/**
    * This file Copyright (c) 2018 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.ui.framework;
  
  import static net.bytebuddy.dynamic.loading.ClassLoadingStrategy.Default.WRAPPER;
  import static net.bytebuddy.implementation.FixedValue.value;
  import static net.bytebuddy.implementation.MethodCall.invoke;
  import static net.bytebuddy.implementation.MethodDelegation.to;
  import static net.bytebuddy.matcher.ElementMatchers.*;
  
  import java.io.Serializable;
  import java.lang.reflect.Constructor;
  import java.lang.reflect.Method;
  import java.lang.reflect.Modifier;
  import java.util.HashMap;
  import java.util.Map;
  
  import org.reflections.ReflectionUtils;
  
  import lombok.SneakyThrows;
  import net.bytebuddy.ByteBuddy;
  import net.bytebuddy.TypeCache;
  import net.bytebuddy.dynamic.scaffold.subclass.ConstructorStrategy;
  import net.bytebuddy.implementation.bind.annotation.Origin;
  import net.bytebuddy.implementation.bind.annotation.RuntimeType;
  import net.bytebuddy.implementation.bind.annotation.This;
  
  /**
   * ByteBuddy-based proxy implementation of an interface derived from {@link ViewContext}.
   * By convention, generates the boilerplate for the methods that return {@link ContextProperty}.
   */
  public final class ViewContextProxy {
  
      static TypeCache<Class> proxyTypeCache = new TypeCache.WithInlineExpunction<>(TypeCache.Sort.WEAK);
  
      @SneakyThrows
      public <T extends ViewContext> T createViewContext(Class<T> clazz) {
          return createViewContext(clazz, new HashMap<>());
      }
  
      @SneakyThrows
      public <T extends ViewContext> T createViewContext(Class<T> clazz, Map<String, ContextProperty> properties) {
          if (!clazz.isInterface()) {
              throw new RuntimeException("Context type has to be an interface");
          }
  
          return (T) proxyTypeCache.findOrInsert(Thread.currentThread().getContextClassLoader(), clazz, () -> generateViewContextProxy(clazz)).getConstructor(Map.class).newInstance(properties);
      }
  
      private <T extends ViewContext> Class<T> generateViewContextProxy(Class<T> clazz) throws NoSuchMethodException {
          final Constructor<ViewContextBase> targetCtor = ViewContextBase.class.getConstructor(Map.class);
          final Class<? extends ViewContextBase> getViewContextType = new ByteBuddy()
                  .subclass(ViewContextBase.class, ConstructorStrategy.Default.NO_CONSTRUCTORS)
                  .implement(clazz, Serializable.class)
                  .method(named("getViewContextType")).intercept(value(clazz))
                  .method(returns(ContextProperty.class))
                  .intercept(to(new StatePropertyGetterDelegate()))
                  .defineConstructor(Modifier.PUBLIC)
                  .withParameters(Map.class)
                  .intercept(invoke(targetCtor)
                          .withAllArguments()
                          .andThen(to(new ContextInitializer())))
                  .make()
                  .load(getClass().getClassLoader(), WRAPPER)
                  .getLoaded();
          return (Class<T>) getViewContextType;
      }
  
     /**
      * Initialises {@link ContextProperty} for this view.
      */
     public static class ContextInitializer {
 
         @SuppressWarnings("unchecked")
         public void init(@This ViewContextBase that) {
             ReflectionUtils.getMethods(that.getClass()).stream()
                     .filter(method -> ContextProperty.class.isAssignableFrom(method.getReturnType()))
                     .filter(method -> !that.properties().containsKey(method.getName()))
                     .forEach(method-> that.properties().put(method.getName(), new ContextProperty.Impl()));
         }
     }
 
     /**
      * Delegates a getter method call to a look-up in the property map.
      */
     public static class StatePropertyGetterDelegate {
 
         @RuntimeType
         public ContextProperty getter(@Origin Method method, @This ViewContextBase that) {
             return that.properties().get(method.getName());
         }
     }
 }