/*
    * JavaBean Tester (https://github.com/hazendaz/javabean-tester)
    *
    * Copyright 2012-2021 Hazendaz.
    *
    * All rights reserved. This program and the accompanying materials
    * are made available under the terms of The Apache Software License,
    * Version 2.0 which accompanies this distribution, and is available at
    * http://www.apache.org/licenses/LICENSE-2.0.txt
   *
   * Contributors:
   *     CodeBox (Rob Dawson).
   *     Hazendaz (Jeremy Landis).
   */
  package com.codebox.builders;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Map.Entry;
  import javassist.CannotCompileException;
  import javassist.ClassPool;
  import javassist.CtClass;
  import javassist.CtField;
  import javassist.CtMethod;
  import javassist.NotFoundException;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * The Class ExtensionBuilder.
   *
   * @param <T>
   *            the generic type
   */
  public class ExtensionBuilder<T> {
  
      /** The Constant LOGGER. */
      private static final Logger LOGGER = LoggerFactory.getLogger(ExtensionBuilder.class);
  
      /**
       * Generate.
       *
       * @param clazz
       *            the clazz
       *
       * @return the class
       *
       * @throws NotFoundException
       *             the not found exception
       * @throws CannotCompileException
       *             the cannot compile exception
       */
      public Class<?> generate(final Class<T> clazz) throws NotFoundException, CannotCompileException {
          try {
              // If extension already recreated, return it
              return Class.forName(clazz.getName() + "Extension");
          } catch (final ClassNotFoundException e) {
              // No extension exists, so create it
              ExtensionBuilder.LOGGER.trace("No extension exists, so create it", e);
          }
  
          final ClassPool pool = ClassPool.getDefault();
          final CtClass cc = pool.makeClass(clazz.getName() + "Extension");
  
          // add super class
          cc.setSuperclass(ExtensionBuilder.resolveCtClass(clazz));
  
          final Map<String, Class<?>> properties = new HashMap<>();
          properties.put("jbExtension1", String.class);
          properties.put("jbExtension2", String.class);
          properties.put("jbExtension3", String.class);
          properties.put("jbExtension4", String.class);
  
          for (final Entry<String, Class<?>> entry : properties.entrySet()) {
  
              // Add field
              cc.addField(new CtField(ExtensionBuilder.resolveCtClass(entry.getValue()), entry.getKey(), cc));
  
              // Add getter
              cc.addMethod(ExtensionBuilder.generateGetter(cc, entry.getKey(), entry.getValue()));
  
              // Add setter
              cc.addMethod(ExtensionBuilder.generateSetter(cc, entry.getKey(), entry.getValue()));
          }
  
          return cc.toClass();
      }
  
      /**
       * Generate getter.
       *
       * @param declaringClass
       *            the declaring class
       * @param fieldName
       *            the field name
       * @param fieldClass
       *            the field class
       *
      * @return the ct method
      *
      * @throws CannotCompileException
      *             the cannot compile exception
      */
     private static CtMethod generateGetter(final CtClass declaringClass, final String fieldName,
             final Class<?> fieldClass) throws CannotCompileException {
         final StringBuilder sb = new StringBuilder();
         sb.append("public ");
         sb.append(fieldClass.getName());
         sb.append(" get");
         sb.append(fieldName.substring(0, 1).toUpperCase());
         sb.append(fieldName.substring(1));
         sb.append("(){");
         sb.append("return this.");
         sb.append(fieldName);
         sb.append(";");
         sb.append("}");
         return CtMethod.make(sb.toString(), declaringClass);
     }
 
     /**
      * Generate setter.
      *
      * @param declaringClass
      *            the declaring class
      * @param fieldName
      *            the field name
      * @param fieldClass
      *            the field class
      *
      * @return the ct method
      *
      * @throws CannotCompileException
      *             the cannot compile exception
      */
     private static CtMethod generateSetter(final CtClass declaringClass, final String fieldName,
             final Class<?> fieldClass) throws CannotCompileException {
         final StringBuilder sb = new StringBuilder();
         sb.append("public void set");
         sb.append(fieldName.substring(0, 1).toUpperCase());
         sb.append(fieldName.substring(1));
         sb.append("(");
         sb.append(fieldClass.getName());
         sb.append(" ");
         sb.append(fieldName);
         sb.append(")");
         sb.append("{");
         sb.append("this.");
         sb.append(fieldName);
         sb.append("=");
         sb.append(fieldName);
         sb.append(";");
         sb.append("}");
         return CtMethod.make(sb.toString(), declaringClass);
     }
 
     /**
      * Resolve ct class.
      *
      * @param clazz
      *            the clazz
      *
      * @return the ct class
      *
      * @throws NotFoundException
      *             the not found exception
      */
     private static CtClass resolveCtClass(final Class<?> clazz) throws NotFoundException {
         return ClassPool.getDefault().get(clazz.getName());
     }
 
 }