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With inspiration from other libraries
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/**
 * MVEL 2.0
 * Copyright (C) 2007 The Codehaus
 * Mike Brock, Dhanji Prasanna, John Graham, Mark Proctor
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.mvel2.sh.command.basic;

import org.mvel2.sh.Command;
import org.mvel2.sh.ShellSession;
import org.mvel2.sh.text.TextUtil;
import org.mvel2.util.StringAppender;

import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.LinkedList;
import java.util.List;

import static org.mvel2.sh.text.TextUtil.padTwo;

public class ObjectInspector implements Command {
  private static final int PADDING = 17;

  public Object execute(ShellSession session, String[] args) {

    if (args.length == 0) {
      System.out.println("inspect: requires an argument.");
      return null;
    }

    if (!session.getVariables().containsKey(args[0])) {
      System.out.println("inspect: no such variable: " + args[0]);
      return null;
    }

    Object val = session.getVariables().get(args[0]);

    System.out.println("Object Inspector");
    System.out.println(TextUtil.paint('-', PADDING));

    if (val == null) {
      System.out.println("[Value is Null]");
      return null;
    }


    Class cls = val.getClass();
    boolean serialized = true;
    long serializedSize = 0;

    try {
      ByteArrayOutputStream outStream = new ByteArrayOutputStream();
      ObjectOutputStream objectOut = new ObjectOutputStream(new BufferedOutputStream(outStream));
      objectOut.writeObject(val);
      objectOut.flush();
      outStream.flush();

      serializedSize = outStream.size();
    }
    catch (Exception e) {
      serialized = false;
    }

    write("VariableName", args[0]);
    write("Hashcode", val.hashCode());
    write("ClassType", cls.getName());
    write("Serializable", serialized);
    if (serialized) {
      write("SerializedSize", serializedSize + " bytes");
    }
    write("ClassHierarchy", renderClassHeirarchy(cls));
    write("Fields", cls.getFields().length);
    renderFields(cls);

    write("Methods", cls.getMethods().length);
    renderMethods(cls);


    System.out.println();

    return null;
  }

  private static String renderClassHeirarchy(Class cls) {
    List list = new LinkedList();
    list.add(cls.getName());

    while ((cls = cls.getSuperclass()) != null) {
      list.add(cls.getName());
    }

    StringAppender output = new StringAppender();

    for (int i = list.size() - 1; i != -1; i--) {
      output.append(list.get(i));
      if ((i - 1) != -1) output.append(" -> ");
    }

    return output.toString();
  }

  private static void renderFields(Class cls) {
    Field[] fields = cls.getFields();

    for (int i = 0; i < fields.length; i++) {
      write("", fields[i].getType().getName() + " " + fields[i].getName());
    }
  }

  private static void renderMethods(Class cls) {
    Method[] methods = cls.getMethods();

    Method m;
    StringAppender appender = new StringAppender();
    int mf;
    for (int i = 0; i < methods.length; i++) {
      appender.append(TextUtil.paint(' ', PADDING + 2));
      if (((mf = (m = methods[i]).getModifiers()) & Modifier.PUBLIC) != 0) appender.append("public");
      else if ((mf & Modifier.PRIVATE) != 0) appender.append("private");
      else if ((mf & Modifier.PROTECTED) != 0) appender.append("protected");

      appender.append(' ').append(m.getReturnType().getName()).append(' ').append(m.getName()).append("(");
      Class[] parmTypes = m.getParameterTypes();
      for (int y = 0; y < parmTypes.length; y++) {
        if (parmTypes[y].isArray()) {
          appender.append(parmTypes[y].getComponentType().getName() + "[]");
        }
        else {
          appender.append(parmTypes[y].getName());
        }
        if ((y + 1) < parmTypes.length) appender.append(", ");
      }
      appender.append(")");

      if (m.getDeclaringClass() != cls) {
        appender.append("    [inherited from: ").append(m.getDeclaringClass().getName()).append("]");
      }


      if ((i + 1) < methods.length) appender.append('\n');
    }

    System.out.println(appender.toString());
  }

  private static void write(Object first, Object second) {
    System.out.println(padTwo(first, ": " + second, PADDING));
  }

  public String getDescription() {
    return "inspects an object";
  }

  public String getHelp() {
    return "No help yet";
  }
}