/**

  * Back 2 Browser Bytecode Translator

  * Copyright (C) 2012-2015 Jaroslav Tulach <jaroslav.tulach@apidesign.org>

  *

  * This program is free software: you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation, version 2 of the License.

  *

  * This program is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

  * GNU General Public License for more details.

  *

  * You should have received a copy of the GNU General Public License

  * along with this program. Look for COPYING file in the top folder.

  * If not, see http://opensource.org/licenses/GPL-2.0.

  */

 package org.apidesign.vm4brwsr;

 import java.io.IOException;

 import java.io.InputStream;

 import java.util.HashMap;

 import java.util.Map;

 import org.apidesign.bck2brwsr.core.ExtraJavaScript;

 import org.apidesign.vm4brwsr.ByteCodeParser.ClassData;

 import org.apidesign.vm4brwsr.ByteCodeParser.FieldData;

 import org.apidesign.vm4brwsr.ByteCodeParser.MethodData;

 @ExtraJavaScript(processByteCode = false, resource="")

 final class ClassDataCache {

     private static final Object MISSING_CLASS = new Object();

     private final Bck2Brwsr.Resources resources;

     private final Map<String, Object> classDataMap;

     ClassDataCache(final Bck2Brwsr.Resources resources) {

         this.resources = resources;

         classDataMap = new HashMap<String, Object>();

     }

     ClassData getClassData(String className) throws IOException {

         if (className.startsWith("[")) {

             // required for accessVirtualMethod, shouldn't be problematic for

             // calls from other sources

             className = "java/lang/Object";

         }

         Object cacheEntry = classDataMap.get(className);

         if (cacheEntry == null) {

             final InputStream is = loadClass(resources, className);

             cacheEntry = (is != null) ? new ClassData(is) : MISSING_CLASS;

             classDataMap.put(className, cacheEntry);

         }

         return (cacheEntry != MISSING_CLASS) ? (ClassData) cacheEntry : null;

     }

     MethodData findMethod(final String startingClass,

                           final String name,

                           final String signature) throws IOException {

         return findMethod(getClassData(startingClass), name, signature);

     }

     FieldData findField(final String startingClass,

                         final String name,

                         final String signature) throws IOException {

         return findField(getClassData(startingClass), name, signature);

     }

     MethodData findMethod(final ClassData startingClass,

                           final String name,

                           final String signature) throws IOException {

         final FindFirstTraversalCallback<MethodData> ffTraversalCallback =

                 new FindFirstTraversalCallback<MethodData>();

         findMethods(startingClass, name, signature, ffTraversalCallback);

         return ffTraversalCallback.getFirst();

     }

     FieldData findField(final ClassData startingClass,

                         final String name,

                         final String signature) throws IOException {

         final FindFirstTraversalCallback<FieldData> ffTraversalCallback =

                 new FindFirstTraversalCallback<FieldData>();

         findFields(startingClass, name, signature, ffTraversalCallback);

         return ffTraversalCallback.getFirst();

     }

     void findMethods(final ClassData startingClass,

                      final String methodName,

                      final String methodSignature,

                      final TraversalCallback<MethodData> mdTraversalCallback)

                              throws IOException {

         traverseHierarchy(

                 startingClass,

                 new FindMethodsTraversalCallback(methodName, methodSignature,

                                                  mdTraversalCallback));

     }

     void findFields(final ClassData startingClass,

                     final String fieldName,

                     final String fieldSignature,

                     final TraversalCallback<FieldData> fdTraversalCallback)

                             throws IOException {

         traverseHierarchy(

                 startingClass,

                 new FindFieldsTraversalCallback(fieldName, fieldSignature,

                                                 fdTraversalCallback));

     }

     private boolean traverseHierarchy(

             ClassData currentClass,

             final TraversalCallback<ClassData> cdTraversalCallback)

                 throws IOException {

         while (currentClass != null) {

             if (!cdTraversalCallback.traverse(currentClass)) {

                 return false;

             }

             for (final String superIfaceName:

                     currentClass.getSuperInterfaces()) {

                 if (!traverseHierarchy(getClassData(superIfaceName),

                                        cdTraversalCallback)) {

                     return false;

                 }

             }

             final String superClassName = currentClass.getSuperClassName();

             if (superClassName == null) {

                 break;

             }

             currentClass = getClassData(superClassName);

         }

         return true;

     }

     interface TraversalCallback<T> {

         boolean traverse(T object);

     }

     private final class FindFirstTraversalCallback<T>

             implements TraversalCallback<T> {

         private T firstObject;

         @Override

         public boolean traverse(final T object) {

             firstObject = object;

             return false;

         }

         public T getFirst() {

             return firstObject;

         }

     }

     private final class FindMethodsTraversalCallback

             implements TraversalCallback<ClassData> {

         private final String methodName;

         private final String methodSignature;

         private final TraversalCallback<MethodData> mdTraversalCallback;

         public FindMethodsTraversalCallback(

                 final String methodName,

                 final String methodSignature,

                 final TraversalCallback<MethodData> mdTraversalCallback) {

             this.methodName = methodName;

             this.methodSignature = methodSignature;

             this.mdTraversalCallback = mdTraversalCallback;

         }

         @Override

         public boolean traverse(final ClassData classData) {

             final MethodData methodData =

                     classData.findMethod(methodName, methodSignature);

             return (methodData != null)

                        ? mdTraversalCallback.traverse(methodData)

                        : true;

         }

     }

     private final class FindFieldsTraversalCallback

             implements TraversalCallback<ClassData> {

         private final String fieldName;

         private final String fieldSignature;

         private final TraversalCallback<FieldData> fdTraversalCallback;

         public FindFieldsTraversalCallback(

                 final String fieldName,

                 final String fieldSignature,

                 final TraversalCallback<FieldData> fdTraversalCallback) {

             this.fieldName = fieldName;

             this.fieldSignature = fieldSignature;

             this.fdTraversalCallback = fdTraversalCallback;

         }

         @Override

         public boolean traverse(final ClassData classData) {

             final FieldData fieldData =

                     classData.findField(fieldName, fieldSignature);

             return (fieldData != null)

                        ? fdTraversalCallback.traverse(fieldData)

                        : true;

         }

     }

     private static InputStream loadClass(Bck2Brwsr.Resources l, String name)

             throws IOException {

         return l.get(name + ".class"); // NOI18N

     }

 }