From b6d5642e1eeaf8e23fe5a6b749f1c66db2f4f46d Mon Sep 17 00:00:00 2001
From: arcataroger <arcataroger@gmail.com>
Date: Fri, 22 Mar 2024 10:32:41 -0700
Subject: [PATCH] Add function to convert Dato URL-safe Base64-encoded IDs back
 to valid UUID hex strings

---
 .../cma-client/__tests__/datoIdToUuid.test.ts | 21 +++++++++++
 packages/cma-client/src/datoIdtoUuid.ts       | 36 +++++++++++++++++++
 packages/cma-client/src/index.ts              |  1 +
 3 files changed, 58 insertions(+)
 create mode 100644 packages/cma-client/__tests__/datoIdToUuid.test.ts
 create mode 100644 packages/cma-client/src/datoIdtoUuid.ts

diff --git a/packages/cma-client/__tests__/datoIdToUuid.test.ts b/packages/cma-client/__tests__/datoIdToUuid.test.ts
new file mode 100644
index 00000000..54ab5d07
--- /dev/null
+++ b/packages/cma-client/__tests__/datoIdToUuid.test.ts
@@ -0,0 +1,21 @@
+import { validate } from 'uuid';
+import { datoIdToUuid } from '../src/datoIdToUuid';
+import { generateId } from '../src/generateId';
+
+describe('datoIdToUuid', () => {
+  it('converts an example URL-safe Base64 DatoID to a valid UUID hex string', () => {
+    const base64url = 'WTyssHtyTzu9_EbszSVhPw';
+    const expectedUuid = '593cacb0-7b72-4f3b-bdfc-46eccd25613f';
+
+    const result = datoIdToUuid(base64url);
+
+    expect(result).toBe(expectedUuid);
+    expect(validate(result)).toBe(true);
+  });
+
+  it('expects an ID from generateId() to validate as a v4 UUID', () => {
+    const base64Id = generateId();
+    const uuid = datoIdToUuid(base64Id);
+    expect(validate(uuid)).toBe(true);
+  });
+});
diff --git a/packages/cma-client/src/datoIdtoUuid.ts b/packages/cma-client/src/datoIdtoUuid.ts
new file mode 100644
index 00000000..4f262d9d
--- /dev/null
+++ b/packages/cma-client/src/datoIdtoUuid.ts
@@ -0,0 +1,36 @@
+import { stringify } from 'uuid';
+function fromBase64toUint8Array(base64String: string) {
+  // Check if Buffer is available, indicating a Node.js environment
+  if (typeof Buffer !== 'undefined') {
+    // Use Buffer to convert base64 to a Uint8Array
+    return new Uint8Array(Buffer.from(base64String, 'base64'));
+  } else {
+    // Assuming a browser environment if Buffer is not available
+    // Use atob to decode base64 to a binary string
+    const binaryString = atob(base64String);
+
+    // Create a Uint8Array of the same length as the binary string
+    const bytes = new Uint8Array(binaryString.length);
+
+    // Convert each character to its byte value
+    for (let i = 0; i < binaryString.length; i++) {
+      bytes[i] = binaryString.charCodeAt(i);
+    }
+    return bytes;
+  }
+}
+
+export const datoIdToUuid = (b64url: string): string => {
+  // Undo the URL encoding we did in generateId()
+  const reversedUrlEncoding: string = `${b64url
+    .replace(/-/g, '+')
+    .replace(/_/g, '/')}==`;
+
+  // Decode the B64 back into a Uint8Array
+  const encodedAsBuffer = fromBase64toUint8Array(reversedUrlEncoding);
+
+  // Stringify the UUID into a hex string
+  const stringified = stringify(encodedAsBuffer);
+
+  return stringified;
+};
diff --git a/packages/cma-client/src/index.ts b/packages/cma-client/src/index.ts
index 03c637d1..f5059e10 100644
--- a/packages/cma-client/src/index.ts
+++ b/packages/cma-client/src/index.ts
@@ -5,5 +5,6 @@ export type { ClientConfigOptions } from './generated/Client';
 export * from './buildClient';
 export * from './buildBlockRecord';
 export * from './generateId';
+export * from './datoIdtoUuid';
 export * as SchemaTypes from './generated/SchemaTypes';
 export * as SimpleSchemaTypes from './generated/SimpleSchemaTypes';