feat: upgrade to v2.0

Signed-off-by: Nam Hoang <hoangxuannam160493@gmail.com>

lib/helpers.js

@@ -0,0 +1,56 @@
+/*!
+ * Copyright (c) 2023 Digital Bazaar, Inc. All rights reserved.
+ */
+const credentialsContext = require('credentials-context');
+
+const {
+  constants: {CREDENTIALS_CONTEXT_V1_URL},
+} = credentialsContext;
+const CREDENTIALS_CONTEXT_V2_URL = 'https://www.w3.org/ns/credentials/v2';
+
+const credentialContextUrls = new Set([
+  CREDENTIALS_CONTEXT_V1_URL,
+  CREDENTIALS_CONTEXT_V2_URL,
+]);
+
+/**
+ * Asserts that a context array's first item is a credentials context.
+ *
+ * @param {object} options - Options.
+ * @param {Array} options.context - An array of contexts.
+ *
+ * @throws {Error} - Throws if the first context
+ *   is not a credentials context.
+ *
+ * @returns {undefined}
+ */
+function assertCredentialContext({context}) {
+  // ensure first context is credentials context url
+  if(credentialContextUrls.has(context[0]) === false) {
+    // throw if the first context is not a credentials context
+    throw new Error(
+      `"${CREDENTIALS_CONTEXT_V1_URL}" or "${CREDENTIALS_CONTEXT_V2_URL}"` +
+        ' needs to be first in the list of contexts.'
+    );
+  }
+}
+
+/**
+ * Checks to see if a VC has a V1 context.
+ *
+ * @param {object} options - Options.
+ * @param {object} options.credential - A VC.
+ *
+ * @returns {boolean} Indicates whether the VC contains a V1 context.
+ */
+function hasV1CredentialContext({credential}) {
+  return credential?.['@context']?.[0] === CREDENTIALS_CONTEXT_V1_URL;
+}
+
+module.exports = {
+  assertCredentialContext,
+  hasV1CredentialContext,
+  CREDENTIALS_CONTEXT_V1_URL,
+  CREDENTIALS_CONTEXT_V2_URL,
+  credentialContextUrls,
+};