MapTransformation.java

package io.monokkel.core.utils;

import java.util.*;

import static java.util.stream.Collectors.toMap;

/**
 * Created by tarjei on 20/09/14.
 */
public class MapTransformation {

    /**
     *
     * A function that transforms a map by utilizing data from a matching map. The target map is filtered and the expressions
     * map is sent to the supplied function. The function supports sub-maps i.e. a map within the map. The expression object
     * CAN (but do not need to) match this sub-map structure and only expressions in the sub-map will be passed to the function.
     *
     * Example of mapToBeTransformed in JSON format:
     * {
     *     "key1":"value",
     *     "key2":{
     *         "subkey":"value"
     *     }
     * }
     *
     * Example of corresponding expressions in JSON format:
     * {
     *     "key1":"some transformation value",
     *     "key2":{
     *         "subkey":"some transformation value"
     *     }
     * }
     *
     * The calls to the function object will in this case be:
     *
     * transform("key1","some transformation value",{"key1":"some transformation value", "key2":{"subkey":"some transformation value"}}
     * transform("subkey","some transformation value","subkey":"some transformation value"}
     *
     * @return a transformed map containing all key values in the original map
     */
    public static Map<String, Object> transformAgainstMap(final Map<String, Object> mapToBeTransformed, final Map<String, Object> expressions, final MapTransformationFunction<String,Object> mapTransformationFunction)
    {
        return mapToBeTransformed.entrySet().stream().collect(toMap(Map.Entry::getKey, entry -> applyOnMap(entry.getKey(), entry.getValue(), expressions, mapTransformationFunction)));
    }

    @SuppressWarnings("unchecked")
    private static Object applyOnMap(String key, Object value, final Map<String, Object> expressionObject, final MapTransformationFunction<String,Object> mapTransformationFunction) {

        if (ParserUtils.isAValidJsonBaseType(value)) {
            return mapTransformationFunction.transform(key, value, expressionObject);
        } else if (value instanceof Map) {
            final Map expressionSubObject = (Map) expressionObject.getOrDefault(key, new LinkedHashMap<>());
            final Map uncleaned = (Map) value;
            return transformAgainstMap(uncleaned, expressionSubObject, mapTransformationFunction);
        } else if (value instanceof ArrayList) {
            // Not supported yet
            return value;
        } else {
            return value;
        }

    }

}