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/************************************************************************
 * © 2019-2022 SAP SE or an SAP affiliate company. All rights reserved. *
 ************************************************************************/
package com.sap.cds.ql.cqn;

import java.util.Map;

import com.sap.cds.CdsException;
import com.sap.cds.JSONizable;

public interface CqnStatement extends JSONizable {

	/**
	 * Returns the reference of this statement.
	 * 
	 * {@link CqnSelect} statements do not necessarily have a reference, e.g. a
	 * select from subquery. This can be checked via {@link CqnSelect#from()}.
	 * 
	 * @throws CdsException if this statement does not have a reference
	 * @return the reference
	 */
	CqnStructuredTypeRef ref();

	/**
	 * Returns the runtime hints of this statement.
	 * 
	 * @return the runtime hints
	 */
	Map hints();

	/**
	 * Returns {@code true} if this is a {@link CqnSelect} statement.
	 * 
	 * @return {@code true} if this is a select statement, otherwise {@code false}
	 */
	default boolean isSelect() {
		return false;
	}

	/**
	 * Returns {@code true} if this is a {@link CqnInsert} statement.
	 * 
	 * @return {@code true} if this is an insert statement, otherwise {@code false}
	 */
	default boolean isInsert() {
		return false;
	}

	/**
	 * Returns {@code true} if this is a {@link CqnUpsert} statement.
	 * 
	 * @return {@code true} if this is an upsert statement, otherwise {@code false}
	 */
	default boolean isUpsert() {
		return false;
	}

	/**
	 * Returns {@code true} if this is a {@link CqnUpdate} statement.
	 * 
	 * @return {@code true} if this is an update statement, otherwise {@code false}
	 */
	default boolean isUpdate() {
		return false;
	}

	/**
	 * Returns {@code true} if this is a {@link CqnDelete} statement.
	 * 
	 * @return {@code true} if this is a delete statement, otherwise {@code false}
	 */
	default boolean isDelete() {
		return false;
	}

	/**
	 * Casts this CQN statement to {@code CqnSelect}.
	 * 
	 * @throws ClassCastException if this statement is not a select
	 * @return this statement as a CqnSelect
	 */
	default CqnSelect asSelect() {
		throw new ClassCastException("Cannot cast to CqnSelect");
	}

	/**
	 * Casts this CQN statement to {@code CqnInsert}.
	 * 
	 * @throws ClassCastException if this statement is not an insert
	 * @return this statement as a CqnInsert
	 */
	default CqnInsert asInsert() {
		throw new ClassCastException("Cannot cast to CqnInsert");
	}

	/**
	 * Casts this CQN statement to {@code CqnUpsert}.
	 * 
	 * @throws ClassCastException if this statement is not an upsert
	 * @return this statement as a CqnUpsert
	 */
	default CqnUpsert asUpsert() {
		throw new ClassCastException("Cannot cast to CqnUpsert");
	}

	/**
	 * Casts this CQN statement to {@code CqnUpdate}.
	 * 
	 * @throws ClassCastException if this statement is not an update
	 * @return this statement as a CqnUpdate
	 */
	default CqnUpdate asUpdate() {
		throw new ClassCastException("Cannot cast to CqnUpdate");
	}

	/**
	 * Casts this CQN statement to {@code CqnDelete}.
	 * 
	 * @throws ClassCastException if this statement is not a delete
	 * @return this statement as a CqnDelete
	 */
	default CqnDelete asDelete() {
		throw new ClassCastException("Cannot cast to CqnDelete");
	}

}