/*
 *
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */

package com.dlink.metadata.query;

/**
 * PostgreSqlQuery
 *
 * @author wenmo
 * @since 2021/7/22 9:29
 **/
public class PostgreSqlQuery extends AbstractDBQuery {
    @Override
    public String schemaAllSql() {
        return "SELECT nspname AS \"schema_name\" FROM pg_namespace WHERE nspname NOT LIKE 'pg_%' AND nspname != 'information_schema'";
    }

    @Override
    public String tablesSql(String schemaName) {
        return "SELECT A.tablename, obj_description(relfilenode, 'pg_class') AS comments FROM pg_tables A, pg_class B WHERE A.schemaname='" + schemaName + "' AND A.tablename = B.relname";
    }

    @Override
    public String columnsSql(String schemaName, String tableName) {
        return "SELECT A.attname AS name,format_type (A.atttypid,A.atttypmod) AS type,col_description (A.attrelid,A.attnum) AS comment,\n"
                + "(CASE WHEN (SELECT COUNT (*) FROM pg_constraint AS PC WHERE A.attnum = PC.conkey[1] AND PC.contype = 'p') > 0 THEN 'PRI' ELSE '' END) AS key \n"
                + "FROM pg_class AS C,pg_attribute AS A WHERE A.attrelid='" + schemaName + "." + tableName
                + "'::regclass AND A.attrelid= C.oid AND A.attnum> 0 AND NOT A.attisdropped ORDER  BY A.attnum";
    }

    @Override
    public String schemaName() {
        return "schema_name";
    }

    @Override
    public String tableName() {
        return "tablename";
    }

    @Override
    public String tableComment() {
        return "comments";
    }

    @Override
    public String columnName() {
        return "name";
    }

    @Override
    public String columnType() {
        return "type";
    }

    @Override
    public String columnComment() {
        return "comment";
    }

    @Override
    public String columnKey() {
        return "key";
    }

    @Override
    public String isNullable() {
        return null;
    }
}
