content: package act.view;
  
  /*-
   * #%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.app.event.SysEventId;
  import act.asm.*;
  import act.inject.genie.GenieInjector;
  import act.inject.param.ParamValueLoader;
  import act.inject.param.ProvidedValueLoader;
  import act.mail.MailerContext;
  import act.plugin.Plugin;
  import act.util.AsmTypes;
  import act.util.ByteCodeVisitor;
  import com.esotericsoftware.reflectasm.MethodAccess;
  import org.osgl.$;
  import org.osgl.inject.BeanSpec;
  import org.osgl.util.E;
  import org.osgl.util.S;
  
  import java.lang.annotation.Annotation;
  import java.lang.reflect.Method;
  import java.util.*;
  
  /**
   * Plugin developer could extend this interface to inject
   * implicit variables to view template
   */
  public abstract class ImplicitVariableProvider implements Plugin {
  
      /**
       * Returns a list of implicit variables the plugin needs to inject
       * into template render arguments for action view
       */
      public abstract List<ActionViewVarDef> implicitActionViewVariables();
  
      /**
       * Returns a list of implicit variables the plugin needs to inject
       * into template render arguments for mailer view
       */
      public abstract List<MailerViewVarDef> implicitMailerViewVariables();
  
      @Override
      public void register() {
          Act.viewManager().register(this);
      }
  
      public static class TemplateVariableScanner extends AppByteCodeScannerBase {
  
          private static class Meta {
              String className;
              String methodName;
              String varName;
              boolean isStatic;
  
              @Override
              public int hashCode() {
                  return $.hc(className, methodName);
              }
  
              @Override
              public boolean equals(Object obj) {
                  if (obj == this) {
                      return true;
                  }
                  if (obj instanceof Meta) {
                      Meta that = $.cast(obj);
                      return $.eq(that.className, this.className) && $.eq(that.methodName, this.methodName);
                  }
                  return false;
              }
  
              String varName() {
                  return (null == varName || S.eq(ProvidesImplicitTemplateVariable.DEFAULT, varName)) ? methodName : varName;
              }
  
              @Override
              public String toString() {
                  return S.concat("Template variable provider: ", className, "::", methodName);
              }
          }
  
          private Set<Meta> providers = new HashSet<>();
  
          public TemplateVariableScanner(final App app) {
              app.jobManager().on(SysEventId.START, "TemplateVariableScanner:registerByteCodeScanner", new Runnable() {
                  @Override
                  public void run() {
                      register(app);
                  }
              });
          }
  
          @Override
          protected boolean shouldScan(String className) {
              return true;
          }
  
          @Override
          public ByteCodeVisitor byteCodeVisitor() {
              return new ByteCodeVisitor() {
                  private String className;
  
                  @Override
                  public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {
                      if (isPublic(access)) {
                          className = Type.getObjectType(name).getClassName();
                      }
                      super.visit(version, access, name, signature, superName, interfaces);
                  }
  
                  @Override
                  public MethodVisitor visitMethod(int access, final String methodName, String desc, String signature, String[] exceptions) {
                      MethodVisitor mv = super.visitMethod(access, methodName, desc, signature, exceptions);
                      if (null == className) {
                          return mv;
                      }
  
                      final boolean isStatic = isStatic(access);
  
                      return new MethodVisitor(ASM5, mv) {
                          @Override
                          public AnnotationVisitor visitAnnotation(String desc, boolean visible) {
                              AnnotationVisitor av = super.visitAnnotation(desc, visible);
                              Type annoType = Type.getType(desc);
                              if (AsmTypes.TEMPLATE_VARIABLE.asmType().equals(annoType)) {
                                  final Meta meta = new Meta();
                                  meta.className = className;
                                  meta.methodName = methodName;
                                  meta.isStatic = isStatic;
                                  if (providers.contains(meta)) {
                                      throw AsmException.of("@ProvidesImplicitTemplateVariable annotated method cannot be overloaded: %s", meta.toString());
                                  }
                                  providers.add(meta);
                                  return new AnnotationVisitor(ASM5, av) {
                                      @Override
                                      public void visit(String name, Object value) {
                                          if ("value".equals(name)) {
                                              meta.varName = value.toString();
                                          }
                                          super.visit(name, value);
                                      }
                                  };
                              }
                              return av;
                          }
                      };
                  }
              };
          }
  
          @Override
          public void scanFinished(String className) {
  
          }
  
          private void register(App app) {
              for (Meta meta : providers) {
                  register(meta, app);
              }
          }
  
          private void register(Meta meta, App app) {
              Class<?> cls = app.classForName(meta.className);
              Method method = findMethod(cls, meta.methodName);
              E.unexpectedIf(null == method, "Unable to find method %s", meta);
              register(meta, cls, method, app);
          }
  
          private Method findMethod(Class<?> cls, String methodName) {
              Method[] methods = cls.getDeclaredMethods();
              for (Method method : methods) {
                  if (!method.getName().equals(methodName)) {
                      continue;
                  }
                  if (method.isAnnotationPresent(ProvidesImplicitTemplateVariable.class)) {
                      return method;
                  }
              }
              return null;
          }
  
          private void register(Meta meta, Class<?> cls, Method method, App app) {
              final ReflectedActionViewVarDef def = new ReflectedActionViewVarDef(meta, cls, method, app);
              if (def.supportMailer) {
                  MailerViewVarDef mailerVarDef = new MailerViewVarDef(meta.varName(), def.returnType(app)) {
                      @Override
                      public Object eval(MailerContext context) {
                          return def.getValue(context.app());
                      }
                  };
                  Act.viewManager().registerAppDefinedVar(mailerVarDef);
              }
              if (def.supportAction) {
                  ActionViewVarDef actionVarDef = new ActionViewVarDef(meta.varName(), def.returnType(app)) {
                      @Override
                      public Object eval(ActionContext context) {
                          return def.getValue(context.app());
                      }
                  };
                  Act.viewManager().registerAppDefinedVar(actionVarDef);
              }
          }
  
          private static class ReflectedActionViewVarDef {
  
              private Class<?> cls;
              private Method method;
              private MethodAccess methodAccess;
              private int methodIndex;
              private ParamValueLoader[] loaders;
              private boolean supportAction;
              private boolean supportMailer;
              private int paramLen;
  
              protected ReflectedActionViewVarDef(Meta meta, Class<?> cls, Method method, App app) {
                  this.cls = cls;
                  this.method = method;
                  if (!meta.isStatic) {
                      methodAccess = MethodAccess.get(cls);
                      methodIndex = methodAccess.getIndex(method.getName(), method.getParameterTypes());
                  }
                  initLoaders(app);
              }
  
              private void initLoaders(App app) {
                  java.lang.reflect.Type[] types = method.getGenericParameterTypes();
                  int len = types.length;
                  ParamValueLoader[] loaders = new ParamValueLoader[len];
                  if (0 < len) {
                      GenieInjector injector = app.injector();
                      Annotation[][] annos = method.getParameterAnnotations();
                      for (int i = 0; i < len; ++i) {
                          java.lang.reflect.Type type = types[i];
                          Annotation[] aa = annos[i];
                          BeanSpec spec = BeanSpec.of(type, aa, injector);
                          E.unexpectedIf(!injector.isProvided(spec), "");
                          loaders[i] = ProvidedValueLoader.get(spec, injector);
                          if (spec.isInstanceOf(ActionContext.class) || requireAction(type)) {
                              supportAction = true;
                          } else if (spec.isInstanceOf(MailerContext.class)) {
                              supportMailer = true;
                          }
                      }
                  }
                  if (!supportAction && !supportMailer) {
                      supportAction = true;
                      supportMailer = true;
                  }
                  this.loaders = loaders;
                  this.paramLen = len;
              }
  
              private boolean requireAction(java.lang.reflect.Type type) {
                  String name = type.toString();
                  if (name.contains("org.osgl.http")) {
                      return true;
                  }
                  return false;
              }
  
              BeanSpec returnType(App app) {
                  return BeanSpec.of(method.getGenericReturnType(), null, app.injector());
              }
  
              Object getValue(App app) {
                  Object[] params = params();
                  if (null != methodAccess) {
                      return methodAccess.invoke(app.getInstance(cls), methodIndex, params);
                  } else {
                      return $.invokeStatic(method, params);
                  }
              }
  
              private Object[] params() {
                  Object[] params = new Object[paramLen];
                  for (int i = 0; i < paramLen; ++i) {
                      ParamValueLoader loader = loaders[i];
                      params[i] = loader.load(null, null, false);
                  }
                  return params;
              }
  
          }
  
      }
  
  }
  