AnnotationClassParser.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.sling.caconfig.impl.metadata;

import java.lang.reflect.Method;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.lang3.StringUtils;
import org.apache.sling.caconfig.annotation.Configuration;
import org.apache.sling.caconfig.annotation.Property;
import org.apache.sling.caconfig.spi.metadata.ConfigurationMetadata;
import org.apache.sling.caconfig.spi.metadata.PropertyMetadata;

/**
 * Helper methods for parsing metadata from configuration annotation classes.
 */
public final class AnnotationClassParser {
    
    private static final Pattern METHOD_NAME_MAPPING = Pattern.compile("(\\$\\$)|(\\$)|(__)|(_)");
    
    private AnnotationClassParser() {
        // static methods only
    }

    /**
     * Checks if the given class is suitable to be mapped with context-aware configuration.
     * The given class has to be an annotation class, and the {@link Configuration} annotation has to be present.
     * @param clazz Given class
     * @return True if class is suitable for context-aware configuration
     */
    public static boolean isContextAwareConfig(Class<?> clazz) {
        return clazz.isAnnotation() && clazz.isAnnotationPresent(Configuration.class);
    }
    
    /**
     * Get configuration name for given configuration annotation class.
     * @param clazz Annotation class
     * @return Configuration name
     */
    public static String getConfigurationName(Class<?> clazz) {
        Configuration configAnnotation = clazz.getAnnotation(Configuration.class);
        if (configAnnotation == null) {
            return null;
        }
        return getConfigurationName(clazz, configAnnotation);
    }

    /**
     * Get configuration name for given configuration annotation class.
     * @param clazz Annotation class
     * @param configAnnotation Configuration metadata
     * @return Configuration name
     */
    private static String getConfigurationName(Class<?> clazz, Configuration configAnnotation) {
        String configName = configAnnotation.name();
        if (StringUtils.isBlank(configName)) {
            configName = clazz.getName();
        }
        return configName;
    }

    /**
     * Implements the method name mapping as defined in OSGi R6 Compendium specification,
     * Chapter 112. Declarative Services Specification, Chapter 112.8.2.1. Component Property Mapping.
     * @param methodName Method name
     * @return Mapped property name
     */
    public static String getPropertyName(String methodName) {
        Matcher matcher = METHOD_NAME_MAPPING.matcher(methodName);
        StringBuffer mappedName = new StringBuffer();
        while (matcher.find()) {
            String replacement = "";
            if (matcher.group(1) != null) {
                replacement = "\\$";
            }
            if (matcher.group(2) != null) {
                replacement = "";
            }
            if (matcher.group(3) != null) {
                replacement = "_";
            }
            if (matcher.group(4) != null) {
                replacement = ".";
            }
            matcher.appendReplacement(mappedName, replacement);
        }
        matcher.appendTail(mappedName);
        return mappedName.toString();
    }
    
    /**
     * Build configuration metadata by parsing the given annotation interface class and it's configuration annotations.
     * @param clazz Configuration annotation class
     * @return Configuration metadata
     */
    public static ConfigurationMetadata buildConfigurationMetadata(Class<?> clazz) {
        Configuration configAnnotation = clazz.getAnnotation(Configuration.class);
        if (configAnnotation == null) {
            throw new IllegalArgumentException("Class has not @Configuration annotation: " + clazz.getName());
        }
        
        // configuration metadata and property metadata
        String configName = getConfigurationName(clazz, configAnnotation);
        ConfigurationMetadata configMetadata = new ConfigurationMetadata(configName,
                buildConfigurationMetadata_PropertyMetadata(clazz),
                configAnnotation.collection())
                .label(emptyToNull(configAnnotation.label()))
                .description(emptyToNull(configAnnotation.description()))
                .properties(propsArrayToMap(configAnnotation.property()));
        
        return configMetadata;
    }
    
    /**
     * Build configuration metadata by parsing the given annotation interface class which is used for nested configurations.
     * @param clazz Configuration annotation class
     * @return Configuration metadata
     */
    private static ConfigurationMetadata buildConfigurationMetadata_Nested(Class<?> clazz, String configName, boolean collection) {
        return new ConfigurationMetadata(configName,
                buildConfigurationMetadata_PropertyMetadata(clazz),
                collection);
    }
    
    private static Collection<PropertyMetadata<?>> buildConfigurationMetadata_PropertyMetadata(Class<?> clazz) {
        // sort properties by order number, or alternatively by label, name
        SortedSet<PropertyMetadata<?>> propertyMetadataSet = new TreeSet<>(new Comparator<PropertyMetadata<?>>() {
            @Override
            public int compare(PropertyMetadata<?> o1, PropertyMetadata<?> o2) {
                int compare = Integer.compare(o1.getOrder(), o2.getOrder());
                if (compare == 0) {
                    String sort1 = StringUtils.defaultString(o1.getLabel(), o1.getName());
                    String sort2 = StringUtils.defaultString(o2.getLabel(), o2.getName());
                    compare = sort1.compareTo(sort2);
                }
                return compare;
            }
          });
        Method[] propertyMethods = clazz.getDeclaredMethods();
        for (Method propertyMethod : propertyMethods) {
            PropertyMetadata<?> propertyMetadata = buildPropertyMetadata(propertyMethod, propertyMethod.getReturnType());
            propertyMetadataSet.add(propertyMetadata);
        }
        return propertyMetadataSet;
    }
    
    @SuppressWarnings("unchecked")
    private static <T> PropertyMetadata<T> buildPropertyMetadata(Method propertyMethod, Class<T> type) {
        String propertyName = getPropertyName(propertyMethod.getName());
        
        PropertyMetadata<?> propertyMetadata;
        if (type.isArray() && type.getComponentType().isAnnotation()) {
            ConfigurationMetadata nestedConfigMetadata = buildConfigurationMetadata_Nested(type.getComponentType(), propertyName, true);
            propertyMetadata = new PropertyMetadata<>(propertyName, ConfigurationMetadata[].class)
                    .configurationMetadata(nestedConfigMetadata);
        }
        else if (type.isAnnotation()) {
            ConfigurationMetadata nestedConfigMetadata = buildConfigurationMetadata_Nested(type, propertyName, false);
            propertyMetadata = new PropertyMetadata<>(propertyName, ConfigurationMetadata.class)
                    .configurationMetadata(nestedConfigMetadata);
        }
        else {
            propertyMetadata = new PropertyMetadata<>(propertyName, type)            
                    .defaultValue((T)propertyMethod.getDefaultValue());
        }
        
        Property propertyAnnotation = propertyMethod.getAnnotation(Property.class);
        if (propertyAnnotation != null) {            
            propertyMetadata.label(emptyToNull(propertyAnnotation.label()))
                .description(emptyToNull(propertyAnnotation.description()))
                .properties(propsArrayToMap(propertyAnnotation.property()))
                .order(propertyAnnotation.order());
        }
        else {
            Map<String,String> emptyMap = Collections.emptyMap();
            propertyMetadata.properties(emptyMap);
        }
        
        return (PropertyMetadata)propertyMetadata;
    }
    
    private static String emptyToNull(String value) {
        if (StringUtils.isEmpty(value)) {
            return null;
        }
        else {
            return value;
        }
    }
    
    private static Map<String,String> propsArrayToMap(String[] properties) {
        Map<String,String> props = new HashMap<>();
        for (String property : properties) {
            int index = StringUtils.indexOf(property,  "=");
            if (index >= 0) {
                String key = property.substring(0, index);
                String value = property.substring(index + 1);
                props.put(key, value);
            }
        }
        return props;
    }
    
}