package web

import (
	"path"
	"strings"
)

// safeName reduces a user supplied file name to a safe base name: directory
// components are dropped and unusual characters replaced by '_'. fallback is
// returned if nothing usable is left.
func safeName(name, fallback string) string {
	name = path.Base(strings.ReplaceAll(strings.TrimSpace(name), `\`, "/"))
	name = strings.Map(func(r rune) rune {
		if r >= 'a' && r <= 'z' || r >= 'A' && r <= 'Z' || r >= '0' && r <= '9' || r == '-' || r == '_' || r == '.' {
			return r
		}
		return '_'
	}, name)
	if strings.Trim(name, "._") == "" {
		return fallback
	}
	return name
}

// pcapFilename sanitizes a user supplied download name and gives it a .pcap extension.
func pcapFilename(name string) string {
	return strings.TrimSuffix(safeName(name, "packet.pcap"), ".pcap") + ".pcap"
}