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A single bundled dependency that includes all service and dependent JARs with third-party libraries relocated to different namespaces.
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/*
 * Copyright 2010-2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file 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 software.amazon.awssdk.utils;

import java.util.Optional;
import software.amazon.awssdk.annotations.SdkProtectedApi;
import software.amazon.awssdk.utils.internal.SystemSettingUtils;

/**
 * An interface implemented by enums in other packages in order to define the system settings the want loaded. An enum
 * is expected to implement this interface, and then have values loaded from the {@link System} using methods like
 * {@link #getStringValue()}.
 */
@SdkProtectedApi
public interface SystemSetting {
    /**
     * The system property of the setting (or null if there is no property for this setting).
     */
    String property();

    /**
     * The environment variable of the setting (or null if there is no environment variable for this setting).
     */
    String environmentVariable();

    /**
     * The default value of the setting (or empty if there is no default). This value will be applied if the customer did not
     * specify a setting.
     */
    String defaultValue();

    /**
     * Attempt to load a system setting from {@link System#getProperty(String)} and {@link System#getenv(String)}. This should be
     * used in favor of those methods because the SDK should support both methods of configuration.
     *
     * {@link System#getProperty(String)} takes precedent over {@link System#getenv(String)} if both are specified.
     *
     * @return The requested setting, or {@link Optional#empty()} if the values were not set, or the security manager did not
     *         allow reading the setting.
     */
    default Optional getStringValue() {
        return SystemSettingUtils.resolveSetting(this);
    }

    /**
     * Load the requested system setting as per the documentation in {@link #getStringValue()}, throwing an exception if the value
     * was not set and had no default.
     *
     * @return The requested setting.
     */
    default String getStringValueOrThrow() {
        return getStringValue().orElseThrow(() ->
                new IllegalStateException("Either the environment variable " + environmentVariable() + " or the java"
                                          + "property " + property() + " must be set."));
    }

    /**
     * Attempt to load a system setting from {@link System#getProperty(String)} and {@link System#getenv(String)}. This should be
     * used in favor of those methods because the SDK should support both methods of configuration.
     *
     * The result will be converted to a boolean.
     *
     * {@link System#getProperty(String)} takes precedent over {@link System#getenv(String)} if both are specified.
     *
     * @return The requested setting, or {@link Optional#empty()} if the values were not set, or the security manager did not
     *         allow reading the setting.
     */
    default Optional getBooleanValue() {
        return getStringValue().map(value -> SystemSettingUtils.safeStringToBoolean(this, value));
    }

    /**
     * Load the requested system setting as per the documentation in {@link #getBooleanValue()}, throwing an
     * exception if the value was not set and had no default.
     *
     * @return The requested setting.
     */
    default Boolean getBooleanValueOrThrow() {
        return getBooleanValue().orElseThrow(() ->
                new IllegalStateException("Either the environment variable " + environmentVariable() + " or the java"
                                          + "property " + property() + " must be set."));
    }
}