/*
 * Copyright 2002-2019 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 org.springframework.security.config.crypto;

import java.beans.PropertyEditor;
import java.beans.PropertyEditorSupport;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UncheckedIOException;
import java.nio.charset.StandardCharsets;
import java.security.Key;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.converter.Converter;
import org.springframework.core.convert.converter.ConverterRegistry;
import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.security.converter.RsaKeyConverters;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

/**
 * Adds {@link RsaKeyConverters} to the configured {@link ConversionService} or
 * {@link PropertyEditor}s
 *
 * @author Josh Cummings
 * @since 5.2
 */
public class RsaKeyConversionServicePostProcessor implements BeanFactoryPostProcessor {

	private static final String CONVERSION_SERVICE_BEAN_NAME = "conversionService";

	private ResourceKeyConverterAdapter<RSAPublicKey> x509 = new ResourceKeyConverterAdapter<>(RsaKeyConverters.x509());

	private ResourceKeyConverterAdapter<RSAPrivateKey> pkcs8 = new ResourceKeyConverterAdapter<>(
			RsaKeyConverters.pkcs8());

	public void setResourceLoader(ResourceLoader resourceLoader) {
		Assert.notNull(resourceLoader, "resourceLoader cannot be null");
		this.x509.setResourceLoader(resourceLoader);
		this.pkcs8.setResourceLoader(resourceLoader);
	}

	@Override
	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
		if (hasUserDefinedConversionService(beanFactory)) {
			return;
		}
		ConversionService service = beanFactory.getConversionService();
		if (service instanceof ConverterRegistry registry) {
			registry.addConverter(String.class, RSAPrivateKey.class, this.pkcs8);
			registry.addConverter(String.class, RSAPublicKey.class, this.x509);
		}
		else {
			beanFactory.addPropertyEditorRegistrar((registry) -> {
				registry.registerCustomEditor(RSAPublicKey.class, new ConverterPropertyEditorAdapter<>(this.x509));
				registry.registerCustomEditor(RSAPrivateKey.class, new ConverterPropertyEditorAdapter<>(this.pkcs8));
			});
		}
	}

	private boolean hasUserDefinedConversionService(ConfigurableListableBeanFactory beanFactory) {
		return beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME)
				&& beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class);
	}

	private static class ConverterPropertyEditorAdapter<T> extends PropertyEditorSupport {

		private final Converter<String, T> converter;

		ConverterPropertyEditorAdapter(Converter<String, T> converter) {
			this.converter = converter;
		}

		@Override
		public String getAsText() {
			return null;
		}

		@Override
		public void setAsText(String text) throws IllegalArgumentException {
			if (StringUtils.hasText(text)) {
				setValue(this.converter.convert(text));
			}
			else {
				setValue(null);
			}
		}

	}

	static class ResourceKeyConverterAdapter<T extends Key> implements Converter<String, T> {

		private ResourceLoader resourceLoader = new DefaultResourceLoader();

		private final Converter<String, T> delegate;

		/**
		 * Construct a {@link ResourceKeyConverterAdapter} with the provided parameters
		 * @param delegate converts a stream of key material into a {@link Key}
		 */
		ResourceKeyConverterAdapter(Converter<InputStream, T> delegate) {
			this.delegate = pemInputStreamConverter().andThen(autoclose(delegate));
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public T convert(String source) {
			return this.delegate.convert(source);
		}

		/**
		 * Use this {@link ResourceLoader} to read the key material
		 * @param resourceLoader the {@link ResourceLoader} to use
		 */
		void setResourceLoader(ResourceLoader resourceLoader) {
			Assert.notNull(resourceLoader, "resourceLoader cannot be null");
			this.resourceLoader = resourceLoader;
		}

		private Converter<String, InputStream> pemInputStreamConverter() {
			return (source) -> source.startsWith("-----") ? toInputStream(source)
					: toInputStream(this.resourceLoader.getResource(source));
		}

		private InputStream toInputStream(String raw) {
			return new ByteArrayInputStream(raw.getBytes(StandardCharsets.UTF_8));
		}

		private InputStream toInputStream(Resource resource) {
			try {
				return resource.getInputStream();
			}
			catch (IOException ex) {
				throw new UncheckedIOException(ex);
			}
		}

		private <T> Converter<InputStream, T> autoclose(Converter<InputStream, T> inputStreamKeyConverter) {
			return (inputStream) -> {
				try (InputStream is = inputStream) {
					return inputStreamKeyConverter.convert(is);
				}
				catch (IOException ex) {
					throw new UncheckedIOException(ex);
				}
			};
		}

	}

}
