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package io.crnk.jpa.internal.query;

import io.crnk.jpa.query.AnyTypeObject;
import io.crnk.meta.model.MetaAttribute;
import io.crnk.meta.model.MetaDataObject;
import io.crnk.meta.provider.MetaPartition;

public class AnyUtils {

	private static final Object TYPE_ATTRIBUTE = "type";

	private AnyUtils() {
	}

	/**
	 * Sets the value of the given anytype.
	 *
	 * @param partition to use to retrieve information
	 * @param dataObject the anytype for which the value is set.
	 * @param value      the new value
	 */
	public static void setValue(MetaPartition partition, AnyTypeObject dataObject, Object value) {
		MetaDataObject meta = (MetaDataObject) partition.getMeta(dataObject.getClass());
		if (value == null) {
			for (MetaAttribute attr : meta.getAttributes()) {
				attr.setValue(dataObject, null);
			}
		} else {
			boolean found = false;
			for (MetaAttribute attr : meta.getAttributes()) {
				if (attr.getName().equals(TYPE_ATTRIBUTE)) {
					continue;
				}
				if (attr.getType().getImplementationClass().isAssignableFrom(value.getClass())) {
					attr.setValue(dataObject, value);
					found = true;
				} else {
					attr.setValue(dataObject, null);
				}
			}
			if (!found) {
				throw new IllegalStateException("cannot assign " + value + " to " + dataObject);
			}
		}
	}

	/**
	 * Finds a matching attribute for a given value.
	 *
	 * @param meta  the metadataobject
	 * @param value the value
	 * @return the attribute which will accept the given value
	 */
	public static MetaAttribute findAttribute(MetaDataObject meta, Object value) {
		if (value == null) {
			throw new IllegalArgumentException("null as value not supported");
		}

		for (MetaAttribute attr : meta.getAttributes()) {
			if (attr.getName().equals(TYPE_ATTRIBUTE)) {
				continue;
			}
			if (attr.isDerived()) {
				// we only consider persisted classes, not derived ones like
				// "value" itself
				continue;
			}
			if (attr.getType().getImplementationClass().isAssignableFrom(value.getClass())) {
				return attr;
			}
		}
		throw new IllegalArgumentException("cannot find anyType attribute for value '" + value + '\'');
	}
}