Refactor API types and sync logic

Rename and refactor the types passed over the API to be based on an
entity that's either living or a tombstone.  A living entity has a
deleted property that's either undefined or false, while a tombstone
has a deleted property set to true.  All entities have a numeric id
and an updatedAt timestamp.

To sync entities, an array of replacements are passed around. Living
entities are replaced with tombstones when they're deleted. And
tombstones are replaced with living entities when restored.

shared/utils/changes.ts

@@ -1,21 +0,0 @@
-import type { ChangeRecord } from "~/shared/types/schedule";
-
-export function applyChange<T extends { id: string }>(change: ChangeRecord<T>, data: T[]) {
-	const index = data.findIndex(item => item.id === change.data.id);
-	if (change.op === "del") {
-		if (index !== -1)
-			data.splice(index, 1);
-	} else if (change.op === "set") {
-		if (index !== -1)
-			data.splice(index, 1, change.data);
-		else
-			data.push(change.data)
-	}
-}
-
-export function applyChangeArray<T extends { id: string }>(changes: ChangeRecord<T>[], data: T[]) {
-	// Note: quadratic complexity due to findIndex in applyChange
-	for (const change of changes) {
-		applyChange(change, data);
-	}
-}

shared/utils/functions.ts

@@ -6,6 +6,15 @@ export function* enumerate<T>(iterable: Iterable<T>) {
 	}
 }
 
+/** Filters an iterable based on the passed predicate function */
+export function* filter<T, S extends T>(it: Iterable<T>, predicate: (value: T) => value is S) {
+	for (const value of it) {
+		if (predicate(value)) {
+			yield value;
+		}
+	}
+}
+
 /** Converts a name to an id */
 export function toId(name: string) {
 	return name.toLowerCase().replace(/[^a-z0-9]+/g, "-");

shared/utils/update.ts

@@ -0,0 +1,14 @@
+import type { Entity } from "~/shared/types/common";
+
+export function applyUpdatesToArray<T extends Entity>(updates: T[], entities: T[]) {
+	const idMap = new Map(entities.map((e, i) => [e.id, i]));
+	for (const update of updates) {
+		const index = idMap.get(update.id);
+		if (index !== undefined) {
+			entities[index] = update;
+		} else {
+			idMap.set(update.id, entities.length);
+			entities.push(update);
+		}
+	}
+}