Bug 1877278 - AC Translations Check for if the Engine is Supported

This patch supports the workflow for checking if the device architecture
supports translations.

This patch adds:
* New `isEngineSupported` on `TranslationsState`
  * New `FETCH_IS_ENGINE_SUPPORTED` to request fetching and setting the value
  * New `SetEngineSupportAction` to set the `isEngineSupported` value
* `TabListAction.AddTabAction`, `TabListAction.RestoreAction`, and
`TabListAction.SelectTabAction` to eagerly request `FETCH_IS_ENGINE_SUPPORTED`

android-components/components/browser/state/src/main/java/mozilla/components/browser/state/action/BrowserAction.kt

@@ -948,6 +948,17 @@ sealed class TranslationsAction : BrowserAction() {
         val operation: TranslationOperation,
     ) : TranslationsAction(), ActionWithTab
 
+    /**
+     * Sets whether the device architecture supports translations or not.
+     *
+     * @property tabId The ID of the tab the [EngineSession] that requested the list.
+     * @property isEngineSupported If the engine supports translations on this device.
+     */
+    data class SetEngineSupportAction(
+        override val tabId: String,
+        val isEngineSupported: Boolean,
+    ) : TranslationsAction(), ActionWithTab
+
     /**
      * Sets the languages that are supported by the translations engine.
      *

android-components/components/browser/state/src/main/java/mozilla/components/browser/state/engine/middleware/TranslationsMiddleware.kt

@@ -7,9 +7,11 @@ package mozilla.components.browser.state.engine.middleware
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.launch
 import mozilla.components.browser.state.action.BrowserAction
+import mozilla.components.browser.state.action.TabListAction
 import mozilla.components.browser.state.action.TranslationsAction
 import mozilla.components.browser.state.selector.findTab
 import mozilla.components.browser.state.state.BrowserState
+import mozilla.components.browser.state.state.TranslationsState
 import mozilla.components.concept.engine.Engine
 import mozilla.components.concept.engine.EngineSession
 import mozilla.components.concept.engine.translate.LanguageSetting
@@ -39,8 +41,52 @@ class TranslationsMiddleware(
     ) {
         // Pre process actions
         when (action) {
+            // Initially adding the tab
+            is TabListAction.AddTabAction -> {
+                if (translationsState(context, action.tab.id)?.isEngineSupported == null) {
+                    context.store.dispatch(
+                        TranslationsAction.OperationRequestedAction(
+                            tabId = action.tab.id,
+                            operation = TranslationOperation.FETCH_IS_ENGINE_SUPPORTED,
+                        ),
+                    )
+                }
+            }
+
+            // Restoring a tab from a closed app
+            is TabListAction.RestoreAction -> {
+                if (translationsState(context, action.selectedTabId)?.isEngineSupported == null) {
+                    action.selectedTabId?.let { id ->
+                        context.store.dispatch(
+                            TranslationsAction.OperationRequestedAction(
+                                tabId = id,
+                                operation = TranslationOperation.FETCH_IS_ENGINE_SUPPORTED,
+                            ),
+                        )
+                    }
+                }
+            }
+
+            // Switching to a new tab
+            is TabListAction.SelectTabAction -> {
+                if (translationsState(context, action.tabId)?.isEngineSupported == null) {
+                    context.store.dispatch(
+                        TranslationsAction.OperationRequestedAction(
+                            tabId = action.tabId,
+                            operation = TranslationOperation.FETCH_IS_ENGINE_SUPPORTED,
+                        ),
+                    )
+                }
+            }
+
             is TranslationsAction.OperationRequestedAction -> {
                 when (action.operation) {
+                    TranslationOperation.FETCH_IS_ENGINE_SUPPORTED -> {
+                        scope.launch {
+                            requestEngineSupport(context, action.tabId)
+                        }
+                    }
+
                     TranslationOperation.FETCH_SUPPORTED_LANGUAGES -> {
                         scope.launch {
                             requestSupportedLanguages(context, action.tabId)
@@ -70,6 +116,53 @@ class TranslationsMiddleware(
         next(action)
     }
 
+    /**
+     * Convenience method to get the translations state from the store.
+     *
+     * @param context Context to use to find the state of the store.
+     * @param tabId Tab ID associated with the request.
+     */
+    private fun translationsState(
+        context: MiddlewareContext<BrowserState, BrowserAction>,
+        tabId: String?,
+    ): TranslationsState? {
+        return tabId?.let { context.store.state.findTab(it)?.translationsState }
+    }
+
+    /**
+     * Checks if the translations engine supports the device architecture.
+     *
+     * @param context Context to use to dispatch to the store.
+     * @param tabId Tab ID associated with the request.
+     */
+    private fun requestEngineSupport(
+        context: MiddlewareContext<BrowserState, BrowserAction>,
+        tabId: String,
+    ) {
+        engine.isTranslationsEngineSupported(
+            onSuccess = { isEngineSupported ->
+                context.store.dispatch(
+                    TranslationsAction.SetEngineSupportAction(
+                        tabId = tabId,
+                        isEngineSupported = isEngineSupported,
+                    ),
+                )
+                logger.info("Success requesting engine support.")
+            },
+
+            onError = { error ->
+                context.store.dispatch(
+                    TranslationsAction.TranslateExceptionAction(
+                        tabId = tabId,
+                        operation = TranslationOperation.FETCH_IS_ENGINE_SUPPORTED,
+                        translationError = TranslationError.UnknownEngineSupportError(error),
+                    ),
+                )
+                logger.error("Error requesting engine support: ", error)
+            },
+        )
+    }
+
     /**
      * Retrieves the list of supported languages using [scope] and dispatches the result to the
      * store via [TranslationsAction.TranslateSetLanguagesAction] or else dispatches the failure

android-components/components/browser/state/src/main/java/mozilla/components/browser/state/reducer/TranslationsStateReducer.kt

@@ -83,6 +83,15 @@ internal object TranslationsStateReducer {
                     }
                 }
 
+                TranslationOperation.FETCH_IS_ENGINE_SUPPORTED -> {
+                    state.copyWithTranslationsState(action.tabId) {
+                        it.copy(
+                            isEngineSupported = true,
+                            translationError = null,
+                        )
+                    }
+                }
+
                 TranslationOperation.FETCH_SUPPORTED_LANGUAGES -> {
                     // Reset the error state, and then generally expect
                     // [TranslationsAction.SetSupportedLanguagesAction] to update state in the
@@ -138,6 +147,15 @@ internal object TranslationsStateReducer {
                     }
                 }
 
+                TranslationOperation.FETCH_IS_ENGINE_SUPPORTED ->
+                    state.copyWithTranslationsState(action.tabId) {
+                        it.copy(
+                            // An error here doesn't necessarily imply the device doesn't support
+                            // the engine, so not changing [isEngineSupported] state.
+                            translationError = action.translationError,
+                        )
+                    }
+
                 TranslationOperation.FETCH_SUPPORTED_LANGUAGES -> {
                     state.copyWithTranslationsState(action.tabId) {
                         it.copy(
@@ -167,6 +185,14 @@ internal object TranslationsStateReducer {
             }
         }
 
+        is TranslationsAction.SetEngineSupportAction ->
+            state.copyWithTranslationsState(action.tabId) {
+                it.copy(
+                    isEngineSupported = action.isEngineSupported,
+                    translationError = null,
+                )
+            }
+
         is TranslationsAction.SetSupportedLanguagesAction ->
             state.copyWithTranslationsState(action.tabId) {
                 it.copy(
@@ -213,7 +239,10 @@ internal object TranslationsStateReducer {
                         )
                     }
                 }
-                TranslationOperation.TRANSLATE, TranslationOperation.RESTORE -> {
+                TranslationOperation.TRANSLATE,
+                TranslationOperation.RESTORE,
+                TranslationOperation.FETCH_IS_ENGINE_SUPPORTED,
+                -> {
                     // No state change for these operations
                     state
                 }

android-components/components/browser/state/src/main/java/mozilla/components/browser/state/state/TranslationsState.kt

@@ -19,6 +19,7 @@ import mozilla.components.concept.engine.translate.TranslationSupport
  * @property isTranslated The page is currently translated.
  * @property isTranslateProcessing The page is currently attempting a translation.
  * @property isRestoreProcessing The page is currently attempting a restoration.
+ * @property isEngineSupported The translations engine supports the device architecture.
  * @property supportedLanguages Set of languages the translation engine supports.
  * @property pageSettings The translation engine settings that relate to the current page.
  * @property neverTranslateSites List of sites the user has opted to never translate.
@@ -33,6 +34,7 @@ data class TranslationsState(
     val isTranslated: Boolean = false,
     val isTranslateProcessing: Boolean = false,
     val isRestoreProcessing: Boolean = false,
+    val isEngineSupported: Boolean? = null,
     val supportedLanguages: TranslationSupport? = null,
     val pageSettings: TranslationPageSettings? = null,
     val neverTranslateSites: List<String>? = null,

android-components/components/browser/state/src/test/java/mozilla/components/browser/state/action/TranslationsActionTest.kt

@@ -387,4 +387,74 @@ class TranslationsActionTest {
         // Action success
         assertNull(tabState().translationsState.supportedLanguages)
     }
+
+    @Test
+    fun `WHEN a TranslateSetEngineSupportAction is dispatched THEN update the store to match`() {
+        // Initial state
+        assertNull(tabState().translationsState.isEngineSupported)
+
+        // Dispatch
+        store.dispatch(
+            TranslationsAction.SetEngineSupportAction(
+                tabId = tab.id,
+                isEngineSupported = true,
+            ),
+        ).joinBlocking()
+
+        // Final state
+        assertTrue(tabState().translationsState.isEngineSupported!!)
+    }
+
+    @Test
+    fun `WHEN a OperationRequestedAction is dispatched for FETCH_IS_ENGINE_SUPPORTED THEN do NOT clear isEngineSupported`() {
+        // Setting first to have a more robust initial state
+        assertNull(tabState().translationsState.isEngineSupported)
+
+        store.dispatch(
+            TranslationsAction.SetEngineSupportAction(
+                tabId = tab.id,
+                isEngineSupported = true,
+            ),
+        ).joinBlocking()
+
+        assertTrue(tabState().translationsState.isEngineSupported!!)
+
+        // Action started
+        store.dispatch(
+            TranslationsAction.OperationRequestedAction(
+                tabId = tab.id,
+                operation = TranslationOperation.FETCH_IS_ENGINE_SUPPORTED,
+            ),
+        ).joinBlocking()
+
+        // Action success
+        assertTrue(tabState().translationsState.isEngineSupported!!)
+    }
+
+    @Test
+    fun `WHEN a TranslateExceptionAction is dispatched for FETCH_IS_ENGINE_SUPPORTED THEN do NOT clear or alter isEngineSupported`() {
+        // Setting first to have a more robust initial state
+        assertNull(tabState().translationsState.isEngineSupported)
+
+        store.dispatch(
+            TranslationsAction.SetEngineSupportAction(
+                tabId = tab.id,
+                isEngineSupported = true,
+            ),
+        ).joinBlocking()
+
+        assertTrue(tabState().translationsState.isEngineSupported!!)
+
+        // Action started
+        store.dispatch(
+            TranslationsAction.TranslateExceptionAction(
+                tabId = tab.id,
+                operation = TranslationOperation.FETCH_IS_ENGINE_SUPPORTED,
+                translationError = TranslationError.UnknownEngineSupportError(null),
+            ),
+        ).joinBlocking()
+
+        // Action success
+        assertTrue(tabState().translationsState.isEngineSupported!!)
+    }
 }