/*
 * 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 build.tools.module;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import javax.xml.namespace.QName;
import javax.xml.stream.*;
import javax.xml.stream.events.Attribute;
import javax.xml.stream.events.XMLEvent;

/**
 * GenJdepsModulesXml augments the input modules.xml file(s)
 * to include the module membership from the given path to
 * the JDK exploded image.  The output file is used by jdeps 
 * to analyze dependencies and enforce module boundaries.
 *
 * The input modules.xml file defines the modular structure of 
 * the JDK as described in JEP 200: The Modular JDK
 * (http://openjdk.java.net/jeps/200).
 *
 * $ java build.tools.module.GenJdepsModulesXml \
 *        -o com/sun/tools/jdeps/resources/modules.xml \
 *        -mp $OUTPUTDIR/modules \
 *        top/modules.xml
 */
public final class GenJdepsModulesXml {
    private final static String USAGE =
        "Usage: GenJdepsModulesXml -o <output file> -mp build/modules path-to-modules-xml";

    public static void main(String[] args) throws Exception {
        Path outfile = null;
        Path modulepath = null;
        int i = 0;
        while (i < args.length) {
            String arg = args[i];
            if (arg.equals("-o")) {
                outfile = Paths.get(args[i+1]);
                i = i+2;
            } else if (arg.equals("-mp")) {
                modulepath = Paths.get(args[i+1]);
                i = i+2;
                if (!Files.isDirectory(modulepath)) {
                    System.err.println(modulepath + " is not a directory");
                    System.exit(1);
                }
            } else {
                break;
            } 
        }
        if (outfile == null || modulepath == null || i >= args.length) {
            System.err.println(USAGE);
            System.exit(-1);
        }

        GenJdepsModulesXml gentool = new GenJdepsModulesXml(modulepath);
        Set<Module> modules = new HashSet<>();
        for (; i < args.length; i++) {
            Path p = Paths.get(args[i]);
            try (InputStream in = new BufferedInputStream(Files.newInputStream(p))) {
                Set<Module> mods = gentool.load(in);
                modules.addAll(mods);
            }
        }

        Files.createDirectories(outfile.getParent());
        gentool.writeXML(modules, outfile);
    }

    final Path modulepath;
    public GenJdepsModulesXml(Path modulepath) {
        this.modulepath = modulepath;
    }

    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");
    private Set<Module> load(InputStream in) throws XMLStreamException, IOException {
        Set<Module> modules = new HashSet<>();
        XMLInputFactory factory = XMLInputFactory.newInstance();
        XMLEventReader stream = factory.createXMLEventReader(in);
        Module.Builder mb = null;
        String modulename = null;
        String pkg = null;
        Set<String> permits = new HashSet<>();
        while (stream.hasNext()) {
            XMLEvent event = stream.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(stream, 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(stream), reexports);
                        break;
                    case INCLUDE:
                        throw new RuntimeException("unexpected " + event);
                    case EXPORT:
                        pkg = getNextTag(stream, NAME);
                        break;
                    case TO:
                        permits.add(getData(stream));
                        break;
                    default:
                }
            } else if (event.isEndElement()) {
                String endTag = event.asEndElement().getName().getLocalPart();
                switch (endTag) {
                    case MODULE:
                        buildIncludes(mb, modulename);
                        modules.add(mb.build());
                        mb = null;
                        break;
                    case EXPORT:
                        if (pkg == null) {
                            throw new RuntimeException("export-to is malformed");
                        }
                        mb.exportTo(pkg, permits);
                        pkg = 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);
    }
    private void writeXML(Set<Module> modules, Path path)
            throws IOException, XMLStreamException
    {
        XMLOutputFactory xof = XMLOutputFactory.newInstance();
        try (OutputStream out = Files.newOutputStream(path)) {
            int depth = 0;
            XMLStreamWriter xtw = xof.createXMLStreamWriter(out, "UTF-8");
            xtw.writeStartDocument("utf-8","1.0");
            writeStartElement(xtw, MODULES, depth);
            modules.stream()
                   .sorted(Comparator.comparing(Module::name))
                   .forEach(m -> writeModuleElement(xtw, m, depth+1));
            writeEndElement(xtw, depth);
            xtw.writeCharacters("\n");
            xtw.writeEndDocument();
            xtw.flush();
            xtw.close();
        }
    }

    private void writeElement(XMLStreamWriter xtw, String element, String value, int depth) {
        try {
            writeStartElement(xtw, element, depth);
            xtw.writeCharacters(value);
            xtw.writeEndElement();
        } catch (XMLStreamException e) {
            throw new RuntimeException(e);
        }
    }

    private void writeDependElement(XMLStreamWriter xtw, Module.Dependence d, int depth) {
        try {
            writeStartElement(xtw, DEPEND, depth);
            if (d.reexport) {
                xtw.writeAttribute("re-exports", "true");
            }
            xtw.writeCharacters(d.name);
            xtw.writeEndElement();
        } catch (XMLStreamException e) {
            throw new RuntimeException(e);
        }
    }

    private void writeExportElement(XMLStreamWriter xtw, String pkg, int depth) {
        writeExportElement(xtw, pkg, Collections.emptySet(), depth);
    }

    private void writeExportElement(XMLStreamWriter xtw, String pkg,
                                    Set<String> permits, int depth) {
        try {
            writeStartElement(xtw, EXPORT, depth);
            writeElement(xtw, NAME, pkg, depth+1);
            if (!permits.isEmpty()) {
                permits.stream().sorted()
                       .forEach(m -> writeElement(xtw, TO, m, depth + 1));
            }
            writeEndElement(xtw, depth);
        } catch (XMLStreamException e) {
            throw new RuntimeException(e);
        }
    }
    private void writeModuleElement(XMLStreamWriter xtw, Module m, int depth) {
        try {
            writeStartElement(xtw, MODULE, depth);
            writeElement(xtw, NAME, m.name(), depth+1);
            m.requires().stream().sorted(Comparator.comparing(d -> d.name))
                        .forEach(d -> writeDependElement(xtw, d, depth+1));
            m.exports().keySet().stream()
                       .filter(pn -> m.exports().get(pn).isEmpty())
                       .sorted()
                       .forEach(pn -> GenJdepsModulesXml.this.writeExportElement(xtw, pn, depth+1));
            m.exports().entrySet().stream()
                       .filter(e -> !e.getValue().isEmpty())
                       .sorted(Map.Entry.comparingByKey())
                       .forEach(e -> writeExportElement(xtw, e.getKey(), e.getValue(), depth+1));
            m.packages().stream().sorted()
                        .forEach(p -> writeElement(xtw, INCLUDE, p, depth+1));
            writeEndElement(xtw, depth);
        } catch (XMLStreamException e) {
            throw new RuntimeException(e);

        }
    }

    /** Two spaces; the default indentation. */
    public static final String DEFAULT_INDENT = "  ";

    /** stack[depth] indicates what's been written into the current scope. */
    private static String[] stack = new String[] { "\n",
        "\n" + DEFAULT_INDENT,
        "\n" + DEFAULT_INDENT + DEFAULT_INDENT,
        "\n" + DEFAULT_INDENT + DEFAULT_INDENT + DEFAULT_INDENT};

    private void writeStartElement(XMLStreamWriter xtw, String name, int depth)
            throws XMLStreamException
    {
        xtw.writeCharacters(stack[depth]);
        xtw.writeStartElement(name);
    }

    private void writeEndElement(XMLStreamWriter xtw, int depth) throws XMLStreamException {
        xtw.writeCharacters(stack[depth]);
        xtw.writeEndElement();
    }

    private String packageName(Path p) {
        return packageName(p.toString().replace(File.separatorChar, '/'));
    }
    private String packageName(String name) {
        int i = name.lastIndexOf('/');
        return (i > 0) ? name.substring(0, i).replace('/', '.') : "";
    }

    private boolean includes(String name) {
        return name.endsWith(".class") && !name.equals("module-info.class");
    }

    public void buildIncludes(Module.Builder mb, String modulename) throws IOException {
        Path mclasses = modulepath.resolve(modulename);
        try {
            Files.find(mclasses, Integer.MAX_VALUE, (Path p, BasicFileAttributes attr)
                         -> includes(p.getFileName().toString()))
                 .map(p -> packageName(mclasses.relativize(p)))
                 .forEach(mb::include);
        } catch (NoSuchFileException e) {
            // aggregate module may not have class
        }
    }

    static class Module {
        static class Dependence {
            final String name;
            final boolean reexport;
            Dependence(String name) {
                this(name, false);
            }
            Dependence(String name, boolean reexport) {
                this.name = name;
                this.reexport = reexport;
            }

            @Override
            public int hashCode() {
                int hash = 5;
                hash = 11 * hash + Objects.hashCode(this.name);
                hash = 11 * hash + (this.reexport ? 1 : 0);
                return hash;
            }

            public boolean equals(Object o) {
                Dependence d = (Dependence)o;
                return this.name.equals(d.name) && this.reexport == d.reexport;
            }
        }
        private final String moduleName;
        private final Set<Dependence> requires;
        private final Map<String, Set<String>> exports;
        private final Set<String> packages;

        private Module(String name,
                Set<Dependence> requires,
                Map<String, Set<String>> exports,
                Set<String> packages) {
            this.moduleName = name;
            this.requires = Collections.unmodifiableSet(requires);
            this.exports = Collections.unmodifiableMap(exports);
            this.packages = Collections.unmodifiableSet(packages);
        }

        public String name() {
            return moduleName;
        }

        public Set<Dependence> requires() {
            return requires;
        }

        public Map<String, Set<String>> exports() {
            return exports;
        }

        public Set<String> packages() {
            return packages;
        }

        @Override
        public boolean equals(Object ob) {
            if (!(ob instanceof Module)) {
                return false;
            }
            Module that = (Module) ob;
            return (moduleName.equals(that.moduleName)
                    && requires.equals(that.requires)
                    && exports.equals(that.exports)
                    && packages.equals(that.packages));
        }

        @Override
        public int hashCode() {
            int hc = moduleName.hashCode();
            hc = hc * 43 + requires.hashCode();
            hc = hc * 43 + exports.hashCode();
            hc = hc * 43 + packages.hashCode();
            return hc;
        }

        @Override
        public String toString() {
            StringBuilder sb = new StringBuilder();
            sb.append("module ").append(moduleName).append(" {").append("\n");
            requires.stream().sorted().forEach(d ->
                    sb.append(String.format("   requires %s%s%n", d.reexport ? "public " : "", d.name)));
            exports.entrySet().stream().filter(e -> e.getValue().isEmpty())
                    .sorted(Map.Entry.comparingByKey())
                    .forEach(e -> sb.append(String.format("   exports %s%n", e.getKey())));
            exports.entrySet().stream().filter(e -> !e.getValue().isEmpty())
                    .sorted(Map.Entry.comparingByKey())
                    .forEach(e -> sb.append(String.format("   exports %s to %s%n", e.getKey(), e.getValue())));
            packages.stream().sorted().forEach(pn -> sb.append(String.format("   includes %s%n", pn)));
            sb.append("}");
            return sb.toString();
        }

        static class Builder {
            private String name;
            private final Set<Dependence> requires = new HashSet<>();
            private final Map<String, Set<String>> exports = new HashMap<>();
            private final Set<String> packages = new HashSet<>();

            public Builder() {
            }

            public Builder name(String n) {
                name = n;
                return this;
            }

            public Builder require(String d, boolean reexport) {
                requires.add(new Dependence(d, reexport));
                return this;
            }

            public Builder include(String p) {
                packages.add(p);
                return this;
            }

            public Builder export(String p) {
                return exportTo(p, Collections.emptySet());
            }

            public Builder exportTo(String p, Set<String> ms) {
                Objects.requireNonNull(p);
                Objects.requireNonNull(ms);
                if (exports.containsKey(p)) {
                    throw new RuntimeException(name + " already exports " + p);
                }
                exports.put(p, new HashSet<>(ms));
                return this;
            }

            public Module build() {
                Module m = new Module(name, requires, exports, packages);
                return m;
            }
        }
    }
}