/*

 * Copyright (c) 2015, 2015, 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.

 */

package org.graalvm.compiler.test;

import java.io.BufferedReader;

import java.io.File;

import java.io.IOException;

import java.io.InputStreamReader;

import java.nio.file.Files;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Formatter;

import java.util.List;

import java.util.Map;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

/**

 * Utility methods for spawning a VM in a subprocess during unit tests.

 */

public final class SubprocessUtil {

    private SubprocessUtil() {

    }

    /**

     * Gets the command line for the current process.

     *

     * @return the command line arguments for the current process or {@code null} if they are not

     *         available

     */

    public static List<String> getProcessCommandLine() {

        String processArgsFile = System.getenv().get("MX_SUBPROCESS_COMMAND_FILE");

        if (processArgsFile != null) {

            try {

                return Files.readAllLines(new File(processArgsFile).toPath());

            } catch (IOException e) {

            }

        }

        return null;

    }

    /**

     * Pattern for a single shell command argument that does not need to quoted.

     */

    private static final Pattern SAFE_SHELL_ARG = Pattern.compile("[A-Za-z0-9@%_\\-\\+=:,\\./]+");

    /**

     * Reliably quote a string as a single shell command argument.

     */

    public static String quoteShellArg(String arg) {

        if (arg.isEmpty()) {

            return "\"\"";

        }

        Matcher m = SAFE_SHELL_ARG.matcher(arg);

        if (m.matches()) {

            return arg;

        }

        // See http://stackoverflow.com/a/1250279

        return "'" + arg.replace("'", "'\"'\"'") + "'";

    }

    /**

     * Returns a new copy {@code args} with debugger arguments removed.

     */

    public static List<String> withoutDebuggerArguments(List<String> args) {

        List<String> result = new ArrayList<>(args.size());

        for (String arg : args) {

            if (!(arg.equals("-Xdebug") || arg.startsWith("-Xrunjdwp:"))) {

                result.add(arg);

            }

        }

        return result;

    }

    /**

     * Gets the command line used to start the current Java VM, including all VM arguments, but not

     * including the main class or any Java arguments. This can be used to spawn an identical VM,

     * but running different Java code.

     */

    public static List<String> getVMCommandLine() {

        List<String> args = getProcessCommandLine();

        if (args == null) {

            return null;

        } else {

            int index = findMainClassIndex(args);

            return args.subList(0, index);

        }

    }

    /**

     * The details of a subprocess execution.

     */

    public static class Subprocess {

        /**

         * The command line of the subprocess.

         */

        public final List<String> command;

        /**

         * Exit code of the subprocess.

         */

        public final int exitCode;

        /**

         * Output from the subprocess broken into lines.

         */

        public final List<String> output;

        public Subprocess(List<String> command, int exitCode, List<String> output) {

            this.command = command;

            this.exitCode = exitCode;

            this.output = output;

        }

        public static final String DASHES_DELIMITER = "-------------------------------------------------------";

        /**

         * Returns the command followed by the output as a string.

         *

         * @param delimiter if non-null, the returned string has this value as a prefix and suffix

         */

        public String toString(String delimiter) {

            Formatter msg = new Formatter();

            if (delimiter != null) {

                msg.format("%s%n", delimiter);

            }

            msg.format("%s%n", CollectionsUtil.mapAndJoin(command, e -> quoteShellArg(String.valueOf(e)), " "));

            for (String line : output) {

                msg.format("%s%n", line);

            }

            if (delimiter != null) {

                msg.format("%s%n", delimiter);

            }

            return msg.toString();

        }

        /**

         * Returns the command followed by the output as a string delimited by

         * {@value #DASHES_DELIMITER}.

         */

        @Override

        public String toString() {

            return toString(DASHES_DELIMITER);

        }

    }

    /**

     * Executes a Java subprocess.

     *

     * @param vmArgs the VM arguments

     * @param mainClassAndArgs the main class and its arguments

     */

    public static Subprocess java(List<String> vmArgs, String... mainClassAndArgs) throws IOException, InterruptedException {

        return java(vmArgs, Arrays.asList(mainClassAndArgs));

    }

    /**

     * Executes a Java subprocess.

     *

     * @param vmArgs the VM arguments

     * @param mainClassAndArgs the main class and its arguments

     */

    public static Subprocess java(List<String> vmArgs, List<String> mainClassAndArgs) throws IOException, InterruptedException {

        return javaHelper(vmArgs, null, mainClassAndArgs);

    }

    /**

     * Executes a Java subprocess.

     *

     * @param vmArgs the VM arguments

     * @param env the environment variables

     * @param mainClassAndArgs the main class and its arguments

     */

    public static Subprocess java(List<String> vmArgs, Map<String, String> env, String... mainClassAndArgs) throws IOException, InterruptedException {

        return java(vmArgs, env, Arrays.asList(mainClassAndArgs));

    }

    /**

     * Executes a Java subprocess.

     *

     * @param vmArgs the VM arguments

     * @param env the environment variables

     * @param mainClassAndArgs the main class and its arguments

     */

    public static Subprocess java(List<String> vmArgs, Map<String, String> env, List<String> mainClassAndArgs) throws IOException, InterruptedException {

        return javaHelper(vmArgs, env, mainClassAndArgs);

    }

    /**

     * Executes a Java subprocess.

     *

     * @param vmArgs the VM arguments

     * @param env the environment variables

     * @param mainClassAndArgs the main class and its arguments

     */

    private static Subprocess javaHelper(List<String> vmArgs, Map<String, String> env, List<String> mainClassAndArgs) throws IOException, InterruptedException {

        List<String> command = new ArrayList<>(vmArgs);

        command.addAll(mainClassAndArgs);

        ProcessBuilder processBuilder = new ProcessBuilder(command);

        if (env != null) {

            Map<String, String> processBuilderEnv = processBuilder.environment();

            processBuilderEnv.putAll(env);

        }

        processBuilder.redirectErrorStream(true);

        Process process = processBuilder.start();

        BufferedReader stdout = new BufferedReader(new InputStreamReader(process.getInputStream()));

        String line;

        List<String> output = new ArrayList<>();

        while ((line = stdout.readLine()) != null) {

            output.add(line);

        }

        return new Subprocess(command, process.waitFor(), output);

    }

    private static final boolean isJava8OrEarlier = System.getProperty("java.specification.version").compareTo("1.9") < 0;

    private static boolean hasArg(String optionName) {

        if (optionName.equals("-cp") || optionName.equals("-classpath")) {

            return true;

        }

        if (!isJava8OrEarlier) {

            if (optionName.equals("--version") ||

                            optionName.equals("--show-version") ||

                            optionName.equals("--dry-run") ||

                            optionName.equals("--disable-@files") ||

                            optionName.equals("--dry-run") ||

                            optionName.equals("--help") ||

                            optionName.equals("--help-extra")) {

                return false;

            }

            if (optionName.startsWith("--")) {

                return optionName.indexOf('=') == -1;

            }

        }

        return false;

    }

    private static int findMainClassIndex(List<String> commandLine) {

        int i = 1; // Skip the java executable

        while (i < commandLine.size()) {

            String s = commandLine.get(i);

            if (s.charAt(0) != '-') {

                return i;

            } else if (hasArg(s)) {

                i += 2;

            } else {

                i++;

            }

        }

        throw new InternalError();

    }

}