package furcadia

import (
	"fmt"
	"strings"
	"unicode"
)

///////////////////////////////////////////////////////////////////////////////////////////////////
// FUNCTIONS //////////////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////////////////////////

// GetShortName returns a "shortname" derived from a given Furcadia display name
func GetShortName(displayName string) string {
	sb := &strings.Builder{}
	for _, r := range displayName {
		if unicode.IsLetter(r) || unicode.IsNumber(r) {
			sb.WriteRune(unicode.ToLower(r))
		}
	}
	return sb.String()
}

// GetShortDreamURL converts a regular "furc://uploader:name/" dream url into
// a "short" form that can be used as a hash key (e.g., "uploader:name").
//
// ErrInvalidDreamURL is returned if the given url is not a valid dream URL.
func GetShortDreamURL(url string) (string, error) {
	// cut prefix
	u, found := strings.CutPrefix(strings.ToLower(url), "furc://")
	if !found {
		return "", ErrInvalidDreamURL
	}

	// cut suffix
	u = strings.SplitN(u, "/", 2)[0]

	// split uploader name and dream name
	var uploaderName string
	var dreamName string

	elements := strings.Split(u, ":")
	switch len(elements) {
	case 0:
		panic(fmt.Sprintf("len(%v) == 0", elements))
	case 1:
		uploaderName = elements[0]
		dreamName = ""
	case 2:
		uploaderName = elements[0]
		dreamName = elements[1]
	default:
		return "", ErrInvalidDreamURL
	}

	short := GetShortDreamURLFromName(uploaderName, dreamName)
	if short == "" || short[0] == ':' {
		// furc://
		// furc:///
		// furc://:/
		// furc://:something/
		return "", ErrInvalidDreamURL
	}

	return short, nil
}

func GetShortDreamURLFromName(uploaderName, dreamName string) (short string) {
	shortName := GetShortName(uploaderName)
	shortDream := GetShortName(dreamName)
	if shortDream == "" {
		short = shortName
	} else {
		short = shortName + ":" + shortDream
	}
	return
}