Remove page's prev & weird reverse handling

api/src/models/utils/keyset-paginate.ts

@@ -3,7 +3,7 @@ import { eq, or, type Column, and, gt, lt } from "drizzle-orm";
 
 type Table<Name extends string> = Record<Name, Column>;
 
-type After = [boolean, ...[string | number | boolean | undefined]];
+type After = (string | number | boolean | undefined)[];
 
 // Create a filter (where) expression on the query to skip everything before/after the referenceID.
 // The generalized expression for this in pseudocode is:
@@ -29,7 +29,7 @@ export const keysetPaginate = <
 	sort: Sort<T, Remap>;
 }) => {
 	if (!after) return undefined;
-	const [reverse, ...cursor]: After = JSON.parse(
+	const cursor: After = JSON.parse(
 		Buffer.from(after, "base64").toString("utf-8"),
 	);
 
@@ -40,7 +40,7 @@ export const keysetPaginate = <
 	let where = undefined;
 	let previous = undefined;
 	for (const [i, by] of [...sort, pkSort].entries()) {
-		const cmp = by.desc !== reverse ? lt : gt;
+		const cmp = by.desc ? lt : gt;
 		where = or(where, and(previous, cmp(table[by.key], cursor[i])));
 		previous = and(previous, eq(table[by.key], cursor[i]));
 	}
@@ -48,18 +48,7 @@ export const keysetPaginate = <
 	return where;
 };
 
-export const generateAfter = (
-	cursor: any,
-	sort: Sort<any, any>,
-	reverse?: boolean,
-) => {
-	const ret = [
-		reverse ?? false,
-		...sort.map((by) => cursor[by.key]),
-		cursor.pk,
-	];
+export const generateAfter = (cursor: any, sort: Sort<any, any>) => {
+	const ret = [...sort.map((by) => cursor[by.key]), cursor.pk];
 	return Buffer.from(JSON.stringify(ret), "utf-8").toString("base64url");
 };
-
-const reverseStart = Buffer.from("[true,", "utf-8").toString("base64url");
-export const isReverse = (x: string) => x.startsWith(reverseStart);

api/src/models/utils/page.ts

@@ -1,14 +1,13 @@
 import type { ObjectOptions } from "@sinclair/typebox";
 import { t, type TSchema } from "elysia";
 import type { Sort } from "./sort";
-import { generateAfter, isReverse } from "./keyset-paginate";
+import { generateAfter } from "./keyset-paginate";
 
 export const Page = <T extends TSchema>(schema: T, options?: ObjectOptions) =>
 	t.Object(
 		{
 			items: t.Array(schema),
 			this: t.String({ format: "uri" }),
-			prev: t.Nullable(t.String({ format: "uri" })),
 			next: t.Nullable(t.String({ format: "uri" })),
 		},
 		options,
@@ -18,27 +17,12 @@ export const createPage = <T>(
 	items: T[],
 	{ url, sort, limit }: { url: string; sort: Sort<any, any>; limit: number },
 ) => {
-	let prev: string | null = null;
 	let next: string | null = null;
 
-	const uri = new URL(url);
-	const after = uri.searchParams.get("after");
-	const reverse = after && isReverse(after) ? 1 : 0;
-
-	const has = [
-		// prev
-		items.length > 0 && after,
-		// next
-		items.length === limit && limit > 0,
-	];
-
-	if (has[0 + reverse]) {
-		uri.searchParams.set("after", generateAfter(items[0], sort, true));
-		prev = uri.toString();
-	}
-	if (has[1 - reverse]) {
+	if (items.length === limit && limit > 0) {
+		const uri = new URL(url);
 		uri.searchParams.set("after", generateAfter(items[items.length - 1], sort));
 		next = uri.toString();
 	}
-	return { items, this: url, prev, next };
+	return { items, this: url, next };
 };