utils: merging two (reverse) sorted lists of events.

utils.ts

@@ -1,4 +1,4 @@
-import type { Event } from './core.ts'
+import type { NostrEvent } from './core.ts'
 
 export const utf8Decoder: TextDecoder = new TextDecoder('utf-8')
 export const utf8Encoder: TextEncoder = new TextEncoder()
@@ -22,7 +22,7 @@ export function normalizeURL(url: string): string {
   }
 }
 
-export function insertEventIntoDescendingList(sortedArray: Event[], event: Event): Event[] {
+export function insertEventIntoDescendingList(sortedArray: NostrEvent[], event: NostrEvent): NostrEvent[] {
   const [idx, found] = binarySearch(sortedArray, b => {
     if (event.id === b.id) return 0
     if (event.created_at === b.created_at) return -1
@@ -34,7 +34,7 @@ export function insertEventIntoDescendingList(sortedArray: Event[], event: Event
   return sortedArray
 }
 
-export function insertEventIntoAscendingList(sortedArray: Event[], event: Event): Event[] {
+export function insertEventIntoAscendingList(sortedArray: NostrEvent[], event: NostrEvent): NostrEvent[] {
   const [idx, found] = binarySearch(sortedArray, b => {
     if (event.id === b.id) return 0
     if (event.created_at === b.created_at) return -1
@@ -68,6 +68,62 @@ export function binarySearch<T>(arr: T[], compare: (b: T) => number): [number, b
   return [start, false]
 }
 
+export function mergeReverseSortedLists(list1: NostrEvent[], list2: NostrEvent[]): NostrEvent[] {
+  const result: NostrEvent[] = new Array(list1.length + list2.length)
+  result.length = 0
+  let i1 = 0
+  let i2 = 0
+  let sameTimestampIds: string[] = []
+
+  while (i1 < list1.length && i2 < list2.length) {
+    let next: NostrEvent
+    if (list1[i1]?.created_at > list2[i2]?.created_at) {
+      next = list1[i1]
+      i1++
+    } else {
+      next = list2[i2]
+      i2++
+    }
+
+    if (result.length > 0 && result[result.length - 1].created_at === next.created_at) {
+      if (sameTimestampIds.includes(next.id)) continue
+    } else {
+      sameTimestampIds.length = 0
+    }
+
+    result.push(next)
+    sameTimestampIds.push(next.id)
+  }
+
+  while (i1 < list1.length) {
+    const next = list1[i1]
+    i1++
+
+    if (result.length > 0 && result[result.length - 1].created_at === next.created_at) {
+      if (sameTimestampIds.includes(next.id)) continue
+    } else {
+      sameTimestampIds.length = 0
+    }
+    result.push(next)
+    sameTimestampIds.push(next.id)
+  }
+
+  while (i2 < list2.length) {
+    const next = list2[i2]
+    i2++
+
+    if (result.length > 0 && result[result.length - 1].created_at === next.created_at) {
+      if (sameTimestampIds.includes(next.id)) continue
+    } else {
+      sameTimestampIds.length = 0
+    }
+    result.push(next)
+    sameTimestampIds.push(next.id)
+  }
+
+  return result
+}
+
 export class QueueNode<V> {
   public value: V
   public next: QueueNode<V> | null = null