feat(phone): add SMS OTP auto-fill via Google Play Services

apps/flipcash/features/contact-verification/src/main/kotlin/com/flipcash/app/contact/verification/internal/phone/PhoneCodeScreen.kt

@@ -28,6 +28,7 @@ import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.text.style.TextDecoration
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import com.flipcash.app.phone.components.OtpInputField
+import com.flipcash.app.phone.components.SmsOtpAutofill
 import com.flipcash.features.contact.verification.R
 import com.getcode.theme.CodeTheme
 import com.getcode.ui.components.OnWindowFocusedRequester
@@ -54,6 +55,12 @@ private fun PhoneCodeScreenContent(
     val focusRequester = remember { FocusRequester() }
     val keyboard = rememberKeyboardController()
 
+    SmsOtpAutofill(
+        otpState = state.codeTextFieldState,
+        otpLength = state.otpLength,
+        attempts = state.attempts,
+    )
+
     CodeScaffold(
         modifier = Modifier
             .fillMaxSize()

apps/flipcash/shared/phone/build.gradle.kts

@@ -11,6 +11,8 @@ dependencies {
 
     api(libs.rinku.compose)
 
+    implementation(libs.play.services.auth.api.phone)
+
     testImplementation(kotlin("test"))
     testImplementation(libs.bundles.unit.testing)
     testImplementation(libs.robolectric)

apps/flipcash/shared/phone/src/main/kotlin/com/flipcash/app/phone/components/SmsOtpAutofill.kt

@@ -0,0 +1,124 @@
+package com.flipcash.app.phone.components
+
+import android.app.Activity.RESULT_OK
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import android.content.IntentFilter
+import android.os.Build
+import android.os.Bundle
+import androidx.activity.compose.rememberLauncherForActivityResult
+import androidx.activity.result.contract.ActivityResultContracts.StartActivityForResult
+import androidx.compose.foundation.text.input.TextFieldState
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberUpdatedState
+import androidx.compose.ui.platform.LocalContext
+import androidx.core.os.BundleCompat
+import com.getcode.utils.trace
+import com.google.android.gms.auth.api.phone.SmsRetriever
+import com.google.android.gms.common.api.CommonStatusCodes
+import com.google.android.gms.common.api.Status
+
+@Composable
+fun SmsOtpAutofill(
+    otpState: TextFieldState,
+    otpLength: Int,
+    attempts: Int,
+) {
+    val context = LocalContext.current
+    val currentOtpState by rememberUpdatedState(otpState)
+    val currentOtpLength by rememberUpdatedState(otpLength)
+    val filled = remember { mutableStateOf(false) }
+
+    val consentLauncher = rememberLauncherForActivityResult(StartActivityForResult()) { result ->
+        if (result.resultCode == RESULT_OK) {
+            val message = result.data?.getStringExtra(SmsRetriever.EXTRA_SMS_MESSAGE)
+                ?: return@rememberLauncherForActivityResult
+            parseAndFill(message, currentOtpLength, currentOtpState, filled)
+        }
+    }
+
+    DisposableEffect(attempts) {
+        filled.value = false
+
+        val client = SmsRetriever.getClient(context)
+        client.startSmsRetriever()
+            .addOnSuccessListener { trace("SmsRetriever started") }
+            .addOnFailureListener { trace("SmsRetriever failed to start: ${it.message}") }
+        client.startSmsUserConsent(null)
+            .addOnSuccessListener { trace("SmsUserConsent started") }
+            .addOnFailureListener { trace("SmsUserConsent failed to start: ${it.message}") }
+
+        val filter = IntentFilter(SmsRetriever.SMS_RETRIEVED_ACTION)
+
+        val receiver = object : BroadcastReceiver() {
+            override fun onReceive(ctx: Context, intent: Intent) {
+                if (intent.action != SmsRetriever.SMS_RETRIEVED_ACTION) return
+                val extras: Bundle = intent.extras ?: return
+                // GMS classes (Status) need the GMS class loader for deserialization
+                extras.classLoader = SmsRetriever::class.java.classLoader
+
+                val status = BundleCompat.getParcelable(extras, SmsRetriever.EXTRA_STATUS, Status::class.java)
+                if (status?.statusCode != CommonStatusCodes.SUCCESS) {
+                    trace("SMS retrieval failed with status: ${status?.statusCode}")
+                    return
+                }
+
+                // Retriever path: SMS message directly available
+                val message = extras.getString(SmsRetriever.EXTRA_SMS_MESSAGE)
+                if (message != null) {
+                    trace("SmsRetriever received message")
+                    parseAndFill(message, currentOtpLength, currentOtpState, filled)
+                    return
+                }
+
+                // User Consent path: need to launch consent dialog
+                if (filled.value) return
+
+                val consentIntent = BundleCompat.getParcelable(
+                    extras,
+                    SmsRetriever.EXTRA_CONSENT_INTENT,
+                    Intent::class.java
+                )
+                if (consentIntent != null) {
+                    trace("Launching SMS consent dialog")
+                    try {
+                        consentLauncher.launch(consentIntent)
+                    } catch (e: Exception) {
+                        trace("Failed to launch consent dialog: ${e.message}")
+                    }
+                }
+            }
+        }
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.UPSIDE_DOWN_CAKE) {
+            context.registerReceiver(
+                receiver, filter, SmsRetriever.SEND_PERMISSION,
+                null, Context.RECEIVER_EXPORTED,
+            )
+        } else {
+            context.registerReceiver(receiver, filter, SmsRetriever.SEND_PERMISSION, null)
+        }
+
+        onDispose {
+            context.unregisterReceiver(receiver)
+        }
+    }
+}
+
+private fun parseAndFill(
+    message: String,
+    otpLength: Int,
+    state: TextFieldState,
+    filled: androidx.compose.runtime.MutableState<Boolean>,
+) {
+    if (filled.value) return
+    val otp = """\b(\d{$otpLength})\b""".toRegex().find(message)?.groupValues?.get(1) ?: return
+    trace("Auto-filling OTP")
+    state.edit { replace(0, length, otp) }
+    filled.value = true
+}

gradle/libs.versions.toml

@@ -52,6 +52,7 @@ grpc-android = "1.82.0"
 slf4j = "1.7.36"
 firebase-bom = "34.14.1"
 play-service-ml-barcode = "18.3.1"
+play-services-auth-api-phone = "18.3.0"
 google-play-billing = "9.0.0"
 google-play-updates = "2.1.0"
 
@@ -220,6 +221,7 @@ firebase-perf = { module = "com.google.firebase:firebase-perf" }
 # Google Play Services
 play-integrity = { module = "com.google.android.play:integrity", version = "1.6.0" }
 play-service-ml-barcode = { module = "com.google.android.gms:play-services-mlkit-barcode-scanning", version.ref = "play-service-ml-barcode" }
+play-services-auth-api-phone = { module = "com.google.android.gms:play-services-auth-api-phone", version.ref = "play-services-auth-api-phone" }
 play-services-wallet = { module = "com.google.android.gms:play-services-wallet", version = "20.0.0" }
 
 # Google Play Billing