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/*
 * Copyright 2013-2023 the original author or authors.
 *
 * 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
 *
 *      https://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.alibaba.cloud.nacos.utils;

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Properties;

import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.EnumerablePropertySource;
import org.springframework.core.env.MutablePropertySources;
import org.springframework.core.env.PropertyResolver;
import org.springframework.core.env.PropertySource;
import org.springframework.core.env.PropertySources;
import org.springframework.core.env.PropertySourcesPropertyResolver;

import static java.util.Collections.unmodifiableMap;

/**
 * @author Mercy
 * @author yuluo
 * {@link PropertySources} Utilities
 * {@see PropertySources}
 */
public final class PropertySourcesUtils {

	private PropertySourcesUtils() {
	}

	/**
	 * Empty String array.
	 */
	public static final String[] EMPTY_STRING_ARRAY = {};

	/**
	 * Get Sub {@link Properties}.
	 *
	 * @param propertySources {@link PropertySource} Iterable.
	 * @param prefix          the prefix of property name.
	 * @return Map
	 * @see Properties
	 */
	public static Map getSubProperties(Iterable> propertySources, String prefix) {

		MutablePropertySources mutablePropertySources = new MutablePropertySources();

		for (PropertySource source : propertySources) {
			mutablePropertySources.addLast(source);
		}

		return getSubProperties(mutablePropertySources, prefix);

	}

	/**
	 * Get Sub {@link Properties}.
	 *
	 * @param environment {@link ConfigurableEnvironment}.
	 * @param prefix      the prefix of property name.
	 * @return Map
	 * @see Properties
	 */
	public static Map getSubProperties(ConfigurableEnvironment environment, String prefix) {

		return getSubProperties(environment.getPropertySources(), environment, prefix);
	}

	/**
	 * Normalize the prefix.
	 *
	 * @param prefix the prefix.
	 * @return the prefix.
	 */
	public static String normalizePrefix(String prefix) {
		return prefix.endsWith(".") ? prefix : prefix + ".";
	}

	/**
	 * Get prefixed {@link Properties}.
	 *
	 * @param propertySources {@link PropertySources}.
	 * @param prefix          the prefix of property name.
	 * @return Map
	 * @see Properties
	 */
	public static Map getSubProperties(PropertySources propertySources, String prefix) {

		return getSubProperties(propertySources, new PropertySourcesPropertyResolver(propertySources), prefix);
	}

	/**
	 * Get prefixed {@link Properties}.
	 *
	 * @param propertySources  {@link PropertySources}.
	 * @param propertyResolver {@link PropertyResolver} to resolve the placeholder if present.
	 * @param prefix           the prefix of property name.
	 * @return Map
	 * @see Properties
	 */
	public static Map getSubProperties(PropertySources propertySources, PropertyResolver propertyResolver, String prefix) {

		Map subProperties = new LinkedHashMap();

		String normalizedPrefix = normalizePrefix(prefix);

		for (PropertySource source : propertySources) {
			for (String name : getPropertyNames(source)) {
				if (!subProperties.containsKey(name) && name.startsWith(normalizedPrefix)) {
					String subName = name.substring(normalizedPrefix.length());
					if (!subProperties.containsKey(subName)) { // take first one
						Object value = source.getProperty(name);
						if (value instanceof String) {
							// Resolve placeholder
							value = propertyResolver.resolvePlaceholders((String) value);
						}
						subProperties.put(subName, value);
					}
				}
			}
		}

		return unmodifiableMap(subProperties);
	}

	/**
	 * Get the property names as the array from the specified {@link PropertySource} instance.
	 *
	 * @param propertySource {@link PropertySource} instance.
	 * @return non-null
	 */
	public static String[] getPropertyNames(PropertySource propertySource) {

		String[] propertyNames = propertySource instanceof EnumerablePropertySource ?
				((EnumerablePropertySource) propertySource).getPropertyNames() : null;

		if (propertyNames == null) {
			propertyNames = EMPTY_STRING_ARRAY;
		}

		return propertyNames;
	}

}