From f0a1c26c00ebfefffa9c3695235cf7d68866762d Mon Sep 17 00:00:00 2001
From: Katja Lutz <mail@katjalutz.ch>
Date: Fri, 30 Aug 2024 17:38:28 +0200
Subject: [PATCH] fix: hash chunks with djb2

---
 .changeset/tough-timers-admire.md |  5 +++++
 packages/vinxi/lib/chunks.js      | 30 +++++++++++++++++++++---------
 packages/vinxi/lib/chunks.test.js |  9 +++++++++
 3 files changed, 35 insertions(+), 9 deletions(-)
 create mode 100644 .changeset/tough-timers-admire.md
 create mode 100644 packages/vinxi/lib/chunks.test.js

diff --git a/.changeset/tough-timers-admire.md b/.changeset/tough-timers-admire.md
new file mode 100644
index 00000000..c628c843
--- /dev/null
+++ b/.changeset/tough-timers-admire.md
@@ -0,0 +1,5 @@
+---
+"vinxi": patch
+---
+
+fix: hash chunks with djb2
diff --git a/packages/vinxi/lib/chunks.js b/packages/vinxi/lib/chunks.js
index 2e30f940..81242c4f 100644
--- a/packages/vinxi/lib/chunks.js
+++ b/packages/vinxi/lib/chunks.js
@@ -1,7 +1,7 @@
 import { readFileSync } from "fs";
-import { join } from "vinxi/lib/path";
 
 import { viteManifestPath } from "./manifest-path.js";
+import { join } from "./path.js";
 
 const CHUNK_PREFIX = "c_";
 
@@ -57,19 +57,31 @@ export const chunksServerVirtualModule =
 		`;
 	};
 
+const hashes = new Map();
+const regexReturnCharacters = /\r/g;
+
 /**
+ * djb2 hashing
  *
- * @param {string} str
- * @returns
+ * @param {string} input
+ * @returns {string}
+ *
+ * Source: https://github.com/sveltejs/svelte/blob/0203eb319b5d86138236158e3ae6ecf29e26864c/packages/svelte/src/utils.js#L7
+ * Source License: MIT
  */
-export function hash(str) {
-	let hash = 0;
+export function hash(input) {
+	const cachedResult = hashes.get(input);
+	if (cachedResult) return cachedResult;
 
-	for (let i = 0; i < str.length; i++) {
-		hash += str.charCodeAt(i);
-	}
+	let str = input.replace(regexReturnCharacters, "");
+	let hash = 5381;
+	let i = str.length;
+
+	while (i--) hash = ((hash << 5) - hash) ^ str.charCodeAt(i);
+	const result = (hash >>> 0).toString(36);
+	hashes.set(input, result);
 
-	return hash;
+	return result;
 }
 
 /**
diff --git a/packages/vinxi/lib/chunks.test.js b/packages/vinxi/lib/chunks.test.js
new file mode 100644
index 00000000..ae9acc55
--- /dev/null
+++ b/packages/vinxi/lib/chunks.test.js
@@ -0,0 +1,9 @@
+import { describe, expect, it } from "vitest";
+
+import { hash } from "./chunks";
+
+describe("hash", () => {
+	it("should create different hashes for abc and cba", () => {
+		expect(hash("abc")).not.toEqual(hash("cba"));
+	});
+});