GatewayServiceUnavailableException.java

/*
 * Copyright (c) 2017-2018 Bosch Software Innovations GmbH.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/org/documents/epl-2.0/index.php
 *
 * SPDX-License-Identifier: EPL-2.0
 */
package org.eclipse.ditto.signals.commands.base.exceptions;

import java.net.URI;

import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
import javax.annotation.concurrent.NotThreadSafe;

import org.eclipse.ditto.json.JsonObject;
import org.eclipse.ditto.model.base.common.HttpStatusCode;
import org.eclipse.ditto.model.base.exceptions.DittoRuntimeException;
import org.eclipse.ditto.model.base.exceptions.DittoRuntimeExceptionBuilder;
import org.eclipse.ditto.model.base.headers.DittoHeaders;

/**
 * This exception indicates that a service the API Gateway proxies was not available.
 */
@Immutable
public final class GatewayServiceUnavailableException extends DittoRuntimeException implements GatewayException {

    /**
     * Error code of this exception.
     */
    public static final String ERROR_CODE = ERROR_CODE_PREFIX + "service.unavailable";

    private static final String DEFAULT_MESSAGE = "The service you wanted to reach is currently not available.";
    private static final String DEFAULT_DESCRIPTION = "Please contact the service team if this happens again.";

    private static final long serialVersionUID = 1164234483383740723L;

    private GatewayServiceUnavailableException(final DittoHeaders dittoHeaders, @Nullable final String message,
            @Nullable final String description, @Nullable final Throwable cause, @Nullable final URI href) {
        super(ERROR_CODE, HttpStatusCode.SERVICE_UNAVAILABLE, dittoHeaders, message, description, cause, href);
    }

    /**
     * A mutable builder for a {@code GatewayServiceUnavailableException}.
     *
     * @return the builder.
     */
    public static Builder newBuilder() {
        return new Builder();
    }

    /**
     * Constructs a new {@code GatewayServiceUnavailableException} object with given message.
     *
     * @param message detail message. This message can be later retrieved by the {@link #getMessage()} method.
     * @param dittoHeaders the headers of the command which resulted in this exception.
     * @return the new GatewayServiceUnavailableException.
     */
    public static GatewayServiceUnavailableException fromMessage(final String message,
            final DittoHeaders dittoHeaders) {
        return new Builder()
                .dittoHeaders(dittoHeaders)
                .message(message)
                .build();
    }

    /**
     * Constructs a new {@code GatewayServiceUnavailableException} object with the exception message extracted from the given
     * JSON object.
     *
     * @param jsonObject the JSON to read the {@link JsonFields#MESSAGE} field from.
     * @param dittoHeaders the headers of the command which resulted in this exception.
     * @return the new GatewayServiceUnavailableException.
     * @throws org.eclipse.ditto.json.JsonMissingFieldException if the {@code jsonObject} does not have the {@link
     * JsonFields#MESSAGE} field.
     */
    public static GatewayServiceUnavailableException fromJson(final JsonObject jsonObject,
            final DittoHeaders dittoHeaders) {
        return new Builder()
                .dittoHeaders(dittoHeaders)
                .message(readMessage(jsonObject))
                .description(readDescription(jsonObject).orElse(DEFAULT_DESCRIPTION))
                .href(readHRef(jsonObject).orElse(null))
                .build();
    }

    /**
     * A mutable builder with a fluent API for a {@link GatewayServiceUnavailableException}.
     */
    @NotThreadSafe
    public static final class Builder extends DittoRuntimeExceptionBuilder<GatewayServiceUnavailableException> {

        private Builder() {
            message(DEFAULT_MESSAGE);
            description(DEFAULT_DESCRIPTION);
        }

        @Override
        protected GatewayServiceUnavailableException doBuild(final DittoHeaders dittoHeaders,
                @Nullable final String message, @Nullable final String description, @Nullable final Throwable cause,
                @Nullable final URI href) {
            return new GatewayServiceUnavailableException(dittoHeaders, message, description, cause, href);
        }
    }
}