/*
 * Copyright (C) 2003-2011 eXo Platform SAS.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package org.etk.kernel.management.jmx;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

import javax.management.ObjectName;

import org.etk.kernel.management.jmx.annotations.Property;

/**
 * Created by The eXo Platform SAS
 * Author : eXoPlatform
 *          exo@exoplatform.com
 * Jul 28, 2011  
 */
public class PropertyInfo {

  /** . */
  private final String key;

  /** . */
  private final Value  value;

  public PropertyInfo(Class clazz, Property def) {
    String tmp = def.value();
    Value value;
    int length = tmp.length();
    if (length > 2 && tmp.charAt(0) == '{' && tmp.charAt(length - 1) == '}') {
      String s = tmp.substring(1, length - 1);
      String getterName = "get" + s;
      Method getter;
      try {
        getter = clazz.getMethod(getterName);
      } catch (NoSuchMethodException e) {
            throw new IllegalArgumentException("Getter parameter for property " + s + " on class " + clazz.getName()
               + " does not exist", e);
         }

         //
         if (getter.getReturnType() == void.class)
         {
            throw new IllegalArgumentException("Getter return type for property " + s + " on class " + clazz.getName()
               + " cannot be void");
         }
         if (getter.getParameterTypes().length > 0)
         {
            throw new IllegalArgumentException("Getter parameter type for property " + s + " on class "
               + clazz.getName() + " is not empty");
         }
         if (Modifier.isStatic(getter.getModifiers()))
         {
            throw new IllegalArgumentException("Getter for property " + s + " on class " + clazz.getName()
               + " is static");
         }

         //
         value = new DynamicValue(getter);
      }
      else
      {
         value = new LitteralValue(tmp);
      }

      //
      this.key = def.key();
      this.value = value;
   }

  public String resolveValue(Object instance) {
    return value.resolve(instance);
  }

  public String getKey() {
    return key;
  }

  private abstract static class Value {
    abstract String resolve(Object instance);
  }

  private class DynamicValue extends Value {

    /** . */
    private final Method getter;

    private DynamicValue(Method getter) {
      this.getter = getter;
    }

    String resolve(Object instance) {
      Object value;
      try {
        value = getter.invoke(instance);
      } catch (IllegalAccessException e) {
            throw new IllegalArgumentException("Getter for property " + key + " on class "
               + getter.getClass().getName() + " cannot be invoked", e);
      } catch (InvocationTargetException e) {
            throw new IllegalArgumentException("Getter for property " + key + " on class "
               + getter.getClass().getName() + " threw an exception during invocation", e);
      }
      if (value == null) {
            throw new IllegalArgumentException("Getter for property " + key + " on class "
               + getter.getClass().getName() + " returned a null value");
      }
      return ObjectName.quote(value.toString());
    }
   }

  private static class LitteralValue extends Value {

    /** . */
    private final String litteral;

    private LitteralValue(String litteral) {
      this.litteral = litteral;
    }

    String resolve(Object instance) {
      return litteral;
    }
  }

}