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package io.katharsis.jpa.internal.query;

import java.util.ArrayList;
import java.util.List;

import io.katharsis.jpa.internal.meta.MetaAttribute;
import io.katharsis.jpa.internal.meta.MetaAttributePath;
import io.katharsis.jpa.internal.meta.MetaDataObject;
import io.katharsis.jpa.internal.meta.MetaKey;
import io.katharsis.jpa.internal.meta.MetaMapType;
import io.katharsis.jpa.internal.meta.MetaType;
import io.katharsis.jpa.internal.query.backend.JpaQueryBackend;
import io.katharsis.jpa.query.AnyTypeObject;
import io.katharsis.queryspec.Direction;
import io.katharsis.queryspec.SortSpec;

public class QuerySortBuilder {

	protected JpaQueryBackend backend;
	protected AbstractJpaQueryImpl query;

	public QuerySortBuilder(AbstractJpaQueryImpl query, JpaQueryBackend backend) {
		this.backend = backend;
		this.query = query;
	}

	public void applySortSpec() {
		List sortSpecs = query.getSortSpecs();
		if (!sortSpecs.isEmpty()) {
			backend.setOrder(sortSpecListToArray());
		}

		// ensure a total order, add primary key if necessary necssary
		if (query.getEnsureTotalOrder() && !QueryUtil.hasTotalOrder(query.getMeta(), sortSpecs)) {
			List totalOrderList = backend.getOrderList();
			MetaKey primaryKey = query.getMeta().getPrimaryKey();
			if (primaryKey != null) {
				for (MetaAttribute primaryKeyElem : primaryKey.getElements()) {
					E primaryKeyExpr = backend.getAttribute(new MetaAttributePath(primaryKeyElem));
					O primaryKeyElemOrder = backend.newSort(primaryKeyExpr, Direction.ASC);
					totalOrderList.add(primaryKeyElemOrder);
				}
			}
			backend.setOrder(totalOrderList);
		}
	}

	protected List sortSpecListToArray() {
		ArrayList orderList = new ArrayList<>();
		for (SortSpec sortSpec : query.getSortSpecs()) {
			orderList.addAll(sortSpecToOrder(sortSpec));
		}
		return orderList;
	}

	private List sortSpecToOrder(SortSpec sortSpec) {
		List orders = new ArrayList<>();

		// check for AnyType
		MetaAttributePath path = query.getMeta().resolvePath(sortSpec.getAttributePath(), true);
		MetaAttribute attr = path.getLast();
		MetaType valueType = attr.getType();
		if (valueType instanceof MetaMapType) {
			valueType = ((MetaMapType) valueType).getValueType();
		}
		boolean anyType = AnyTypeObject.class.isAssignableFrom(valueType.getImplementationClass());
		if (anyType) {
			// order by anything, if types are not mixed for a given key, it
			// will be ok
			MetaDataObject anyMeta = valueType.asDataObject();
			for (MetaAttribute anyAttr : anyMeta.getAttributes()) {
				if (!anyAttr.isDerived()) {
					E expr = backend.getAttribute(path.concat(anyAttr));
					orders.add(backend.newSort(expr, sortSpec.getDirection()));
				}
			}
		} else {
			E expr = backend.getAttribute(path);
			orders.add(backend.newSort(expr, sortSpec.getDirection()));
		}
		return orders;
	}

}