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/*
 * Copyright 2015 Austin Keener, Michael Ritter, Florian Spieß, and the JDA contributors
 *
 * 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 net.dv8tion.jda.api.exceptions;

import net.dv8tion.jda.internal.utils.Helpers;

import javax.annotation.Nonnull;
import java.util.function.Consumer;

/**
 * Used to pass a context to async exception handling for debugging purposes.
 */
public class ContextException extends Exception
{
    /**
     * Creates a failure consumer that appends a context cause
     * before printing the stack trace using {@link Throwable#printStackTrace()}.
     * 
Equivalent to {@code here(Throwable::printStackTrace)}
     *
     * @return Wrapping failure consumer around {@code Throwable::printStackTrace}
     */
    @Nonnull
    public static Consumer herePrintingTrace()
    {
        return here(Throwable::printStackTrace);
    }

    /**
     * Creates a wrapping {@link java.util.function.Consumer Consumer} for
     * the provided target.
     *
     * @param  acceptor
     *         The end-target for the throwable
     *
     * @return Wrapper of the provided consumer that will append a context with the current stack-trace
     */
    @Nonnull
    public static Consumer here(@Nonnull Consumer acceptor)
    {
        return new ContextConsumer(new ContextException(), acceptor);
    }

    /**
     * Wrapper for a failure {@link Consumer} that carries a {@link ContextException} as cause.
     */
    public static class ContextConsumer implements Consumer
    {
        private final ContextException context;
        private final Consumer callback;

        private ContextConsumer(ContextException context, Consumer callback)
        {
            this.context = context;
            this.callback = callback;
        }

        @Override
        public void accept(Throwable throwable)
        {
            if (callback != null)
                callback.accept(Helpers.appendCause(throwable, context));
        }
    }
}