From 2f634b0141ccafa928951c6deebbc90a1980b92c Mon Sep 17 00:00:00 2001
From: Ivar Derksen <ivarderksen@hotmail.nl>
Date: Thu, 31 Oct 2019 14:40:22 +0100
Subject: [PATCH] Feat: replace cred when refreshing non-singleton credential

---
 attributes.go                        | 16 ++++++++++++++++
 internal/sessiontest/session_test.go | 14 ++++++++++++++
 irmaclient/client.go                 | 15 ++++++++++++---
 3 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/attributes.go b/attributes.go
index bb0c678..26d7109 100644
--- a/attributes.go
+++ b/attributes.go
@@ -63,6 +63,22 @@ func (al *AttributeList) Info() *CredentialInfo {
 	return al.info
 }
 
+// EqualsExceptMetadata checks whether two AttributeLists have the same attribute values.
+// The attribute containing the metadata information is skipped in this check.
+func (al *AttributeList) EqualsExceptMetadata(ol *AttributeList) bool {
+	if len(al.Ints) != len(ol.Ints) {
+		return false
+	}
+
+	// Check whether value of all attributes, except for metadata attribute, is equal
+	for i := 1; i < len(al.Ints); i++ {
+		if al.Ints[i].Cmp(ol.Ints[i]) != 0 {
+			return false
+		}
+	}
+	return true
+}
+
 func (al *AttributeList) Hash() string {
 	if al.h == "" {
 		bytes := []byte{}
diff --git a/internal/sessiontest/session_test.go b/internal/sessiontest/session_test.go
index 79f029d..bb1ad35 100644
--- a/internal/sessiontest/session_test.go
+++ b/internal/sessiontest/session_test.go
@@ -96,6 +96,20 @@ func TestIssuanceOptionalSetAttributes(t *testing.T) {
 	sessionHelper(t, req, "issue", nil)
 }
 
+func TestIssuanceSameAttributesNotSingleton(t *testing.T) {
+	client, _ := parseStorage(t)
+	defer test.ClearTestStorage(t)
+
+	prevLen := len(client.CredentialInfoList())
+
+	req := getIssuanceRequest(true)
+	sessionHelper(t, req, "issue", client)
+
+	req = getIssuanceRequest(false)
+	sessionHelper(t, req, "issue", client)
+	require.Equal(t, prevLen+1, len(client.CredentialInfoList()))
+}
+
 func TestLargeAttribute(t *testing.T) {
 	client, _ := parseStorage(t)
 	defer test.ClearTestStorage(t)
diff --git a/irmaclient/client.go b/irmaclient/client.go
index efc9f95..6673668 100644
--- a/irmaclient/client.go
+++ b/irmaclient/client.go
@@ -217,9 +217,18 @@ func (client *Client) addCredential(cred *credential, storeAttributes bool) (err
 	}
 
 	// If this is a singleton credential type, ensure we have at most one by removing any previous instance
-	if !id.Empty() && cred.CredentialType().IsSingleton {
-		for len(client.attrs(id)) != 0 {
-			client.remove(id, 0, false)
+	// If a credential already exists with exactly the same attribute values (except metadata), delete the previous credential
+	if !id.Empty() {
+		if cred.CredentialType().IsSingleton {
+			for len(client.attrs(id)) != 0 {
+				_ = client.remove(id, 0, false)
+			}
+		}
+
+		for i := len(client.attrs(id)) - 1; i >= 0; i-- { // Go backwards through array because remove manipulates it
+			if client.attrs(id)[i].EqualsExceptMetadata(cred.AttributeList()) {
+				_ = client.remove(id, i, false)
+			}
 		}
 	}
 
-- 
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