Nav3 migration add subscription activity

[ArnyminerZ]

Purpose

Migrate AddSubscriptionActivity to Nav3.

Depends on #640

Short description

• Got rid of the Activity, and moved the logic to nav3.

Checklist

• The PR has a proper title, description and label.
• I have self-reviewed the PR.
• I have added documentation to complex functions and functions that can be used by other modules.
• I have added reasonable tests or consciously decided to not add tests.

[github-actions]

This PR/issue depends on:

• Migration to Nav3 #640

[Copilot]

Pull Request Overview

Migrates the AddSubscriptionActivity to use Nav3 by removing the standalone Activity and integrating its functionality into the Compose navigation system.

• Replaced standalone Activity with Compose screen navigation
• Moved intent handling and file picker logic from Activity to Composable functions
• Updated navigation flow to use Nav3 backstack management

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
AddSubscriptionActivity.kt	Removed entire Activity class, eliminating 133 lines of Activity-based navigation
SubscriptionsScreen.kt	Modified to accept onAddRequested callback instead of launching Activity directly
AddSubscriptionScreen.kt	Added new wrapper Composable with intent handling and file picker logic
MainApp.kt	Integrated AddSubscription destination with intent parsing and navigation setup
Destination.kt	Added AddSubscription destination with title and color parameters
AccountAuthenticatorService.kt	Updated to launch MainActivity instead of the removed AddSubscriptionActivity
AndroidManifest.xml	Merged intent filters into MainActivity and removed AddSubscriptionActivity declaration

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[sunkup]

I don't remember exactly what I did, but when I played around a bit with going forward and backward around the AddSubscriptionScreen, then closing the app and opening via calendar permission request notification and I got this crash:

Details

11:42:21.981  E  FATAL EXCEPTION: main
                 Process: at.bitfire.icsdroid, PID: 14145
                 java.lang.IllegalArgumentException: NavDisplay backstack cannot be empty
                 	at androidx.navigation3.ui.NavDisplayKt.NavDisplay(NavDisplay.kt:170)
                 	at androidx.navigation3.ui.NavDisplayKt.NavDisplay$lambda$11(Unknown Source:36)
                 	at androidx.navigation3.ui.NavDisplayKt.$r8$lambda$SLsTTf3eDnrSQmCrJvKtHwJ4fig(Unknown Source:0)
                 	at androidx.navigation3.ui.NavDisplayKt$$ExternalSyntheticLambda3.invoke(D8$$SyntheticClass:0)
                 	at androidx.compose.runtime.RecomposeScopeImpl.compose(RecomposeScopeImpl.kt:196)
                 	at androidx.compose.runtime.ComposerImpl.recomposeToGroupEnd(Composer.kt:2893)
                 	at androidx.compose.runtime.ComposerImpl.skipCurrentGroup(Composer.kt:3229)
                 	at androidx.compose.runtime.ComposerImpl.doCompose-aFTiNEg(Composer.kt:3853)
                 	at androidx.compose.runtime.ComposerImpl.recompose-aFTiNEg$runtime(Composer.kt:3777)
                 	at androidx.compose.runtime.CompositionImpl.recompose(Composition.kt:1049)
                 	at androidx.compose.runtime.Recomposer.performRecompose(Recomposer.kt:1336)
                 	at androidx.compose.runtime.Recomposer.access$performRecompose(Recomposer.kt:155)
                 	at androidx.compose.runtime.Recomposer$runRecomposeAndApplyChanges$2.invokeSuspend$lambda$22(Recomposer.kt:625)
                 	at androidx.compose.runtime.Recomposer$runRecomposeAndApplyChanges$2.$r8$lambda$OqADLCDYmRw1RgNUvn1CR0kX32M(Unknown Source:0)
                 	at androidx.compose.runtime.Recomposer$runRecomposeAndApplyChanges$2$$ExternalSyntheticLambda0.invoke(D8$$SyntheticClass:0)
                 	at androidx.compose.ui.platform.AndroidUiFrameClock$withFrameNanos$2$callback$1.doFrame(AndroidUiFrameClock.android.kt:39)
                 	at androidx.compose.ui.platform.AndroidUiDispatcher.performFrameDispatch(AndroidUiDispatcher.android.kt:108)
                 	at androidx.compose.ui.platform.AndroidUiDispatcher.access$performFrameDispatch(AndroidUiDispatcher.android.kt:41)
                 	at androidx.compose.ui.platform.AndroidUiDispatcher$dispatchCallback$1.doFrame(AndroidUiDispatcher.android.kt:69)
                 	at android.view.Choreographer$CallbackRecord.run(Choreographer.java:964)
                 	at android.view.Choreographer.doCallbacks(Choreographer.java:790)
                 	at android.view.Choreographer.doFrame(Choreographer.java:721)
                 	at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:951)
                 	at android.os.Handler.handleCallback(Handler.java:883)
                 	at android.os.Handler.dispatchMessage(Handler.java:100)
                 	at android.os.Looper.loop(Looper.java:214)
                 	at android.app.ActivityThread.main(ActivityThread.java:7356)
                 	at java.lang.reflect.Method.invoke(Native Method)
                 	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
                 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
                 	Suppressed: kotlinx.coroutines.internal.DiagnosticCoroutineContextException: [androidx.compose.runtime.PausableMonotonicFrameClock@3f2828a, androidx.compose.ui.platform.MotionDurationScaleImpl@2c3d0fb, StandaloneCoroutine{Cancelling}@42ea518, AndroidUiDispatcher@6b9cb71]

[ArnyminerZ]

Mmmmh... In theory it's possible according to the default onBack implementation:

onBack: (Int) -> Unit = {
    if (backStack is MutableList<T>) {
        repeat(it) { backStack.removeAt(backStack.lastIndex) }
    }
},

Technically, if for some reason it's called when the backstack has length 1, it gets cleared. Maybe we can extend with our own implementation avoiding this scenario

[sunkup]

Seems to work now. There was still some strangeness with going back to the same screen twice, but I can't reproduce it anymore, so I will open an issue when it happens again and I know why ...