content: package act.conf;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2018 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.app.AppByteCodeScannerBase;
  import act.app.event.SysEventId;
  import act.asm.AnnotationVisitor;
  import act.asm.FieldVisitor;
  import act.asm.Type;
  import act.inject.DefaultValue;
  import act.inject.DependencyInjector;
  import act.util.AsmTypes;
  import act.util.ByteCodeVisitor;
  import org.osgl.$;
  import org.osgl.inject.BeanSpec;
  import org.osgl.inject.annotation.Configuration;
  import org.osgl.inject.loader.ConfigurationValueLoader;
  import org.osgl.util.C;
  import org.osgl.util.Const;
  import org.osgl.util.E;
  import org.osgl.util.S;
  
  import java.lang.reflect.Field;
  import java.util.HashMap;
  import java.util.Map;
  
  public class ConfigurationByteCodeScanner extends AppByteCodeScannerBase {
  
      private static final String CONF_DESC = Type.getType(Configuration.class).getDescriptor();
      private String className;
      // map field name to configuration key
      private Map<String, String> staticConfigurationFields = new HashMap<>();
  
      @Override
      protected boolean shouldScan(String className) {
          return true;
      }
  
      @Override
      protected void reset(String className) {
          super.reset(className);
          this.className = className;
          staticConfigurationFields.clear();
      }
  
      @Override
      public ByteCodeVisitor byteCodeVisitor() {
          return new ByteCodeVisitor() {
              @Override
              public FieldVisitor visitField(int access, final String name, String desc, String signature, Object value) {
                  FieldVisitor fv = super.visitField(access, name, desc, signature, value);
                  boolean isStatic = AsmTypes.isStatic(access);
                  if (!isStatic) {
                      return fv;
                  }
                  final String fieldName = name;
                  return new FieldVisitor(ASM5, fv) {
                      @Override
                      public AnnotationVisitor visitAnnotation(String desc, boolean visible) {
                          AnnotationVisitor av = super.visitAnnotation(desc, visible);
                          if (S.eq(CONF_DESC, desc)) {
                              return new AnnotationVisitor(ASM5, av) {
                                  @Override
                                  public void visit(String name, Object value) {
                                      staticConfigurationFields.put(fieldName, S.string(value));
                                      super.visit(name, value);
                                  }
                              };
                          }
                          return av;
                      }
                  };
              }
          };
      }
  
      @Override
      public void scanFinished(final String className) {
          E.unexpectedIf(S.neq(this.className, className), "oops");
          if (staticConfigurationFields.isEmpty()) {
              return;
          }
          final DependencyInjector injector = app().injector();
          final Map<String, String> staticConfigurationFields = new HashMap<>(this.staticConfigurationFields);
          app().jobManager().on(SysEventId.PRE_START, "ConfigurationByteCodeScanner:loadIntoStaticFieldsOf:" + className, new Runnable() {
              @Override
              public void run() {
                  Class<?> theClass = app().classForName(className);
                  for (Map.Entry<String, String> entry : staticConfigurationFields.entrySet()) {
                      String fieldName = entry.getKey();
                      String conf = entry.getValue();
                      Field field = $.fieldOf(theClass, fieldName, false);
                      DefaultValue defaultValue = field.getAnnotation(DefaultValue.class);
                      field.setAccessible(true);
                      Class<?> fieldType = field.getType();
                      boolean isConst = false;
                      boolean isVal = false;
                      BeanSpec valueSpec = BeanSpec.of(field, injector);
                      if (Const.class.isAssignableFrom(fieldType)) {
                          valueSpec = BeanSpec.of(field, injector).componentSpec();
                          isConst = true;
                      } else if ($.Val.class.isAssignableFrom(fieldType)) {
                          valueSpec = BeanSpec.of(field, injector).componentSpec();
                          isVal = true;
                      }
                      ConfigurationValueLoader loader = app().getInstance(ConfigurationValueLoader.class);
                      Map<String, String> map = C.newMap("value", conf);
                      if (null != defaultValue) {
                          map.put("defaultValue", defaultValue.value());
                      }
                      loader.init(map, valueSpec);
                      Object value = loader.get();
                      if (null == value) {
                          return;
                      }
                      try {
                          if (isConst) {
                              Const<?> fieldValue = $.cast(field.get(null));
                              if (null == fieldValue) {
                                  fieldValue = $.constant(value);
                                  field.set(null, fieldValue);
                              } else {
                                  Field fv = Const.class.getDeclaredField("v");
                                  fv.setAccessible(true);
                                  fv.set(fieldValue, value);
                              }
                          } else if (isVal) {
                              $.Val<?> fieldValue = $.cast(field.get(null));
                              if (null == fieldValue) {
                                  fieldValue = $.val(value);
                                  field.set(null, fieldValue);
                              } else {
                                  Field fv = $.Var.class.getDeclaredField("v");
                                  fv.setAccessible(true);
                                  fv.set(fieldValue, value);
                              }
                          } else {
                              field.set(null, value);
                          }
                      } catch (Exception e) {
                          throw E.unexpected(e, "failed to set configuration value[%s] to field[%s]", value, field);
                      }
                  }
              }
          });
      }
  }
  