/*
 * 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.autoconfigure.condition;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.HierarchicalBeanFactory;
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.boot.autoconfigure.condition.ConditionMessage.Style;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.context.annotation.ConfigurationCondition;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.core.type.AnnotatedTypeMetadata;
import org.springframework.core.type.MethodMetadata;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.MultiValueMap;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.ReflectionUtils.MethodCallback;
import org.springframework.util.StringUtils;

/**
 * {@link Condition} that checks for the presence or absence of specific beans.
 *
 * @author Phillip Webb
 * @author Dave Syer
 * @author Jakub Kubrynski
 * @author Stephane Nicoll
 * @author Andy Wilkinson
 */
@Order(Ordered.LOWEST_PRECEDENCE)
class OnBeanCondition extends SpringBootCondition implements ConfigurationCondition {

	/**
	 * Bean definition attribute name for factory beans to signal their product type (if
	 * known and it can't be deduced from the factory bean class).
	 */
	public static final String FACTORY_BEAN_OBJECT_TYPE = BeanTypeRegistry.FACTORY_BEAN_OBJECT_TYPE;

	@Override
	public ConfigurationPhase getConfigurationPhase() {
		return ConfigurationPhase.REGISTER_BEAN;
	}

	@Override
	public ConditionOutcome getMatchOutcome(ConditionContext context,
			AnnotatedTypeMetadata metadata) {
		ConditionMessage matchMessage = ConditionMessage.empty();
		if (metadata.isAnnotated(ConditionalOnBean.class.getName())) {
			BeanSearchSpec spec = new BeanSearchSpec(context, metadata,
					ConditionalOnBean.class);
			List<String> matching = getMatchingBeans(context, spec);
			if (matching.isEmpty()) {
				return ConditionOutcome.noMatch(
						ConditionMessage.forCondition(ConditionalOnBean.class, spec)
								.didNotFind("any beans").atAll());
			}
			matchMessage = matchMessage.andCondition(ConditionalOnBean.class, spec)
					.found("bean", "beans").items(Style.QUOTE, matching);
		}
		if (metadata.isAnnotated(ConditionalOnSingleCandidate.class.getName())) {
			BeanSearchSpec spec = new SingleCandidateBeanSearchSpec(context, metadata,
					ConditionalOnSingleCandidate.class);
			List<String> matching = getMatchingBeans(context, spec);
			if (matching.isEmpty()) {
				return ConditionOutcome.noMatch(ConditionMessage
						.forCondition(ConditionalOnSingleCandidate.class, spec)
						.didNotFind("any beans").atAll());
			}
			else if (!hasSingleAutowireCandidate(context.getBeanFactory(), matching,
					spec.getStrategy() == SearchStrategy.ALL)) {
				return ConditionOutcome.noMatch(ConditionMessage
						.forCondition(ConditionalOnSingleCandidate.class, spec)
						.didNotFind("a primary bean from beans")
						.items(Style.QUOTE, matching));
			}
			matchMessage = matchMessage
					.andCondition(ConditionalOnSingleCandidate.class, spec)
					.found("a primary bean from beans").items(Style.QUOTE, matching);
		}
		if (metadata.isAnnotated(ConditionalOnMissingBean.class.getName())) {
			BeanSearchSpec spec = new BeanSearchSpec(context, metadata,
					ConditionalOnMissingBean.class);
			List<String> matching = getMatchingBeans(context, spec);
			if (!matching.isEmpty()) {
				return ConditionOutcome.noMatch(ConditionMessage
						.forCondition(ConditionalOnMissingBean.class, spec)
						.found("bean", "beans").items(Style.QUOTE, matching));
			}
			matchMessage = matchMessage.andCondition(ConditionalOnMissingBean.class, spec)
					.didNotFind("any beans").atAll();
		}
		return ConditionOutcome.match(matchMessage);
	}

	private List<String> getMatchingBeans(ConditionContext context,
			BeanSearchSpec beans) {
		ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
		if (beans.getStrategy() == SearchStrategy.PARENTS) {
			BeanFactory parent = beanFactory.getParentBeanFactory();
			Assert.isInstanceOf(ConfigurableListableBeanFactory.class, parent,
					"Unable to use SearchStrategy.PARENTS");
			beanFactory = (ConfigurableListableBeanFactory) parent;
		}
		if (beanFactory == null) {
			return Collections.emptyList();
		}
		List<String> beanNames = new ArrayList<String>();
		boolean considerHierarchy = beans.getStrategy() != SearchStrategy.CURRENT;
		for (String type : beans.getTypes()) {
			beanNames.addAll(getBeanNamesForType(beanFactory, type,
					context.getClassLoader(), considerHierarchy));
		}
		for (String ignoredType : beans.getIgnoredTypes()) {
			beanNames.removeAll(getBeanNamesForType(beanFactory, ignoredType,
					context.getClassLoader(), considerHierarchy));
		}
		for (String annotation : beans.getAnnotations()) {
			beanNames.addAll(Arrays.asList(getBeanNamesForAnnotation(beanFactory,
					annotation, context.getClassLoader(), considerHierarchy)));
		}
		for (String beanName : beans.getNames()) {
			if (containsBean(beanFactory, beanName, considerHierarchy)) {
				beanNames.add(beanName);
			}
		}
		return beanNames;
	}

	private boolean containsBean(ConfigurableListableBeanFactory beanFactory,
			String beanName, boolean considerHierarchy) {
		if (considerHierarchy) {
			return beanFactory.containsBean(beanName);
		}
		return beanFactory.containsLocalBean(beanName);
	}

	private Collection<String> getBeanNamesForType(ListableBeanFactory beanFactory,
			String type, ClassLoader classLoader, boolean considerHierarchy)
					throws LinkageError {
		try {
			Set<String> result = new LinkedHashSet<String>();
			collectBeanNamesForType(result, beanFactory,
					ClassUtils.forName(type, classLoader), considerHierarchy);
			return result;
		}
		catch (ClassNotFoundException ex) {
			return Collections.emptySet();
		}
		catch (NoClassDefFoundError ex) {
			return Collections.emptySet();
		}
	}

	private void collectBeanNamesForType(Set<String> result,
			ListableBeanFactory beanFactory, Class<?> type, boolean considerHierarchy) {
		result.addAll(BeanTypeRegistry.get(beanFactory).getNamesForType(type));
		if (considerHierarchy && beanFactory instanceof HierarchicalBeanFactory) {
			BeanFactory parent = ((HierarchicalBeanFactory) beanFactory)
					.getParentBeanFactory();
			if (parent instanceof ListableBeanFactory) {
				collectBeanNamesForType(result, (ListableBeanFactory) parent, type,
						considerHierarchy);
			}
		}
	}

	private String[] getBeanNamesForAnnotation(
			ConfigurableListableBeanFactory beanFactory, String type,
			ClassLoader classLoader, boolean considerHierarchy) throws LinkageError {
		Set<String> names = new HashSet<String>();
		try {
			@SuppressWarnings("unchecked")
			Class<? extends Annotation> annotationType = (Class<? extends Annotation>) ClassUtils
					.forName(type, classLoader);
			collectBeanNamesForAnnotation(names, beanFactory, annotationType,
					considerHierarchy);
		}
		catch (ClassNotFoundException e) {
			// Continue
		}
		return StringUtils.toStringArray(names);
	}

	private void collectBeanNamesForAnnotation(Set<String> names,
			ListableBeanFactory beanFactory, Class<? extends Annotation> annotationType,
			boolean considerHierarchy) {
		names.addAll(
				BeanTypeRegistry.get(beanFactory).getNamesForAnnotation(annotationType));
		if (considerHierarchy) {
			BeanFactory parent = ((HierarchicalBeanFactory) beanFactory)
					.getParentBeanFactory();
			if (parent instanceof ListableBeanFactory) {
				collectBeanNamesForAnnotation(names, (ListableBeanFactory) parent,
						annotationType, considerHierarchy);
			}
		}
	}

	private boolean hasSingleAutowireCandidate(
			ConfigurableListableBeanFactory beanFactory, List<String> beanNames,
			boolean considerHierarchy) {
		return (beanNames.size() == 1
				|| getPrimaryBeans(beanFactory, beanNames, considerHierarchy)
						.size() == 1);
	}

	private List<String> getPrimaryBeans(ConfigurableListableBeanFactory beanFactory,
			List<String> beanNames, boolean considerHierarchy) {
		List<String> primaryBeans = new ArrayList<String>();
		for (String beanName : beanNames) {
			BeanDefinition beanDefinition = findBeanDefinition(beanFactory, beanName,
					considerHierarchy);
			if (beanDefinition != null && beanDefinition.isPrimary()) {
				primaryBeans.add(beanName);
			}
		}
		return primaryBeans;
	}

	private BeanDefinition findBeanDefinition(ConfigurableListableBeanFactory beanFactory,
			String beanName, boolean considerHierarchy) {
		if (beanFactory.containsBeanDefinition(beanName)) {
			return beanFactory.getBeanDefinition(beanName);
		}
		if (considerHierarchy && beanFactory
				.getParentBeanFactory() instanceof ConfigurableListableBeanFactory) {
			return findBeanDefinition(((ConfigurableListableBeanFactory) beanFactory
					.getParentBeanFactory()), beanName, considerHierarchy);
		}
		return null;

	}

	private static class BeanSearchSpec {

		private final Class<?> annotationType;

		private final List<String> names = new ArrayList<String>();

		private final List<String> types = new ArrayList<String>();

		private final List<String> annotations = new ArrayList<String>();

		private final List<String> ignoredTypes = new ArrayList<String>();

		private final SearchStrategy strategy;

		BeanSearchSpec(ConditionContext context, AnnotatedTypeMetadata metadata,
				Class<?> annotationType) {
			this.annotationType = annotationType;
			MultiValueMap<String, Object> attributes = metadata
					.getAllAnnotationAttributes(annotationType.getName(), true);
			collect(attributes, "name", this.names);
			collect(attributes, "value", this.types);
			collect(attributes, "type", this.types);
			collect(attributes, "annotation", this.annotations);
			collect(attributes, "ignored", this.ignoredTypes);
			collect(attributes, "ignoredType", this.ignoredTypes);
			this.strategy = (SearchStrategy) metadata
					.getAnnotationAttributes(annotationType.getName()).get("search");
			BeanTypeDeductionException deductionException = null;
			try {
				if (this.types.isEmpty() && this.names.isEmpty()) {
					addDeducedBeanType(context, metadata, this.types);
				}
			}
			catch (BeanTypeDeductionException ex) {
				deductionException = ex;
			}
			validate(deductionException);
		}

		protected void validate(BeanTypeDeductionException ex) {
			if (!hasAtLeastOne(this.types, this.names, this.annotations)) {
				String message = annotationName()
						+ " did not specify a bean using type, name or annotation";
				if (ex == null) {
					throw new IllegalStateException(message);
				}
				throw new IllegalStateException(message + " and the attempt to deduce"
						+ " the bean's type failed", ex);
			}
		}

		private boolean hasAtLeastOne(List<?>... lists) {
			for (List<?> list : lists) {
				if (!list.isEmpty()) {
					return true;
				}
			}
			return false;
		}

		protected String annotationName() {
			return "@" + ClassUtils.getShortName(this.annotationType);
		}

		protected void collect(MultiValueMap<String, Object> attributes, String key,
				List<String> destination) {
			List<?> values = attributes.get(key);
			if (values != null) {
				for (Object value : values) {
					if (value instanceof String[]) {
						Collections.addAll(destination, (String[]) value);
					}
					else {
						destination.add((String) value);
					}
				}
			}
		}

		private void addDeducedBeanType(ConditionContext context,
				AnnotatedTypeMetadata metadata, final List<String> beanTypes) {
			if (metadata instanceof MethodMetadata
					&& metadata.isAnnotated(Bean.class.getName())) {
				addDeducedBeanTypeForBeanMethod(context, metadata, beanTypes,
						(MethodMetadata) metadata);
			}
		}

		private void addDeducedBeanTypeForBeanMethod(ConditionContext context,
				AnnotatedTypeMetadata metadata, final List<String> beanTypes,
				final MethodMetadata methodMetadata) {
			try {
				// We should be safe to load at this point since we are in the
				// REGISTER_BEAN phase
				Class<?> configClass = ClassUtils.forName(
						methodMetadata.getDeclaringClassName(), context.getClassLoader());
				ReflectionUtils.doWithMethods(configClass, new MethodCallback() {
					@Override
					public void doWith(Method method)
							throws IllegalArgumentException, IllegalAccessException {
						if (methodMetadata.getMethodName().equals(method.getName())) {
							beanTypes.add(method.getReturnType().getName());
						}
					}
				});
			}
			catch (Throwable ex) {
				throw new BeanTypeDeductionException(
						methodMetadata.getDeclaringClassName(),
						methodMetadata.getMethodName(), ex);
			}
		}

		public SearchStrategy getStrategy() {
			return (this.strategy != null ? this.strategy : SearchStrategy.ALL);
		}

		public List<String> getNames() {
			return this.names;
		}

		public List<String> getTypes() {
			return this.types;
		}

		public List<String> getAnnotations() {
			return this.annotations;
		}

		public List<String> getIgnoredTypes() {
			return this.ignoredTypes;
		}

		@Override
		public String toString() {
			StringBuilder string = new StringBuilder();
			string.append("(");
			if (!this.names.isEmpty()) {
				string.append("names: ");
				string.append(StringUtils.collectionToCommaDelimitedString(this.names));
				if (!this.types.isEmpty()) {
					string.append("; ");
				}
			}
			if (!this.types.isEmpty()) {
				string.append("types: ");
				string.append(StringUtils.collectionToCommaDelimitedString(this.types));
			}
			string.append("; SearchStrategy: ");
			string.append(this.strategy.toString().toLowerCase());
			string.append(")");
			return string.toString();
		}

	}

	private static class SingleCandidateBeanSearchSpec extends BeanSearchSpec {

		SingleCandidateBeanSearchSpec(ConditionContext context,
				AnnotatedTypeMetadata metadata, Class<?> annotationType) {
			super(context, metadata, annotationType);
		}

		@Override
		protected void collect(MultiValueMap<String, Object> attributes, String key,
				List<String> destination) {
			super.collect(attributes, key, destination);
			destination.removeAll(Arrays.asList("", Object.class.getName()));
		}

		@Override
		protected void validate(BeanTypeDeductionException ex) {
			Assert.isTrue(getTypes().size() == 1, annotationName() + " annotations must "
					+ "specify only one type (got " + getTypes() + ")");
		}

	}

	static final class BeanTypeDeductionException extends RuntimeException {

		private BeanTypeDeductionException(String className, String beanMethodName,
				Throwable cause) {
			super("Failed to deduce bean type for " + className + "." + beanMethodName,
					cause);
		}

	}

}
