// Copyright 2019 PingCAP, Inc.
//
// Licensed 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,
// See the License for the specific language governing permissions and
// limitations under the License.

package randsql

import (
	"database/sql"

	"github.com/pingcap/errors"
)

func GetDataFromDBRows(rows *sql.Rows) ([][]interface{}, error) {
	defer rows.Close()
	// Read all rows.
	var actualRows [][]interface{}
	for rows.Next() {
		cols, err1 := rows.Columns()
		if err1 != nil {
			return nil, errors.Trace(err1)
		}

		// See https://stackoverflow.com/questions/14477941/read-select-columns-into-string-in-go
		rawResult := make([][]byte, len(cols))
		result := make([]interface{}, len(cols))
		dest := make([]interface{}, len(cols))
		for i := range rawResult {
			dest[i] = &rawResult[i]
		}

		err1 = rows.Scan(dest...)
		if err1 != nil {
			return nil, errors.Trace(err1)
		}

		for i, raw := range rawResult {
			if raw == nil {
				result[i] = "NULL"
			} else {
				result[i] = string(raw)
			}
		}
		actualRows = append(actualRows, result)
	}
	if rows.Err() != nil {
		return nil, errors.Trace(rows.Err())
	}
	return actualRows, nil
}