/*

 * Copyright (c) 2005, 2014, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

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

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.tools.javac.model;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.lang.annotation.*;

import java.lang.reflect.Array;

import java.lang.reflect.Method;

import java.util.LinkedHashMap;

import java.util.Map;

import sun.reflect.annotation.*;

import javax.lang.model.type.MirroredTypeException;

import javax.lang.model.type.MirroredTypesException;

import javax.lang.model.type.TypeMirror;

import com.sun.tools.javac.code.*;

import com.sun.tools.javac.code.Symbol.*;

import com.sun.tools.javac.code.Type.ArrayType;

import com.sun.tools.javac.util.*;

import static com.sun.tools.javac.code.Scope.LookupKind.NON_RECURSIVE;

/**

 * A generator of dynamic proxy implementations of

 * java.lang.annotation.Annotation.

 *

 * <p> The "dynamic proxy return form" of an annotation element value is

 * the form used by sun.reflect.annotation.AnnotationInvocationHandler.

 *

 * <p><b>This is NOT part of any supported API.

 * If you write code that depends on this, you do so at your own risk.

 * This code and its internal interfaces are subject to change or

 * deletion without notice.</b>

 */

public class AnnotationProxyMaker {

    private final Attribute.Compound anno;

    private final Class<? extends Annotation> annoType;

    private AnnotationProxyMaker(Attribute.Compound anno,

                                 Class<? extends Annotation> annoType) {

        this.anno = anno;

        this.annoType = annoType;

    }

    /**

     * Returns a dynamic proxy for an annotation mirror.

     */

    public static <A extends Annotation> A generateAnnotation(

            Attribute.Compound anno, Class<A> annoType) {

        AnnotationProxyMaker apm = new AnnotationProxyMaker(anno, annoType);

        return annoType.cast(apm.generateAnnotation());

    }

    /**

     * Returns a dynamic proxy for an annotation mirror.

     */

    private Annotation generateAnnotation() {

        return AnnotationParser.annotationForMap(annoType,

                                                 getAllReflectedValues());

    }

    /**

     * Returns a map from element names to their values in "dynamic

     * proxy return form".  Includes all elements, whether explicit or

     * defaulted.

     */

    private Map<String, Object> getAllReflectedValues() {

        Map<String, Object> res = new LinkedHashMap<>();

        for (Map.Entry<MethodSymbol, Attribute> entry :

                                                  getAllValues().entrySet()) {

            MethodSymbol meth = entry.getKey();

            Object value = generateValue(meth, entry.getValue());

            if (value != null) {

                res.put(meth.name.toString(), value);

            } else {

                // Ignore this element.  May (properly) lead to

                // IncompleteAnnotationException somewhere down the line.

            }

        }

        return res;

    }

    /**

     * Returns a map from element symbols to their values.

     * Includes all elements, whether explicit or defaulted.

     */

    private Map<MethodSymbol, Attribute> getAllValues() {

        Map<MethodSymbol, Attribute> res = new LinkedHashMap<>();

        // First find the default values.

        ClassSymbol sym = (ClassSymbol) anno.type.tsym;

        for (Symbol s : sym.members().getSymbols(NON_RECURSIVE)) {

                MethodSymbol m = (MethodSymbol) s;

                Attribute def = m.getDefaultValue();

                if (def != null)

                    res.put(m, def);

            }

        }

        // Next find the explicit values, possibly overriding defaults.

        for (Pair<MethodSymbol, Attribute> p : anno.values)

            res.put(p.fst, p.snd);

        return res;

    }

    /**

     * Converts an element value to its "dynamic proxy return form".

     * Returns an exception proxy on some errors, but may return null if

     * a useful exception cannot or should not be generated at this point.

     */

    private Object generateValue(MethodSymbol meth, Attribute attr) {

        ValueVisitor vv = new ValueVisitor(meth);

        return vv.getValue(attr);

    }

    private class ValueVisitor implements Attribute.Visitor {

        private MethodSymbol meth;      // annotation element being visited

        private Class<?> returnClass;   // return type of annotation element

        private Object value;           // value in "dynamic proxy return form"

        ValueVisitor(MethodSymbol meth) {

            this.meth = meth;

        }

        Object getValue(Attribute attr) {

            Method method;              // runtime method of annotation element

            try {

                method = annoType.getMethod(meth.name.toString());

            } catch (NoSuchMethodException e) {

                return null;

            }

            returnClass = method.getReturnType();

            attr.accept(this);

            if (!(value instanceof ExceptionProxy) &&

                !AnnotationType.invocationHandlerReturnType(returnClass)

                                                        .isInstance(value)) {

                typeMismatch(method, attr);

            }

            return value;

        }

        public void visitConstant(Attribute.Constant c) {

            value = c.getValue();

        }

        public void visitClass(Attribute.Class c) {

            value = new MirroredTypeExceptionProxy(c.classType);

        }

        public void visitArray(Attribute.Array a) {

            Name elemName = ((ArrayType) a.type).elemtype.tsym.getQualifiedName();

            if (elemName.equals(elemName.table.names.java_lang_Class)) {   // Class[]

                // Construct a proxy for a MirroredTypesException

                ListBuffer<TypeMirror> elems = new ListBuffer<>();

                for (Attribute value : a.values) {

                    Type elem = ((Attribute.Class) value).classType;

                    elems.append(elem);

                }

                value = new MirroredTypesExceptionProxy(elems.toList());

            } else {

                int len = a.values.length;

                Class<?> returnClassSaved = returnClass;

                returnClass = returnClass.getComponentType();

                try {

                    Object res = Array.newInstance(returnClass, len);

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

                        a.values[i].accept(this);

                        if (value == null || value instanceof ExceptionProxy) {

                            return;

                        }

                        try {

                            Array.set(res, i, value);

                        } catch (IllegalArgumentException e) {

                            value = null;       // indicates a type mismatch

                            return;

                        }

                    }

                    value = res;

                } finally {

                    returnClass = returnClassSaved;

                }

            }

        }

        @SuppressWarnings({"unchecked", "rawtypes"})

        public void visitEnum(Attribute.Enum e) {

            if (returnClass.isEnum()) {

                String constName = e.value.toString();

                try {

                    value = Enum.valueOf((Class)returnClass, constName);

                } catch (IllegalArgumentException ex) {

                    value = new EnumConstantNotPresentExceptionProxy(

                                        (Class<Enum<?>>) returnClass, constName);

                }

            } else {

                value = null;   // indicates a type mismatch

            }

        }

        public void visitCompound(Attribute.Compound c) {

            try {

                Class<? extends Annotation> nested =

                    returnClass.asSubclass(Annotation.class);

                value = generateAnnotation(c, nested);

            } catch (ClassCastException ex) {

                value = null;   // indicates a type mismatch

            }

        }

        public void visitError(Attribute.Error e) {

            if (e instanceof Attribute.UnresolvedClass)

                value = new MirroredTypeExceptionProxy(((Attribute.UnresolvedClass)e).classType);

            else

                value = null;       // indicates a type mismatch

        }

        /**

         * Sets "value" to an ExceptionProxy indicating a type mismatch.

         */

        private void typeMismatch(Method method, final Attribute attr) {

            class AnnotationTypeMismatchExceptionProxy extends ExceptionProxy {

                static final long serialVersionUID = 269;

                transient final Method method;

                AnnotationTypeMismatchExceptionProxy(Method method) {

                    this.method = method;

                }

                public String toString() {

                    return "<error>";   // eg:  @Anno(value=<error>)

                }

                protected RuntimeException generateException() {

                    return new AnnotationTypeMismatchException(method,

                                attr.type.toString());

                }

            }

            value = new AnnotationTypeMismatchExceptionProxy(method);

        }

    }

    /**

     * ExceptionProxy for MirroredTypeException.

     * The toString, hashCode, and equals methods forward to the underlying

     * type.

     */

    private static final class MirroredTypeExceptionProxy extends ExceptionProxy {

        static final long serialVersionUID = 269;

        private transient TypeMirror type;

        private final String typeString;

        MirroredTypeExceptionProxy(TypeMirror t) {

            type = t;

            typeString = t.toString();

        }

        public String toString() {

            return typeString;

        }

        public int hashCode() {

            return (type != null ? type : typeString).hashCode();

        }

        public boolean equals(Object obj) {

            return type != null &&

                   obj instanceof MirroredTypeExceptionProxy &&

                   type.equals(((MirroredTypeExceptionProxy) obj).type);

        }

        protected RuntimeException generateException() {

            return new MirroredTypeException(type);

        }

        // Explicitly set all transient fields.

        private void readObject(ObjectInputStream s)

            throws IOException, ClassNotFoundException {

            s.defaultReadObject();

            type = null;

        }

    }

    /**

     * ExceptionProxy for MirroredTypesException.

     * The toString, hashCode, and equals methods foward to the underlying

     * types.

     */

    private static final class MirroredTypesExceptionProxy extends ExceptionProxy {

        static final long serialVersionUID = 269;

        private transient List<TypeMirror> types;

        private final String typeStrings;

        MirroredTypesExceptionProxy(List<TypeMirror> ts) {

            types = ts;

            typeStrings = ts.toString();

        }

        public String toString() {

            return typeStrings;

        }

        public int hashCode() {

            return (types != null ? types : typeStrings).hashCode();

        }

        public boolean equals(Object obj) {

            return types != null &&

                   obj instanceof MirroredTypesExceptionProxy &&

                   types.equals(

                      ((MirroredTypesExceptionProxy) obj).types);

        }

        protected RuntimeException generateException() {

            return new MirroredTypesException(types);

        }

        // Explicitly set all transient fields.

        private void readObject(ObjectInputStream s)

            throws IOException, ClassNotFoundException {

            s.defaultReadObject();

            types = null;

        }

    }

}