/*

 * 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.platform;

import java.io.IOException;

import java.nio.file.DirectoryStream;

import java.nio.file.FileSystem;

import java.nio.file.FileSystems;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Collections;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.Set;

import java.util.TreeSet;

import javax.annotation.processing.Processor;

import com.sun.source.util.Plugin;

import com.sun.tools.javac.jvm.Target;

/** PlatformProvider for JDK N.

 *

 *  <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 class JDKPlatformProvider implements PlatformProvider {

    @Override

    public Iterable<String> getSupportedPlatformNames() {

        return SUPPORTED_JAVA_PLATFORM_VERSIONS;

    }

    @Override

    public PlatformDescription getPlatform(String platformName, String options) {

        return new PlatformDescriptionImpl(platformName);

    }

    private static final String[] symbolFileLocation = { "lib", "ct.sym" };

    private static final Set<String> SUPPORTED_JAVA_PLATFORM_VERSIONS;

    static {

        SUPPORTED_JAVA_PLATFORM_VERSIONS = new TreeSet<>();

        Path ctSymFile = findCtSym();

        if (Files.exists(ctSymFile)) {

            try (FileSystem fs = FileSystems.newFileSystem(ctSymFile, null);

                 DirectoryStream<Path> dir =

                         Files.newDirectoryStream(fs.getRootDirectories().iterator().next())) {

                for (Path section : dir) {

                    for (char ver : section.getFileName().toString().toCharArray()) {

                        String verString = Character.toString(ver);

                        Target t = Target.lookup(verString);

                        if (t != null) {

                            SUPPORTED_JAVA_PLATFORM_VERSIONS.add(targetNumericVersion(t));

                        }

                    }

                }

            } catch (IOException ex) {

            }

        }

        SUPPORTED_JAVA_PLATFORM_VERSIONS.add(targetNumericVersion(Target.DEFAULT));

    }

    private static String targetNumericVersion(Target target) {

        return Integer.toString(target.ordinal() - Target.JDK1_1.ordinal() + 1);

    }

    static class PlatformDescriptionImpl implements PlatformDescription {

        private final Map<Path, FileSystem> ctSym2FileSystem = new HashMap<>();

        private final String version;

        PlatformDescriptionImpl(String version) {

            this.version = version;

        }

        @Override

        public Collection<Path> getPlatformPath() {

            if (Target.lookup(version) == Target.DEFAULT) {

                return null;

            }

            List<Path> paths = new ArrayList<>();

            Path file = findCtSym();

            // file == ${jdk.home}/lib/ct.sym

            if (Files.exists(file)) {

                FileSystem fs = ctSym2FileSystem.get(file);

                if (fs == null) {

                    try {

                        ctSym2FileSystem.put(file, fs = FileSystems.newFileSystem(file, null));

                    } catch (IOException ex) {

                        throw new IllegalStateException(ex);

                    }

                }

                Path root = fs.getRootDirectories().iterator().next();

                try (DirectoryStream<Path> dir = Files.newDirectoryStream(root)) {

                    for (Path section : dir) {

                        if (section.getFileName().toString().contains(version)) {

                            paths.add(section);

                        }

                    }

                } catch (IOException ex) {

                    throw new IllegalStateException(ex);

                }

            } else {

                throw new IllegalStateException("Cannot find ct.sym!");

            }

            return paths;

        }

        @Override

        public String getSourceVersion() {

            return version;

        }

        @Override

        public String getTargetVersion() {

            return version;

        }

        @Override

        public List<PluginInfo<Processor>> getAnnotationProcessors() {

            return Collections.emptyList();

        }

        @Override

        public List<PluginInfo<Plugin>> getPlugins() {

            return Collections.emptyList();

        }

        @Override

        public List<String> getAdditionalOptions() {

            return Collections.emptyList();

        }

        @Override

        public void close() throws IOException {

            for (FileSystem fs : ctSym2FileSystem.values()) {

                fs.close();

            }

            ctSym2FileSystem.clear();

        }

    }

    static Path findCtSym() {

        String javaHome = System.getProperty("java.home");

        Path file = Paths.get(javaHome);

        // file == ${jdk.home}

        for (String name : symbolFileLocation)

            file = file.resolve(name);

        return file;

    }

}