/*

 * 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

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

 * questions.

 */

/*

 * This file is available under and governed by the GNU General Public

 * License version 2 only, as published by the Free Software Foundation.

 * However, the following notice accompanied the original version of this

 * file, and Oracle licenses the original version of this file under the BSD

 * license:

 */

/*

   Copyright 2009-2013 Attila Szegedi

*/

package jdk.dynalink.beans;

import java.lang.invoke.MethodHandle;

import jdk.dynalink.linker.GuardedInvocation;

/**

 * Represents one component for a GuardedInvocation of a potentially multi-namespace operation of an

 * {@link AbstractJavaLinker}. In addition to holding a guarded invocation, it holds semantic information about its

 * guard. All guards produced in the AbstractJavaLinker are either "Class.isInstance()" or "getClass() == clazz"

 * expressions. This allows choosing the most restrictive guard as the guard for the composition of two components.

 */

class GuardedInvocationComponent {

    enum ValidationType {

        NONE, // No guard; the operation can be linked unconditionally (quite rare); least strict.

        INSTANCE_OF, // "validatorClass.isInstance(obj)" guard

        EXACT_CLASS, // "obj.getClass() == validatorClass" guard; most strict.

        IS_ARRAY, // "obj.getClass().isArray()"

    }

    private final GuardedInvocation guardedInvocation;

    private final Validator validator;

    GuardedInvocationComponent(final MethodHandle invocation) {

        this(invocation, null, ValidationType.NONE);

    }

    GuardedInvocationComponent(final MethodHandle invocation, final MethodHandle guard, final ValidationType validationType) {

        this(invocation, guard, null, validationType);

    }

    GuardedInvocationComponent(final MethodHandle invocation, final MethodHandle guard, final Class<?> validatorClass,

            final ValidationType validationType) {

        this(invocation, guard, new Validator(validatorClass, validationType));

    }

    GuardedInvocationComponent(final GuardedInvocation guardedInvocation, final Class<?> validatorClass,

            final ValidationType validationType) {

        this(guardedInvocation, new Validator(validatorClass, validationType));

    }

    GuardedInvocationComponent replaceInvocation(final MethodHandle newInvocation) {

        return replaceInvocation(newInvocation, guardedInvocation.getGuard());

    }

    GuardedInvocationComponent replaceInvocation(final MethodHandle newInvocation, final MethodHandle newGuard) {

        return new GuardedInvocationComponent(guardedInvocation.replaceMethods(newInvocation,

                newGuard), validator);

    }

    private GuardedInvocationComponent(final MethodHandle invocation, final MethodHandle guard, final Validator validator) {

        this(new GuardedInvocation(invocation, guard), validator);

    }

    private GuardedInvocationComponent(final GuardedInvocation guardedInvocation, final Validator validator) {

        this.guardedInvocation = guardedInvocation;

        this.validator = validator;

    }

    GuardedInvocation getGuardedInvocation() {

        return guardedInvocation;

    }

    Class<?> getValidatorClass() {

        return validator.validatorClass;

    }

    ValidationType getValidationType() {

        return validator.validationType;

    }

    GuardedInvocationComponent compose(final MethodHandle compositeInvocation, final MethodHandle otherGuard,

            final Class<?> otherValidatorClass, final ValidationType otherValidationType) {

        final Validator compositeValidator = validator.compose(new Validator(otherValidatorClass, otherValidationType));

        final MethodHandle compositeGuard = compositeValidator == validator ? guardedInvocation.getGuard() : otherGuard;

        return new GuardedInvocationComponent(compositeInvocation, compositeGuard, compositeValidator);

    }

    private static class Validator {

        /*private*/ final Class<?> validatorClass;

        /*private*/ final ValidationType validationType;

        Validator(final Class<?> validatorClass, final ValidationType validationType) {

            this.validatorClass = validatorClass;

            this.validationType = validationType;

        }

        Validator compose(final Validator other) {

            if(other.validationType == ValidationType.NONE) {

                return this;

            }

            switch(validationType) {

                case NONE:

                    return other;

                case INSTANCE_OF:

                    switch(other.validationType) {

                        case INSTANCE_OF:

                            if(isAssignableFrom(other)) {

                                return other;

                            } else if(other.isAssignableFrom(this)) {

                                return this;

                            }

                            break;

                        case EXACT_CLASS:

                            if(isAssignableFrom(other)) {

                                return other;

                            }

                            break;

                        case IS_ARRAY:

                            if(validatorClass.isArray()) {

                                return this;

                            }

                            break;

                        default:

                            throw new AssertionError();

                    }

                    break;

                case EXACT_CLASS:

                    switch(other.validationType) {

                        case INSTANCE_OF:

                            if(other.isAssignableFrom(this)) {

                                return this;

                            }

                            break;

                        case EXACT_CLASS:

                            if(validatorClass == other.validatorClass) {

                                return this;

                            }

                            break;

                        case IS_ARRAY:

                            if(validatorClass.isArray()) {

                                return this;

                            }

                            break;

                        default:

                            throw new AssertionError();

                    }

                    break;

                case IS_ARRAY:

                    switch(other.validationType) {

                        case INSTANCE_OF:

                        case EXACT_CLASS:

                            if(other.validatorClass.isArray()) {

                                return other;

                            }

                            break;

                        case IS_ARRAY:

                            return this;

                        default:

                            throw new AssertionError();

                    }

                    break;

                default:

                    throw new AssertionError();

            }

            throw new AssertionError("Incompatible composition " + this + " vs " + other);

        }

        private boolean isAssignableFrom(final Validator other) {

            return validatorClass.isAssignableFrom(other.validatorClass);

        }

        @Override

        public String toString() {

            return "Validator[" + validationType + (validatorClass == null ? "" : (" " + validatorClass.getName())) + "]";

        }

    }

}