/**

  * HTML via Java(tm) Language Bindings

  * Copyright (C) 2013 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. apidesign.org

  * designates this particular file as subject to the

  * "Classpath" exception as provided by apidesign.org

  * in the License file that accompanied this code.

  *

  * 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://wiki.apidesign.org/wiki/GPLwithClassPathException

  */

 package org.apidesign.html.boot.impl;

 import java.io.Closeable;

 import java.io.InputStream;

 import java.io.InputStreamReader;

 import java.io.Reader;

 import java.net.URL;

 import java.util.ArrayList;

 import java.util.Collections;

 import java.util.Enumeration;

 import java.util.List;

 import java.util.Map;

 import java.util.concurrent.Callable;

 import org.apidesign.html.boot.spi.Fn;

 import org.objectweb.asm.AnnotationVisitor;

 import org.objectweb.asm.ClassReader;

 import org.objectweb.asm.ClassVisitor;

 import org.objectweb.asm.ClassWriter;

 import org.objectweb.asm.Label;

 import org.objectweb.asm.MethodVisitor;

 import org.objectweb.asm.Opcodes;

 import org.objectweb.asm.Type;

 import org.objectweb.asm.signature.SignatureReader;

 import org.objectweb.asm.signature.SignatureVisitor;

 import org.objectweb.asm.signature.SignatureWriter;

 /**

  *

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

  */

 public final class FnUtils implements Fn.Presenter {

     private FnUtils() {

     }

     /** Seeks for {@link JavaScriptBody} and {@link JavaScriptResource} annotations

      * in the bytecode and converts them into real code. Used by Maven plugin

      * postprocessing classes.

      * 

      * @param bytecode the original bytecode with javascript specific annotations

      * @param resources the resources to load

      * @return the transformed bytecode

      * @since 0.7

      */

     public static byte[] transform(byte[] bytecode, Map<String,InputStream> resources) {

         return transform(null, bytecode);

     }

     public static boolean isJavaScriptCapable(ClassLoader l) {

         if (l instanceof JsClassLoader) {

             return true;

         }

         Class<?> clazz;

         try (Closeable c = Fn.activate(new FnUtils())) {

             clazz = Class.forName(Test.class.getName(), true, l);

             final Object is = ((Callable<?>)clazz.newInstance()).call();

             return Boolean.TRUE.equals(is);

         } catch (Exception ex) {

             return false;

         }

     }

     public static boolean isValid(Fn fn) {

         return fn != null && fn.isValid();

     }

     public static ClassLoader newLoader(final FindResources f, final Fn.Presenter d, ClassLoader parent) {

         return new JsClassLoader(parent) {

             @Override

             protected URL findResource(String name) {

                 List<URL> l = res(name, true);

                 return l.isEmpty() ? null : l.get(0);

             }

             @Override

             protected Enumeration<URL> findResources(String name) {

                 return Collections.enumeration(res(name, false));

             }

             private List<URL> res(String name, boolean oneIsEnough) {

                 List<URL> l = new ArrayList<URL>();

                 f.findResources(name, l, oneIsEnough);

                 return l;

             }

             @Override

             protected Fn defineFn(String code, String... names) {

                 return d.defineFn(code, names);

             }

             @Override

             protected void loadScript(Reader code) throws Exception {

                 d.loadScript(code);

             }

         };

     }

     static String callback(final String body) {

         return new JsCallback() {

             @Override

             protected CharSequence callMethod(

                 String ident, String fqn, String method, String params

             ) {

                 StringBuilder sb = new StringBuilder();

                 sb.append("vm.").append(mangle(fqn, method, params));

                 sb.append("(");

                 if (ident != null) {

                     sb.append(ident);

                 }

                 return sb;

             }

         }.parse(body);

     }

     static void loadScript(ClassLoader jcl, String resource) {

         final InputStream script = jcl.getResourceAsStream(resource);

         if (script == null) {

             throw new NullPointerException("Can't find " + resource);

         }

         try {

             Reader isr = null;

             try {

                 isr = new InputStreamReader(script, "UTF-8");

                 FnContext.currentPresenter().loadScript(isr);

             } finally {

                 if (isr != null) {

                     isr.close();

                 }

             }

         } catch (Exception ex) {

             throw new IllegalStateException("Can't execute " + resource, ex);

         } 

     }

     @Override

     public Fn defineFn(String code, String... names) {

         return new TrueFn();

     }

     @Override

     public void displayPage(URL page, Runnable onPageLoad) {

     }

     @Override

     public void loadScript(Reader code) throws Exception {

     }

     private static final class FindInClass extends ClassVisitor {

         private String name;

         private int found;

         private ClassLoader loader;

         public FindInClass(ClassLoader l, ClassVisitor cv) {

             super(Opcodes.ASM4, cv);

             this.loader = l;

         }

         @Override

         public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {

             this.name = name;

             super.visit(version, access, name, signature, superName, interfaces);

         }

         @Override

         public AnnotationVisitor visitAnnotation(String desc, boolean visible) {

             if ("Lnet/java/html/js/JavaScriptResource;".equals(desc)) {

                 return new LoadResource();

             }

             return super.visitAnnotation(desc, visible);

         }

         @Override

         public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {

             return new FindInMethod(access, name, desc,

                     super.visitMethod(access & (~Opcodes.ACC_NATIVE), name, desc, signature, exceptions)

             );

         }

         private final class FindInMethod extends MethodVisitor {

             private final String name;

             private final String desc;

             private final int access;

             private List<String> args;

             private String body;

             private boolean bodyGenerated;

             public FindInMethod(int access, String name, String desc, MethodVisitor mv) {

                 super(Opcodes.ASM4, mv);

                 this.access = access;

                 this.name = name;

                 this.desc = desc;

             }

             @Override

             public AnnotationVisitor visitAnnotation(String desc, boolean visible) {

                 if ("Lnet/java/html/js/JavaScriptBody;".equals(desc) // NOI18N

                         || "Lorg/apidesign/bck2brwsr/core/JavaScriptBody;".equals(desc) // NOI18N

                         ) {

                     found++;

                     return new FindInAnno();

                 }

                 return super.visitAnnotation(desc, visible);

             }

             private void generateJSBody(List<String> args, String body) {

                 this.args = args;

                 this.body = body;

             }

             @Override

             public void visitCode() {

                 if (body == null) {

                     return;

                 }

                 generateBody();

             }

             private boolean generateBody() {

                 if (bodyGenerated) {

                     return false;

                 }

                 bodyGenerated = true;

                 super.visitFieldInsn(

                         Opcodes.GETSTATIC, FindInClass.this.name,

                         "$$fn$$" + name + "_" + found,

                         "Lorg/apidesign/html/boot/spi/Fn;"

                 );

                 super.visitInsn(Opcodes.DUP);

                 super.visitMethodInsn(

                         Opcodes.INVOKESTATIC,

                         "org/apidesign/html/boot/spi/Fn", "isValid",

                         "(Lorg/apidesign/html/boot/spi/Fn;)Z"

                 );

                 Label ifNotNull = new Label();

                 super.visitJumpInsn(Opcodes.IFNE, ifNotNull);

                 // init Fn

                 super.visitInsn(Opcodes.POP);

                 super.visitLdcInsn(Type.getObjectType(FindInClass.this.name));

                 super.visitLdcInsn(body);

                 super.visitIntInsn(Opcodes.SIPUSH, args.size());

                 super.visitTypeInsn(Opcodes.ANEWARRAY, "java/lang/String");

                 boolean needsVM = false;

                 for (int i = 0; i < args.size(); i++) {

                     assert !needsVM;

                     String argName = args.get(i);

                     needsVM = "vm".equals(argName);

                     super.visitInsn(Opcodes.DUP);

                     super.visitIntInsn(Opcodes.BIPUSH, i);

                     super.visitLdcInsn(argName);

                     super.visitInsn(Opcodes.AASTORE);

                 }

                 super.visitMethodInsn(Opcodes.INVOKESTATIC,

                         "org/apidesign/html/boot/spi/Fn", "define",

                         "(Ljava/lang/Class;Ljava/lang/String;[Ljava/lang/String;)Lorg/apidesign/html/boot/spi/Fn;"

                 );

                 super.visitInsn(Opcodes.DUP);

                 super.visitFieldInsn(

                         Opcodes.PUTSTATIC, FindInClass.this.name,

                         "$$fn$$" + name + "_" + found,

                         "Lorg/apidesign/html/boot/spi/Fn;"

                 );

                 // end of Fn init

                 super.visitLabel(ifNotNull);

                 final int offset;

                 if ((access & Opcodes.ACC_STATIC) == 0) {

                     offset = 1;

                     super.visitIntInsn(Opcodes.ALOAD, 0);

                 } else {

                     offset = 0;

                     super.visitInsn(Opcodes.ACONST_NULL);

                 }

                 super.visitIntInsn(Opcodes.SIPUSH, args.size());

                 super.visitTypeInsn(Opcodes.ANEWARRAY, "java/lang/Object");

                 class SV extends SignatureVisitor {

                     private boolean nowReturn;

                     private Type returnType;

                     private int index;

                     private int loadIndex = offset;

                     public SV() {

                         super(Opcodes.ASM4);

                     }

                     @Override

                     public void visitBaseType(char descriptor) {

                         final Type t = Type.getType("" + descriptor);

                         if (nowReturn) {

                             returnType = t;

                             return;

                         }

                         FindInMethod.super.visitInsn(Opcodes.DUP);

                         FindInMethod.super.visitIntInsn(Opcodes.SIPUSH, index++);

                         FindInMethod.super.visitVarInsn(t.getOpcode(Opcodes.ILOAD), loadIndex++);

                         String factory;

                         switch (descriptor) {

                             case 'I':

                                 factory = "java/lang/Integer";

                                 break;

                             case 'J':

                                 factory = "java/lang/Long";

                                 loadIndex++;

                                 break;

                             case 'S':

                                 factory = "java/lang/Short";

                                 break;

                             case 'F':

                                 factory = "java/lang/Float";

                                 break;

                             case 'D':

                                 factory = "java/lang/Double";

                                 loadIndex++;

                                 break;

                             case 'Z':

                                 factory = "java/lang/Boolean";

                                 break;

                             case 'C':

                                 factory = "java/lang/Character";

                                 break;

                             case 'B':

                                 factory = "java/lang/Byte";

                                 break;

                             default:

                                 throw new IllegalStateException(t.toString());

                         }

                         FindInMethod.super.visitMethodInsn(Opcodes.INVOKESTATIC,

                                 factory, "valueOf", "(" + descriptor + ")L" + factory + ";"

                         );

                         FindInMethod.super.visitInsn(Opcodes.AASTORE);

                     }

                     @Override

                     public SignatureVisitor visitArrayType() {

                         if (nowReturn) {

                             throw new IllegalStateException("Not supported yet");

                         }

                         loadObject();

                         return new SignatureWriter();

                     }

                     @Override

                     public void visitClassType(String name) {

                         if (nowReturn) {

                             returnType = Type.getObjectType(name);

                             return;

                         }

                         loadObject();

                     }

                     @Override

                     public SignatureVisitor visitReturnType() {

                         nowReturn = true;

                         return this;

                     }

                     private void loadObject() {

                         FindInMethod.super.visitInsn(Opcodes.DUP);

                         FindInMethod.super.visitIntInsn(Opcodes.SIPUSH, index++);

                         FindInMethod.super.visitVarInsn(Opcodes.ALOAD, loadIndex++);

                         FindInMethod.super.visitInsn(Opcodes.AASTORE);

                     }

                 }

                 SV sv = new SV();

                 SignatureReader sr = new SignatureReader(desc);

                 sr.accept(sv);

                 if (needsVM) {

                     FindInMethod.super.visitInsn(Opcodes.DUP);

                     FindInMethod.super.visitIntInsn(Opcodes.SIPUSH, sv.index);

                     int lastSlash = FindInClass.this.name.lastIndexOf('/');

                     String jsCallbacks = FindInClass.this.name.substring(0, lastSlash + 1) + "$JsCallbacks$";

                     FindInMethod.super.visitFieldInsn(Opcodes.GETSTATIC, jsCallbacks, "VM", "L" + jsCallbacks + ";");

                     FindInMethod.super.visitMethodInsn(Opcodes.INVOKEVIRTUAL, jsCallbacks, "current", "()L" + jsCallbacks + ";");

                     FindInMethod.super.visitInsn(Opcodes.AASTORE);

                 }

                 super.visitMethodInsn(Opcodes.INVOKEVIRTUAL,

                         "org/apidesign/html/boot/spi/Fn", "invoke", "(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;"

                 );

                 switch (sv.returnType.getSort()) {

                     case Type.VOID:

                         super.visitInsn(Opcodes.RETURN);

                         break;

                     case Type.ARRAY:

                     case Type.OBJECT:

                         super.visitTypeInsn(Opcodes.CHECKCAST, sv.returnType.getInternalName());

                         super.visitInsn(Opcodes.ARETURN);

                         break;

                     case Type.BOOLEAN:

                         super.visitTypeInsn(Opcodes.CHECKCAST, "java/lang/Boolean");

                         super.visitMethodInsn(Opcodes.INVOKEVIRTUAL,

                                 "java/lang/Boolean", "booleanValue", "()Z"

                         );

                         super.visitInsn(Opcodes.IRETURN);

                         break;

                     default:

                         super.visitTypeInsn(Opcodes.CHECKCAST, "java/lang/Number");

                         super.visitMethodInsn(Opcodes.INVOKEVIRTUAL,

                                 "java/lang/Number", sv.returnType.getClassName() + "Value", "()" + sv.returnType.getDescriptor()

                         );

                         super.visitInsn(sv.returnType.getOpcode(Opcodes.IRETURN));

                 }

                 return true;

             }

             @Override

             public void visitEnd() {

                 super.visitEnd();

                 if (body != null) {

                     if (generateBody()) {

                         // native method

                         super.visitMaxs(1, 0);

                     }

                     FindInClass.this.visitField(

                             Opcodes.ACC_PRIVATE | Opcodes.ACC_STATIC,

                             "$$fn$$" + name + "_" + found,

                             "Lorg/apidesign/html/boot/spi/Fn;",

                             null, null

                     );

                 }

             }

             private final class FindInAnno extends AnnotationVisitor {

                 private List<String> args = new ArrayList<String>();

                 private String body;

                 private boolean javacall = false;

                 public FindInAnno() {

                     super(Opcodes.ASM4);

                 }

                 @Override

                 public void visit(String name, Object value) {

                     if (name == null) {

                         args.add((String) value);

                         return;

                     }

                     if (name.equals("javacall")) { // NOI18N

                         javacall = (Boolean) value;

                         return;

                     }

                     assert name.equals("body");

                     body = (String) value;

                 }

                 @Override

                 public AnnotationVisitor visitArray(String name) {

                     return this;

                 }

                 @Override

                 public void visitEnd() {

                     if (body != null) {

                         if (javacall) {

                             body = callback(body);

                             args.add("vm");

                         }

                         generateJSBody(args, body);

                     }

                 }

             }

         }

         private final class LoadResource extends AnnotationVisitor {

             public LoadResource() {

                 super(Opcodes.ASM4);

             }

             @Override

             public void visit(String attrName, Object value) {

                 String relPath = (String) value;

                 if (relPath.startsWith("/")) {

                     loadScript(loader, relPath);

                 } else {

                     int last = name.lastIndexOf('/');

                     String fullPath = name.substring(0, last + 1) + relPath;

                     loadScript(loader, fullPath);

                 }

             }

         }

     }

     private static class ClassWriterEx extends ClassWriter {

         private ClassLoader loader;

         public ClassWriterEx(ClassLoader l, ClassReader classReader, int flags) {

             super(classReader, flags);

             this.loader = l;

         }

         @Override

         protected String getCommonSuperClass(final String type1, final String type2) {

             Class<?> c, d;

             try {

                 c = Class.forName(type1.replace('/', '.'), false, loader);

                 d = Class.forName(type2.replace('/', '.'), false, loader);

             } catch (Exception e) {

                 throw new RuntimeException(e.toString());

             }

             if (c.isAssignableFrom(d)) {

                 return type1;

             }

             if (d.isAssignableFrom(c)) {

                 return type2;

             }

             if (c.isInterface() || d.isInterface()) {

                 return "java/lang/Object";

             } else {

                 do {

                     c = c.getSuperclass();

                 } while (!c.isAssignableFrom(d));

                 return c.getName().replace('.', '/');

             }

         }

     }

     static byte[] transform(ClassLoader loader, byte[] arr) {

         ClassReader cr = new ClassReader(arr) {

             // to allow us to compile with -profile compact1 on 

             // JDK8 while processing the class as JDK7, the highest

             // class format asm 4.1 understands to

             @Override

             public short readShort(int index) {

                 short s = super.readShort(index);

                 if (index == 6 && s > Opcodes.V1_7) {

                     return Opcodes.V1_7;

                 }

                 return s;

             }

         };

         FindInClass tst = new FindInClass(loader, null);

         cr.accept(tst, 0);

         if (tst.found > 0) {

             ClassWriter w = new ClassWriterEx(loader, cr, ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);

             FindInClass fic = new FindInClass(loader, w);

             cr.accept(fic, 0);

             arr = w.toByteArray();

         }

         return arr;

     }

     private static final class TrueFn extends Fn {

         @Override

         public Object invoke(Object thiz, Object... args) throws Exception {

             return Boolean.TRUE;

         }

     } // end of TrueFn

 }