lnd.xprv/zpay32/amountunits.go
2020-04-24 19:15:08 +02:00

159 lines
4.1 KiB
Go

package zpay32
import (
"fmt"
"strconv"
"github.com/lightningnetwork/lnd/lnwire"
)
var (
// toMSat is a map from a unit to a function that converts an amount
// of that unit to millisatoshis.
toMSat = map[byte]func(uint64) (lnwire.MilliSatoshi, error){
'm': mBtcToMSat,
'u': uBtcToMSat,
'n': nBtcToMSat,
'p': pBtcToMSat,
}
// fromMSat is a map from a unit to a function that converts an amount
// in millisatoshis to an amount of that unit.
fromMSat = map[byte]func(lnwire.MilliSatoshi) (uint64, error){
'm': mSatToMBtc,
'u': mSatToUBtc,
'n': mSatToNBtc,
'p': mSatToPBtc,
}
)
// mBtcToMSat converts the given amount in milliBTC to millisatoshis.
func mBtcToMSat(m uint64) (lnwire.MilliSatoshi, error) {
return lnwire.MilliSatoshi(m) * 100000000, nil
}
// uBtcToMSat converts the given amount in microBTC to millisatoshis.
func uBtcToMSat(u uint64) (lnwire.MilliSatoshi, error) {
return lnwire.MilliSatoshi(u * 100000), nil
}
// nBtcToMSat converts the given amount in nanoBTC to millisatoshis.
func nBtcToMSat(n uint64) (lnwire.MilliSatoshi, error) {
return lnwire.MilliSatoshi(n * 100), nil
}
// pBtcToMSat converts the given amount in picoBTC to millisatoshis.
func pBtcToMSat(p uint64) (lnwire.MilliSatoshi, error) {
if p < 10 {
return 0, fmt.Errorf("minimum amount is 10p")
}
if p%10 != 0 {
return 0, fmt.Errorf("amount %d pBTC not expressible in msat",
p)
}
return lnwire.MilliSatoshi(p / 10), nil
}
// mSatToMBtc converts the given amount in millisatoshis to milliBTC.
func mSatToMBtc(msat lnwire.MilliSatoshi) (uint64, error) {
if msat%100000000 != 0 {
return 0, fmt.Errorf("%d msat not expressible "+
"in mBTC", msat)
}
return uint64(msat / 100000000), nil
}
// mSatToUBtc converts the given amount in millisatoshis to microBTC.
func mSatToUBtc(msat lnwire.MilliSatoshi) (uint64, error) {
if msat%100000 != 0 {
return 0, fmt.Errorf("%d msat not expressible "+
"in uBTC", msat)
}
return uint64(msat / 100000), nil
}
// mSatToNBtc converts the given amount in millisatoshis to nanoBTC.
func mSatToNBtc(msat lnwire.MilliSatoshi) (uint64, error) {
if msat%100 != 0 {
return 0, fmt.Errorf("%d msat not expressible in nBTC", msat)
}
return uint64(msat / 100), nil
}
// mSatToPBtc converts the given amount in millisatoshis to picoBTC.
func mSatToPBtc(msat lnwire.MilliSatoshi) (uint64, error) {
return uint64(msat * 10), nil
}
// decodeAmount returns the amount encoded by the provided string in
// millisatoshi.
func decodeAmount(amount string) (lnwire.MilliSatoshi, error) {
if len(amount) < 1 {
return 0, fmt.Errorf("amount must be non-empty")
}
// If last character is a digit, then the amount can just be
// interpreted as BTC.
char := amount[len(amount)-1]
digit := char - '0'
if digit >= 0 && digit <= 9 {
btc, err := strconv.ParseUint(amount, 10, 64)
if err != nil {
return 0, err
}
return lnwire.MilliSatoshi(btc) * mSatPerBtc, nil
}
// If not a digit, it must be part of the known units.
conv, ok := toMSat[char]
if !ok {
return 0, fmt.Errorf("unknown multiplier %c", char)
}
// Known unit.
num := amount[:len(amount)-1]
if len(num) < 1 {
return 0, fmt.Errorf("number must be non-empty")
}
am, err := strconv.ParseUint(num, 10, 64)
if err != nil {
return 0, err
}
return conv(am)
}
// encodeAmount encodes the provided millisatoshi amount using as few characters
// as possible.
func encodeAmount(msat lnwire.MilliSatoshi) (string, error) {
// If possible to express in BTC, that will always be the shortest
// representation.
if msat%mSatPerBtc == 0 {
return strconv.FormatInt(int64(msat/mSatPerBtc), 10), nil
}
// Should always be expressible in pico BTC.
pico, err := fromMSat['p'](msat)
if err != nil {
return "", fmt.Errorf("unable to express %d msat as pBTC: %v",
msat, err)
}
shortened := strconv.FormatUint(pico, 10) + "p"
for unit, conv := range fromMSat {
am, err := conv(msat)
if err != nil {
// Not expressible using this unit.
continue
}
// Save the shortest found representation.
str := strconv.FormatUint(am, 10) + string(unit)
if len(str) < len(shortened) {
shortened = str
}
}
return shortened, nil
}