package infra

import (
	"database/sql"
	"fmt"
	"regexp"
	"strings"
)

var validIdentifier = regexp.MustCompile(`^[a-zA-Z_][a-zA-Z0-9_]*$`)

// DBCreateTable executes CREATE TABLE IF NOT EXISTS for the given table with
// the provided column definitions. Each element of columns should be a full
// SQL column definition, e.g. "id INTEGER PRIMARY KEY" or "name TEXT NOT NULL".
// Returns an error if the table name contains invalid characters.
func DBCreateTable(db *sql.DB, table string, columns []string) error {
	if !validIdentifier.MatchString(table) {
		return fmt.Errorf("db_create_table: invalid table name %q (only alphanumeric and underscore allowed)", table)
	}
	if len(columns) == 0 {
		return fmt.Errorf("db_create_table: at least one column definition required")
	}
	query := fmt.Sprintf(
		"CREATE TABLE IF NOT EXISTS %s (%s)",
		table,
		strings.Join(columns, ", "),
	)
	if _, err := db.Exec(query); err != nil {
		return fmt.Errorf("db_create_table %q: %w", table, err)
	}
	return nil
}