commonMain.fr.acinq.lightning.ShortChannelId.kt Maven / Gradle / Ivy

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A Kotlin Multiplatform implementation of the Lightning Network

There is a newer version: 1.8.4

package fr.acinq.lightning

import fr.acinq.bitcoin.PublicKey
import kotlinx.serialization.Serializable

@Serializable
data class ShortChannelId(private val id: Long) : Comparable {

    fun toLong(): Long = id

    fun blockHeight(): Int = ((id ushr 40) and 0xFFFFFF).toInt()

    fun txIndex(): Int = ((id ushr 16) and 0xFFFFFF).toInt()

    fun outputIndex(): Int = (id and 0xFFFF).toInt()

    fun coordinates(): TxCoordinates = TxCoordinates(blockHeight(), txIndex(), outputIndex())

    override fun toString(): String = "${blockHeight()}x${txIndex()}x${outputIndex()}"

    // we use an unsigned long comparison here
    override fun compareTo(other: ShortChannelId): Int = (this.id + Long.MIN_VALUE).compareTo(other.id + Long.MIN_VALUE)

    companion object {
        operator fun invoke(s: String): ShortChannelId {
            val list = s.split("x")
            if (list.size == 3) {
                val (blockHeight, txIndex, outputIndex) = list
                return ShortChannelId(toShortId(blockHeight.toInt(), txIndex.toInt(), outputIndex.toInt()))
            }
            throw IllegalArgumentException("Invalid short channel id: $s")
        }

        operator fun invoke(blockHeight: Int, txIndex: Int, outputIndex: Int): ShortChannelId = ShortChannelId(toShortId(blockHeight, txIndex, outputIndex))

        fun toShortId(blockHeight: Int, txIndex: Int, outputIndex: Int): Long = ((blockHeight.toLong() and 0xFFFFFFL) shl 40) or ((txIndex.toLong() and 0xFFFFFFL) shl 16) or (outputIndex.toLong() and 0xFFFFL)

        /**
         * This is a trick to encode a partial hash of node id in a short channel id.
         * We use a prefix of 0xff to make it easily distinguishable from normal short channel id.
         *
         * @note Phoenix only.
         */
        fun peerId(remoteNodeId: PublicKey): ShortChannelId {
            val bytes = remoteNodeId.value.takeRight(7)
            var asLong = 0xFFL
            for (i in 0..6) asLong = (asLong shl 8) + (bytes[i].toLong() and 0xffL)
            return ShortChannelId(asLong)
        }

        fun isPeerId(shortChannelId: ShortChannelId): Boolean = (shortChannelId.id.ushr(56) == 0xffL)
    }
}

data class TxCoordinates(val blockHeight: Int, val txIndex: Int, val outputIndex: Int)