package main

import (
	"fmt"
	"regexp"
	"strings"
)

// SQL identifiers in this migrator are always static allowlisted names or
// programmer-supplied column paths — never end-user free text. Still quote
// and validate before interpolating into DDL/DML to fail closed on mistakes.

var sqlIdentSegment = regexp.MustCompile(`^[A-Za-z_][A-Za-z0-9_]*$`)

func quoteMySQLIdent(ident string) (string, error) {
	if !sqlIdentSegment.MatchString(ident) {
		return "", fmt.Errorf("invalid MySQL identifier %q", ident)
	}
	return "`" + strings.ReplaceAll(ident, "`", "``") + "`", nil
}

// quoteMySQLIdentPath quotes dotted paths such as company_id or cf.company_id.
func quoteMySQLIdentPath(path string) (string, error) {
	path = strings.TrimSpace(path)
	if path == "" {
		return "", fmt.Errorf("empty MySQL identifier path")
	}
	parts := strings.Split(path, ".")
	out := make([]string, len(parts))
	for i, part := range parts {
		q, err := quoteMySQLIdent(part)
		if err != nil {
			return "", err
		}
		out[i] = q
	}
	return strings.Join(out, "."), nil
}

func mustQuoteMySQLIdent(ident string) string {
	q, err := quoteMySQLIdent(ident)
	if err != nil {
		panic(err)
	}
	return q
}

func quotePGIdent(ident string) (string, error) {
	if !sqlIdentSegment.MatchString(ident) {
		return "", fmt.Errorf("invalid Postgres identifier %q", ident)
	}
	return `"` + strings.ReplaceAll(ident, `"`, `""`) + `"`, nil
}