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/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.gh.bmd.jrt.invocation;

import com.gh.bmd.jrt.channel.RoutineException;
import com.gh.bmd.jrt.util.ClassToken;

import java.lang.reflect.Constructor;
import java.util.Arrays;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

import static com.gh.bmd.jrt.util.Reflection.NO_ARGS;
import static com.gh.bmd.jrt.util.Reflection.findConstructor;

/**
 * Utility class for creating invocation factory objects.
 * 
 * Created by davide-maestroni on 2/12/15.
 */
public class Invocations {

    /**
     * Avoid direct instantiation.
     */
    protected Invocations() {

    }

    /**
     * Builds and returns a new invocation factory creating instances of the specified class.
     *
     * @param invocationClass the invocation class.
     * @param          the input data type.
     * @param         the output data type.
     * @return the invocation factory.
     * @throws java.lang.IllegalArgumentException if no default constructor was found.
     */
    @Nonnull
    public static  InvocationFactory factoryOf(
            @Nonnull final Class> invocationClass) {

        return factoryOf(invocationClass, (Object[]) null);
    }

    /**
     * Builds and returns a new invocation factory creating instances of the specified class by
     * passing the specified arguments to the class constructor.
     * 

     * Note that inner and anonymous classes can be passed as well. Remember however that Java
     * creates synthetic constructors for such classes, so be sure to specify the correct arguments
     * to guarantee proper instantiation. In fact, inner classes always have the outer instance as
     * first constructor parameter, and anonymous classes have both the outer instance and all the
     * variables captured in the closure.
     *
     * @param invocationClass the invocation class.
     * @param args            the invocation constructor arguments.
     * @param          the input data type.
     * @param         the output data type.
     * @return the invocation factory.
     * @throws java.lang.IllegalArgumentException if no constructor taking the specified objects as
     *                                            parameters was found.
     */
    @Nonnull
    public static  InvocationFactory factoryOf(
            @Nonnull final Class> invocationClass,
            @Nullable final Object... args) {

        return new DefaultInvocationFactory(invocationClass, args);
    }

    /**
     * Builds and returns a new invocation factory creating instances of the specified class token.
     *
     * @param invocationToken the invocation class token.
     * @param          the input data type.
     * @param         the output data type.
     * @return the invocation factory.
     * @throws java.lang.IllegalArgumentException if no default constructor was found.
     */
    @Nonnull
    public static  InvocationFactory factoryOf(
            @Nonnull final ClassToken> invocationToken) {

        return factoryOf(invocationToken.getRawClass());
    }

    /**
     * Builds and returns a new invocation factory creating instances of the specified class token
     * by passing the specified arguments to the class constructor.
     * 

     * Note that class tokens of inner and anonymous classes can be passed as well. Remember however
     * that Java creates synthetic constructors for such classes, so be sure to specify the correct
     * arguments to guarantee proper instantiation. In fact, inner classes always have the outer
     * instance as first constructor parameter, and anonymous classes have both the outer instance
     * and all the variables captured in the closure.
     *
     * @param invocationToken the invocation class token.
     * @param args            the invocation constructor arguments.
     * @param          the input data type.
     * @param         the output data type.
     * @return the invocation factory.
     * @throws java.lang.IllegalArgumentException if no constructor taking the specified objects as
     *                                            parameters was found.
     */
    @Nonnull
    public static  InvocationFactory factoryOf(
            @Nonnull final ClassToken> invocationToken,
            @Nullable final Object... args) {

        return factoryOf(invocationToken.getRawClass(), args);
    }

    /**
     * Builds and returns a new invocation factory creating instances of the specified object.
     *
     * @param invocation the invocation instance.
     * @param     the input data type.
     * @param    the output data type.
     * @return the invocation factory.
     * @throws java.lang.IllegalArgumentException if no default constructor was found.
     */
    @Nonnull
    @SuppressWarnings("unchecked")
    public static  InvocationFactory factoryOf(
            @Nonnull final Invocation invocation) {

        return factoryOf((Class>) invocation.getClass());
    }

    /**
     * Builds and returns a new invocation factory creating instances of the specified object by
     * passing the specified arguments to the class constructor.
     * 
     * Note that inner and anonymous objects can be passed as well. Remember however that Java
     * creates synthetic constructors for such classes, so be sure to specify the correct arguments
     * to guarantee proper instantiation. In fact, inner classes always have the outer instance as
     * first constructor parameter, and anonymous classes have both the outer instance and all the
     * variables captured in the closure.
     *
     * @param invocation the invocation instance.
     * @param args       the invocation constructor arguments.
     * @param     the input data type.
     * @param    the output data type.
     * @return the invocation factory.
     * @throws java.lang.IllegalArgumentException if no constructor taking the specified objects as
     *                                            parameters was found.
     */
    @Nonnull
    @SuppressWarnings("unchecked")
    public static  InvocationFactory factoryOf(
            @Nonnull final Invocation invocation, @Nullable final Object... args) {

        return factoryOf((Class>) invocation.getClass(), args);
    }

    /**
     * Default implementation of an invocation factory.
     *
     * @param   the input data type.
     * @param  the output data type.
     */
    public static class DefaultInvocationFactory
            implements InvocationFactory {

        private final Object[] mArgs;

        private final Constructor> mConstructor;

        /**
         * Constructor.
         *
         * @param invocationClass the invocation class.
         * @param args            the invocation constructor arguments.
         * @throws java.lang.IllegalArgumentException if no constructor taking the specified objects
         *                                            as parameters was found.
         */
        @SuppressWarnings("ConstantConditions")
        private DefaultInvocationFactory(
                @Nonnull final Class> invocationClass,
                @Nullable final Object[] args) {

            final Object[] invocationArgs = (mArgs = (args != null) ? args.clone() : NO_ARGS);
            mConstructor = findConstructor(invocationClass, invocationArgs);
        }

        @Override
        public int hashCode() {

            // auto-generated code
            int result = Arrays.hashCode(mArgs);
            result = 31 * result + mConstructor.hashCode();
            return result;
        }

        @Override
        public boolean equals(final Object o) {

            // auto-generated code
            if (this == o) {

                return true;
            }

            if (!(o instanceof DefaultInvocationFactory)) {

                return false;
            }

            final DefaultInvocationFactory that = (DefaultInvocationFactory) o;
            return Arrays.equals(mArgs, that.mArgs) && mConstructor.equals(that.mConstructor);
        }

        @Nonnull
        public Invocation newInvocation() {

            try {

                return mConstructor.newInstance(mArgs);

            } catch (final RoutineException e) {

                throw e;

            } catch (final Throwable t) {

                throw new InvocationException(t);
            }
        }
    }
}