Small fixes, rework zaps

packages/util/src/Handles.ts

@@ -0,0 +1,47 @@
+import {fetchJson, last} from "@welshman/lib"
+import type {Maybe} from "@welshman/lib"
+
+/**
+ * NIP-05: mapping nostr public keys to DNS-based internet identifiers (e.g.
+ * `name@example.com`), resolved via each domain's `/.well-known/nostr.json`.
+ */
+export type Handle = {
+  nip05: string
+  pubkey?: string
+  nip46?: string[]
+  relays?: string[]
+}
+
+export async function queryProfile(nip05: string): Promise<Maybe<Handle>> {
+  const parts = nip05.split("@")
+  const name = parts.length > 1 ? parts[0] : "_"
+  const domain = last(parts)
+
+  try {
+    const {
+      names,
+      relays = {},
+      nip46 = {},
+    } = await fetchJson(`https://${domain}/.well-known/nostr.json?name=${name}`)
+
+    const pubkey = names[name]
+
+    if (!pubkey) {
+      return undefined
+    }
+
+    return {
+      nip05,
+      pubkey,
+      nip46: nip46[pubkey],
+      relays: relays[pubkey],
+    }
+  } catch (_e) {
+    return undefined
+  }
+}
+
+export const displayNip05 = (nip05: string) =>
+  nip05?.startsWith("_@") ? last(nip05.split("@")) : nip05
+
+export const displayHandle = (handle: Handle) => displayNip05(handle.nip05)

packages/util/src/Kinds.ts

@@ -123,7 +123,7 @@ export const ROOM_JOIN = 9021
 export const ROOM_LEAVE = 9022
 export const ZAP_GOAL = 9041
 export const ZAP_REQUEST = 9734
-export const ZAP_RESPONSE = 9735
+export const ZAP_RECEIPT = 9735
 export const HIGHLIGHT = 9802
 export const MUTES = 10000
 export const PINS = 10001

packages/util/src/Zaps.ts

@@ -1,5 +1,5 @@
-import {now, tryCatch, fetchJson, hexToBech32, fromPairs} from "@welshman/lib"
-import {ZAP_RESPONSE, ZAP_REQUEST} from "./Kinds.js"
+import {now, tryCatch, fetchJson, hexToBech32, fromPairs, sum, allPass, nthEq, nth} from "@welshman/lib"
+import {ZAP_RECEIPT, ZAP_REQUEST} from "./Kinds.js"
 import {getTagValue} from "./Tags.js"
 import type {Filter} from "./Filters.js"
 import type {TrustedEvent, SignedEvent} from "./Events.js"
@@ -138,6 +138,79 @@ export const zapFromEvent = (response: TrustedEvent, zapper: Zapper | undefined)
   return zap
 }
 
+/**
+ * A single recipient of an event's zaps, parsed from a NIP-57 Appendix G `zap`
+ * tag of the form `["zap", <pubkey>, <relay hint>, <weight>]`.
+ */
+export type ZapSplit = {
+  pubkey: string
+  relay?: string
+  weight: number
+}
+
+export type ZapSplitAmount = ZapSplit & {amount: number}
+
+const parseWeight = (weight: string | undefined) => {
+  const n = weight === undefined ? NaN : parseFloat(weight)
+
+  return Number.isFinite(n) && n > 0 ? n : 0
+}
+
+/**
+ * Resolve an event's zap-split recipients per NIP-57 Appendix G:
+ *
+ * - With no `zap` tags the whole zap goes to the event's author.
+ * - If no recipient carries a weight, the zap is split equally (weight 1 each).
+ * - If weights are only partially present, unweighted recipients drop to weight
+ *   0 (i.e. they should not be zapped).
+ *
+ * Weight-0 recipients are still returned so callers have the full recipient set;
+ * they simply receive 0 from `splitZapAmount`.
+ */
+export const getZapSplits = (event: TrustedEvent): ZapSplit[] => {
+  const zapTags = event.tags.filter(allPass(nthEq(0, "zap"), nth(1)))
+
+  if (zapTags.length === 0) {
+    return [{pubkey: event.pubkey, weight: 1}]
+  }
+
+  const anyWeighted = zapTags.some(nth(3))
+
+  return zapTags.map(([, pubkey, relay, weight]) => ({
+    pubkey,
+    relay: relay || undefined,
+    weight: anyWeighted ? parseWeight(weight) : 1,
+  }))
+}
+
+/**
+ * Divide `total` (in any integer unit, e.g. millisats) across an event's
+ * zap-split recipients proportionally to their weights. Any rounding remainder
+ * is handed to the highest-weighted recipient so the parts sum back to exactly
+ * `total`. If every weight is 0, nobody is zapped.
+ */
+export const splitZapAmount = (event: TrustedEvent, total: number): ZapSplitAmount[] => {
+  const splits = getZapSplits(event)
+  const totalWeight = sum(splits.map(split => split.weight))
+
+  if (totalWeight === 0) {
+    return splits.map(split => ({...split, amount: 0}))
+  }
+
+  const amounts = splits.map(split => Math.floor((total * split.weight) / totalWeight))
+
+  let maxIndex = 0
+  splits.forEach((split, i) => {
+    if (split.weight > splits[maxIndex].weight) {
+      maxIndex = i
+    }
+  })
+
+  amounts[maxIndex] += total - sum(amounts)
+
+  return splits.map((split, i) => ({...split, amount: amounts[i]}))
+}
+
 export type ZapRequestParams = {
   msats: number
   zapper: Zapper
@@ -201,7 +274,7 @@ export const getZapResponseFilter = ({zapper, pubkey, eventId}: ZapResponseFilte
   }
 
   const filter: Filter = {
-    kinds: [ZAP_RESPONSE],
+    kinds: [ZAP_RECEIPT],
     authors: [zapper.nostrPubkey],
     since: now() - 30,
     "#p": [pubkey],

packages/util/src/index.ts

@@ -4,6 +4,7 @@ export * from "./Encryptable.js"
 export * from "./Events.js"
 export * from "./Filters.js"
 export * from "./Handler.js"
+export * from "./Handles.js"
 export * from "./Keys.js"
 export * from "./Kinds.js"
 export * from "./Links.js"