/*

 * Copyright (c) 2014, 2016, 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 com.sun.tools.sjavac.client;

import java.io.BufferedReader;

import java.io.File;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.OutputStreamWriter;

import java.io.PrintStream;

import java.io.PrintWriter;

import java.io.Reader;

import java.io.Writer;

import java.net.InetAddress;

import java.net.InetSocketAddress;

import java.net.Socket;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

import java.util.Scanner;

import java.util.stream.Stream;

import com.sun.tools.sjavac.Log;

import com.sun.tools.sjavac.Util;

import com.sun.tools.sjavac.options.OptionHelper;

import com.sun.tools.sjavac.options.Options;

import com.sun.tools.sjavac.server.CompilationSubResult;

import com.sun.tools.sjavac.server.PortFile;

import com.sun.tools.sjavac.server.Sjavac;

import com.sun.tools.sjavac.server.SjavacServer;

import static java.util.stream.Collectors.joining;

/**

 * Sjavac implementation that delegates requests to a SjavacServer.

 *

 *  <p><b>This is NOT part of any supported API.

 *  If you write code that depends on this, you do so at your own risk.

 *  This code and its internal interfaces are subject to change or

 *  deletion without notice.</b>

 */

public class SjavacClient implements Sjavac {

    // The id can perhaps be used in the future by the javac server to reuse the

    // JavaCompiler instance for several compiles using the same id.

    private final String id;

    private final PortFile portFile;

    // Default keepalive for server is 120 seconds.

    // I.e. it will accept 120 seconds of inactivity before quitting.

    private final int keepalive;

    private final int poolsize;

    // The sjavac option specifies how the server part of sjavac is spawned.

    // If you have the experimental sjavac in your path, you are done. If not, you have

    // to point to a com.sun.tools.sjavac.Main that supports --startserver

    // for example by setting: sjavac=java%20-jar%20...javac.jar%com.sun.tools.sjavac.Main

    private final String sjavacForkCmd;

    // Wait 2 seconds for response, before giving up on javac server.

    static int CONNECTION_TIMEOUT = 2000;

    static int MAX_CONNECT_ATTEMPTS = 3;

    static int WAIT_BETWEEN_CONNECT_ATTEMPTS = 2000;

    // Store the server conf settings here.

    private final String settings;

    public SjavacClient(Options options) {

        String tmpServerConf = options.getServerConf();

        String serverConf = (tmpServerConf!=null)? tmpServerConf : "";

        String tmpId = Util.extractStringOption("id", serverConf);

        id = (tmpId!=null) ? tmpId : "id"+(((new java.util.Random()).nextLong())&Long.MAX_VALUE);

        String defaultPortfile = options.getDestDir()

                                        .resolve("javac_server")

                                        .toAbsolutePath()

                                        .toString();

        String portfileName = Util.extractStringOption("portfile", serverConf, defaultPortfile);

        portFile = SjavacServer.getPortFile(portfileName);

        sjavacForkCmd = Util.extractStringOption("sjavac", serverConf, "sjavac");

        int poolsize = Util.extractIntOption("poolsize", serverConf);

        keepalive = Util.extractIntOption("keepalive", serverConf, 120);

        this.poolsize = poolsize > 0 ? poolsize : Runtime.getRuntime().availableProcessors();

        settings = (serverConf.equals("")) ? "id="+id+",portfile="+portfileName : serverConf;

    }

    /**

     * Hand out the server settings.

     * @return The server settings, possibly a default value.

     */

    public String serverSettings() {

        return settings;

    }

    @Override

    public int compile(String[] args) {

        int result = -1;

        try (Socket socket = tryConnect()) {

            PrintWriter out = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));

            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));

            // Send args array to server

            out.println(args.length);

            for (String arg : args)

                out.println(arg);

            out.flush();

            // Read server response line by line

            String line;

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

                if (!line.contains(":")) {

                    throw new AssertionError("Could not parse protocol line: >>\"" + line + "\"<<");

                }

                String[] typeAndContent = line.split(":", 2);

                String type = typeAndContent[0];

                String content = typeAndContent[1];

                try {

                    Log.log(Log.Level.valueOf(type), "[server] " + content);

                    continue;

                } catch (IllegalArgumentException e) {

                    // Parsing of 'type' as log level failed.

                }

                if (type.equals(SjavacServer.LINE_TYPE_RC)) {

                    result = Integer.parseInt(content);

                }

            }

        } catch (PortFileInaccessibleException e) {

            Log.error("Port file inaccessible.");

            result = CompilationSubResult.ERROR_FATAL;

        } catch (IOException ioe) {

            Log.error("IOException caught during compilation: " + ioe.getMessage());

            Log.debug(ioe);

            result = CompilationSubResult.ERROR_FATAL;

        } catch (InterruptedException ie) {

            Thread.currentThread().interrupt(); // Restore interrupt

            Log.error("Compilation interrupted.");

            Log.debug(ie);

            result = CompilationSubResult.ERROR_FATAL;

        }

        return result;

    }

    /*

     * Makes MAX_CONNECT_ATTEMPTS attepmts to connect to server.

     */

    private Socket tryConnect() throws IOException, InterruptedException {

        makeSureServerIsRunning(portFile);

        int attempt = 0;

        while (true) {

            Log.info("Trying to connect. Attempt " + (++attempt) + " of " + MAX_CONNECT_ATTEMPTS);

            try {

                return makeConnectionAttempt();

            } catch (IOException ex) {

                Log.error("Connection attempt failed: " + ex.getMessage());

                if (attempt >= MAX_CONNECT_ATTEMPTS) {

                    Log.error("Giving up");

                    throw new IOException("Could not connect to server", ex);

                }

            }

            Thread.sleep(WAIT_BETWEEN_CONNECT_ATTEMPTS);

        }

    }

    private Socket makeConnectionAttempt() throws IOException {

        Socket socket = new Socket();

        InetAddress localhost = InetAddress.getByName(null);

        InetSocketAddress address = new InetSocketAddress(localhost, portFile.getPort());

        socket.connect(address, CONNECTION_TIMEOUT);

        Log.info("Connected");

        return socket;

    }

    /*

     * Will return immediately if a server already seems to be running,

     * otherwise fork a new server and block until it seems to be running.

     */

    private void makeSureServerIsRunning(PortFile portFile)

            throws IOException, InterruptedException {

        if (portFile.exists()) {

            portFile.lock();

            portFile.getValues();

            portFile.unlock();

            if (portFile.containsPortInfo()) {

                // Server seems to already be running

                return;

            }

        }

        // Fork a new server and wait for it to start

        SjavacClient.fork(sjavacForkCmd,

                          portFile,

                          poolsize,

                          keepalive);

    }

    @Override

    public void shutdown() {

        // Nothing to clean up

    }

    /*

     * Fork a server process process and wait for server to come around

     */

    public static void fork(String sjavacCmd, PortFile portFile, int poolsize, int keepalive)

            throws IOException, InterruptedException {

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

        cmd.addAll(Arrays.asList(OptionHelper.unescapeCmdArg(sjavacCmd).split(" ")));

        cmd.add("--startserver:"

              + "portfile=" + portFile.getFilename()

              + ",poolsize=" + poolsize

              + ",keepalive="+ keepalive);

        Process serverProcess;

        Log.info("Starting server. Command: " + String.join(" ", cmd));

        try {

            // If the cmd for some reason can't be executed (file is not found,

            // or is not executable for instance) this will throw an

            // IOException and p == null.

            serverProcess = new ProcessBuilder(cmd)

                    .redirectErrorStream(true)

                    .start();

        } catch (IOException ex) {

            // Message is typically something like:

            // Cannot run program "xyz": error=2, No such file or directory

            Log.error("Failed to create server process: " + ex.getMessage());

            Log.debug(ex);

            throw new IOException(ex);

        }

        // serverProcess != null at this point.

        try {

            // Throws an IOException if no valid values materialize

        } catch (IOException ex) {

            // Process was started, but server failed to initialize. This could

            // for instance be due to the JVM not finding the server class,

            // or the server running in to some exception early on.

            Log.error("Sjavac server failed to initialize: " + ex.getMessage());

            Log.error("Process output:");

            Reader serverStdoutStderr = new InputStreamReader(serverProcess.getInputStream());

            try (BufferedReader br = new BufferedReader(serverStdoutStderr)) {

                br.lines().forEach(Log::error);

            }

            Log.error("<End of process output>");

            try {

                Log.error("Process exit code: " + serverProcess.exitValue());

            } catch (IllegalThreadStateException e) {

                // Server is presumably still running.

            }

            throw new IOException("Server failed to initialize: " + ex.getMessage(), ex);

        }

    }

}