/**

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

import java.io.IOException;

import java.io.InputStream;

import java.io.Reader;

import java.net.URL;

import java.util.ArrayList;

import java.util.Enumeration;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

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 <jaroslav.tulach@apidesign.org>

 */

abstract class JsClassLoader extends ClassLoader {

    JsClassLoader(ClassLoader parent) {

        super(parent);

        setDefaultAssertionStatus(JsClassLoader.class.desiredAssertionStatus());

    }

    @Override

    protected abstract URL findResource(String name);

    @Override

    protected abstract Enumeration<URL> findResources(String name);

    @Override

    protected Class<?> findClass(String name) throws ClassNotFoundException {

        if (name.startsWith("javafx")) {

            return Class.forName(name);

        }

        if (name.startsWith("netscape")) {

            return Class.forName(name);

        }

        if (name.startsWith("com.sun")) {

            return Class.forName(name);

        }

        if (name.equals(JsClassLoader.class.getName())) {

            return JsClassLoader.class;

        }

        if (name.equals(Fn.class.getName())) {

            return Fn.class;

        }

        if (name.equals(FnUtils.class.getName())) {

            return FnUtils.class;

        }

        URL u = findResource(name.replace('.', '/') + ".class");

        if (u != null) {

            InputStream is = null;

            try {

                is = u.openStream();

                byte[] arr = new byte[is.available()];

                int len = 0;

                while (len < arr.length) {

                    int read = is.read(arr, len, arr.length - len);

                    if (read == -1) {

                        throw new IOException("Can't read " + u);

                    }

                    len += read;

                }

                is.close();

                is = null;

                ClassReader cr = new ClassReader(arr);

                FindInClass tst = new FindInClass(null, new HashMap<String,String>());

                cr.accept(tst, 0);

                if (tst.found > 0) {

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

                    FindInClass fic = new FindInClass(w, tst.methods);

                    cr.accept(fic, 0);

                    arr = w.toByteArray();

                }

                if (arr != null) {

                    return defineClass(name, arr, 0, arr.length);

                }

            } catch (IOException ex) {

                throw new ClassNotFoundException("Can't load " + name, ex);

            } finally {

                try {

                    if (is != null) is.close();

                } catch (IOException ex) {

                    throw new ClassNotFoundException(null, ex);

                }

            }

        }

        if (

            name.equals("org.apidesign.html.boot.spi.Fn") ||

            name.equals("org.apidesign.html.boot.impl.FnUtils")

        ) {

            return Class.forName(name);

        }

        return super.findClass(name);

    }

    protected abstract Fn defineFn(String code, String... names);

    protected abstract void loadScript(Reader code) throws Exception;

    private final class FindInClass extends ClassVisitor {

        private String name;

        private int found;

        private final Map<String,String> methods;

        public FindInClass(ClassVisitor cv, Map<String,String> methods) {

            super(Opcodes.ASM4, cv);

            this.methods = methods;

        }

        @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) {

            int end = desc.indexOf(')');

            methods.put(name + desc.substring(0, end + 1), desc);

            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);

                Label ifNotNull = new Label();

                super.visitJumpInsn(Opcodes.IFNONNULL, 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");

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

                    String name = args.get(i);

                    super.visitInsn(Opcodes.DUP);

                    super.visitIntInsn(Opcodes.BIPUSH, i);

                    super.visitLdcInsn(name);

                    super.visitInsn(Opcodes.AASTORE);

                }

                super.visitMethodInsn(Opcodes.INVOKESTATIC, 

                    "org/apidesign/html/boot/impl/FnUtils", "define", 

                    "(Ljava/lang/Class;Ljava/lang/String;[Ljava/lang/String;)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;

                    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), index + offset);

                        String factory;

                        switch (descriptor) {

                        case 'I': factory = "java/lang/Integer"; break;

                        case 'J': factory = "java/lang/Long"; break;

                        case 'S': factory = "java/lang/Short"; break;

                        case 'F': factory = "java/lang/Float"; break;

                        case 'D': factory = "java/lang/Double"; 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);

                        index++;

                    }

                    @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, index + offset);

                        FindInMethod.super.visitInsn(Opcodes.AASTORE);

                        index++;

                    }

                }

                SV sv = new SV();

                SignatureReader sr = new SignatureReader(desc);

                sr.accept(sv);

                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) {

                        generateJSBody(args, javacall ? 

                            FnUtils.callback(body, JsClassLoader.this, FindInClass.this.name, FindInClass.this.methods) : 

                            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("/")) {

                    FnUtils.loadScript(JsClassLoader.this, relPath);

                } else {

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

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

                    FnUtils.loadScript(JsClassLoader.this, fullPath);

                }

            }

        }

    }

    private class ClassWriterEx extends ClassWriter {

        public ClassWriterEx(ClassReader classReader, int flags) {

            super(classReader, flags);

        }

        @Override

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

            Class<?> c, d;

            ClassLoader classLoader = JsClassLoader.this;

            try {

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

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

            } 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('.', '/');

            }

        }        

    }

}