/*

 * Copyright (c) 2011, 2015, 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.

 *

 * 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 jdk.vm.ci.hotspot;

import static jdk.vm.ci.hotspot.HotSpotJVMCIRuntime.runtime;

import static jdk.vm.ci.hotspot.HotSpotVMConfig.config;

import java.lang.annotation.Annotation;

import java.lang.reflect.Field;

import jdk.vm.ci.common.JVMCIError;

import jdk.vm.ci.meta.JavaType;

import jdk.vm.ci.meta.LocationIdentity;

import jdk.vm.ci.meta.MetaAccessProvider;

import jdk.vm.ci.meta.ModifiersProvider;

import jdk.vm.ci.meta.ResolvedJavaField;

import jdk.vm.ci.meta.ResolvedJavaType;

import jdk.vm.ci.options.Option;

import jdk.vm.ci.options.OptionType;

import jdk.vm.ci.options.OptionValue;

/**

 * Represents a field in a HotSpot type.

 */

class HotSpotResolvedJavaFieldImpl implements HotSpotResolvedJavaField, HotSpotProxified {

    static class Options {

        //@formatter:off

        @Option(help = "Mark well-known stable fields as such.", type = OptionType.Debug)

        public static final OptionValue<Boolean> ImplicitStableValues = new OptionValue<>(true);

        //@formatter:on

    }

    private final HotSpotResolvedObjectTypeImpl holder;

    private final String name;

    private JavaType type;

    private final int offset;

    /**

     * This value contains all flags as stored in the VM including internal ones.

     */

    private final int modifiers;

    private final LocationIdentity locationIdentity = new FieldLocationIdentity(this);

    public static class FieldLocationIdentity extends LocationIdentity {

        HotSpotResolvedJavaField inner;

        public FieldLocationIdentity(HotSpotResolvedJavaFieldImpl inner) {

            this.inner = inner;

        }

        @Override

        public boolean isImmutable() {

            return false;

        }

        @Override

        public boolean equals(Object obj) {

            if (this == obj) {

                return true;

            }

            if (obj instanceof FieldLocationIdentity) {

                FieldLocationIdentity fieldLocationIdentity = (FieldLocationIdentity) obj;

                return inner.equals(fieldLocationIdentity.inner);

            }

            return false;

        }

        @Override

        public int hashCode() {

            return inner.hashCode();

        }

        @Override

        public String toString() {

            return inner.getName();

        }

    }

    HotSpotResolvedJavaFieldImpl(HotSpotResolvedObjectTypeImpl holder, String name, JavaType type, long offset, int modifiers) {

        this.holder = holder;

        this.name = name;

        this.type = type;

        assert offset != -1;

        assert offset == (int) offset : "offset larger than int";

        this.offset = (int) offset;

        this.modifiers = modifiers;

    }

    @Override

    public boolean equals(Object obj) {

        if (this == obj) {

            return true;

        }

        if (obj instanceof HotSpotResolvedJavaField) {

            HotSpotResolvedJavaFieldImpl that = (HotSpotResolvedJavaFieldImpl) obj;

            if (that.offset != this.offset || that.isStatic() != this.isStatic()) {

                return false;

            } else if (this.holder.equals(that.holder)) {

                assert this.name.equals(that.name) && this.type.equals(that.type);

                return true;

            }

        }

        return false;

    }

    @Override

    public int hashCode() {

        return name.hashCode();

    }

    @Override

    public int getModifiers() {

        return modifiers & ModifiersProvider.jvmFieldModifiers();

    }

    @Override

    public boolean isInternal() {

        return (modifiers & config().jvmAccFieldInternal) != 0;

    }

    /**

     * Determines if a given object contains this field.

     *

     * @return true iff this is a non-static field and its declaring class is assignable from

     *         {@code object}'s class

     */

    public boolean isInObject(Object object) {

        if (isStatic()) {

            return false;

        }

        return getDeclaringClass().isAssignableFrom(HotSpotResolvedObjectTypeImpl.fromObjectClass(object.getClass()));

    }

    @Override

    public HotSpotResolvedObjectTypeImpl getDeclaringClass() {

        return holder;

    }

    @Override

    public String getName() {

        return name;

    }

    @Override

    public JavaType getType() {

        // Pull field into local variable to prevent a race causing

        // a ClassCastException below

        JavaType currentType = type;

        if (currentType instanceof HotSpotUnresolvedJavaType) {

            // Don't allow unresolved types to hang around forever

            HotSpotUnresolvedJavaType unresolvedType = (HotSpotUnresolvedJavaType) currentType;

            ResolvedJavaType resolved = unresolvedType.reresolve(holder);

            if (resolved != null) {

                type = resolved;

            }

        }

        return type;

    }

    public int offset() {

        return offset;

    }

    @Override

    public String toString() {

        return format("HotSpotField<%H.%n %t:") + offset + ">";

    }

    @Override

    public boolean isSynthetic() {

    }

    /**

     * Checks if this field has the {@link Stable} annotation.

     *

     * @return true if field has {@link Stable} annotation, false otherwise

     */

    public boolean isStable() {

        if ((config().jvmAccFieldStable & modifiers) != 0) {

            return true;

        }

        assert getAnnotation(Stable.class) == null;

        if (Options.ImplicitStableValues.getValue() && isImplicitStableField()) {

            return true;

        }

        return false;

    }

    @Override

    public Annotation[] getAnnotations() {

        Field javaField = toJava();

        if (javaField != null) {

            return javaField.getAnnotations();

        }

        return new Annotation[0];

    }

    @Override

    public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {

        Field javaField = toJava();

        if (javaField != null) {

            return javaField.getAnnotation(annotationClass);

        }

        return null;

    }

    private Field toJavaCache;

    private Field toJava() {

        if (toJavaCache != null) {

            return toJavaCache;

        }

        if (isInternal()) {

            return null;

        }

        try {

            return toJavaCache = holder.mirror().getDeclaredField(name);

        } catch (NoSuchFieldException | NoClassDefFoundError e) {

            return null;

        }

    }

    private boolean isArray() {

        JavaType fieldType = getType();

        return fieldType instanceof ResolvedJavaType && ((ResolvedJavaType) fieldType).isArray();

    }

    private boolean isImplicitStableField() {

        if (isSyntheticEnumSwitchMap()) {

            return true;

        }

        if (isWellKnownImplicitStableField()) {

            return true;

        }

        return false;

    }

    public boolean isDefaultStable() {

        assert this.isStable();

        if (isSyntheticEnumSwitchMap()) {

            return true;

        }

        return false;

    }

    private boolean isSyntheticEnumSwitchMap() {

        if (isSynthetic() && isStatic() && isArray()) {

            if (isFinal() && name.equals("$VALUES") || name.equals("ENUM$VALUES")) {

                // generated int[] field for EnumClass::values()

                return true;

            } else if (name.startsWith("$SwitchMap$") || name.startsWith("$SWITCH_TABLE$")) {

                // javac and ecj generate a static field in an inner class for a switch on an enum

                // named $SwitchMap$p$k$g$EnumClass and $SWITCH_TABLE$p$k$g$EnumClass, respectively

                return true;

            }

        }

        return false;

    }

    private boolean isWellKnownImplicitStableField() {

        return WellKnownImplicitStableField.test(this);

    }

    static class WellKnownImplicitStableField {

        /**

         * @return {@code true} if the field is a well-known stable field.

         */

        public static boolean test(HotSpotResolvedJavaField field) {

            return field.equals(STRING_VALUE_FIELD);

        }

        private static final ResolvedJavaField STRING_VALUE_FIELD;

        static {

            try {

                MetaAccessProvider metaAccess = runtime().getHostJVMCIBackend().getMetaAccess();

                STRING_VALUE_FIELD = metaAccess.lookupJavaField(String.class.getDeclaredField("value"));

            } catch (SecurityException | NoSuchFieldException e) {

                throw new JVMCIError(e);

            }

        }

    }

    public LocationIdentity getLocationIdentity() {

        return locationIdentity;

    }

}