/**

  * Back 2 Browser Bytecode Translator

  * Copyright (C) 2012 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.lang.reflect.Method;

 import javax.script.Invocable;

 import javax.script.ScriptEngine;

 import javax.script.ScriptEngineManager;

 import org.testng.Assert;

 import org.testng.ITest;

 import org.testng.annotations.Factory;

 import org.testng.annotations.Test;

 /** A TestNG {@link Factory} that seeks for {@link Compare} annotations

  * in provided class and builds set of tests that compare the computations

  * in real as well as JavaScript virtual machines. Use as:<pre>

  * {@code @}{@link Factory} public static create() {

  *   return @{link CompareVMs}.{@link #create(YourClass.class);

  * }</pre>

  *

  * @author Jaroslav Tulach <jtulach@netbeans.org>

  */

 public final class CompareVMs implements ITest {

     private final Method m;

     private final boolean js;

     private final CompareVMs first, second;

     private Object value;

     private static Invocable code;

     private static CharSequence codeSeq;

     private CompareVMs(Method m, boolean js) {

         this.m = m;

         this.js = js;

         this.first = null;

         this.second = null;

     }

     private CompareVMs(Method m, CompareVMs first, CompareVMs second) {

         this.first = first;

         this.second = second;

         this.m = m;

         this.js = false;

     }

     private static void compileTheCode(Class<?> clazz) throws Exception {

         if (code != null) {

             return;

         }

         StringBuilder sb = new StringBuilder();

         class SkipMe extends GenJS {

             public SkipMe(Appendable out) {

                 super(out);

             }

             @Override

             protected boolean requireReference(String cn) {

                 if (cn.contains("CompareVMs")) {

                     return true;

                 }

                 return super.requireReference(cn);

             }

         }

         SkipMe sm = new SkipMe(sb);

         sm.doCompile(CompareVMs.class.getClassLoader(), StringArray.asList(

             clazz.getName().replace('.', '/')

         ));

         ScriptEngineManager sem = new ScriptEngineManager();

         ScriptEngine js = sem.getEngineByExtension("js");

         Object res = js.eval(sb.toString());

         Assert.assertTrue(js instanceof Invocable, "It is invocable object: " + res);

         code = (Invocable)js;

         codeSeq = sb;

     }

     public static Object[] create(Class<?> clazz) {

         Method[] arr = clazz.getMethods();

         Object[] ret = new Object[3 * arr.length];

         int cnt = 0;

         for (Method m : arr) {

             Compare c = m.getAnnotation(Compare.class);

             if (c == null) {

                 continue;

             }

             final CompareVMs real = new CompareVMs(m, false);

             final CompareVMs js = new CompareVMs(m, true);

             ret[cnt++] = real;

             ret[cnt++] = js;

             ret[cnt++] = new CompareVMs(m, real, js);

         }

         Object[] r = new Object[cnt];

         for (int i = 0; i < cnt; i++) {

             r[i] = ret[i];

         }

         return r;

     }

     @Test public void runTest() throws Throwable {

         if (first != null) {

             Object v1 = first.value;

             Object v2 = second.value;

             if (v1 instanceof Number) {

                 v1 = ((Number)v1).doubleValue();

             }

             Assert.assertEquals(v1, v2, "Comparing results");

         } else {

             if (js) {

                 try {

                     compileTheCode(m.getDeclaringClass());

                     Object vm = code.invokeFunction("bck2brwsr");

                     Object inst = code.invokeMethod(vm, "loadClass", m.getDeclaringClass().getName().replace('.', '_'));

                     value = code.invokeMethod(inst, m.getName() + "__I");

                 } catch (Exception ex) {

                     throw new AssertionError(StaticMethodTest.dumpJS(codeSeq)).initCause(ex);

                 }

             } else {

                 value = m.invoke(m.getDeclaringClass().newInstance());

             }

         }

     }

     @Override

     public String getTestName() {

         if (first != null) {

             return m.getName() + "[Compare]";

         }

         return m.getName() + (js ? "[JavaScript]" : "[Java]");

     }

 }