cnlink/lib/tools.go

package lib

import (
	"git.sfnt.net/sfnt/cnlink/conf"
	"math"
	"strings"
)

// Int2String converts an unsigned 64bit integer to a string.
func Int2String(seq uint64, cn bool) (shortURL string) {
	charSeq := []rune{}
	baseStringRune := []rune(conf.Conf.Common.BaseString)
	baseStringLength :=conf.Conf.Common.BaseStringLength
	if cn == true {
		baseStringRune = []rune(conf.Conf.Common.BaseStringCn)
		baseStringLength =conf.Conf.Common.BaseStringCnLength
	}
	if seq != 0 {
		for seq != 0 {
			mod := seq % baseStringLength
			div := seq / baseStringLength
			charSeq = append(charSeq, rune(baseStringRune[mod]))
			seq = div
		}
	} else {
		charSeq = append(charSeq, rune(baseStringRune[seq]))
	}

	tmpShortURL := string(charSeq)
	shortURL = string(reverse(tmpShortURL))
	return
}

// String2Int converts a short URL string to an unsigned 64bit integer.
func String2Int(shortURL string, cn bool) (seq uint64) {
	shortURLRune := reverse(shortURL)
	baseString :=conf.Conf.Common.BaseString
	baseStringRune := []rune(baseString)
	baseStringLength :=conf.Conf.Common.BaseStringLength
	if cn == true {
		baseString =conf.Conf.Common.BaseStringCn
		baseStringRune = []rune(baseString)
		baseStringLength =conf.Conf.Common.BaseStringCnLength
	}
	for index, char := range shortURLRune {
		base := uint64(math.Pow(float64(baseStringLength), float64(index)))
		if cn==true {
			seq += uint64(getRuneIndex(baseStringRune, string(char))) * base
		} else {
			seq += uint64(strings.Index(baseString, string(char))) * base
		}
	}
	return
}
func getRuneIndex(r []rune, c string) (i int){
	for index ,rc := range r {
		if rc == ([]rune(c))[0] {
			i = index
			return i
		}
	}
	return -1
}
func reverse(s string) []rune {
	r := []rune(s)
	for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 {
		r[i], r[j] = r[j], r[i]
	}
	return r
}