/*
 * Copyright (c) 2015, 2017, 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 jdk.tools.jlink.builder;

import java.io.BufferedOutputStream;
import java.io.BufferedWriter;
import java.io.ByteArrayInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UncheckedIOException;
import java.io.Writer;
import java.lang.module.ModuleDescriptor;
import java.nio.charset.StandardCharsets;
import java.nio.file.FileAlreadyExistsException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.nio.file.attribute.PosixFilePermission;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.Properties;
import java.util.Set;
import static java.util.stream.Collectors.*;

import jdk.tools.jlink.internal.BasicImageWriter;
import jdk.tools.jlink.internal.ExecutableImage;
import jdk.tools.jlink.internal.Platform;
import jdk.tools.jlink.plugin.ResourcePool;
import jdk.tools.jlink.plugin.ResourcePoolEntry;
import jdk.tools.jlink.plugin.ResourcePoolEntry.Type;
import jdk.tools.jlink.plugin.ResourcePoolModule;
import jdk.tools.jlink.plugin.PluginException;

/**
 *
 * Default Image Builder. This builder creates the default runtime image layout.
 */
public final class DefaultImageBuilder implements ImageBuilder {
    // Top-level directory names in a modular runtime image
    public static final String BIN_DIRNAME      = "bin";
    public static final String CONF_DIRNAME     = "conf";
    public static final String INCLUDE_DIRNAME  = "include";
    public static final String LIB_DIRNAME      = "lib";
    public static final String LEGAL_DIRNAME    = "legal";
    public static final String MAN_DIRNAME      = "man";

    /**
     * The default java executable Image.
     */
    static final class DefaultExecutableImage implements ExecutableImage {

        private final Path home;
        private final List<String> args;
        private final Set<String> modules;

        DefaultExecutableImage(Path home, Set<String> modules) {
            Objects.requireNonNull(home);
            if (!Files.exists(home)) {
                throw new IllegalArgumentException("Invalid image home");
            }
            this.home = home;
            this.modules = Collections.unmodifiableSet(modules);
            this.args = createArgs(home);
        }

        private static List<String> createArgs(Path home) {
            Objects.requireNonNull(home);
            Path binDir = home.resolve("bin");
            String java = Files.exists(binDir.resolve("java"))? "java" : "java.exe";
            return List.of(binDir.resolve(java).toString());
        }

        @Override
        public Path getHome() {
            return home;
        }

        @Override
        public Set<String> getModules() {
            return modules;
        }

        @Override
        public List<String> getExecutionArgs() {
            return args;
        }

        @Override
        public void storeLaunchArgs(List<String> args) {
            try {
                patchScripts(this, args);
            } catch (IOException ex) {
                throw new UncheckedIOException(ex);
            }
        }
    }

    private final Path root;
    private final Map<String, String> launchers;
    private final Path mdir;
    private final Set<String> modules = new HashSet<>();
    private Platform targetPlatform;

    /**
     * Default image builder constructor.
     *
     * @param root The image root directory.
     * @throws IOException
     */
    public DefaultImageBuilder(Path root, Map<String, String> launchers) throws IOException {
        this.root = Objects.requireNonNull(root);
        this.launchers = Objects.requireNonNull(launchers);
        this.mdir = root.resolve("lib");
        Files.createDirectories(mdir);
    }

    @Override
    public void storeFiles(ResourcePool files) {
        try {
            String value = files.moduleView()
                                .findModule("java.base")
                                .map(ResourcePoolModule::targetPlatform)
                                .orElse(null);
            if (value == null) {
                throw new PluginException("ModuleTarget attribute is missing for java.base module");
            }
            this.targetPlatform = Platform.toPlatform(value);

            checkResourcePool(files);

            Path bin = root.resolve(BIN_DIRNAME);

            // write non-classes resource files to the image
            files.entries()
                .filter(f -> f.type() != ResourcePoolEntry.Type.CLASS_OR_RESOURCE)
                .forEach(f -> {
                    try {
                        accept(f);
                    } catch (FileAlreadyExistsException e) {
                        // Should not happen! Duplicates checking already done!
                        throw new AssertionError("Duplicate entry!", e);
                    } catch (IOException ioExp) {
                        throw new UncheckedIOException(ioExp);
                    }
                });

            files.moduleView().modules().forEach(m -> {
                // Only add modules that contain packages
                if (!m.packages().isEmpty()) {
                    modules.add(m.name());
                }
            });

            if (root.getFileSystem().supportedFileAttributeViews()
                    .contains("posix")) {
                // launchers in the bin directory need execute permission.
                // On Windows, "bin" also subdirectories containing jvm.dll.
                if (Files.isDirectory(bin)) {
                    Files.find(bin, 2, (path, attrs) -> {
                        return attrs.isRegularFile() && !path.toString().endsWith(".diz");
                    }).forEach(this::setExecutable);
                }

                // jspawnhelper is in lib or lib/<arch>
                Path lib = root.resolve(LIB_DIRNAME);
                if (Files.isDirectory(lib)) {
                    Files.find(lib, 2, (path, attrs) -> {
                        return path.getFileName().toString().equals("jspawnhelper")
                                || path.getFileName().toString().equals("jexec");
                    }).forEach(this::setExecutable);
                }

                // read-only legal notices/license files
                Path legal = root.resolve(LEGAL_DIRNAME);
                if (Files.isDirectory(legal)) {
                    Files.find(legal, 2, (path, attrs) -> {
                        return attrs.isRegularFile();
                    }).forEach(this::setReadOnly);
                }
            }

            // If native files are stripped completely, <root>/bin dir won't exist!
            // So, don't bother generating launcher scripts.
            if (Files.isDirectory(bin)) {
                 prepareApplicationFiles(files);
            }
        } catch (IOException ex) {
            throw new PluginException(ex);
        }
    }

    private void checkResourcePool(ResourcePool pool) {
        // For now, only duplicate resources check. Add more checks here (if any)
        checkDuplicateResources(pool);
    }

    private void checkDuplicateResources(ResourcePool pool) {
        // check any duplicated resources
        Map<Path, Set<String>> duplicates = new HashMap<>();
        pool.entries()
             .filter(f -> f.type() != ResourcePoolEntry.Type.CLASS_OR_RESOURCE)
             .collect(groupingBy(this::entryToImagePath,
                      mapping(ResourcePoolEntry::moduleName, toSet())))
             .entrySet()
             .stream()
             .filter(e -> e.getValue().size() > 1)
             .forEach(e -> duplicates.put(e.getKey(), e.getValue()));
        if (!duplicates.isEmpty()) {
            throw new PluginException("Duplicate resources: " + duplicates);
        }
    }

    /**
     * Generates launcher scripts.
     *
     * @param imageContent The image content.
     * @throws IOException
     */
    protected void prepareApplicationFiles(ResourcePool imageContent) throws IOException {
        // generate launch scripts for the modules with a main class
        for (Map.Entry<String, String> entry : launchers.entrySet()) {
            String launcherEntry = entry.getValue();
            int slashIdx = launcherEntry.indexOf("/");
            String module, mainClassName;
            if (slashIdx == -1) {
                module = launcherEntry;
                mainClassName = null;
            } else {
                module = launcherEntry.substring(0, slashIdx);
                assert !module.isEmpty();
                mainClassName = launcherEntry.substring(slashIdx + 1);
                assert !mainClassName.isEmpty();
            }

            if (mainClassName == null) {
                String path = "/" + module + "/module-info.class";
                Optional<ResourcePoolEntry> res = imageContent.findEntry(path);
                if (!res.isPresent()) {
                    throw new IOException("module-info.class not found for " + module + " module");
                }
                ByteArrayInputStream stream = new ByteArrayInputStream(res.get().contentBytes());
                Optional<String> mainClass = ModuleDescriptor.read(stream).mainClass();
                if (mainClass.isPresent()) {
                    mainClassName = mainClass.get();
                }
            }

            if (mainClassName != null) {
                // make sure main class exists!
                if (!imageContent.findEntry("/" + module + "/" +
                        mainClassName.replace('.', '/') + ".class").isPresent()) {
                    throw new IllegalArgumentException(module + " does not have main class: " + mainClassName);
                }

                String launcherFile = entry.getKey();
                Path cmd = root.resolve("bin").resolve(launcherFile);
                // generate shell script for Unix platforms
                StringBuilder sb = new StringBuilder();
                sb.append("#!/bin/sh")
                        .append("\n");
                sb.append("JLINK_VM_OPTIONS=")
                        .append("\n");
                sb.append("DIR=`dirname $0`")
                        .append("\n");
                sb.append("$DIR/java $JLINK_VM_OPTIONS -m ")
                        .append(module).append('/')
                        .append(mainClassName)
                        .append(" \"$@\"\n");

                try (BufferedWriter writer = Files.newBufferedWriter(cmd,
                        StandardCharsets.ISO_8859_1,
                        StandardOpenOption.CREATE_NEW)) {
                    writer.write(sb.toString());
                }
                if (root.resolve("bin").getFileSystem()
                        .supportedFileAttributeViews().contains("posix")) {
                    setExecutable(cmd);
                }
                // generate .bat file for Windows
                if (isWindows()) {
                    Path bat = root.resolve(BIN_DIRNAME).resolve(launcherFile + ".bat");
                    sb = new StringBuilder();
                    sb.append("@echo off")
                            .append("\r\n");
                    sb.append("set JLINK_VM_OPTIONS=")
                            .append("\r\n");
                    sb.append("set DIR=%~dp0")
                            .append("\r\n");
                    sb.append("\"%DIR%\\java\" %JLINK_VM_OPTIONS% -m ")
                            .append(module).append('/')
                            .append(mainClassName)
                            .append(" %*\r\n");

                    try (BufferedWriter writer = Files.newBufferedWriter(bat,
                            StandardCharsets.ISO_8859_1,
                            StandardOpenOption.CREATE_NEW)) {
                        writer.write(sb.toString());
                    }
                }
            } else {
                throw new IllegalArgumentException(module + " doesn't contain main class & main not specified in command line");
            }
        }
    }

    @Override
    public DataOutputStream getJImageOutputStream() {
        try {
            Path jimageFile = mdir.resolve(BasicImageWriter.MODULES_IMAGE_NAME);
            OutputStream fos = Files.newOutputStream(jimageFile);
            BufferedOutputStream bos = new BufferedOutputStream(fos);
            return new DataOutputStream(bos);
        } catch (IOException ex) {
            throw new UncheckedIOException(ex);
        }
    }

    /**
     * Returns the file name of this entry
     */
    private String entryToFileName(ResourcePoolEntry entry) {
        if (entry.type() == ResourcePoolEntry.Type.CLASS_OR_RESOURCE)
            throw new IllegalArgumentException("invalid type: " + entry);

        String module = "/" + entry.moduleName() + "/";
        String filename = entry.path().substring(module.length());

        // Remove radical lib|config|...
        return filename.substring(filename.indexOf('/') + 1);
    }

    /**
     * Returns the path of the given entry to be written in the image
     */
    private Path entryToImagePath(ResourcePoolEntry entry) {
        switch (entry.type()) {
            case NATIVE_LIB:
                String filename = entryToFileName(entry);
                return Paths.get(nativeDir(filename), filename);
            case NATIVE_CMD:
                return Paths.get(BIN_DIRNAME, entryToFileName(entry));
            case CONFIG:
                return Paths.get(CONF_DIRNAME, entryToFileName(entry));
            case HEADER_FILE:
                return Paths.get(INCLUDE_DIRNAME, entryToFileName(entry));
            case MAN_PAGE:
                return Paths.get(MAN_DIRNAME, entryToFileName(entry));
            case LEGAL_NOTICE:
                return Paths.get(LEGAL_DIRNAME, entryToFileName(entry));
            case TOP:
                return Paths.get(entryToFileName(entry));
            default:
                throw new IllegalArgumentException("invalid type: " + entry);
        }
    }

    private void accept(ResourcePoolEntry file) throws IOException {
        if (file.linkedTarget() != null && file.type() != Type.LEGAL_NOTICE) {
            throw new UnsupportedOperationException("symbolic link not implemented: " + file);
        }

        try (InputStream in = file.content()) {
            switch (file.type()) {
                case NATIVE_LIB:
                    Path dest = root.resolve(entryToImagePath(file));
                    writeEntry(in, dest);
                    break;
                case NATIVE_CMD:
                    Path p = root.resolve(entryToImagePath(file));
                    writeEntry(in, p);
                    p.toFile().setExecutable(true);
                    break;
                case CONFIG:
                case HEADER_FILE:
                case MAN_PAGE:
                    writeEntry(in, root.resolve(entryToImagePath(file)));
                    break;
                case LEGAL_NOTICE:
                    Path source = entryToImagePath(file);
                    if (file.linkedTarget() == null) {
                        writeEntry(in, root.resolve(source));
                    } else {
                        Path target = entryToImagePath(file.linkedTarget());
                        Path relPath = source.getParent().relativize(target);
                        writeSymLinkEntry(root.resolve(source), relPath);
                    }
                    break;
                case TOP:
                    // Copy TOP files of the "java.base" module (only)
                    if ("java.base".equals(file.moduleName())) {
                        writeEntry(in, root.resolve(entryToImagePath(file)));
                    } else {
                        throw new InternalError("unexpected TOP entry: " + file.path());
                    }
                    break;
                default:
                    throw new InternalError("unexpected entry: " + file.path());
            }
        }
    }

    private void writeEntry(InputStream in, Path dstFile) throws IOException {
        Objects.requireNonNull(in);
        Objects.requireNonNull(dstFile);
        Files.createDirectories(Objects.requireNonNull(dstFile.getParent()));
        Files.copy(in, dstFile);
    }

    private void writeSymEntry(Path dstFile, Path target) throws IOException {
        Objects.requireNonNull(dstFile);
        Objects.requireNonNull(target);
        Files.createDirectories(Objects.requireNonNull(dstFile.getParent()));
        Files.createLink(dstFile, target);
    }

    /*
     * Create a symbolic link to the given target if the target platform
     * supports symbolic link; otherwise, it will create a tiny file
     * to contain the path to the target.
     */
    private void writeSymLinkEntry(Path dstFile, Path target) throws IOException {
        Objects.requireNonNull(dstFile);
        Objects.requireNonNull(target);
        Files.createDirectories(Objects.requireNonNull(dstFile.getParent()));
        if (!isWindows() && root.getFileSystem()
                                .supportedFileAttributeViews()
                                .contains("posix")) {
            Files.createSymbolicLink(dstFile, target);
        } else {
            try (BufferedWriter writer = Files.newBufferedWriter(dstFile)) {
                writer.write(String.format("Please see %s%n", target.toString()));
            }
        }
    }

    private String nativeDir(String filename) {
        if (isWindows()) {
            if (filename.endsWith(".dll") || filename.endsWith(".diz")
                    || filename.endsWith(".pdb") || filename.endsWith(".map")) {
                return BIN_DIRNAME;
            } else {
                return LIB_DIRNAME;
            }
        } else {
            return LIB_DIRNAME;
        }
    }

    private boolean isWindows() {
        return targetPlatform == Platform.WINDOWS;
    }

    /**
     * chmod ugo+x file
     */
    private void setExecutable(Path file) {
        try {
            Set<PosixFilePermission> perms = Files.getPosixFilePermissions(file);
            perms.add(PosixFilePermission.OWNER_EXECUTE);
            perms.add(PosixFilePermission.GROUP_EXECUTE);
            perms.add(PosixFilePermission.OTHERS_EXECUTE);
            Files.setPosixFilePermissions(file, perms);
        } catch (IOException ioe) {
            throw new UncheckedIOException(ioe);
        }
    }

    /**
     * chmod ugo-w file
     */
    private void setReadOnly(Path file) {
        try {
            Set<PosixFilePermission> perms = Files.getPosixFilePermissions(file);
            perms.remove(PosixFilePermission.OWNER_WRITE);
            perms.remove(PosixFilePermission.GROUP_WRITE);
            perms.remove(PosixFilePermission.OTHERS_WRITE);
            Files.setPosixFilePermissions(file, perms);
        } catch (IOException ioe) {
            throw new UncheckedIOException(ioe);
        }
    }

    private static void createUtf8File(File file, String content) throws IOException {
        try (OutputStream fout = new FileOutputStream(file);
                Writer output = new OutputStreamWriter(fout, "UTF-8")) {
            output.write(content);
        }
    }

    @Override
    public ExecutableImage getExecutableImage() {
        return new DefaultExecutableImage(root, modules);
    }

    // This is experimental, we should get rid-off the scripts in a near future
    private static void patchScripts(ExecutableImage img, List<String> args) throws IOException {
        Objects.requireNonNull(args);
        if (!args.isEmpty()) {
            Files.find(img.getHome().resolve(BIN_DIRNAME), 2, (path, attrs) -> {
                return img.getModules().contains(path.getFileName().toString());
            }).forEach((p) -> {
                try {
                    String pattern = "JLINK_VM_OPTIONS=";
                    byte[] content = Files.readAllBytes(p);
                    String str = new String(content, StandardCharsets.UTF_8);
                    int index = str.indexOf(pattern);
                    StringBuilder builder = new StringBuilder();
                    if (index != -1) {
                        builder.append(str.substring(0, index)).
                                append(pattern);
                        for (String s : args) {
                            builder.append(s).append(" ");
                        }
                        String remain = str.substring(index + pattern.length());
                        builder.append(remain);
                        str = builder.toString();
                        try (BufferedWriter writer = Files.newBufferedWriter(p,
                                StandardCharsets.ISO_8859_1,
                                StandardOpenOption.WRITE)) {
                            writer.write(str);
                        }
                    }
                } catch (IOException ex) {
                    throw new RuntimeException(ex);
                }
            });
        }
    }

    public static ExecutableImage getExecutableImage(Path root) {
        Path binDir = root.resolve(BIN_DIRNAME);
        if (Files.exists(binDir.resolve("java")) ||
            Files.exists(binDir.resolve("java.exe"))) {
            return new DefaultExecutableImage(root, retrieveModules(root));
        }
        return null;
    }

    private static Set<String> retrieveModules(Path root) {
        Path releaseFile = root.resolve("release");
        Set<String> modules = new HashSet<>();
        if (Files.exists(releaseFile)) {
            Properties release = new Properties();
            try (FileInputStream fi = new FileInputStream(releaseFile.toFile())) {
                release.load(fi);
            } catch (IOException ex) {
                System.err.println("Can't read release file " + ex);
            }
            String mods = release.getProperty("MODULES");
            if (mods != null) {
                String[] arr = mods.substring(1, mods.length() - 1).split(" ");
                for (String m : arr) {
                    modules.add(m.trim());
                }

            }
        }
        return modules;
    }
}