Merge pull request #7292 from thunderbird/one_time_initialization

Add support for one-time (initialization) events

core/ui/compose/common/src/main/kotlin/app/k9mail/core/ui/compose/common/mvi/BaseViewModel.kt

@@ -35,6 +35,8 @@ abstract class BaseViewModel<STATE, EVENT, EFFECT>(
     private val _effect = MutableSharedFlow<EFFECT>()
     override val effect: SharedFlow<EFFECT> = _effect.asSharedFlow()
 
+    private val handledOneTimeEvents = mutableSetOf<EVENT>()
+
     /**
      * Updates the [STATE] of the ViewModel.
      *
@@ -54,4 +56,20 @@ abstract class BaseViewModel<STATE, EVENT, EFFECT>(
             _effect.emit(effect)
         }
     }
+
+    /**
+     * Ensures that one-time events are only handled once.
+     *
+     * When you can't ensure that an event is only sent once, but you want the event to only be handled once, call this
+     * method. It will ensure [block] is only executed the first time this function is called. Subsequent calls with an
+     * [event] argument equal to that of a previous invocation will not execute [block].
+     *
+     * Multiple one-time events are supported.
+     */
+    protected fun handleOneTimeEvent(event: EVENT, block: () -> Unit) {
+        if (event !in handledOneTimeEvents) {
+            handledOneTimeEvents.add(event)
+            block()
+        }
+    }
 }

core/ui/compose/common/src/test/kotlin/app/k9mail/core/ui/compose/common/mvi/BaseViewModelTest.kt

@@ -4,6 +4,8 @@ import app.cash.turbine.test
 import app.k9mail.core.ui.compose.testing.MainDispatcherRule
 import assertk.assertThat
 import assertk.assertions.isEqualTo
+import assertk.assertions.isFalse
+import assertk.assertions.isTrue
 import kotlinx.coroutines.test.runTest
 import org.junit.Rule
 import org.junit.Test
@@ -47,10 +49,61 @@ class BaseViewModelTest {
         }
     }
 
+    @Test
+    fun `handleOneTimeEvent() should execute block`() = runTest {
+        val viewModel = TestBaseViewModel()
+        var eventHandled = false
+
+        viewModel.callHandleOneTimeEvent(event = "event") {
+            eventHandled = true
+        }
+
+        assertThat(eventHandled).isTrue()
+    }
+
+    @Test
+    fun `handleOneTimeEvent() should execute block only once`() = runTest {
+        val viewModel = TestBaseViewModel()
+        var eventHandledCount = 0
+
+        repeat(2) {
+            viewModel.callHandleOneTimeEvent(event = "event") {
+                eventHandledCount++
+            }
+        }
+
+        assertThat(eventHandledCount).isEqualTo(1)
+    }
+
+    @Test
+    fun `handleOneTimeEvent() should support multiple one-time events`() = runTest {
+        val viewModel = TestBaseViewModel()
+        var eventOneHandled = false
+        var eventTwoHandled = false
+
+        viewModel.callHandleOneTimeEvent(event = "eventOne") {
+            eventOneHandled = true
+        }
+
+        assertThat(eventOneHandled).isTrue()
+        assertThat(eventTwoHandled).isFalse()
+
+        viewModel.callHandleOneTimeEvent(event = "eventTwo") {
+            eventTwoHandled = true
+        }
+
+        assertThat(eventOneHandled).isTrue()
+        assertThat(eventTwoHandled).isTrue()
+    }
+
     private class TestBaseViewModel : BaseViewModel<String, String, String>("Initial state") {
         override fun event(event: String) {
             updateState { event }
             emitEffect(event)
         }
+
+        fun callHandleOneTimeEvent(event: String, block: () -> Unit) {
+            handleOneTimeEvent(event, block)
+        }
     }
 }

feature/account/edit/src/main/kotlin/app/k9mail/feature/account/edit/ui/server/settings/save/BaseSaveServerSettingsViewModel.kt

@@ -24,7 +24,7 @@ abstract class BaseSaveServerSettingsViewModel(
 
     override fun event(event: Event) {
         when (event) {
-            Event.SaveServerSettings -> onSaveServerSettings()
+            Event.SaveServerSettings -> handleOneTimeEvent(event, ::onSaveServerSettings)
             Event.OnNextClicked -> navigateNext()
             Event.OnBackClicked -> navigateBack()
         }

feature/account/server/settings/src/main/kotlin/app/k9mail/feature/account/server/settings/ui/incoming/IncomingServerSettingsViewModel.kt

@@ -23,7 +23,7 @@ open class IncomingServerSettingsViewModel(
     @Suppress("CyclomaticComplexMethod")
     override fun event(event: Event) {
         when (event) {
-            Event.LoadAccountState -> loadAccountState()
+            Event.LoadAccountState -> handleOneTimeEvent(event, ::loadAccountState)
 
             is Event.ProtocolTypeChanged -> updateProtocolType(event.protocolType)
             is Event.ServerChanged -> updateState { it.copy(server = it.server.updateValue(event.server)) }

feature/account/server/settings/src/main/kotlin/app/k9mail/feature/account/server/settings/ui/outgoing/OutgoingServerSettingsViewModel.kt

@@ -21,7 +21,7 @@ open class OutgoingServerSettingsViewModel(
 
     override fun event(event: Event) {
         when (event) {
-            Event.LoadAccountState -> loadAccountState()
+            Event.LoadAccountState -> handleOneTimeEvent(event, ::loadAccountState)
 
             is Event.ServerChanged -> updateState { it.copy(server = it.server.updateValue(event.server)) }
             is Event.SecurityChanged -> updateSecurity(event.security)

feature/account/server/validation/src/main/kotlin/app/k9mail/feature/account/server/validation/ui/BaseServerValidationViewModel.kt

@@ -37,7 +37,7 @@ abstract class BaseServerValidationViewModel(
 
     override fun event(event: Event) {
         when (event) {
-            Event.LoadAccountStateAndValidate -> loadAccountStateAndValidate()
+            Event.LoadAccountStateAndValidate -> handleOneTimeEvent(event, ::loadAccountStateAndValidate)
             is Event.OnOAuthResult -> onOAuthResult(event.result)
             Event.ValidateServerSettings -> onValidateConfig()
             Event.OnNextClicked -> navigateNext()

feature/account/setup/src/main/kotlin/app/k9mail/feature/account/setup/ui/options/AccountOptionsViewModel.kt

@@ -20,7 +20,7 @@ internal class AccountOptionsViewModel(
 
     override fun event(event: Event) {
         when (event) {
-            Event.LoadAccountState -> loadAccountState()
+            Event.LoadAccountState -> handleOneTimeEvent(event, ::loadAccountState)
 
             is Event.OnAccountNameChanged -> updateState { state ->
                 state.copy(