/*
 * Copyright 2013-2021 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.cloud.sleuth.autoconfig.instrument.redis;

import java.net.SocketAddress;

import brave.Tracing;
import io.lettuce.core.protocol.RedisCommand;
import io.lettuce.core.resource.ClientResources;
import io.lettuce.core.tracing.BraveTracing;
import io.lettuce.core.tracing.TraceContext;
import io.lettuce.core.tracing.TraceContextProvider;
import io.lettuce.core.tracing.Tracer;
import io.lettuce.core.tracing.TracerProvider;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.cloud.sleuth.autoconfig.brave.instrument.redis.TraceRedisProperties;
import org.springframework.cloud.sleuth.instrument.redis.TraceLettuceClientResourcesBuilderCustomizer;
import org.springframework.cloud.sleuth.internal.ContextUtil;

/**
 * {@link BeanPostProcessor} for wrapping Lettuce components in a tracing representation.
 *
 * @author Marcin Grzejszczak
 * @since 3.0.0
 * @deprecated please use {@link TraceLettuceClientResourcesBuilderCustomizer}.
 */
public class TraceLettuceClientResourcesBeanPostProcessor implements BeanPostProcessor {

	private static final Log log = LogFactory.getLog(TraceLettuceClientResourcesBeanPostProcessor.class);

	private final BeanFactory beanFactory;

	public TraceLettuceClientResourcesBeanPostProcessor(BeanFactory beanFactory) {
		this.beanFactory = beanFactory;
	}

	@Override
	public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
		return bean;
	}

	@Override
	public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
		if (bean instanceof ClientResources) {
			ClientResources cr = (ClientResources) bean;
			if (!cr.tracing().isEnabled()) {
				if (log.isDebugEnabled()) {
					log.debug("Lettuce ClientResources bean is auto-configured to enable tracing.");
				}
				return cr.mutate().tracing(new LazyTracing(this.beanFactory)).build();
			}
			else if (log.isDebugEnabled()) {
				log.debug(
						"Lettuce ClientResources bean is skipped for auto-configuration because tracing was already enabled.");
			}
		}
		return bean;
	}

}

class LazyTracing implements io.lettuce.core.tracing.Tracing {

	private final BeanFactory beanFactory;

	private final io.lettuce.core.tracing.Tracing noOpTracing = NoOpTracing.INSTANCE;

	private BraveTracing braveTracing;

	LazyTracing(BeanFactory beanFactory) {
		this.beanFactory = beanFactory;
	}

	@Override
	public TracerProvider getTracerProvider() {
		return () -> {
			if (ContextUtil.isContextUnusable(beanFactory)) {
				return noOpTracing.getTracerProvider().getTracer();
			}
			return braveTracing().getTracerProvider().getTracer();
		};
	}

	@Override
	public TraceContextProvider initialTraceContextProvider() {
		return () -> {
			if (ContextUtil.isContextUnusable(beanFactory)) {
				return noOpTracing.initialTraceContextProvider().getTraceContext();
			}
			return braveTracing().initialTraceContextProvider().getTraceContext();
		};
	}

	@Override
	public boolean isEnabled() {
		return true;
	}

	@Override
	public boolean includeCommandArgsInSpanTags() {
		if (ContextUtil.isContextUnusable(this.beanFactory)) {
			return this.noOpTracing.includeCommandArgsInSpanTags();
		}
		return braveTracing().includeCommandArgsInSpanTags();
	}

	@Override
	public Endpoint createEndpoint(SocketAddress socketAddress) {
		if (ContextUtil.isContextUnusable(this.beanFactory)) {
			return this.noOpTracing.createEndpoint(socketAddress);
		}
		return braveTracing().createEndpoint(socketAddress);
	}

	private BraveTracing braveTracing() {
		if (this.braveTracing == null) {
			this.braveTracing = BraveTracing.builder().tracing(this.beanFactory.getBean(Tracing.class))
					.excludeCommandArgsFromSpanTags()
					.serviceName(this.beanFactory.getBean(TraceRedisProperties.class).getRemoteServiceName()).build();
		}
		return this.braveTracing;
	}

}

enum NoOpTracing implements io.lettuce.core.tracing.Tracing, TraceContextProvider, TracerProvider {

	INSTANCE;

	private final Endpoint NOOP_ENDPOINT = new Endpoint() {
	};

	@Override
	public TraceContext getTraceContext() {
		return TraceContext.EMPTY;
	}

	@Override
	public Tracer getTracer() {
		return NoOpTracer.INSTANCE;
	}

	@Override
	public TracerProvider getTracerProvider() {
		return this;
	}

	@Override
	public TraceContextProvider initialTraceContextProvider() {
		return this;
	}

	@Override
	public boolean isEnabled() {
		return false;
	}

	@Override
	public boolean includeCommandArgsInSpanTags() {
		return false;
	}

	@Override
	public Endpoint createEndpoint(SocketAddress socketAddress) {
		return NOOP_ENDPOINT;
	}

	static class NoOpTracer extends Tracer {

		static final Tracer INSTANCE = new NoOpTracer();

		@Override
		public Span nextSpan(TraceContext traceContext) {
			return NoOpSpan.INSTANCE;
		}

		@Override
		public Span nextSpan() {
			return NoOpSpan.INSTANCE;
		}

	}

	public static class NoOpSpan extends Tracer.Span {

		static final NoOpSpan INSTANCE = new NoOpSpan();

		@Override
		public Tracer.Span start(RedisCommand<?, ?, ?> redisCommand) {
			return this;
		}

		@Override
		public Tracer.Span name(String name) {
			return this;
		}

		@Override
		public Tracer.Span annotate(String value) {
			return this;
		}

		@Override
		public Tracer.Span tag(String key, String value) {
			return this;
		}

		@Override
		public Tracer.Span error(Throwable throwable) {
			return this;
		}

		@Override
		public Tracer.Span remoteEndpoint(io.lettuce.core.tracing.Tracing.Endpoint endpoint) {
			return this;
		}

		@Override
		public void finish() {
		}

	}

}
