MetadataHandler.java

/**
 * Copyright (c) 2010-2016 by the respective copyright holders.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.openhab.binding.weather.internal.metadata;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.lang.StringUtils;
import org.openhab.binding.weather.internal.annotation.Forecast;
import org.openhab.binding.weather.internal.annotation.ForecastMappings;
import org.openhab.binding.weather.internal.annotation.Provider;
import org.openhab.binding.weather.internal.annotation.ProviderMappings;
import org.openhab.binding.weather.internal.converter.Converter;
import org.openhab.binding.weather.internal.converter.ConverterFactory;
import org.openhab.binding.weather.internal.converter.ConverterType;
import org.openhab.binding.weather.internal.model.ProviderName;
import org.openhab.binding.weather.internal.model.Weather;
import org.openhab.binding.weather.internal.utils.PropertyResolver;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Scans the model package and extracts mapping infos from the annotations.
 *
 * @author Gerhard Riegler
 * @since 1.6.0
 */
public class MetadataHandler {
    private static final Logger logger = LoggerFactory.getLogger(MetadataHandler.class);

    private static final String PACKAGE_TO_SCAN = StringUtils.substringBeforeLast(Weather.class.getName(), ".");
    private Map<ProviderName, Map<String, ProviderMappingInfo>> providerMappings = new HashMap<ProviderName, Map<String, ProviderMappingInfo>>();
    private Map<ProviderName, List<String>> forecastMappings = new HashMap<ProviderName, List<String>>();

    private static MetadataHandler instance;

    private MetadataHandler() {
    }

    /**
     * Returns the singleton instance of the MetadataHandler.
     */
    public static MetadataHandler getInstance() {
        if (instance == null) {
            instance = new MetadataHandler();
        }
        return instance;
    }

    /**
     * Scans the class and generates metadata.
     */
    public void generate(Class<?> clazz) throws IllegalAccessException {
        if (clazz == null) {
            return;
        }

        for (Field field : clazz.getDeclaredFields()) {
            if (field.getType().getName().startsWith(PACKAGE_TO_SCAN) && !field.isEnumConstant()) {
                generate(field.getType());
            } else {
                for (Annotation annotation : field.getAnnotations()) {
                    if (annotation.annotationType().equals(ProviderMappings.class)) {
                        ProviderMappings providerAnnotations = (ProviderMappings) annotation;
                        for (Provider provider : providerAnnotations.value()) {
                            Map<String, ProviderMappingInfo> mappings = providerMappings.get(provider.name());

                            if (mappings == null) {
                                mappings = new HashMap<String, ProviderMappingInfo>();
                                providerMappings.put(provider.name(), mappings);
                            }

                            Converter<?> converter = getConverter(field, provider.converter());
                            String target = clazz.getSimpleName().toLowerCase() + "." + field.getName();
                            ProviderMappingInfo pm = new ProviderMappingInfo(provider.property(), target, converter);
                            mappings.put(pm.getSource(), pm);
                            logger.trace("Added provider mapping {}: {}", provider.name(), pm);
                        }
                    } else if (annotation.annotationType().equals(ForecastMappings.class)) {
                        ForecastMappings forecastsAnnotations = (ForecastMappings) annotation;
                        for (Forecast forecast : forecastsAnnotations.value()) {
                            List<String> forecastProperties = forecastMappings.get(forecast.provider());
                            if (forecastProperties == null) {
                                forecastProperties = new ArrayList<String>();
                                forecastMappings.put(forecast.provider(), forecastProperties);
                            }
                            forecastProperties.add(forecast.property());
                            logger.trace("Added forecast mapping {}: {}", forecast.provider(), forecast.property());
                        }
                    }
                }
            }
        }
    }

    /**
     * Autodetects a converter or returns a specified instance.
     */
    private Converter<?> getConverter(Field field, ConverterType type) {
        if (type == ConverterType.AUTO) {
            String fieldType = field.getType().getSimpleName().toUpperCase();
            return ConverterFactory.getConverter(ConverterType.valueOf(fieldType));
        } else if (type == ConverterType.NONE) {
            return null;
        } else {
            return ConverterFactory.getConverter(type);
        }
    }

    /**
     * Returns the MappingInfo for the specified provider and property.
     */
    public ProviderMappingInfo getProviderMappingInfo(ProviderName provider, String property) {
        Map<String, ProviderMappingInfo> mapping = providerMappings.get(provider);
        if (mapping == null) {
            return null;
        }

        ProviderMappingInfo provMapping = mapping.get(property);

        String nestedProperty = property;
        while (provMapping == null && PropertyResolver.hasNested(nestedProperty)) {
            nestedProperty = PropertyResolver.removeFirst(nestedProperty);
            provMapping = mapping.get(nestedProperty);
        }

        return provMapping;
    }

    /**
     * Returns true, if the property is a forecast property.
     */
    public boolean isForecast(ProviderName provider, String property) {
        if (property == null || !forecastMappings.containsKey(provider)) {
            return false;
        }
        return forecastMappings.get(provider).contains(property);
    }
}