Sort credential list by registrable domain

app/build.gradle.kts

@@ -58,6 +58,7 @@ dependencies {
     implementation(libs.androidx.credentials)
     implementation(libs.kotlinx.coroutines.android)
     implementation(libs.material)
+    implementation(libs.etldx)
     testImplementation(libs.junit)
     androidTestImplementation(libs.androidx.junit)
     androidTestImplementation(libs.androidx.espresso.core)

app/src/main/java/pl/lebihan/authnkey/CredentialSorting.kt

@@ -0,0 +1,34 @@
+package pl.lebihan.authnkey
+
+import pl.lebihan.etldx.InvalidDomainNameException
+import pl.lebihan.etldx.PublicSuffixList
+
+/** An rpId split into the parts we order by. Both parts are already lower cased. */
+private class DomainKey(val registrable: String, val subdomain: String)
+
+private fun PublicSuffixList.keyFor(rpId: String): DomainKey =
+    try {
+        val domain = split(rpId)
+        // registrableDomain is null when the rpId is a public suffix itself
+        DomainKey(domain.registrableDomain ?: domain.name, domain.subdomain.orEmpty())
+    } catch (_: InvalidDomainNameException) {
+        // The RP registered something that is not a domain name.
+        DomainKey(rpId.lowercase(), "")
+    }
+
+/**
+ * Orders credentials by registrable domain, then by subdomain, then by user name.
+ *
+ * Sorting on the eTLD+1 keeps `example.com`, `login.example.com` and `account.example.com` together
+ * under E instead of scattering them across the list.
+ */
+fun List<CredentialItem>.sortedByRegistrableDomain(psl: PublicSuffixList): List<CredentialItem> {
+    val keys = map { it.rpId }.distinct().associateWith(psl::keyFor)
+    return sortedWith(
+        compareBy<CredentialItem> { keys.getValue(it.rpId).registrable }
+            .thenBy { keys.getValue(it.rpId).subdomain }
+            .thenBy(String.CASE_INSENSITIVE_ORDER) {
+                it.credential.userName ?: it.credential.userDisplayName ?: ""
+            }
+    )
+}

app/src/main/java/pl/lebihan/authnkey/MainActivity.kt

@@ -861,13 +861,17 @@ class MainActivity : AppCompatActivity() {
             }
         }
 
-        val credentialItems = rpsWithCredentials.flatMap { rpWithCreds ->
-            rpWithCreds.credentials?.map { cred ->
-                CredentialItem(
-                    rpId = rpWithCreds.relyingParty.rpId ?: rpWithCreds.relyingParty.rpIdHash.toHex(),
-                    credential = cred
-                )
-            } ?: emptyList()
+        val credentialItems = withContext(Dispatchers.IO) {
+            val psl = PublicSuffixes.get(this@MainActivity)
+            rpsWithCredentials.flatMap { rpWithCreds ->
+                rpWithCreds.credentials?.map { cred ->
+                    CredentialItem(
+                        rpId = rpWithCreds.relyingParty.rpId
+                            ?: rpWithCreds.relyingParty.rpIdHash.toHex(),
+                        credential = cred
+                    )
+                } ?: emptyList()
+            }.sortedByRegistrableDomain(psl)
         }
 
         showCredentialsDialog(metadata, credentialItems)

app/src/main/java/pl/lebihan/authnkey/PublicSuffixes.kt

@@ -0,0 +1,24 @@
+package pl.lebihan.authnkey
+
+import android.content.Context
+import pl.lebihan.etldx.PublicSuffixList
+
+/**
+ * Holds the parsed public suffix list.
+ *
+ * Parsing walks the whole list, so it is done once and the instance kept. [PublicSuffixList] is
+ * immutable and thread safe.
+ */
+object PublicSuffixes {
+
+    @Volatile
+    private var instance: PublicSuffixList? = null
+
+    /** Returns the list, parsing it on first use. Call from a background thread. */
+    fun get(context: Context): PublicSuffixList =
+        instance ?: synchronized(this) {
+            instance ?: PublicSuffixList(
+                context.applicationContext.resources.openRawResource(R.raw.public_suffix_list)
+            ).also { instance = it }
+        }
+}

gradle/libs.versions.toml

@@ -9,6 +9,7 @@ appcompat = "1.7.1"
 kotlinxCoroutinesAndroid = "1.11.0"
 credentials = "1.6.0"
 material = "1.14.0"
+etldx = "0.1.0"
 
 [libraries]
 androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
@@ -19,6 +20,7 @@ androidx-appcompat = { group = "androidx.appcompat", name = "appcompat", version
 androidx-credentials = { group = "androidx.credentials", name = "credentials", version.ref = "credentials" }
 kotlinx-coroutines-android = { module = "org.jetbrains.kotlinx:kotlinx-coroutines-android", version.ref = "kotlinxCoroutinesAndroid" }
 material = { group = "com.google.android.material", name = "material", version.ref = "material" }
+etldx = { module = "com.github.mimi89999:etldx", version.ref = "etldx" }
 
 [plugins]
 android-application = { id = "com.android.application", version.ref = "agp" }

settings.gradle.kts

@@ -16,6 +16,10 @@ dependencyResolutionManagement {
     repositories {
         google()
         mavenCentral()
+        maven {
+            url = uri("https://jitpack.io")
+            content { includeGroup("com.github.mimi89999") }
+        }
     }
 }