/*

 * 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

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 */

package com.sun.tools.jdeps;

import com.sun.tools.classfile.ClassFile;

import com.sun.tools.jdeps.PlatformClassPath.LegacyImageHelper;

import java.io.IOException;

import java.io.InputStream;

import java.nio.file.Files;

import java.nio.file.Path;

import java.util.Collections;

import java.util.HashSet;

import java.util.List;

import java.util.Set;

import javax.xml.namespace.QName;

import javax.xml.stream.XMLEventReader;

import javax.xml.stream.XMLInputFactory;

import javax.xml.stream.XMLStreamException;

import javax.xml.stream.events.Attribute;

import javax.xml.stream.events.XMLEvent;

abstract class ModulesXmlReader {

    abstract ClassFileReader getClassFileReader(String modulename, Set<String> packages)

        throws IOException;

    static class ImageReader extends ModulesXmlReader {

        final LegacyImageHelper helper;

        ImageReader(LegacyImageHelper helper) {

            this.helper = helper;

        }

        ClassFileReader getClassFileReader(String modulename, Set<String> packages)

            throws IOException

        {

            return helper.getClassReader(modulename, packages);

        }

    }

    static class ModulePathReader extends ModulesXmlReader {

        final Path mpath;

        final ClassFileReader defaultReader;

        ModulePathReader(Path mp) throws IOException {

            this.mpath = mp;

            this.defaultReader = new NonExistModuleReader(mpath);

        }

        ClassFileReader getClassFileReader(String modulename, Set<String> packages)

            throws IOException

        {

            Path mdir = mpath.resolve(modulename);

            if (Files.exists(mdir) && Files.isDirectory(mdir)) {

                return ClassFileReader.newInstance(mdir);

            } else {

                // aggregator module or os-specific module in modules.xml

                // mdir not exist

                return defaultReader;

            }

        }

        class NonExistModuleReader extends ClassFileReader {

            private final List<ClassFile> classes = Collections.emptyList();

            private NonExistModuleReader(Path mpath) {

                super(mpath);

            }

            public ClassFile getClassFile(String name) throws IOException {

                return null;

            }

            public Iterable<ClassFile> getClassFiles() throws IOException {

                return classes;

            }

        }

    }

    public static Set<Module> load(Path mpath, InputStream in)

        throws IOException

    {

        try {

            ModulePathReader reader = new ModulePathReader(mpath);

            return reader.load(in);

        } catch (XMLStreamException e) {

            throw new RuntimeException(e);

        }

    }

    public static Set<Module> loadFromImage(LegacyImageHelper helper, InputStream in)

        throws IOException

    {

        try {

            ImageReader reader = new ImageReader(helper);

            return reader.load(in);

        } catch (XMLStreamException e) {

            throw new RuntimeException(e);

        }

    }

    private static final String MODULES   = "modules";

    private static final String MODULE    = "module";

    private static final String NAME      = "name";

    private static final String DEPEND    = "depend";

    private static final String EXPORT    = "export";

    private static final String TO        = "to";

    private static final String INCLUDE   = "include";

    private static final QName  REEXPORTS = new QName("re-exports");

    public Set<Module> load(InputStream in) throws XMLStreamException, IOException {

        Set<Module> modules = new HashSet<>();

        if (in == null) {

            System.err.println("WARNING: modules.xml doesn't exist");

            return modules;

        }

        XMLInputFactory factory = XMLInputFactory.newInstance();

        XMLEventReader reader = factory.createXMLEventReader(in, "UTF-8");

        Module.Builder mb = null;

        String modulename = null;

        String exportedPackage = null;

        Set<String> permits = new HashSet<>();

        while (reader.hasNext()) {

            XMLEvent event = reader.nextEvent();

            if (event.isStartElement()) {

                String startTag = event.asStartElement().getName().getLocalPart();

                switch (startTag) {

                    case MODULES:

                        break;

                    case MODULE:

                        if (mb != null) {

                            throw new RuntimeException("end tag for module is missing");

                        }

                        modulename = getNextTag(reader, NAME);

                        mb = new Module.Builder();

                        mb.name(modulename);

                        break;

                    case NAME:

                        throw new RuntimeException(event.toString());

                    case DEPEND:

                        boolean reexports = false;

                        Attribute attr = event.asStartElement().getAttributeByName(REEXPORTS);

                        if (attr != null) {

                            String value = attr.getValue();

                            if (value.equals("true") || value.equals("false")) {

                                reexports = Boolean.parseBoolean(value);

                            } else {

                                throw new RuntimeException("unexpected attribute " + attr.toString());

                            }

                        }

                        mb.require(getData(reader), reexports);

                        break;

                    case INCLUDE:

                        mb.include(getData(reader));

                        break;

                    case EXPORT:

                        exportedPackage = getNextTag(reader, NAME);

                        break;

                    case TO:

                        permits.add(getData(reader));

                        break;

                    default:

                        throw new RuntimeException("invalid element: " + event);

                }

            } else if (event.isEndElement()) {

                String endTag = event.asEndElement().getName().getLocalPart();

                switch (endTag) {

                    case MODULE:

                        ClassFileReader cfr = getClassFileReader(modulename, mb.packages);

                        mb.classes(cfr);

                        modules.add(mb.build());

                        mb = null;

                        break;

                    case EXPORT:

                        if (exportedPackage == null) {

                            throw new RuntimeException("export's name is missing");

                        }

                        mb.export(exportedPackage, permits);

                        exportedPackage = null;

                        permits.clear();

                        break;

                    default:

                }

            } else if (event.isCharacters()) {

                String s = event.asCharacters().getData();

                if (!s.trim().isEmpty()) {

                    throw new RuntimeException("export-to is malformed");

                }

            }

        }

        return modules;

    }

    private String getData(XMLEventReader reader) throws XMLStreamException {

        XMLEvent e = reader.nextEvent();

        if (e.isCharacters()) {

            return e.asCharacters().getData();

        }

        throw new RuntimeException(e.toString());

    }

    private String getNextTag(XMLEventReader reader, String tag) throws XMLStreamException {

        XMLEvent e = reader.nextTag();

        if (e.isStartElement()) {

            String t = e.asStartElement().getName().getLocalPart();

            if (!tag.equals(t)) {

                throw new RuntimeException(e + " expected: " + tag);

            }

            return getData(reader);

        }

        throw new RuntimeException("export-to name is missing:" + e);

    }

}