/*
Copyright © 2020 Marvin

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,
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 dbutil

import (
	"strings"

	"github.com/go-sql-driver/mysql"
	"github.com/pingcap/errors"
	"github.com/pingcap/tidb/errno"
)

var (
	// Retryable1105Msgs list the error messages of some retryable error with `1105` code (`ErrUnknown`).
	Retryable1105Msgs = []string{
		"Information schema is out of date",
		"Information schema is changed",
	}
)

// IsRetryableError checks whether the SQL statement can be retry directly when encountering this error.
// NOTE: this should be compatible with different TiDB versions.
// some errors are only retryable in some special cases, then we mark it as un-retryable:
// - errno.ErrTiKVServerTimeout
// - errno.ErrTableLocked
//
// some errors are un-retryable:
// - errno.ErrQueryInterrupted
//
// some errors are unknown:
// - errno.ErrRegionUnavailable
func IsRetryableError(err error) bool {
	err = errors.Cause(err) // check the original error
	mysqlErr, ok := err.(*mysql.MySQLError)
	if !ok {
		return false
	}

	switch mysqlErr.Number {
	case errno.ErrLockDeadlock: // https://dev.mysql.com/doc/refman/5.7/en/innodb-deadlocks.html
		return true // retryable error in MySQL
	case errno.ErrPDServerTimeout,
		errno.ErrTiKVServerBusy,
		errno.ErrResolveLockTimeout,
		errno.ErrInfoSchemaExpired,
		errno.ErrInfoSchemaChanged,
		errno.ErrWriteConflictInTiDB,
		errno.ErrWriteConflict:
		return true // retryable error in TiDB
	case errno.ErrUnknown: // the old version of TiDB uses `1105` frequently, this should be compatible.
		for _, msg := range Retryable1105Msgs {
			if strings.Contains(mysqlErr.Message, msg) {
				return true
			}
		}
	}

	return false
}