// Copyright (c) 2026 Probo Inc <hello@probo.com>.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

// Package stringsx holds small, dependency-free string helpers shared
// across packages.
package stringsx

import "strings"

// NormalizeAlnum lowercases s and keeps only ASCII letters and digits, so
// vendor names and domains can be compared free of spacing, punctuation,
// and casing differences (e.g. "Letaido" and "letaido.com" both reduce to
// a comparable form).
func NormalizeAlnum(s string) string {
	var b strings.Builder

	for _, r := range strings.ToLower(s) {
		if (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') {
			b.WriteRune(r)
		}
	}

	return b.String()
}