/*
    * Copyright 2012 Oracle Corporation. All Rights Reserved.
    *
    * 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 com.fatwire.gst.foundation.controller.action.support;
  
  import java.lang.reflect.Constructor;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.lang.reflect.Modifier;
  import java.util.Arrays;
  import java.util.HashMap;
  import java.util.Map;
  
  import org.apache.commons.lang.StringUtils;
  import org.apache.commons.logging.Log;
  
  import COM.FutureTense.Interfaces.ICS;
  
  import com.fatwire.gst.foundation.controller.action.Factory;
  import com.fatwire.gst.foundation.controller.annotation.ServiceProducer;
  import com.fatwire.gst.foundation.facade.logging.LogUtil;
  
  /**
   * Factory making use to reflection ({@link #reflectionStrategy(String, Class)}
   * and {@link #ctorStrategy(String, Class)}) to produce objects.
   * <p/>
   * This class caches the produced objects for the lifetime of this object.
   * Effectively this means the lifetime of the ICS object.
   * 
   * @author Dolf Dijkstra
   * 
   */
  public abstract class BaseFactory implements Factory {
  
      protected static final Log LOG = LogUtil.getLog(IcsBackedObjectFactoryTemplate.class);
  
      protected final ICS ics;
  
      private final Map<String, Object> objectCache = new HashMap<String, Object>();
      private Factory[] roots = new Factory[0];;
  
      public BaseFactory(ICS ics) {
          super();
          this.ics = ics;
  
      }
  
      public BaseFactory(ICS ics, Factory... roots) {
          super();
          this.ics = ics;
          if (roots != null)
              this.roots = roots;
      }
  
      @Override
      public final <T> T getObject(final String name, final Class<T> fieldType) {
  
          T o;
          try {
              o = locate(name, fieldType);
              if (o == null) {
                  for (Factory root : roots) {
                      o = root.getObject(name, fieldType);
                      if (o != null)
                          return o;
  
                  }
                  // only try ctor at the root level, otherwise
                  // it will be invoked on each BaseFactory
                  if (roots.length == 0)
                      o = ctorStrategy(name, fieldType);
              }
          } catch (InvocationTargetException e) {
              throw new RuntimeException(e.getTargetException());
          }
          return o;
      }
  
      /**
       * Internal method to check for Services or create Services.
       * 
       * @param name
       * @param c
       * @return the found service, null if no T can be created.
       * @throws InvocationTargetException
       */
      @SuppressWarnings("unchecked")
     protected <T> T locate(final String askedName, final Class<T> c) throws InvocationTargetException {
         if (ICS.class.isAssignableFrom(c)) {
             return (T) ics;
         }
         if (c.isArray()) {
             throw new IllegalArgumentException("Arrays are not supported");
         }
         final String name = StringUtils.isNotBlank(askedName) ? askedName : c.getSimpleName();
 
         if (StringUtils.isBlank(name)) {
             return null;
         }
 
         Object o = objectCache.get(name);
         if (o != null && !c.isAssignableFrom(o.getClass()))
             throw new IllegalStateException("Name conflict: '" + name + "' is in cache and is of type  '"
                     + o.getClass() + "' but a '" + c.getName()
                     + "' was asked for. Please check your factories for naming conflicts.");
         if (o == null) {
             o = namedAnnotationStrategy(name, c);
         }
         if (o == null) {
             o = unnamedAnnotationStrategy(name, c);
         }
 
         if (o == null) {
             o = reflectionStrategy(name, c);
         }
 
         return (T) o;
     }
 
     /**
      * Method to find classes to use for the producer methods. This
      * implementation returns {@link #getClass()}.</p> Subclasses can return and
      * are encouraged to return other classes.
      * 
      * @param ics
      * @return array of classes to use for reflection
      */
     protected Class<?>[] factoryClasses(ICS ics) {
         return new Class[] { getClass() };
     }
 
     /**
      * Tries to create the object based on the {@link ServiceProducer}
      * annotation where the names match.
      * 
      * @param name
      * @param c
      * @return
      * @throws InvocationTargetException
      */
     protected <T> T namedAnnotationStrategy(String name, Class<T> c) throws InvocationTargetException {
 
         for (Class<?> reflectionClass : factoryClasses(ics)) {
             for (Method m : reflectionClass.getMethods()) {
                 if (m.isAnnotationPresent(ServiceProducer.class)) {
                     if (c.isAssignableFrom(m.getReturnType())) {
                         String n = m.getAnnotation(ServiceProducer.class).name();
                         if (name.equals(n)) {
                             return createFromMethod(name, c, m);
                         }
                     }
                 }
 
             }
         }
         return null;
     }
 
     /**
      * Tries to create the object based on the {@link ServiceProducer}
      * annotation without a name.
      * 
      * @param name
      * @param c
      * @return
      * @throws InvocationTargetException
      */
     protected <T> T unnamedAnnotationStrategy(String name, Class<T> c) throws InvocationTargetException {
 
         for (Class<?> reflectionClass : factoryClasses(ics)) {
             for (Method m : reflectionClass.getMethods()) {
                 if (m.isAnnotationPresent(ServiceProducer.class)) {
                     if (c.isAssignableFrom(m.getReturnType())) {
                         String n = m.getAnnotation(ServiceProducer.class).name();
                         if (StringUtils.isBlank(n)) {
                             return createFromMethod(name, c, m);
                         }
                     }
                 }
 
             }
         }
         return null;
     }
 
     /**
      * Reflection based producer method.
      * <p/>
      * This method uses reflection to find producer methods to the following
      * rules:
      * <ul>
      * <li>public <b>static</b> Foo createFoo(ICS ics, Factory factory){}</li>
      * <li>public Foo createFoo(ICS ics){}</li>
      * </ul>
      * If the non-static version is used the implementing class needs to have a
      * public constructor that takes {@link ICS} and {@link Factory} as
      * arguments. To this class the current ICS and this object will be passed.
      * 
      * 
      * @param name the simple name of the object to produce
      * @param c the class with the type information of the object to produce
      * @return the created object, null if no producer method was found or when
      *         that method returned null.
      * @throws InvocationTargetException when the create&lt;Type&gt; method
      *             throws an exception.
      */
     protected <T> T reflectionStrategy(String name, Class<T> c) throws InvocationTargetException {
 
         for (Class<?> reflectionClass : factoryClasses(ics)) {
 
             for (Method m : reflectionClass.getMethods()) {
                 if (m.getName().equals("create" + c.getSimpleName())) {
                     if (c.isAssignableFrom(m.getReturnType())) {
                         return createFromMethod(name, c, m);
                     }
                 }
             }
         }
         return null;
     }
 
     /**
      * @param name name of the object
      * @param c the type of the object to create
      * @param m the method to use to create the object
      * @return
      * @throws InvocationTargetException
      */
     @SuppressWarnings("unchecked")
     protected <T> T createFromMethod(String name, Class<T> c, Method m) throws InvocationTargetException {
         Object o = null;
         if (LOG.isTraceEnabled()) {
             LOG.trace("trying to create a " + c.getName() + " object with name " + name + "  from method "
                     + m.toGenericString());
         }
 
         if (c.isAssignableFrom(m.getReturnType())) {
             Object from = null;
 
             if (!Modifier.isStatic(m.getModifiers())) {
                 Class<?> reflectionClass = m.getDeclaringClass();
 
                 if (reflectionClass.isAssignableFrom(getClass())) {
                     from = this; // TODO will this clash if this class and
                                  // declared class have same parent class?
                 } else {
                     Constructor<?> ctor;
 
                     try {
                         ctor = reflectionClass.getConstructor(ICS.class, Factory.class);
                         if (Modifier.isPublic(ctor.getModifiers())) {
                             from = ctor.newInstance(ics, this);
                         } else {
                             throw new NoSuchMethodExceptionRuntimeException(reflectionClass.getName()
                                     + " does not have a public (ICS,Factory) constructor.");
                         }
                     } catch (NoSuchMethodException e) {
                         throw new NoSuchMethodExceptionRuntimeException(reflectionClass.getName()
                                 + " should have a public constructor accepting a ICS and Factory.");
                     } catch (InstantiationException e) {
                         LOG.error(e.getMessage());
                     } catch (IllegalArgumentException e) {
                         LOG.error("Huh, Can't happen, the arguments are checked: " + m.toString() + ", "
                                 + e.getMessage());
                     } catch (IllegalAccessException e) {
                         LOG.error("Huh, Can't happen, the modifier is checked for public: " + m.toString() + ", "
                                 + e.getMessage());
                     }
                 }
 
             }
             if (m.getParameterTypes().length == 2 && m.getParameterTypes()[0].isAssignableFrom(ICS.class)
                     && m.getParameterTypes()[1].isAssignableFrom(Factory.class)) {
                 o = invokeCreateMethod(m, from, name, ics, this);
             } else if (m.getParameterTypes().length == 1 && m.getParameterTypes()[0].isAssignableFrom(ICS.class)) {
                 o = invokeCreateMethod(m, from, name, ics);
             } else if (m.getParameterTypes().length == 0) {
                 o = invokeCreateMethod(m, from, name);
             }
             if (shouldCache(m))
                 objectCache.put(name, o);
 
         }
         return (T) o;
     }
 
     /**
      * @param m method in invoke
      * @param from object to invoke from
      * @param name the name of the object
      * @param arguments the arguments to pass to the method
      * @return
      * @throws InvocationTargetException
      */
     protected Object invokeCreateMethod(Method m, Object from, String name, Object... arguments)
             throws InvocationTargetException {
         try {
             return m.invoke(from, arguments);
         } catch (IllegalArgumentException e) {
             LOG.error("Huh, Can't happen, the arguments are checked: " + m.toString() + ", " + e.getMessage());
         } catch (IllegalAccessException e) {
             LOG.error("Huh, Can't happen, the modifier is checked for public: " + m.toString() + ", " + e.getMessage());
         }
         return null;
     }
 
     protected boolean shouldCache(Method m) {
         boolean r = false;
         if (m.isAnnotationPresent(ServiceProducer.class)) {
             ServiceProducer annon = m.getAnnotation(ServiceProducer.class);
             r = annon.cache();
         }
         return r;
     }
 
     /**
      * @param e
      */
     protected void throwRuntimeException(InvocationTargetException e) {
         Throwable t = e.getTargetException();
         if (t == null) {
             throw new RuntimeException(e);
         } else if (t instanceof RuntimeException) {
             throw (RuntimeException) t;
         } else {
             throw new RuntimeException(t);
         }
     }
 
     /**
      * @param name
      * @param c
      * @return
      * @throws InvocationTargetException
      */
     protected <T> T ctorStrategy(final String name, final Class<T> c) throws InvocationTargetException {
         T o = null;
         try {
             if (c.isInterface() || Modifier.isAbstract(c.getModifiers())) {
                 if (LOG.isDebugEnabled())
                     LOG.debug("Could not create  a " + c.getName() + " via a Template method. The class '"
                             + c.getName()
                             + "' is an interface or abstract class, giving up as a class cannot be constructed.");
                 return null;
             }
 
             if (LOG.isDebugEnabled())
                 LOG.debug("Could not create  a " + c.getName() + " via a Template method, trying via constructor.");
             final Constructor<T> constr = c.getConstructor(ICS.class);
             o = constr.newInstance(ics);
         } catch (final NoSuchMethodException e1) {
             LOG.debug("Could not create  a " + c.getName() + " via a constructor method.");
         } catch (IllegalArgumentException e) {
             LOG.debug("Could not create  a " + c.getName() + " via a constructor method.");
         } catch (InstantiationException e) {
             LOG.debug("Could not create  a " + c.getName() + " via a constructor method.");
         } catch (IllegalAccessException e) {
             LOG.debug("Could not create  a " + c.getName() + " via a constructor method.");
         }
         return o;
     }
 
     @ServiceProducer(cache = false)
     public ICS createICS(final ICS ics) {
         return ics;
     }
 
     @Override
     public String toString() {
         return "BaseFactory [roots=" + Arrays.toString(roots) + "]";
     }
 
 }