content: package act.inject.param;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2017 ActFramework
   * %%
   * 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.
   * #L%
   */
  
  import act.Act;
  import act.app.*;
  import act.db.DbBind;
  import act.inject.DependencyInjector;
  import act.util.ReflectedInvokerHelper;
  import org.osgl.$;
  import org.osgl.exception.UnexpectedException;
  import org.osgl.inject.BeanSpec;
  import org.osgl.util.*;
  
  import java.lang.annotation.Annotation;
  import java.lang.reflect.*;
  import java.util.*;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import javax.inject.Inject;
  
  public class JsonDtoClassManager extends AppServiceBase<JsonDtoClassManager> {
  
      static class DynamicClassLoader extends ClassLoader {
          private DynamicClassLoader(AppClassLoader parent) {
              super(parent);
          }
  
          Class<?> defineClass(String name, byte[] b) {
              AppClassLoader loader = (AppClassLoader) getParent();
              return loader.defineClass(name, b, 0, b.length, true);
          }
      }
  
      private ConcurrentMap<String, Class<? extends JsonDto>> dtoClasses = new ConcurrentHashMap<String, Class<? extends JsonDto>>();
  
      private DependencyInjector<?> injector;
      private DynamicClassLoader dynamicClassLoader;
      private Map<$.T2<Class, Method>, List<BeanSpec>> beanSpecCache = new HashMap<>();
  
  
      public JsonDtoClassManager(App app) {
          super(app);
          this.injector = app.injector();
          this.dynamicClassLoader = new DynamicClassLoader(app.classLoader());
      }
  
      @Override
      protected void releaseResources() {
  
      }
  
      public Class<? extends JsonDto> get(List<BeanSpec> beanSpecs, Class<?> host) {
          String key = key(beanSpecs);
          if (S.blank(key)) {
              return null;
          }
          Class<? extends JsonDto> cls = dtoClasses.get(key);
          if (null == cls) {
              try {
                  Map<String, Class> typeParamLookup = Generics.buildTypeParamImplLookup(host);
                  Class<? extends JsonDto> newClass = generate(key, beanSpecs, typeParamLookup);
                  cls = dtoClasses.putIfAbsent(key, newClass);
                  if (null == cls) {
                      cls = newClass;
                  }
              } catch (LinkageError e) {
                  if (e.getMessage().contains("duplicate class definition")) {
                      // another thread has already the DTO class
                      cls = dtoClasses.get(key);
                      E.unexpectedIf(null == cls, "We don't know what happened here ...");
                  } else {
                      throw e;
                  }
              }
          }
          return cls;
      }
  
      private Class<? extends JsonDto> generate(String name, List<BeanSpec> beanSpecs, Map<String, Class> typeParamLookup) {
          return new JsonDtoClassGenerator(name, beanSpecs, dynamicClassLoader, typeParamLookup).generate();
      }
  
      public static final $.Predicate<Class<?>> CLASS_FILTER = new $.Predicate<Class<?>>() {
          @Override
          public boolean test(Class<?> aClass) {
              if (null == aClass || Object.class == aClass) {
                  return false;
              }
              if (aClass.isAnnotationPresent(NoBind.class)) {
                  return false;
              }
              return !Act.injector().isProvided(aClass);
          }
      };
  
      public static final $.Predicate<Field> FIELD_FILTER = new $.Predicate<Field>() {
          @Override
          public boolean test(Field field) {
              int mod = field.getModifiers();
              if (Modifier.isStatic(mod) || Modifier.isFinal(mod)) {
                  return false;
              }
              if (ReflectedInvokerHelper.isGlobalOrStateless(field)) {
                  return false;
              }
              if (field.isAnnotationPresent(NoBind.class)) {
                  return false;
              }
              DependencyInjector injector = Act.injector();
              return !ParamValueLoaderService.provided(BeanSpec.of(field, injector), injector);
          }
      };
  
      public List<BeanSpec> beanSpecs(Class<?> host, Method method) {
          $.T2<Class, Method> key = $.cast($.T2(host, method));
          List<BeanSpec> list = beanSpecCache.get(key);
          if (null == list) {
              list = new ArrayList<>();
              beanSpecCache.put(key, list);
              if (!Modifier.isStatic(method.getModifiers())) {
                  extractBeanSpec(list, $.fieldsOf(host, CLASS_FILTER, FIELD_FILTER), host);
              }
              extractBeanSpec(list, method, host);
              Collections.sort(list, CMP);
          }
          return list;
      }
  
      private void extractBeanSpec(List<BeanSpec> beanSpecs, List<Field> fields, Class<?> host) {
          for (Field field : fields) {
              BeanSpec spec = null;
              Type genericType = field.getGenericType();
              if (genericType instanceof Class || genericType instanceof ParameterizedType) {
                  spec = BeanSpec.of(field.getGenericType(), field.getDeclaredAnnotations(), field.getName(), injector);
              } else if (genericType instanceof TypeVariable) {
                  // can determine type by field, check inject constructor parameter
                  TypeVariable tv = (TypeVariable)genericType;
                  Type[] bounds = tv.getBounds();
                  if (bounds != null && bounds.length == 1) {
                      Type bound = bounds[0];
                      if (bound instanceof ParameterizedType || bound instanceof Class) {
                          Class<?> boundClass = BeanSpec.rawTypeOf(bound);
                          Constructor<?>[] ca = host.getConstructors();
                          CONSTRUCTORS:
                          for (Constructor<?> c : ca) {
                              if (c.getAnnotation(Inject.class) != null) {
                                  // check all param types
                                  Type[] constructorParams = c.getGenericParameterTypes();
                                  for (Type paramType : constructorParams) {
                                      if (paramType instanceof ParameterizedType || paramType instanceof Class) {
                                          Class<?> paramClass = BeanSpec.rawTypeOf(paramType);
                                          if (boundClass.isAssignableFrom(paramClass)) {
                                              spec = BeanSpec.of(paramType, field.getDeclaredAnnotations(), field.getName(), injector);
                                              break CONSTRUCTORS;
                                          }
                                      }
                                  }
                              }
                          }
                      }
                  }
              }
              if (null == spec) {
                  throw E.unexpected("Cannot determine bean spec of field: %s", field);
              }
              if (ParamValueLoaderService.providedButNotDbBind(spec, injector)) {
                  continue;
              }
              String dbBindName = dbBindName(spec);
              if (null != dbBindName) {
                  beanSpecs.add(BeanSpec.of(String.class, new Annotation[0], dbBindName, injector));
              } else {
                  if (ParamValueLoaderService.providedButNotDbBind(spec, injector)) {
                      return;
                  }
                  beanSpecs.add(spec);
              }
          }
      }
  
      private void extractBeanSpec(List<BeanSpec> beanSpecs, Method method, Class host) {
          Type[] paramTypes = method.getGenericParameterTypes();
          int sz = paramTypes.length;
          if (0 == sz) {
              return;
          }
          List<BeanSpec> newSpecs = new ArrayList<>();
          Annotation[][] annotations = ReflectedInvokerHelper.requestHandlerMethodParamAnnotations(method);
          for (int i = 0; i < sz; ++i) {
              Type type = paramTypes[i];
              boolean isStatic = Modifier.isStatic(method.getModifiers());
              if (type instanceof TypeVariable && !isStatic) {
                  // explore type variable impl
                  TypeVariable typeVar = $.cast(type);
                  String typeVarName = typeVar.getName();
                  // find all generic types on host
                  Map<String, Class> typeVarLookup = Generics.buildTypeParamImplLookup(host);
                  type = typeVarLookup.get(typeVarName);
                  if (null == type) {
                      throw new UnexpectedException("Cannot determine concrete type of method parameter %s", typeVarName);
                  }
              }
              Annotation[] anno = annotations[i];
              BeanSpec spec;
              if (type instanceof ParameterizedType && !isStatic) {
                  // find all generic types on host
                  Map<String, Class> typeVarLookup = Generics.buildTypeParamImplLookup(host);
                  spec = BeanSpec.of(type, anno, injector, typeVarLookup);
              } else {
                  spec = BeanSpec.of(type, anno, injector);
              }
              if (ParamValueLoaderService.providedButNotDbBind(spec, injector)) {
                  continue;
              }
              String dbBindName = dbBindName(spec);
              if (null != dbBindName) {
                  newSpecs.add(BeanSpec.of(String.class, new Annotation[0], dbBindName, injector));
              } else {
                  newSpecs.add(spec);
              }
          }
          beanSpecs.addAll(newSpecs);
      }
  
      private static String dbBindName(BeanSpec spec) {
          for (Annotation annotation : spec.allAnnotations()) {
              if (annotation.annotationType().getName().equals(DbBind.class.getName())) {
                  String value = $.invokeVirtual(annotation, "value");
                  return (S.blank(value)) ? spec.name() : value;
              }
          }
          return null;
      }
  
      private static final Comparator<BeanSpec> CMP = new Comparator<BeanSpec>() {
          @Override
          public int compare(BeanSpec o1, BeanSpec o2) {
              return o1.name().compareTo(o2.name());
          }
      };
  
      private static String key(List<BeanSpec> beanSpecs) {
          S.Buffer sb = S.buffer();
          for (BeanSpec beanSpec : beanSpecs) {
              sb.append(S.underscore(beanSpec.name())).append(beanSpec.type().hashCode());
          }
          return sb.toString();
      }
  
  }
  