Compose Navigation: start migration with AccountsActivity

[ArnyminerZ]

Purpose

As the first step of #1172, started by renaming AccountsActivity to MainActivity, and start adding navigation functionality.

Short description

• Renamed AccountsActivity and its usages to MainActivity.
• Added the compose navigation dependency.
• Added the first route to the nav graph: accounts list.
• Added a method for initializing AccountsRoute from the intent data of MainActivity.
• Added LocalNavController which holds a reference to the currently being used nav controller.
• Moved injection of AccountsDrawerHandler from activity to model to decouple it completely from activities.
• Added a redirection from old AccountsActivity to MainActivity for external applications.

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.

[ArnyminerZ]

I think this can be a good first PR on the topic.

[ArnyminerZ]

LocalNavController is used in order to access the nav controller from outside MainActivity. For example, from a composable:

@Composable
fun Example() {
  val navController = LocalNavController.current

  navController.navigate(ExampleRoute)

[rfc2822]

Can we move the NavController to the navigation package? Just so that there are no packages that only contain one class.

But didn't have an in-depth look yet. Please @sunkup also have a look first (we can talk tomorrow about it).

[sunkup]

Can we move the NavController to the navigation package? Just so that there are no packages that only contain one class.

But didn't have an in-depth look yet. Please @sunkup also have a look first (we can talk tomorrow about it).

@ArnyminerZ maybe you can make the suggested change and request a new review from me? I will use the opportunity to get to know compose navigation.

[ArnyminerZ]

maybe you can make the suggested change and request a new review from me?

Done

[sunkup]

Looks really good!

For some reason I am sceptical about moving the AccountsDrawerHandler injection to the model. I feel like it does not really belong there, but in favor of the new navigation paradigm I can't give a good reason not to do it ...

See the comment about broken reference, but yeah, otherwise it's really nice.

[rfc2822]

Also I think we could inject the AccountsDrawerHandler directly in MainActivity, rather than in a model. Because it's not really a state, and models are basically state holders (+ maybe a little logic).

Also, the idea is that the intro check occurs / the intro is potentially shown when the app UI starts. In the past we could only put it into the launcher activity (AccountsActivity) and hope that this is the first activity started.

In the future we could put it into the MainActivity.onCreate, and later maybe even in the MainActivity's composition.

[sunkup]

Looks like it's working now 👍

[rfc2822]

I have renamed Routes to Destination, hope that's in compliance with Compose Navigation terminology. Otherwise please correct me.

Also I think we should think about how to pass destinations directly to MainScreen (see comments).

[rfc2822]

I played around a bit and changed some things. Notably:

• move navigation to separate file, because it's not related to the Activity itself
• don't pass NavController between routes, keep future relations between screens in NavHost
• move AccountsDrawerHandler injection back to model for simplicity
• tried to generate/parse deep links with builders

@ArnyminerZ Do you have further comments / suggestions?

[ArnyminerZ]

I haven't tested it, but it looks good to me.

[sunkup]

Looks okay.

One thing, where I am not sure if it's desired: If I open the app via launcher and see the accounts screen I can go back (system) to the launcher directly. If I start it like so: adb shell am start -n at.bitfire.davdroid/at.bitfire.davdroid.ui.AccountsActivity I will have to "go back" twice before the app is closed and I get to see the launcher.

[rfc2822]

If I start it like so: adb shell am start -n at.bitfire.davdroid/at.bitfire.davdroid.ui.AccountsActivity I will have to "go back" twice before the app is closed and I get to see the launcher.

I think it should only take one "go back".

@ArnyminerZ Can you have a look?

[ArnyminerZ]

Okay, so the issue comes because we are redirecting to the same page when launching from AccountsActivity.

When we launch MainActivity normally, we provide no deepLinkUri, and the default destination is set by Navigation to Destination.Accounts(). When coming from AccountsActivity, we have this destination, and a uri (which leads to the same place), so the default destination is loaded, and then a new destination is added to the stack with the LaunchedEffect.

I've fixed it by setting single-top to the navigation:

navController.navigate(
    deepLinkRq,
    NavOptions.Builder().setLaunchSingleTop(true).build()
)