package filename import (	"encoding/base64"	"encoding/binary" 	"github.com/dop251/scsu"	"github.com/klauspost/compress/huff0") // Encode will encode the string and return a base64 (url) compatible version of it.// Calling Decode with the returned string should always succeed.// It is not a requirement that the input string is valid utf-8.func Encode(s string) string {	table, payload := EncodeBytes(s)	return string(encodeURL[table]) + base64.URLEncoding.EncodeToString(payload)} // EncodeBytes will compress the given string and return a table identifier and a payload.func EncodeBytes(s string) (table byte, payload []byte) {	initCoders()	bestSize := len(s)	bestTable := byte(tableUncompressed)	org := []byte(s)	bestOut := []byte(s)	// Try all tables and choose the best	for i, enc := range encTables[:] {		org := org		if len(org) <= 1 || len(org) > maxLength {			// Use the uncompressed			break		} 		if enc == nil {			continue		} 		if i == tableSCSU {			var err error			olen := len(org)			org, err = scsu.EncodeStrict(s, make([]byte, 0, len(org)))			if err != nil || olen <= len(org) {				continue			}			if len(org) < bestSize {				// This is already better, store so we can use if the table cannot.				bestOut = bestOut[:len(org)]				bestTable = tableSCSUPlain				bestSize = len(org)				copy(bestOut, org)			}		} 		// Try to encode using table.		err := func() error {			encTableLocks[i].Lock()			defer encTableLocks[i].Unlock()			out, _, err := huff0.Compress1X(org, enc)			if err != nil {				return err			}			if len(out) < bestSize {				bestOut = bestOut[:len(out)]				bestTable = byte(i)				bestSize = len(out)				copy(bestOut, out)			}			return nil		}()		// If input is a single byte repeated store as RLE or save uncompressed.		if err == huff0.ErrUseRLE && i != tableSCSU {			if len(org) > 2 {				// Encode as one byte repeated since it will be smaller than uncompressed.				n := binary.PutUvarint(bestOut, uint64(len(org)))				bestOut = bestOut[:n+1]				bestOut[n] = org[0]				bestSize = n + 1				bestTable = tableRLE			}			break		}	} 	return bestTable, bestOut}