        }

    }

    static class TestCase {

        String classId;

        List<Dir> dirs;

        ImplicitOption option;

        public TestCase(List<Dir> dirs, ImplicitOption option, int testCaseNum) {

            this.dirs = dirs;

            this.option = option;

            this.classId = "XPreferTestImplicit" + testCaseNum;

        }

        void run() throws Exception {

            System.out.println("Test:");

            System.out.println("    Class id: " + classId);

            System.out.println("    Dirs:     " + dirs);

            System.out.println("    Option:   " + option);

            createTestFiles();

            String compileOutput = compile();

            Dir actual = getChosenOrigin(compileOutput);

            Dir expected = getExpectedOrigin();

            System.out.println("    Expected: " + expected);

            System.out.println("    Actual:   " + actual);

            if (actual != expected) {

                throw new RuntimeException(String.format(

                        "Expected javac to choose %s but %s was chosen",

                        expected == null ? "<none>" : expected.name(),

                        actual   == null ? "<none>" : actual.name()));

            }

        }

        Dir getExpectedOrigin() {

            Dir newest = dirs.get(0);

            switch (option) {

            case XPREFER_NEWER:

                Dir cls = dirs.contains(Dir.BOOT_PATH) ? Dir.BOOT_PATH

                        : dirs.contains(Dir.CLASS_PATH) ? Dir.CLASS_PATH

                        : null;

                Dir src = dirs.contains(Dir.SOURCE_PATH) ? Dir.SOURCE_PATH

                        : null;

                for (Dir dir : dirs)

                    if (dir == cls || dir == src)

                        return dir;

                return null;

            case XPREFER_SOURCE:

                return dirs.contains(Dir.SOURCE_PATH) ? Dir.SOURCE_PATH

                     : dirs.contains(Dir.BOOT_PATH) ? Dir.BOOT_PATH

                     : dirs.contains(Dir.CLASS_PATH) ? Dir.CLASS_PATH

                     : null;

            case XXUSERPATHSFIRST:

                for (Dir dir : dirs)

                    if (dir == Dir.SOURCE_PATH || dir == Dir.CLASS_PATH)

                        return dir;

                // Neither SOURCE_PATH nor CLASS_PATH among dirs. Safty check:

                if (newest != Dir.BOOT_PATH)

                    throw new AssertionError("Expected to find BOOT_PATH");

                return Dir.BOOT_PATH;

            default:

                throw new RuntimeException("Unhandled policy case.");

            }

        }

        Dir getChosenOrigin(String compilerOutput) {

            Scanner s = new Scanner(compilerOutput);

            while (s.hasNextLine()) {

                String line = s.nextLine();

                if (line.matches("\\[loading .*\\]"))

                    for (Dir dir : Dir.values())

                        if (line.contains(dir.file.getName() + "/" + classId))

                            return dir;

            }

            return null;

        }

        String compile() throws IOException {

            // Create a class that references classId

            File explicit = new File("ExplicitClass.java");

            FileWriter filewriter = new FileWriter(explicit);

            filewriter.append("class ExplicitClass { " + classId + " implicit; }");

            filewriter.close();

            StringWriter sw = new StringWriter();

            com.sun.tools.javac.Main.compile(new String[] {

                    "-verbose",

                    option.optionString,

                    "-sourcepath", Dir.SOURCE_PATH.file.getPath(),

                    "-classpath", Dir.CLASS_PATH.file.getPath(),

                    "-Xbootclasspath/p:" + Dir.BOOT_PATH.file.getPath(),

                    "-d", XPreferTest.OUTPUT_DIR.getPath(),

                    explicit.getPath()

            }, new PrintWriter(sw));

            return sw.toString();

        }

        void createTestFiles() throws IOException {

            long t = 1390927988755L;  // Tue Jan 28 17:53:08 CET 2014

            for (Dir dir : dirs) {

                createFile(dir).setLastModified(t);

                t -= 10000;

            }

        }

        File createFile(Dir dir) throws IOException {

            File src = new File(dir.file, classId + ".java");

            try (FileWriter w = new FileWriter(src)) {

                w.append("public class " + classId + " {}");

            }

            // If we're after the ".java" representation, we're done...

            if(dir == Dir.SOURCE_PATH)

                return src;

            // ...otherwise compile into a ".class".

            CompilationTask task = comp.getTask(null, null, null, null, null,

                    comp.getStandardFileManager(null, null, null).getJavaFileObjects(src));

            File dest = new File(dir.file, classId + ".class");

            if(!task.call() || !dest.exists())

                throw new RuntimeException("Compilation failure.");

            src.delete();

            return dest;

        }

    }

}

// Iterator for iteration over all subsequences of a given list.

class SubseqIter<T> implements Iterator<List<T>> {

    List<T> elements;

    boolean[] states;

    public SubseqIter(Collection<T> c) {

        states = new boolean[c.size()];

        elements = new ArrayList<T>(c);

    }

    public static <T> Iterable<List<T>> subseqsOf(final T[] t) {

        return new Iterable<List<T>>() {

            @Override

            public Iterator<List<T>> iterator() {

                return new SubseqIter<T>(Arrays.asList(t));

            }

        };

    }

    // Roll values in 'states' from index i and forward.

    // Return true if we wrapped back to zero.

    private boolean roll(int i) {

        if (i == states.length)

            return true;

        if (!roll(i + 1))

            return false;

        states[i] = !states[i];

        return !states[i];

    }

    @Override

    public List<T> next() {

        if (!hasNext())

            throw new NoSuchElementException();

        // Include element i if states[i] is true

        List<T> next = new ArrayList<T>();

        for (int i = 0; i < states.length; i++)

            if (states[i])

                next.add(elements.get(i));

        if (roll(0))

            states = null; // hasNext() == false from now on.

        return next;

    }

    @Override

    public boolean hasNext() {

        return states != null;

    }

    @Override

    public void remove() {

        throw new UnsupportedOperationException();

    }

}

class PermutationIterator<T> implements Iterator<List<T>> {

    DirInt head;

    boolean hasNext = true;

    public PermutationIterator(List<T> toPermute) {

        ListIterator<T> iter = toPermute.listIterator();

        if (iter.hasNext())

            head = new DirInt(iter.nextIndex(), iter.next());

        DirInt prev = head;

        while (iter.hasNext()) {

            DirInt di = new DirInt(iter.nextIndex(), iter.next());

            di.left = prev;

            prev.right = di;

            prev = di;

        }

    }

    public static <T> Iterable<List<T>> permutationsOf(final List<T> list) {

        return new Iterable<List<T>>() {

            public Iterator<List<T>> iterator() {

                return new PermutationIterator<>(list);

            }

        };

    }

    @Override

    public boolean hasNext() {

        return hasNext;

    }

    @Override

    public List<T> next() {

        // Prep return value based on current state

        List<T> result = new ArrayList<>();

        for (DirInt di = head; di != null; di = di.right)

            result.add(di.object);

        // Step state forward

        DirInt maxMob = null;

        for (DirInt di = head; di != null; di = di.right)

            if (di.isMobile() && (maxMob == null || di.val > maxMob.val))

                maxMob = di;

        if (maxMob == null) {

            hasNext = false;

        } else {

            maxMob.swapWithAdjacent();

            for (DirInt di = head; di != null; di = di.right)

                if (di.val > maxMob.val)

                    di.facingLeft = !di.facingLeft;

        }

        return result;

    }

    private final class DirInt {

        int val;

        T object;

        DirInt left, right;

        boolean facingLeft = true;

        public DirInt(int val, T object) {

            this.val = val;

            this.object = object;

        }

        boolean isMobile() {

            DirInt adjacent = facingLeft ? left : right;

            return adjacent != null && val > adjacent.val;

        }

        public void swapWithAdjacent() {

            DirInt l = facingLeft ? left : this;

            DirInt r = facingLeft ? this : right;

            if (head == l) head = r;

            if (l.left  != null) l.left.right = r;

            if (r.right != null) r.right.left = l;

            l.right = r.right;

            r.left = l.left;

            r.right = l;

            l.left = r;

        }

    }

    @Override

    public void remove() {

        throw new UnsupportedOperationException();

    }

}