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package org.zeroturnaround.javarebel.integration.resin;

import java.io.File;
import java.util.List;
import java.util.ListIterator;
import org.zeroturnaround.bundled.javassist.CannotCompileException;
import org.zeroturnaround.bundled.javassist.ClassPool;
import org.zeroturnaround.bundled.javassist.CtClass;
import org.zeroturnaround.bundled.javassist.NotFoundException;
import org.zeroturnaround.bundled.javassist.expr.ExprEditor;
import org.zeroturnaround.bundled.javassist.expr.MethodCall;
import org.zeroturnaround.javarebel.Logger;
import org.zeroturnaround.javarebel.LoggerFactory;
import org.zeroturnaround.javarebel.integration.support.JavassistClassBytecodeProcessor;
import org.zeroturnaround.javarebel.integration.util.AgentUtil;

/**
 * Processes com.caucho.boot.ResinWatchdog
 * or com.caucho.boot.WatchdogProcess.
 * 
 * 
 * Starting from Resin 3.1 a so called "WatchDog" forks a new JVM with a custom system class loader.
 * Since JavaRebel cannot instrument the system class loader and it's dependencies directly
 * the necessary classes are transformed and written into a special JAR file which is
 * prepended to the class path of the forked JVM.
 * 
 * 
 * Tested on Resin 3.1.3, 3.1.9, 3.2.1 and 4.0.0.
 * 
 * @author Rein Raudjärv
 * 
 * @see ResinWatchdogCBP
 */
public class WatchdogProcessCBP extends JavassistClassBytecodeProcessor {
  
  private static final Logger log = LoggerFactory.getInstance();
  
  /**
   * Class path separator character.
   */
  private static final char CLASSPATH_SEPARATOR = File.pathSeparatorChar;
  
  /**
   * >-noverify JVM option.
   */
  private static final String NO_VERIFY = "-noverify";
  
  /**
   * -javaagent JVM option of JavaRebel.  
   */
  private static final String JAVA_AGENT = "-javaagent:" + AgentUtil.getRebelJarPath();
  
  private static final String REBEL_LOG_FILE = "rebel.log.file";
  private static final String REBEL_LOG_FILE_PREFIX = "-D" + REBEL_LOG_FILE + "=";
  private static final String REBEL_LOG_FILE_SUFFIX = "-fork";
  
  public void process(ClassPool cp, ClassLoader cl, CtClass ctClass) throws Exception {
    cp.importPackage("java.io");
    cp.importPackage("java.net");
    cp.importPackage("org.zeroturnaround.javarebel");
    cp.importPackage("org.zeroturnaround.javarebel.integration.resin");
    
    processConnectToChild(ctClass);
    processCreateProcess(cl, ctClass);
  }

  private void processConnectToChild(CtClass ctClass) throws CannotCompileException {
    try {
      ctClass.getDeclaredMethod("connectToChild").instrument(new ExprEditor() {
        public void edit(MethodCall m) throws CannotCompileException {
          if ("java.net.ServerSocket".equals(m.getClassName()) && "accept".equals(m.getMethodName())) {
            m.replace(
                "{" +
                "  Logger log = LoggerFactory.getInstance();" +
                "  if (log.isEnabled())" +
                "    log.log(\"JRebel-Resin: Listening for connections on port \" + $0.getLocalPort());" +
                
                "  Socket result = $proceed($$);" +
                "  $_ = result;" +
                
                "  if (log.isEnabled())" +
                "    log.log(\"JRebel-Resin: Accepted connection \" + result + \" on port \" + $0.getLocalPort());" +
            "}");
          }
        }
      });
    } catch (NotFoundException e) {
      // Missing up to Resin 3.1.4, available since Resin 3.1.5 
    }
  }

  private void processCreateProcess(ClassLoader cl, CtClass ctClass) throws Exception {
    final File jar = ResinPatchHelper.createResinPatch(cl);
    
    ctClass.getDeclaredMethod("createProcess").instrument(new ExprEditor() {
      public void edit(MethodCall m) throws CannotCompileException {
        String className = m.getClassName();
        String methodName = m.getMethodName();
        
        /*
         * Process class path of the forked JVM.
         */
        if ((className.equals("com.caucho.boot.ResinWatchdogManager")    // Resin 3.1.x
            || className.equals("com.caucho.boot.WatchdogArgs"))         // Resin 3.2.x
            && methodName.equals("calculateClassPath")) {
          m.replace(
              "{" +
              "  String result = $proceed($$);" +
              "  Logger log = LoggerFactory.getInstance();" +

              "  if (log.isEnabled())" +
              "    log.log(\"JRebel-Resin: Resin original classpath: \" + result);" +

              "  result = \"" + escape(jar.getPath()) + CLASSPATH_SEPARATOR + "\" + result;" +

              "  if (log.isEnabled())" +
              "    log.log(\"JRebel-Resin: Resin modified classpath: \" + result);" +

              "  $_ = result;" +
              "}");
        }
        /*
         * Add JVM options for JavaRebel. 
         */
        else if ((className.equals("com.caucho.boot.Boot") && methodName.equals("exec"))
            || (className.equals("java.lang.ProcessBuilder") && methodName.equals("command"))) {
          m.replace(
              "{" +
              "  WatchdogProcessCBP.processArguments($1);" +
              "  $_ = $proceed($$);" +
              "}");
        }
      }
    });
  }
  
  public static void processArguments(List commandArgs) {
    try {
      commandArgs.add(1, NO_VERIFY);
      commandArgs.add(1, JAVA_AGENT);
      
      // Modify -Drebel.log.file value
      String path = System.getProperty(REBEL_LOG_FILE);
      if (path != null) {
        for (ListIterator it = commandArgs.listIterator(); it.hasNext();) {
          String arg = (String) it.next();
          if (arg.startsWith(REBEL_LOG_FILE_PREFIX)) {
            
            int i = arg.lastIndexOf('.');
            if (i < REBEL_LOG_FILE_PREFIX.length())
              arg += REBEL_LOG_FILE_SUFFIX;
            else
              arg = arg.substring(0, i) + REBEL_LOG_FILE_SUFFIX + arg.substring(i);
              
            it.set(arg);
          }
        }
      }
      
      if (log.isEnabled())
        log.log("JRebel-Resin: Exec args:" + commandArgs);
    } catch (Throwable t) {
      log.error(t);
    }
  }

  /**
   * Escape a String to be used in Javassist code. 
   */
  private static String escape(String str) {
    StringBuffer sb = new StringBuffer(str.length());
    for (int i = 0; i < str.length(); i++) {
      char c = str.charAt(i);
      
      // Add additional backslash
      if (c == '\"' || c == '\\')
        sb.append('\\');
      
      sb.append(c);
    }
    return sb.toString();
  }
  
}