package postgres

import (
	"errors"
	"strconv"
	"strings"

	"github.com/jackc/pgx/v5/pgconn"
)

// uniqueViolation is the SQLSTATE class PostgreSQL raises for a duplicate
// key, whichever constraint caught it.
const uniqueViolation = "23505"

// isUniqueViolation reports whether err is PostgreSQL complaining about a
// duplicate key.
func isUniqueViolation(err error) bool {
	var pgErr *pgconn.PgError
	return errors.As(err, &pgErr) && pgErr.Code == uniqueViolation
}

// rebind turns the `?` placeholders the shared component stores are written
// with into PostgreSQL's numbered form. It is a straight scan rather than a
// SQL parser, which is safe because the statements it sees are constants in
// this repository: none of them contains a `?` inside a string literal, and
// none is built from user input beyond a run of placeholders.
func rebind(query string) string {
	if !strings.Contains(query, "?") {
		return query
	}
	var b strings.Builder
	b.Grow(len(query) + 8)
	n := 0
	for i := range len(query) {
		if query[i] != '?' {
			b.WriteByte(query[i])
			continue
		}
		n++
		b.WriteByte('$')
		b.WriteString(strconv.Itoa(n))
	}
	return b.String()
}