package db

import (
    "database/sql"
    "strings"

    _ "github.com/go-sql-driver/mysql"
)

func ConnectMySQL(dsn string) (*sql.DB, error) {
    db, err := sql.Open("mysql", dsn)
    if err != nil {
        return nil, err
    }
    if err := db.Ping(); err != nil {
        // Error 8001: Not allowed to execute statement that may change data on polar slave
        // This error can occur on read-only replicas but the connection may still be usable
        // Try a simple SELECT to verify the connection is actually working
        if strings.Contains(err.Error(), "8001") || strings.Contains(err.Error(), "polar slave") {
            var dummy int
            if testErr := db.QueryRow("SELECT 1").Scan(&dummy); testErr == nil {
                // Connection is actually working, ignore the ping error
                return db, nil
            }
        }
        return nil, err
    }
    return db, nil
}