/*
 * Copyright 2012-2017 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
 *
 *      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 org.springframework.boot.actuate.endpoint;

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.core.env.CompositePropertySource;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.EnumerablePropertySource;
import org.springframework.core.env.Environment;
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 org.springframework.core.env.StandardEnvironment;

/**
 * {@link Endpoint} to expose {@link ConfigurableEnvironment environment} information.
 *
 * @author Dave Syer
 * @author Phillip Webb
 * @author Christian Dupuis
 * @author Madhura Bhave
 */
@ConfigurationProperties(prefix = "endpoints.env")
public class EnvironmentEndpoint extends AbstractEndpoint<Map<String, Object>> {

	private final Sanitizer sanitizer = new Sanitizer();

	/**
	 * Create a new {@link EnvironmentEndpoint} instance.
	 */
	public EnvironmentEndpoint() {
		super("env");
	}

	public void setKeysToSanitize(String... keysToSanitize) {
		this.sanitizer.setKeysToSanitize(keysToSanitize);
	}

	@Override
	public Map<String, Object> invoke() {
		Map<String, Object> result = new LinkedHashMap<String, Object>();
		result.put("profiles", getEnvironment().getActiveProfiles());
		PropertyResolver resolver = getResolver();
		for (Entry<String, PropertySource<?>> entry : getPropertySourcesAsMap()
				.entrySet()) {
			PropertySource<?> source = entry.getValue();
			String sourceName = entry.getKey();
			if (source instanceof EnumerablePropertySource) {
				EnumerablePropertySource<?> enumerable = (EnumerablePropertySource<?>) source;
				Map<String, Object> properties = new LinkedHashMap<String, Object>();
				for (String name : enumerable.getPropertyNames()) {
					properties.put(name, sanitize(name, resolver.getProperty(name)));
				}
				properties = postProcessSourceProperties(sourceName, properties);
				if (properties != null) {
					result.put(sourceName, properties);
				}
			}
		}
		return result;
	}

	public PropertyResolver getResolver() {
		PlaceholderSanitizingPropertyResolver resolver = new PlaceholderSanitizingPropertyResolver(
				getPropertySources(), this.sanitizer);
		resolver.setIgnoreUnresolvableNestedPlaceholders(true);
		return resolver;
	}

	private Map<String, PropertySource<?>> getPropertySourcesAsMap() {
		Map<String, PropertySource<?>> map = new LinkedHashMap<String, PropertySource<?>>();
		for (PropertySource<?> source : getPropertySources()) {
			extract("", map, source);
		}
		return map;
	}

	private MutablePropertySources getPropertySources() {
		MutablePropertySources sources;
		Environment environment = getEnvironment();
		if (environment != null && environment instanceof ConfigurableEnvironment) {
			sources = ((ConfigurableEnvironment) environment).getPropertySources();
		}
		else {
			sources = new StandardEnvironment().getPropertySources();
		}
		return sources;
	}

	private void extract(String root, Map<String, PropertySource<?>> map,
			PropertySource<?> source) {
		if (source instanceof CompositePropertySource) {
			for (PropertySource<?> nest : ((CompositePropertySource) source)
					.getPropertySources()) {
				extract(source.getName() + ":", map, nest);
			}
		}
		else {
			map.put(root + source.getName(), source);
		}
	}

	public Object sanitize(String name, Object object) {
		return this.sanitizer.sanitize(name, object);
	}

	/**
	 * Apply any post processing to source data before it is added.
	 * @param sourceName the source name
	 * @param properties the properties
	 * @return the post-processed properties or {@code null} if the source should not be
	 * added
	 * @since 1.4.0
	 */
	protected Map<String, Object> postProcessSourceProperties(String sourceName,
			Map<String, Object> properties) {
		return properties;
	}

	/**
	 * {@link PropertySourcesPropertyResolver} that sanitizes sensitive placeholders if
	 * present.
	 */
	private class PlaceholderSanitizingPropertyResolver
			extends PropertySourcesPropertyResolver {

		private final Sanitizer sanitizer;

		/**
		 * Create a new resolver against the given property sources.
		 * @param propertySources the set of {@link PropertySource} objects to use
		 * @param sanitizer the sanitizer used to sanitize sensitive values
		 */
		PlaceholderSanitizingPropertyResolver(PropertySources propertySources,
				Sanitizer sanitizer) {
			super(propertySources);
			this.sanitizer = sanitizer;
		}

		@Override
		protected String getPropertyAsRawString(String key) {
			String value = super.getPropertyAsRawString(key);
			return (String) this.sanitizer.sanitize(key, value);
		}

	}

}
