Show remaining time in TOTP field (#1766)

* Pass down remaining time for TOTPs to UI layer

* format-common: switch TOTP flow to use co-operative cancelation

* format-common: add a regression test for OTP duration calculation

* Abstract out labels

* Switch to launchIn

4 files changed, 54 insertions, 12 deletions

diff --git a/format-common/src/main/kotlin/dev/msfjarvis/aps/data/passfile/PasswordEntry.kt b/format-common/src/main/kotlin/dev/msfjarvis/aps/data/passfile/PasswordEntry.kt
index 94149477..a0a85f3e 100644
--- a/format-common/src/main/kotlin/dev/msfjarvis/aps/data/passfile/PasswordEntry.kt
+++ b/format-common/src/main/kotlin/dev/msfjarvis/aps/data/passfile/PasswordEntry.kt
@@ -13,12 +13,17 @@ import dev.msfjarvis.aps.util.time.UserClock
 import dev.msfjarvis.aps.util.totp.Otp
 import dev.msfjarvis.aps.util.totp.TotpFinder
 import kotlin.collections.set
+import kotlin.coroutines.coroutineContext
+import kotlin.time.Duration.Companion.seconds
+import kotlin.time.ExperimentalTime
 import kotlinx.coroutines.awaitCancellation
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.isActive
 
 /** Represents a single entry in the password store. */
+@OptIn(ExperimentalTime::class)
 public class PasswordEntry
 @AssistedInject
 constructor(
@@ -52,13 +57,13 @@ constructor(
    * does not have a TOTP secret, the flow will never emit. Users should call [hasTotp] before
    * collection to check if it is valid to collect this [Flow].
    */
-  public val totp: Flow<String> = flow {
+  public val totp: Flow<Totp> = flow {
     if (totpSecret != null) {
-      repeat(Int.MAX_VALUE) {
-        val (otp, remainingTime) = calculateTotp()
+      do {
+        val otp = calculateTotp()
         emit(otp)
-        delay(remainingTime)
-      }
+        delay(1000L)
+      } while (coroutineContext.isActive)
     } else {
       awaitCancellation()
     }
@@ -169,17 +174,17 @@ constructor(
     return null
   }
 
-  private fun calculateTotp(): Pair<String, Long> {
+  private fun calculateTotp(): Totp {
     val digits = totpFinder.findDigits(content)
     val totpPeriod = totpFinder.findPeriod(content)
     val totpAlgorithm = totpFinder.findAlgorithm(content)
     val issuer = totpFinder.findIssuer(content)
     val millis = clock.millis()
-    val remainingTime = totpPeriod - (millis % totpPeriod)
+    val remainingTime = (totpPeriod - ((millis / 1000) % totpPeriod)).seconds
     Otp.calculateCode(totpSecret!!, millis / (1000 * totpPeriod), totpAlgorithm, digits, issuer)
       .mapBoth(
         { code ->
-          return code to remainingTime
+          return Totp(code, remainingTime)
         },
         { throwable -> throw throwable }
       )
diff --git a/format-common/src/main/kotlin/dev/msfjarvis/aps/data/passfile/Totp.kt b/format-common/src/main/kotlin/dev/msfjarvis/aps/data/passfile/Totp.kt
new file mode 100644
index 00000000..a43cce6a
--- /dev/null
+++ b/format-common/src/main/kotlin/dev/msfjarvis/aps/data/passfile/Totp.kt
@@ -0,0 +1,8 @@
+package dev.msfjarvis.aps.data.passfile
+
+import kotlin.time.Duration
+import kotlin.time.ExperimentalTime
+
+/** Holder for a TOTP secret and the duration for which it is valid. */
+@OptIn(ExperimentalTime::class)
+public data class Totp(public val value: String, public val remainingTime: Duration)
diff --git a/format-common/src/test/kotlin/dev/msfjarvis/aps/data/passfile/PasswordEntryTest.kt b/format-common/src/test/kotlin/dev/msfjarvis/aps/data/passfile/PasswordEntryTest.kt
index d8a1fdc2..55c62533 100644
--- a/format-common/src/test/kotlin/dev/msfjarvis/aps/data/passfile/PasswordEntryTest.kt
+++ b/format-common/src/test/kotlin/dev/msfjarvis/aps/data/passfile/PasswordEntryTest.kt
@@ -8,6 +8,7 @@ package dev.msfjarvis.aps.data.passfile
 import dev.msfjarvis.aps.test.CoroutineTestRule
 import dev.msfjarvis.aps.test.test2
 import dev.msfjarvis.aps.util.time.TestUserClock
+import dev.msfjarvis.aps.util.time.UserClock
 import dev.msfjarvis.aps.util.totp.TotpFinder
 import java.util.Locale
 import kotlin.test.Test
@@ -15,6 +16,7 @@ import kotlin.test.assertEquals
 import kotlin.test.assertNotNull
 import kotlin.test.assertNull
 import kotlin.test.assertTrue
+import kotlin.time.Duration.Companion.seconds
 import kotlin.time.ExperimentalTime
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.test.runTest
@@ -24,9 +26,9 @@ import org.junit.Rule
 class PasswordEntryTest {
 
   @get:Rule val coroutineTestRule: CoroutineTestRule = CoroutineTestRule()
-  private fun makeEntry(content: String) =
+  private fun makeEntry(content: String, clock: UserClock = fakeClock) =
     PasswordEntry(
-      fakeClock,
+      clock,
       testFinder,
       content.encodeToByteArray(),
     )
@@ -134,7 +136,26 @@ class PasswordEntryTest {
     val entry = makeEntry("secret\nextra\n$TOTP_URI")
     assertTrue(entry.hasTotp())
     entry.totp.test2 {
-      assertEquals("818800", expectMostRecentItem())
+      val otp = expectMostRecentItem()
+      assertEquals("818800", otp.value)
+      assertEquals(30.seconds, otp.remainingTime)
+      cancelAndIgnoreRemainingEvents()
+    }
+  }
+
+  /**
+   * Same as [testGeneratesOtpFromTotpUri], but advances the clock by 5 seconds. This exercises the
+   * [Totp.remainingTime] calculation logic, and acts as a regression test to resolve the bug which
+   * blocked https://msfjarvis.dev/aps/issue/1550.
+   */
+  @Test
+  fun testGeneratedOtpHasCorrectRemainingTime() = runTest {
+    val entry = makeEntry("secret\nextra\n$TOTP_URI", TestUserClock.withAddedSeconds(5))
+    assertTrue(entry.hasTotp())
+    entry.totp.test2 {
+      val otp = expectMostRecentItem()
+      assertEquals("818800", otp.value)
+      assertEquals(25.seconds, otp.remainingTime)
       cancelAndIgnoreRemainingEvents()
     }
   }
@@ -144,7 +165,9 @@ class PasswordEntryTest {
     val entry = makeEntry(TOTP_URI)
     assertNull(entry.password)
     entry.totp.test2 {
-      assertEquals("818800", expectMostRecentItem())
+      val otp = expectMostRecentItem()
+      assertEquals("818800", otp.value)
+      assertEquals(30.seconds, otp.remainingTime)
       cancelAndIgnoreRemainingEvents()
     }
   }
diff --git a/format-common/src/test/kotlin/dev/msfjarvis/aps/util/time/TestClocks.kt b/format-common/src/test/kotlin/dev/msfjarvis/aps/util/time/TestClocks.kt
index 5098bec9..ee74a40d 100644
--- a/format-common/src/test/kotlin/dev/msfjarvis/aps/util/time/TestClocks.kt
+++ b/format-common/src/test/kotlin/dev/msfjarvis/aps/util/time/TestClocks.kt
@@ -24,4 +24,10 @@ class TestUserClock(instant: Instant) : UserClock() {
   override fun getZone(): ZoneId = UTC
 
   override fun instant(): Instant = clock.instant()
+
+  companion object {
+    fun withAddedSeconds(secondsToAdd: Long): TestUserClock {
+      return TestUserClock(Instant.EPOCH.plusSeconds(secondsToAdd))
+    }
+  }
 }