Refactor task button implementation

[andreia-ferreira]

Towards #3437

[gemini-code-assist]

Summary of Changes

Hello @andreia-ferreira, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly refactors the task button implementation within the data collection flow. The changes aim to create a more consistent and maintainable system for handling user interactions with task-specific buttons. By introducing a dedicated state class and a Composable for buttons, and centralizing button logic within ViewModels, the PR enhances the reactivity and clarity of the UI, making it easier to manage button states dynamically based on task data and user progress.

Highlights

• Standardized Button Management: Introduced a new ButtonActionState data class and a TaskButton Composable to centralize and standardize the display and behavior of task action buttons across the application.
• Reactive Button States: The AbstractTaskViewModel and its subclasses now expose a taskActionButtonStates StateFlow, allowing button visibility and enabled states to be dynamically controlled and observed, leading to a more reactive UI.
• ViewModel Initialization Enhancements: The initialize method in DataCollectionViewModel and AbstractTaskViewModel has been updated to accept lambdas for isFirstPosition and isLastPositionWithValue, providing more context for button logic.
• Abstract Class Enforcement: AbstractMapTaskViewModel and AbstractTaskViewModel have been changed from open to abstract, enforcing their role as base classes for specific task ViewModels.
• Map Task Specific Button Logic: Implemented specific button logic for map-related tasks like CaptureLocationTaskViewModel, DropPinTaskViewModel, and DrawAreaTaskViewModel, including actions like 'Capture Location', 'Drop Pin', 'Undo', 'Redo', 'Add Point', and 'Complete'.
• Camera Movement Events for Draw Area Task: Added cameraMoveEvents to DrawAreaTaskViewModel to allow one-shot camera movements, particularly useful for 'Undo' and 'Redo' actions in polygon drawing.

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[gemini-code-assist]

Code Review

This pull request is a great step towards refactoring the task button implementation. Moving the button state logic into the respective ViewModels and using a declarative approach with StateFlow and ButtonActionState significantly improves the separation of concerns and maintainability. The new TaskButton composable is a clean implementation.

I've found a critical issue in DrawAreaTaskViewModel where some state changes don't trigger UI updates for the buttons. I've also left a minor suggestion to improve code readability in AbstractTaskFragment. Please see the detailed comments.

[gemini-code-assist]

The combine operator for taskActionButtonStates is missing dependencies, which will cause the UI to not update correctly. The states for the "Redo" and "Complete" buttons depend on redoVertexStack and hasSelfIntersection respectively. Since these are mutable properties and not StateFlows, changes to them will not trigger a recalculation of the button states, leading to a stale UI.

To fix this, you should:

1. Convert _redoVertexStack and hasSelfIntersection to be StateFlows. For example:

   private val _redoVertexStack = MutableStateFlow<List<Coordinates>>(emptyList())
   val redoVertexStack: StateFlow<List<Coordinates>> = _redoVertexStack.asStateFlow()
   
   private val _hasSelfIntersection = MutableStateFlow(false)
   val hasSelfIntersection: StateFlow<Boolean> = _hasSelfIntersection.asStateFlow()

2. Update the places where these properties are modified to use .update{} or .value = ....
3. Add these new StateFlows to the combine block and pass their values to getRedoButtonState and getCompleteButton.

This is a critical issue as it leads to incorrect button states being displayed to the user.

[gemini-code-assist]

Using the fully qualified name for TaskButton makes the code a bit harder to read. It's better to add an import for org.groundplatform.android.ui.datacollection.components.refactor.TaskButton at the top of the file and use the class name directly here.

          TaskButton(
            state = state,
            onClick = { handleButtonClick(state.action) },
          )