add fast insert-into-sorted-list utils.

utils.ts

@@ -1,2 +1,97 @@
+import {Event} from './event'
+
 export const utf8Decoder = new TextDecoder('utf-8')
 export const utf8Encoder = new TextEncoder()
+
+//
+// fast insert-into-sorted-array functions adapted from https://github.com/terrymorse58/fast-sorted-array
+//
+export function insertEventIntoDescendingList(
+  sortedArray: Event[],
+  event: Event
+) {
+  let start = 0
+  let end = sortedArray.length - 1
+  let midPoint
+  let position = start
+
+  if (end < 0) {
+    position = 0
+  } else if (event.created_at < sortedArray[end].created_at) {
+    position = end + 1
+  } else if (event.created_at >= sortedArray[start].created_at) {
+    position = start
+  } else
+    while (true) {
+      if (end <= start + 1) {
+        position = end
+        break
+      }
+      midPoint = Math.floor(start + (end - start) / 2)
+      if (sortedArray[midPoint].created_at > event.created_at) {
+        start = midPoint
+      } else if (sortedArray[midPoint].created_at < event.created_at) {
+        end = midPoint
+      } else {
+        // aMidPoint === num
+        position = midPoint
+        break
+      }
+    }
+
+  // insert when num is NOT already in (no duplicates)
+  if (sortedArray[position]?.id !== event.id) {
+    return [
+      ...sortedArray.slice(0, position),
+      event,
+      ...sortedArray.slice(position)
+    ]
+  }
+
+  return sortedArray
+}
+
+export function insertEventIntoAscendingList(
+  sortedArray: Event[],
+  event: Event
+) {
+  let start = 0
+  let end = sortedArray.length - 1
+  let midPoint
+  let position = start
+
+  if (end < 0) {
+    position = 0
+  } else if (event.created_at > sortedArray[end].created_at) {
+    position = end + 1
+  } else if (event.created_at <= sortedArray[start].created_at) {
+    position = start
+  } else
+    while (true) {
+      if (end <= start + 1) {
+        position = end
+        break
+      }
+      midPoint = Math.floor(start + (end - start) / 2)
+      if (sortedArray[midPoint].created_at < event.created_at) {
+        start = midPoint
+      } else if (sortedArray[midPoint].created_at > event.created_at) {
+        end = midPoint
+      } else {
+        // aMidPoint === num
+        position = midPoint
+        break
+      }
+    }
+
+  // insert when num is NOT already in (no duplicates)
+  if (sortedArray[position]?.id !== event.id) {
+    return [
+      ...sortedArray.slice(0, position),
+      event,
+      ...sortedArray.slice(position)
+    ]
+  }
+
+  return sortedArray
+}