/*
 * Copyright (c) 2005, 2019, 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
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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 java.util.stream.Collectors;
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;
import static com.sun.tools.javac.code.Kinds.Kind.*;

A generator of dynamic proxy implementations of
java.lang.annotation.Annotation.
 The "dynamic proxy return form" of an annotation element value is
the form used by sun.reflect.annotation.AnnotationInvocationHandler.
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.
/**
 * 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.
/**
     * 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.
/**
     * 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.
/**
     * 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.
/**
     * 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)) {
            if (s.kind == MTH) {
                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.
/**
     * 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.
/**
         * 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.
/**
     * 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 + ".class";
        }

        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.
/**
     * 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 types.stream()
                .map(t -> t.toString() + ".class")
                .collect(Collectors.joining(", ", "{", "}"));
        }

        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;
        }
    }
}