package util

import (
	"crypto/rand"
	"encoding/hex"
	"net/http"
	"regexp"
	"strings"
	"unicode"
)

// TODO: make names match to fields of config file
var (
	SiteName    string
	SiteNavIcon string

	HomePage         string
	UserHypha        string
	HeaderLinksHypha string

	ServerPort     string
	URL            string
	GeminiCertPath string

	WikiDir        string
	ConfigFilePath string

	UseFixedAuth                bool
	FixedCredentialsPath        string
	UseRegistration             bool
	RegistrationCredentialsPath string
	LimitRegistration           uint64
)

// LettersNumbersOnly keeps letters and numbers only in the given string.
func LettersNumbersOnly(s string) string {
	var (
		ret            strings.Builder
		usedUnderscore bool
	)
	for _, r := range s {
		if unicode.IsLetter(r) || unicode.IsNumber(r) {
			ret.WriteRune(r)
			usedUnderscore = false
		} else if !usedUnderscore {
			ret.WriteRune('_')
			usedUnderscore = true
		}
	}
	return strings.Trim(ret.String(), "_")
}

// ShorterPath is used by handlerList to display shorter path to the files. It simply strips WikiDir.
func ShorterPath(path string) string {
	if strings.HasPrefix(path, WikiDir) {
		tmp := strings.TrimPrefix(path, WikiDir)
		if tmp == "" {
			return ""
		}
		return tmp[1:]
	}
	return path
}

// HTTP404Page writes a 404 error in the status, needed when no content is found on the page.
func HTTP404Page(w http.ResponseWriter, page string) {
	w.Header().Set("Content-Type", "text/html;charset=utf-8")
	w.WriteHeader(http.StatusNotFound)
	w.Write([]byte(page))
}

// HTTP200Page wraps some frequently used things for successful 200 responses.
func HTTP200Page(w http.ResponseWriter, page string) {
	w.Header().Set("Content-Type", "text/html;charset=utf-8")
	w.WriteHeader(http.StatusOK)
	w.Write([]byte(page))
}

func RandomString(n int) (string, error) {
	bytes := make([]byte, n)
	if _, err := rand.Read(bytes); err != nil {
		return "", err
	}
	return hex.EncodeToString(bytes), nil
}

// Strip hypha name from all ancestor names, replace _ with spaces, title case
func BeautifulName(uglyName string) string {
	if uglyName == "" {
		return uglyName
	}
	return strings.Title(strings.ReplaceAll(uglyName, "_", " "))
}

// CanonicalName makes sure the `name` is canonical. A name is canonical if it is lowercase and all spaces are replaced with underscores.
func CanonicalName(name string) string {
	return strings.ToLower(strings.ReplaceAll(name, " ", "_"))
}

// HyphaPattern is a pattern which all hyphae must match.
var HyphaPattern = regexp.MustCompile(`[^?!:#@><*|"\'&%{}]+`)

// IsCanonicalName checks if the `name` is canonical.
func IsCanonicalName(name string) bool {
	return HyphaPattern.MatchString(name)
}