/*

 * Copyright (c) 2010, 2013, 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 jdk.nashorn.internal.runtime;

import static jdk.nashorn.internal.runtime.linker.Lookup.MH;

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodHandles;

import jdk.nashorn.internal.runtime.linker.NashornCallSiteDescriptor;

import org.dynalang.dynalink.CallSiteDescriptor;

import org.dynalang.dynalink.linker.GuardedInvocation;

import org.dynalang.dynalink.support.CallSiteDescriptorFactory;

/**

 * This class supports the handling of scope in a with body.

 *

 */

public class WithObject extends ScriptObject implements Scope {

    private static final MethodHandle WITHEXPRESSIONFILTER = findOwnMH("withFilterExpression", Object.class, Object.class);

    private static final MethodHandle WITHSCOPEFILTER      = findOwnMH("withFilterScope",      Object.class, Object.class);

    private static final MethodHandle BIND_TO_EXPRESSION   = findOwnMH("bindToExpression",     Object.class, Object.class, Object.class);

    /** With expression object. */

    private final Object expression;

    /**

     * Constructor

     *

     * @param scope scope object

     * @param expression with expression

     */

    public WithObject(final ScriptObject scope, final Object expression) {

        super();

        setIsScope();

        setProto(scope);

        this.expression = expression;

    }

    /**

     * Delete a property based on a key.

     * @param key Any valid JavaScript value.

     * @param strict strict mode execution.

     * @return True if deleted.

     */

    @Override

    public boolean delete(final Object key, final boolean strict) {

        if (expression instanceof ScriptObject) {

            final ScriptObject self = (ScriptObject)expression;

            final String propName = ScriptObject.convertKey(key);

            final FindProperty find = self.findProperty(propName, true);

            if (find != null) {

                return self.delete(propName, strict);

            }

        }

        return false;

    }

    @Override

        // With scopes can never be observed outside of Nashorn code, so all call sites that can address it will of

        // necessity have a Nashorn descriptor - it is safe to cast.

        final NashornCallSiteDescriptor ndesc = (NashornCallSiteDescriptor)desc;

        FindProperty find = null;

        GuardedInvocation link = null;

        ScriptObject self = null;

        final boolean isNamedOperation;

        final String name;

        if(desc.getNameTokenCount() > 2) {

            isNamedOperation = true;

            name = desc.getNameToken(CallSiteDescriptor.NAME_OPERAND);

        } else {

            isNamedOperation = false;

            name = null;

        }

        if (expression instanceof ScriptObject) {

            self = (ScriptObject)expression;

            if (isNamedOperation) {

                find = self.findProperty(name, true);

            }

            if (find != null) {

                if (link != null) {

                    return fixExpressionCallSite(ndesc, link);

                }

            }

        }

        final ScriptObject scope = getProto();

        if (isNamedOperation) {

            find = scope.findProperty(name, true);

        }

        if (find != null) {

        }

        // the property is not found - now check for

        // __noSuchProperty__ and __noSuchMethod__ in expression

        if (self != null) {

            final String fallBack;

            final String operator = CallSiteDescriptorFactory.tokenizeOperators(desc).get(0);

            switch (operator) {

            case "callMethod":

                throw new AssertionError(); // Nashorn never emits callMethod

            case "getMethod":

                fallBack = NO_SUCH_METHOD_NAME;

                break;

            case "getProp":

            case "getElem":

                fallBack = NO_SUCH_PROPERTY_NAME;

                break;

            default:

                fallBack = null;

                break;

            }

            if (fallBack != null) {

                find = self.findProperty(fallBack, true);

                if (find != null) {

                    switch (operator) {

                    case "getMethod":

                        break;

                    case "getProp":

                    case "getElem":

                        break;

                    default:

                        break;

                    }

                }

            }

            if (link != null) {

                return fixExpressionCallSite(ndesc, link);

            }

        }

        // still not found, may be scope can handle with it's own

        // __noSuchProperty__, __noSuchMethod__ etc.

        if (link != null) {

            return fixScopeCallSite(link);

        }

        return null;

    }

    @Override

    public void setSplitState(final int state) {

        getNonWithParent().setSplitState(state);

    }

    @Override

    public int getSplitState() {

        return getNonWithParent().getSplitState();

    }

    /**

     * Get first parent scope that is not an instance of WithObject.

     */

    private Scope getNonWithParent() {

        ScriptObject proto = getProto();

        while (proto != null && proto instanceof WithObject) {

            proto = proto.getProto();

        }

        assert proto instanceof Scope : "with scope without parent scope";

        return (Scope) proto;

    }

    private static GuardedInvocation fixExpressionCallSite(final NashornCallSiteDescriptor desc, final GuardedInvocation link) {

        // If it's not a getMethod, just add an expression filter that converts WithObject in "this" position to its

        // expression.

        if(!"getMethod".equals(desc.getFirstOperator())) {

            return link.filterArguments(0, WITHEXPRESSIONFILTER);

        }

        return link.replaceMethods(

                // Make sure getMethod will bind the script functions it receives to WithObject.expression

                MH.foldArguments(BIND_TO_EXPRESSION, filter(link.getInvocation(), WITHEXPRESSIONFILTER)),

                // No clever things for the guard -- it is still identically filtered.

                filterGuard(link, WITHEXPRESSIONFILTER));

    }

    private static GuardedInvocation fixScopeCallSite(final GuardedInvocation link) {

        return link.replaceMethods(filter(link.getInvocation(), WITHSCOPEFILTER), filterGuard(link, WITHSCOPEFILTER));

    }

    private static MethodHandle filterGuard(final GuardedInvocation link, final MethodHandle filter) {

        final MethodHandle test = link.getGuard();

        return test == null ? null : filter(test, filter);

    }

    private static MethodHandle filter(final MethodHandle mh, final MethodHandle filter) {

        return MH.filterArguments(mh, 0, filter);

    }

    /**

     * Drops the WithObject wrapper from the expression.

     * @param receiver WithObject wrapper.

     * @return The with expression.

     */

    public static Object withFilterExpression(final Object receiver) {

        return ((WithObject)receiver).expression;

    }

    @SuppressWarnings("unused")

    private static Object bindToExpression(final Object fn, final Object receiver) {

        return fn instanceof ScriptFunction ? ((ScriptFunction) fn).makeBoundFunction(withFilterExpression(receiver), new Object[0]) : fn;

    }

    /**

     * Drops the WithObject wrapper from the scope.

     * @param receiver WithObject wrapper.

     * @return The with scope.

     */

    public static Object withFilterScope(final Object receiver) {

        return ((WithObject)receiver).getProto();

    }

    /**

     * Get the with expression for this {@code WithObject}

     * @return the with expression

     */

    public Object getExpression() {

        return expression;

    }

    private static MethodHandle findOwnMH(final String name, final Class<?> rtype, final Class<?>... types) {

        return MH.findStatic(MethodHandles.lookup(), WithObject.class, name, MH.type(rtype, types));

    }

}