Pretty print the push rules content before displaying it

The raw push rules returned by the SDK are a single long line of json, which is
hard to read on a phone. Re-encode the content with a pretty printer using a two
space indentation before handing it to the file viewer.

Parsing to a JsonElement and re-encoding preserves the order of the keys, so the
rules are still listed in the order the server returned them. Content which
cannot be parsed is passed through unchanged, so that a malformed payload remains
viewable.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

features/preferences/impl/build.gradle.kts

@@ -92,6 +92,7 @@ dependencies {
     implementation(libs.color.picker)
     implementation(libs.androidx.browser)
     implementation(libs.androidx.datastore.preferences)
+    implementation(libs.serialization.json)
     api(projects.features.preferences.api)
     implementation(libs.showkase)
 

features/preferences/impl/src/main/kotlin/io/element/android/features/preferences/impl/developer/DeveloperSettingsPresenter.kt

@@ -32,6 +32,7 @@ import io.element.android.libraries.architecture.AsyncData
 import io.element.android.libraries.architecture.Presenter
 import io.element.android.libraries.architecture.runCatchingUpdatingState
 import io.element.android.libraries.core.data.ByteUnit
+import io.element.android.libraries.core.extensions.runCatchingExceptions
 import io.element.android.libraries.core.meta.BuildMeta
 import io.element.android.libraries.matrix.api.analytics.GetDatabaseSizesUseCase
 import io.element.android.libraries.matrix.api.core.DeviceId
@@ -41,6 +42,9 @@ import kotlinx.collections.immutable.ImmutableMap
 import kotlinx.collections.immutable.toImmutableMap
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.launch
+import kotlinx.serialization.ExperimentalSerializationApi
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.JsonElement
 
 @AssistedInject
 class DeveloperSettingsPresenter(
@@ -190,7 +194,7 @@ class DeveloperSettingsPresenter(
                 pushRulesAction.value = AsyncAction.Uninitialized
                 navigator.openPushRules(
                     filename = pushRulesFilename(),
-                    content = content.orEmpty(),
+                    content = content.orEmpty().prettyPrintJson(),
                 )
             }
             .onFailure {
@@ -204,3 +208,18 @@ class DeveloperSettingsPresenter(
      */
     private fun pushRulesFilename() = "push_rules${sessionId.value.replace(':', '_')}.json"
 }
+
+@OptIn(ExperimentalSerializationApi::class)
+private val prettyPrintJson = Json {
+    prettyPrint = true
+    // Keep the indentation small, for a better rendering on mobile.
+    prettyPrintIndent = "  "
+}
+
+/**
+ * Pretty print this json content, so that it is readable when rendered.
+ * Return the content as is if it is not valid json.
+ */
+private fun String.prettyPrintJson(): String = runCatchingExceptions {
+    prettyPrintJson.encodeToString(JsonElement.serializer(), prettyPrintJson.parseToJsonElement(this))
+}.getOrDefault(this)

features/preferences/impl/src/test/kotlin/io/element/android/features/preferences/impl/developer/DeveloperSettingsPresenterTest.kt

@@ -44,7 +44,17 @@ import kotlinx.coroutines.test.runTest
 import org.junit.Rule
 import org.junit.Test
 
-private const val A_PUSH_RULES_CONTENT = "{\"global\":{}}"
+private const val A_PUSH_RULES_CONTENT = """{"global":{"override":[{"rule_id":".m.rule.master","enabled":false}]}}"""
+private const val A_PUSH_RULES_CONTENT_PRETTY_PRINTED = """{
+  "global": {
+    "override": [
+      {
+        "rule_id": ".m.rule.master",
+        "enabled": false
+      }
+    ]
+  }
+}"""
 private val AN_EXCEPTION = Exception("A failure")
 
 class DeveloperSettingsPresenterTest {
@@ -195,7 +205,26 @@ class DeveloperSettingsPresenterTest {
             }
             openPushRulesLambda.assertions().isCalledOnce().with(
                 value("push_rules@alice_server.org.json"),
-                value(A_PUSH_RULES_CONTENT),
+                value(A_PUSH_RULES_CONTENT_PRETTY_PRINTED),
+            )
+        }
+    }
+
+    @Test
+    fun `present - OpenPushRules event keeps the content as is when it is not valid json`() = runTest {
+        val openPushRulesLambda = lambdaRecorder<String, String, Unit> { _, _ -> }
+        val presenter = createDeveloperSettingsPresenter(
+            navigator = DeveloperSettingsNavigator(openPushRulesLambda),
+            notificationSettingsService = FakeNotificationSettingsService(
+                getRawPushRulesResult = { Result.success("not json") },
+            ),
+        )
+        presenter.test {
+            awaitItem().eventSink(DeveloperSettingsEvent.OpenPushRules)
+            skipItems(2)
+            openPushRulesLambda.assertions().isCalledOnce().with(
+                value("push_rules@alice_server.org.json"),
+                value("not json"),
             )
         }
     }