/*

 * Copyright (c) 2010, 2013, 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

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 */

package jdk.nashorn.internal.runtime;

import static jdk.nashorn.internal.lookup.Lookup.MH;

import static jdk.nashorn.internal.runtime.ECMAErrors.typeError;

import static jdk.nashorn.internal.runtime.ScriptRuntime.UNDEFINED;

import java.io.BufferedReader;

import java.io.File;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.OutputStreamWriter;

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodHandles;

import java.util.Map;

import java.util.StringTokenizer;

/**

 * Global functions supported only in scripting mode.

 */

public final class ScriptingFunctions {

    /** Handle to implementation of {@link ScriptingFunctions#readLine} - Nashorn extension */

    public static final MethodHandle READLINE = findOwnMH("readLine", Object.class, Object.class, Object.class);

    /** Handle to implementation of {@link ScriptingFunctions#readFully} - Nashorn extension */

    public static final MethodHandle READFULLY = findOwnMH("readFully",     Object.class, Object.class, Object.class);

    /** Handle to implementation of {@link ScriptingFunctions#exec} - Nashorn extension */

    public static final MethodHandle EXEC = findOwnMH("exec",     Object.class, Object.class, Object.class, Object.class);

    /** EXEC name - special property used by $EXEC API. */

    public static final String EXEC_NAME = "$EXEC";

    /** OUT name - special property used by $EXEC API. */

    public static final String OUT_NAME  = "$OUT";

    /** ERR name - special property used by $EXEC API. */

    public static final String ERR_NAME  = "$ERR";

    /** EXIT name - special property used by $EXEC API. */

    public static final String EXIT_NAME = "$EXIT";

    /** Names of special properties used by $ENV API. */

    public  static final String ENV_NAME  = "$ENV";

    private static final String PWD_NAME  = "PWD";

    private ScriptingFunctions() {

    }

    /**

     * Nashorn extension: global.readLine (scripting-mode-only)

     * Read one line of input from the standard input.

     *

     * @param self   self reference

     * @param prompt String used as input prompt

     *

     * @return line that was read

     *

     * @throws IOException if an exception occurs

     */

    public static Object readLine(final Object self, final Object prompt) throws IOException {

        if (prompt != UNDEFINED) {

            System.out.print(JSType.toString(prompt));

        }

        final BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        return reader.readLine();

    }

    /**

     * Nashorn extension: Read the entire contents of a text file and return as String.

     *

     * @param self self reference

     * @param file The input file whose content is read.

     *

     * @return String content of the input file.

     *

     * @throws IOException if an exception occurs

     */

    public static Object readFully(final Object self, final Object file) throws IOException {

        File f = null;

        if (file instanceof File) {

            f = (File)file;

            f = new java.io.File(((CharSequence)file).toString());

        }

        if (f == null || !f.isFile()) {

            throw typeError("not.a.file", ScriptRuntime.safeToString(file));

        }

        return new String(Source.readFully(f));

    }

    /**

     * Nashorn extension: exec a string in a separate process.

     *

     * @param self   self reference

     * @param string string to execute

     * @param input  input

     *

     * @return output string from the request

     * @throws IOException           if any stream access fails

     * @throws InterruptedException  if execution is interrupted

     */

    public static Object exec(final Object self, final Object string, final Object input) throws IOException, InterruptedException {

        // Current global is need to fetch additional inputs and for additional results.

        final ScriptObject global = Context.getGlobal();

        // Break exec string into tokens.

        final StringTokenizer tokenizer = new StringTokenizer(JSType.toString(string));

        final String[] cmdArray = new String[tokenizer.countTokens()];

        for (int i = 0; tokenizer.hasMoreTokens(); i++) {

            cmdArray[i] = tokenizer.nextToken();

        }

        // Set up initial process.

        final ProcessBuilder processBuilder = new ProcessBuilder(cmdArray);

        // Current ENV property state.

        final Object env = global.get(ENV_NAME);

        if (env instanceof ScriptObject) {

            final ScriptObject envProperties = (ScriptObject)env;

            // If a working directory is present, use it.

            final Object pwd = envProperties.get(PWD_NAME);

            if (pwd != UNDEFINED) {

                processBuilder.directory(new File(JSType.toString(pwd)));

            }

            // Set up ENV variables.

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

            environment.clear();

            for (final Map.Entry<Object, Object> entry : envProperties.entrySet()) {

                environment.put(JSType.toString(entry.getKey()), JSType.toString(entry.getValue()));

            }

        }

        // Start the process.

        final Process process = processBuilder.start();

        final IOException exception[] = new IOException[2];

        // Collect output.

        final StringBuilder outBuffer = new StringBuilder();

        final Thread outThread = new Thread(new Runnable() {

            @Override

            public void run() {

                final char buffer[] = new char[1024];

                try (final InputStreamReader inputStream = new InputStreamReader(process.getInputStream())) {

                    for (int length; (length = inputStream.read(buffer, 0, buffer.length)) != -1; ) {

                        outBuffer.append(buffer, 0, length);

                    }

                } catch (final IOException ex) {

                    exception[0] = ex;

                }

            }

        }, "$EXEC output");

        // Collect errors.

        final StringBuilder errBuffer = new StringBuilder();

        final Thread errThread = new Thread(new Runnable() {

            @Override

            public void run() {

                final char buffer[] = new char[1024];

                try (final InputStreamReader inputStream = new InputStreamReader(process.getErrorStream())) {

                    for (int length; (length = inputStream.read(buffer, 0, buffer.length)) != -1; ) {

                        errBuffer.append(buffer, 0, length);

                    }

                } catch (final IOException ex) {

                    exception[1] = ex;

                }

            }

        }, "$EXEC error");

        // Start gathering output.

        outThread.start();

        errThread.start();

        // If input is present, pass on to process.

        try (OutputStreamWriter outputStream = new OutputStreamWriter(process.getOutputStream())) {

            if (input != UNDEFINED) {

                final String in = JSType.toString(input);

                outputStream.write(in, 0, in.length());

            }

        } catch (final IOException ex) {

            // Process was not expecting input.  May be normal state of affairs.

        }

        // Wait for the process to complete.

        final int exit = process.waitFor();

        outThread.join();

        errThread.join();

        final String out = outBuffer.toString();

        final String err = errBuffer.toString();

        // Set globals for secondary results.

        global.set(OUT_NAME, out, 0);

        global.set(ERR_NAME, err, 0);

        global.set(EXIT_NAME, exit, 0);

        // Propagate exception if present.

        for (final IOException element : exception) {

            if (element != null) {

                throw element;

            }

        }

        // Return the result from stdout.

        return out;

    }

    private static MethodHandle findOwnMH(final String name, final Class<?> rtype, final Class<?>... types) {

        return MH.findStatic(MethodHandles.lookup(), ScriptingFunctions.class, name, MH.type(rtype, types));

    }

}