Require V1 scheduler users to update when they try to study

Studying with the V1 scheduler enabled is no longer possible on recent
Anki, AnkiMobile or AnkiWeb versions, so AnkiDroid is the last one
still supporting it. Pushing users to upgrade will save them from some
of the footguns V1 had, and will allow AnkiDroid to cut out some code
and tests. Many users have likely already upgraded due to the use of
the other clients.

This commit adds support for the backend upgrade code, so that learning
cards will not be reset on upgrade. To make use of this, users will be
automatically updated to the latest schema version, the scheduler
upgrade will be performed, and then they're moved back to the legacy
schema.

I've also added a helper to more ergonomically deal with schema changes.

AnkiDroid/src/main/java/com/ichi2/anki/CoroutineHelpers.kt

@@ -21,13 +21,16 @@ import androidx.appcompat.app.AlertDialog
 import androidx.lifecycle.coroutineScope
 import anki.collection.Progress
 import com.ichi2.anki.UIUtils.showSimpleSnackbar
+import com.ichi2.libanki.Collection
 import com.ichi2.libanki.CollectionV16
 import com.ichi2.themes.StyledProgressDialog
 import kotlinx.coroutines.*
 import net.ankiweb.rsdroid.Backend
 import net.ankiweb.rsdroid.BackendException
 import net.ankiweb.rsdroid.exceptions.BackendInterruptedException
 import timber.log.Timber
+import kotlin.coroutines.resume
+import kotlin.coroutines.suspendCoroutine
 
 /**
  * Launch a job that catches any uncaught errors and reports them to the user.
@@ -127,7 +130,7 @@ suspend fun <T> AnkiActivity.runInBackgroundWithProgress(
  * window with the provided message.
  */
 suspend fun <T> AnkiActivity.runInBackgroundWithProgress(
-    message: String = "",
+    message: String = resources.getString(R.string.dialog_processing),
     op: suspend () -> T
 ): T = withProgressDialog(
     context = this@runInBackgroundWithProgress,
@@ -205,3 +208,27 @@ private fun ProgressContext.updateDialog(dialog: android.app.ProgressDialog) {
     @Suppress("Deprecation") // ProgressDialog deprecation
     dialog.setMessage(text + progressText)
 }
+
+/**
+ * If a full sync is not already required, confirm the user wishes to proceed.
+ * If the user agrees, the schema is bumped and the routine will return true.
+ * On false, calling routine should abort.
+ */
+suspend fun AnkiActivity.userAcceptsSchemaChange(col: Collection): Boolean {
+    if (col.schemaChanged()) {
+        return true
+    }
+    return suspendCoroutine { coroutine ->
+        AlertDialog.Builder(this)
+            // generic message
+            .setMessage(col.tr.deckConfigWillRequireFullSync())
+            .setPositiveButton(R.string.dialog_ok) { _, _ ->
+                col.modSchemaNoCheck()
+                coroutine.resume(true)
+            }
+            .setNegativeButton(R.string.dialog_cancel) { _, _ ->
+                coroutine.resume(false)
+            }
+            .show()
+    }
+}

AnkiDroid/src/main/java/com/ichi2/anki/DeckPicker.kt

@@ -42,6 +42,7 @@ import android.view.WindowManager.BadTokenException
 import android.widget.*
 import androidx.annotation.StringRes
 import androidx.annotation.VisibleForTesting
+import androidx.appcompat.app.AlertDialog
 import androidx.appcompat.widget.SearchView
 import androidx.core.app.ActivityCompat
 import androidx.core.app.ActivityCompat.OnRequestPermissionsResultCallback
@@ -95,6 +96,7 @@ import com.ichi2.libanki.Collection.CheckDatabaseResult
 import com.ichi2.libanki.importer.AnkiPackageImporter
 import com.ichi2.libanki.sched.AbstractDeckTreeNode
 import com.ichi2.libanki.sched.TreeNode
+import com.ichi2.libanki.sched.upgradeScheduler
 import com.ichi2.libanki.sync.CustomSyncServerUrlException
 import com.ichi2.libanki.sync.Syncer.ConnectionResultType
 import com.ichi2.libanki.utils.TimeManager
@@ -1950,11 +1952,41 @@ open class DeckPicker :
         }
     }
 
+    private fun promptUserToUpdateScheduler() {
+        val builder = AlertDialog.Builder(this)
+            .setMessage(col.tr.schedulingUpdateRequired())
+            .setPositiveButton(R.string.dialog_ok) { _, _ ->
+                launchCatchingTask {
+                    if (!userAcceptsSchemaChange(col)) {
+                        return@launchCatchingTask
+                    }
+                    runInBackgroundWithProgress {
+                        CollectionHelper.getInstance().updateScheduler(this@DeckPicker)
+                    }
+                    showThemedToast(this@DeckPicker, col.tr.schedulingUpdateDone(), false)
+                    refreshState()
+                }
+            }
+            .setNegativeButton(R.string.dialog_cancel) { _, _ ->
+                // nothing to do
+            }
+        if (AdaptionUtil.hasWebBrowser(this)) {
+            builder.setNeutralButton(col.tr.schedulingUpdateMoreInfoButton()) { _, _ ->
+                this.openUrl(Uri.parse("https://faqs.ankiweb.net/the-anki-2.1-scheduler.html#updating"))
+            }
+        }
+        builder.show()
+    }
+
     private fun handleDeckSelection(did: Long, selectionType: DeckSelectionType) {
         // Clear the undo history when selecting a new deck
         if (col.decks.selected() != did) {
             col.clearUndo()
         }
+        if (col.get_config_int("schedVer") == 1) {
+            promptUserToUpdateScheduler()
+            return
+        }
         // Select the deck
         col.decks.select(did)
         // Also forget the last deck used by the Browser
@@ -2655,3 +2687,32 @@ open class DeckPicker :
         }
     }
 }
+
+/** Upgrade from v1 to v2 scheduler.
+ * Caller must have confirmed schema modification already.
+ */
+@KotlinCleanup("move into CollectionHelper once it's converted to Kotlin")
+@Synchronized
+fun CollectionHelper.updateScheduler(context: Context) {
+    if (BackendFactory.defaultLegacySchema) {
+        // We'll need to temporarily update to the latest schema.
+        closeCollection(true, "sched upgrade")
+        discardBackend()
+        BackendFactory.defaultLegacySchema = false
+        // Ensure collection closed if upgrade fails, and schema reverted
+        // even if close fails.
+        try {
+            try {
+                getCol(context).newBackend.upgradeScheduler()
+            } finally {
+                closeCollection(true, "sched upgrade")
+            }
+        } finally {
+            BackendFactory.defaultLegacySchema = true
+            discardBackend()
+        }
+    } else {
+        // Can upgrade directly
+        getCol(context).newBackend.upgradeScheduler()
+    }
+}

AnkiDroid/src/main/java/com/ichi2/libanki/Collection.kt

@@ -248,7 +248,7 @@ open class Collection(
     }
 
     // Note: Additional members in the class duplicate this
-    private fun _loadScheduler() {
+    fun _loadScheduler() {
         val ver = schedVer()
         if (ver == 1) {
             sched = Sched(this)

AnkiDroid/src/main/java/com/ichi2/libanki/sched/BackendSched.kt

@@ -55,3 +55,10 @@ fun CollectionV16.deckTreeLegacy(includeCounts: Boolean): List<TreeNode<DeckDueT
     }
     return toLegacyNode(deckTree(includeCounts), "").children
 }
+
+fun CollectionV16.upgradeScheduler() {
+    modSchema()
+    clearUndo()
+    backend.upgradeScheduler()
+    _loadScheduler()
+}

AnkiDroid/src/main/res/values/03-dialogs.xml

@@ -109,6 +109,7 @@
     <string name="dialog_ok">OK</string>
     <string name="dialog_no">No</string>
     <string name="dialog_continue">Continue</string>
+    <string name="dialog_processing">Processing...</string>
     <string name="dialog_positive_create" comment="Create a new collection, probably erasing the previous one, may be necessary in case of error.">Create</string>
     <string name="dialog_positive_delete">Delete</string>
     <!-- Currently unsued, should be useful in the future -->