/**
 * Copyright (C) 2009-2013 FoundationDB, LLC
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.foundationdb.sql.aisddl;

import com.foundationdb.ais.model.AkibanInformationSchema;

import com.foundationdb.ais.model.Schema;
import com.foundationdb.server.api.DDLFunctions;
import com.foundationdb.server.error.ReferencedSchemaException;
import com.foundationdb.server.error.DuplicateSchemaException;
import com.foundationdb.server.error.NoSuchSchemaException;
import com.foundationdb.server.service.session.Session;

import com.foundationdb.sql.parser.CreateSchemaNode;
import com.foundationdb.sql.parser.DropSchemaNode;
import com.foundationdb.sql.parser.StatementType;
import com.foundationdb.qp.operator.QueryContext;

import static com.foundationdb.sql.aisddl.DDLHelper.skipOrThrow;

public class SchemaDDL {
    private SchemaDDL () {
    }
    
    public static void createSchema (AkibanInformationSchema ais,
                                   String defaultSchemaName,
                                   CreateSchemaNode createSchema,
                                   QueryContext context)
    {
        final String schemaName = createSchema.getSchemaName();

        Schema curSchema = ais.getSchema(schemaName);
        if((curSchema != null) &&
           skipOrThrow(context, createSchema.getExistenceCheck(), curSchema, new DuplicateSchemaException(schemaName))) {
            return;
        }

        // If you get to this point, the schema name isn't being used by any user or group table
        // therefore is a valid "new" schema. 
        // TODO: update the AIS to store the new schema. 
    }
    
    public static void dropSchema (DDLFunctions ddlFunctions,
            Session session,
            DropSchemaNode dropSchema,
            QueryContext context)
    {
        AkibanInformationSchema ais = ddlFunctions.getAIS(session);
        final String schemaName = dropSchema.getSchemaName();

        Schema curSchema = ais.getSchema(schemaName);
        if((curSchema == null) &&
           skipOrThrow(context, dropSchema.getExistenceCheck(), curSchema, new NoSuchSchemaException(schemaName))) {
            return;
        }
        // 1 == RESTRICT, meaning no drop if the schema isn't empty
        if (dropSchema.getDropBehavior() == StatementType.DROP_RESTRICT ||
                dropSchema.getDropBehavior() == StatementType.DROP_DEFAULT)
            throw new ReferencedSchemaException(schemaName);
        // If the schema isn't used by any existing tables, it has effectively
        // been dropped, so the drop "succeeds".
        else if (dropSchema.getDropBehavior() == StatementType.DROP_CASCADE)
            ddlFunctions.dropSchema(session, schemaName);
    }
}