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 msat < 0 { return "", fmt.Errorf("amount must be positive: %v", msat) } // 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 }