From 439914f8902a82d87be32675533d38996f55b509 Mon Sep 17 00:00:00 2001
From: Dave Longley <dlongley@digitalbazaar.com>
Date: Mon, 28 Oct 2024 16:59:56 -0400
Subject: [PATCH] Filter by VPR `QueryByExample` `example` JSON-LD context.

---
 CHANGELOG.md         |  6 ++++++
 lib/presentations.js | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c150837..c9d56ef 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # bedrock-web-wallet ChangeLog
 
+## 14.6.2 - 2024-10-dd
+
+### Fixed
+- Filter VPR query matches by JSON-LD context, if one was provided
+  in the query by example `example`.
+
 ## 14.6.1 - 2024-10-02
 
 ### Fixed
diff --git a/lib/presentations.js b/lib/presentations.js
index 3a952ca..e129d67 100644
--- a/lib/presentations.js
+++ b/lib/presentations.js
@@ -384,6 +384,9 @@ async function _getMatches({
   for(const result of results) {
     const {credentialQuery, matches} = result;
 
+    // remove any matches that do not include the requested context
+    result.matches = matches.filter(_matchContextFilter({credentialQuery}));
+
     // apply local filters
     // FIXME: write generalized matching instead
     result.matches = matches.filter(_openBadgeFilter({credentialQuery}));
@@ -422,6 +425,36 @@ function _openBadgeFilter({credentialQuery}) {
   };
 }
 
+function _matchContextFilter({credentialQuery}) {
+  // get expected context
+  let expectedContext = credentialQuery?.example?.['@context'];
+  if(expectedContext === undefined) {
+    // no context specified, allow any result
+    return () => true;
+  }
+  // normalize to an array
+  if(!Array.isArray(expectedContext)) {
+    expectedContext = [expectedContext];
+  }
+  // map to an array of strings for later comparison
+  expectedContext = expectedContext.map(
+    ctx => typeof ctx === 'string' ? ctx : JSON.stringify(ctx));
+  return ({record: {content}}) => {
+    // normalize record context to an array if present
+    let recordContext = content['@context'];
+    if(recordContext !== undefined && !Array.isArray(recordContext)) {
+      recordContext = [recordContext];
+    }
+    // map to an array of strings for later comparison
+    recordContext = recordContext.map(
+      ctx => typeof ctx === 'string' ? ctx : JSON.stringify(ctx));
+
+    // if every context value in `expectedContext` is present in
+    // `recordContext`, then accept the record
+    return expectedContext.every(c => recordContext.includes(c));
+  };
+}
+
 async function _matchQueryByExample({
   verifiablePresentationRequest, query, credentialStore, matches
 }) {