package config

import (
	"strings"
	"unicode"
	"unicode/utf8"
)

const (
	siteNameMaxBytes = 64
	reasonSiteName   = "must be at most 64 bytes of UTF-8 text with a visible character and no control characters (the display-name rule, §3.8)"
)

func siteNameValid(value string) bool {
	if value == "" || len(value) > siteNameMaxBytes || !utf8.ValidString(value) {
		return false
	}
	for _, r := range value {
		if unicode.IsControl(r) {
			return false
		}
	}
	return strings.IndexFunc(value, siteNameVisible) >= 0
}

func siteNameVisible(r rune) bool {
	return !unicode.IsSpace(r) && !unicode.In(r, unicode.Cf, unicode.Variation_Selector, unicode.Other_Default_Ignorable_Code_Point)
}

func (v *validator) siteName(value string) string {
	if !v.idx.has("server.site_name") {
		return ""
	}
	switch {
	case value == "":
		v.add("server.site_name", reasonEmpty)
	case !siteNameValid(value):
		v.add("server.site_name", reasonSiteName)
	}
	return value
}