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package org.apache.cayenne.query;

import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.map.DataMap;
import org.apache.cayenne.map.DbEntity;
import org.apache.cayenne.map.EntityResolver;
import org.apache.cayenne.map.ObjEntity;
import org.apache.cayenne.map.Procedure;

/**
 * A common superclass of Cayenne queries.
 * 
 * @author Andrus Adamchik
 */
public abstract class AbstractQuery implements Query {

    /**
     * The root object this query. May be an entity name, Java class, ObjEntity or
     * DbEntity, depending on the specific query and how it was constructed.
     */
    protected Object root;
    protected String name;

    /**
     * Returns a symbolic name of the query.
     * 
     * @since 1.1
     */
    public String getName() {
        return name;
    }

    /**
     * Sets a symbolic name of the query.
     * 
     * @since 1.1
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * Returns default select parameters.
     * 
     * @since 1.2
     */
    public QueryMetadata getMetaData(EntityResolver resolver) {
        BaseQueryMetadata md = new BaseQueryMetadata();
        md.resolve(getRoot(), resolver, getName());
        return md;
    }

    /**
     * Returns the root of this query.
     */
    // note that while "getRoot()" is deprecated in the Query interface, it is still valid
    // in AbstractQuery.
    public Object getRoot() {
        return root;
    }

    /**
     * Sets the root of the query
     * 
     * @param value The new root
     * @throws IllegalArgumentException if value is not a String, ObjEntity, DbEntity,
     *             Procedure, DataMap, Class or null.
     */
    public void setRoot(Object value) {
        if (value == null) {
            this.root = null;
        }

        // sanity check
        if (!((value instanceof String)
                || (value instanceof ObjEntity)
                || (value instanceof DbEntity)
                || (value instanceof Class)
                || (value instanceof Procedure) || (value instanceof DataMap))) {

            String rootClass = (value != null) ? value.getClass().getName() : "null";

            throw new IllegalArgumentException(
                    getClass().getName()
                            + ": \"setRoot(..)\" takes a DataMap, String, ObjEntity, DbEntity, Procedure, "
                            + "or Class. It was passed a "
                            + rootClass);
        }

        this.root = value;
    }

    public String toString() {
        return new ToStringBuilder(this)
                .append("root", root)
                .append("name", getName())
                .toString();
    }

    /**
     * @since 1.2
     */
    public abstract SQLAction createSQLAction(SQLActionVisitor visitor);

    /**
     * Implements default routing mechanism relying on the EntityResolver to find DataMap
     * based on the query root. This mechanism should be sufficient for most queries that
     * "know" their root.
     * 
     * @since 1.2
     */
    public void route(QueryRouter router, EntityResolver resolver, Query substitutedQuery) {
        DataMap map = getMetaData(resolver).getDataMap();

        if (map == null) {
            throw new CayenneRuntimeException("No DataMap found, can't route query "
                    + this);
        }

        router.route(router.engineForDataMap(map), this, substitutedQuery);
    }
}