Refactor task button implementation

app/src/main/java/org/groundplatform/android/ui/datacollection/DataCollectionViewModel.kt

@@ -205,7 +205,13 @@ internal constructor(
 
     viewModel?.let { created ->
       val taskData = if (shouldLoadFromDraft) getValueFromDraft(state.job, task) else null
-      created.initialize(state.job, task, taskData)
+      created.initialize(
+        job = state.job,
+        task = task,
+        taskData = taskData,
+        isFirstPosition = { isFirstPosition(task.id) },
+        isLastPosition = { isLastPositionWithValue(task, it) },
+      )
       updateDataAndInvalidateTasks(task, taskData)
       taskViewModels.value[task.id] = created
     }

app/src/main/java/org/groundplatform/android/ui/datacollection/components/refactor/ButtonActionState.kt

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.groundplatform.android.ui.datacollection.components.refactor
+
+import org.groundplatform.android.ui.datacollection.components.ButtonAction
+
+data class ButtonActionState(
+  val action: ButtonAction,
+  val isEnabled: Boolean = true,
+  val isVisible: Boolean = true,
+)

app/src/main/java/org/groundplatform/android/ui/datacollection/components/refactor/TaskButton.kt

@@ -0,0 +1,109 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.groundplatform.android.ui.datacollection.components.refactor
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.PaddingValues
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.Button
+import androidx.compose.material3.FilledTonalButton
+import androidx.compose.material3.Icon
+import androidx.compose.material3.OutlinedButton
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.res.vectorResource
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+import org.groundplatform.android.ui.common.ExcludeFromJacocoGeneratedReport
+import org.groundplatform.android.ui.datacollection.components.ButtonAction
+import org.groundplatform.android.ui.theme.AppTheme
+
+@Composable
+fun TaskButton(
+  modifier: Modifier = Modifier,
+  state: ButtonActionState,
+  onClick: (ButtonAction) -> Unit,
+) {
+  when (state.action.theme) {
+    ButtonAction.Theme.DARK_GREEN ->
+      Button(modifier = modifier, onClick = { onClick(state.action) }, enabled = state.isEnabled) {
+        Content(action = state.action)
+      }
+    ButtonAction.Theme.LIGHT_GREEN ->
+      FilledTonalButton(
+        modifier = modifier,
+        onClick = { onClick(state.action) },
+        enabled = state.isEnabled,
+      ) {
+        Content(action = state.action)
+      }
+    ButtonAction.Theme.OUTLINED ->
+      OutlinedButton(
+        modifier = modifier,
+        onClick = { onClick(state.action) },
+        enabled = state.isEnabled,
+      ) {
+        Content(action = state.action)
+      }
+    ButtonAction.Theme.TRANSPARENT ->
+      OutlinedButton(
+        modifier = modifier,
+        border = null,
+        onClick = { onClick(state.action) },
+        enabled = state.isEnabled,
+        contentPadding = PaddingValues(horizontal = 8.dp, vertical = 4.dp),
+      ) {
+        Content(action = state.action)
+      }
+  }
+}
+
+@Composable
+private fun Content(modifier: Modifier = Modifier, action: ButtonAction) {
+  when {
+    action.drawableId != null -> {
+      Icon(
+        modifier = modifier,
+        imageVector = ImageVector.vectorResource(id = action.drawableId),
+        contentDescription = action.contentDescription?.let { resId -> stringResource(resId) },
+      )
+    }
+    action.textId != null -> {
+      Text(modifier = modifier, text = stringResource(id = action.textId))
+    }
+  }
+}
+
+@Preview(showBackground = true)
+@Composable
+@ExcludeFromJacocoGeneratedReport
+private fun TaskButtonAllPreview() {
+  AppTheme {
+    Column(modifier = Modifier.padding(16.dp), verticalArrangement = Arrangement.spacedBy(8.dp)) {
+      ButtonAction.entries.forEach { action ->
+        Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+          TaskButton(state = ButtonActionState(action), onClick = {})
+          TaskButton(state = ButtonActionState(action), onClick = {})
+        }
+      }
+    }
+  }
+}

app/src/main/java/org/groundplatform/android/ui/datacollection/tasks/AbstractMapTaskViewModel.kt

@@ -22,7 +22,7 @@ import org.groundplatform.android.model.map.CameraPosition
 import org.groundplatform.android.ui.common.BaseMapViewModel
 
 /** Defines the state of an inflated Map [Task] and controls its UI. */
-open class AbstractMapTaskViewModel internal constructor() : AbstractTaskViewModel() {
+abstract class AbstractMapTaskViewModel internal constructor() : AbstractTaskViewModel() {
 
   /** Allows control for triggering the location lock programmatically. */
   private val _enableLocationLockFlow = MutableStateFlow(LocationLockEnabledState.UNKNOWN)

app/src/main/java/org/groundplatform/android/ui/datacollection/tasks/AbstractTaskFragment.kt

@@ -240,14 +240,15 @@ abstract class AbstractTaskFragment<T : AbstractTaskViewModel> : AbstractFragmen
         Column(modifier = Modifier.fillMaxWidth()) {
           HeaderCard()
           Spacer(Modifier.height(12.dp))
-          ActionButtonsRow()
+          Footer()
         }
       } else {
-        ActionButtonsRow()
+        Footer()
       }
     }
   }
 
+  @Suppress("UnusedPrivateMember") // andreia: revert this later
   @Composable
   private fun ActionButtonsRow() {
     Row(
@@ -258,6 +259,33 @@ abstract class AbstractTaskFragment<T : AbstractTaskViewModel> : AbstractFragmen
     }
   }
 
+  @Composable
+  private fun Footer() {
+    val taskActionButtonsStates by viewModel.taskActionButtonStates.collectAsStateWithLifecycle()
+    Row(modifier = Modifier.fillMaxWidth(), horizontalArrangement = Arrangement.SpaceBetween) {
+      taskActionButtonsStates.forEach { state ->
+        if (state.isVisible) { // andreia:review
+          org.groundplatform.android.ui.datacollection.components.refactor.TaskButton(
+            state = state,
+            onClick = { handleButtonClick(state.action) },
+          )
+        }
+      }
+    }
+  }
+
+  private fun handleButtonClick(action: ButtonAction) {
+    when (action) {
+      // Navigation actions
+      ButtonAction.PREVIOUS -> moveToPrevious()
+      ButtonAction.NEXT,
+      ButtonAction.DONE -> handleNext()
+      ButtonAction.SKIP -> onSkip()
+      // Task-specific actions - delegate to ViewModel
+      else -> viewModel.onButtonClick(action)
+    }
+  }
+
   // This function can allow any task to show a Header card on top of the Button row.
   open fun shouldShowHeader() = false
 

app/src/main/java/org/groundplatform/android/ui/datacollection/tasks/AbstractTaskViewModel.kt

@@ -23,21 +23,36 @@ import org.groundplatform.android.R
 import org.groundplatform.android.model.job.Job
 import org.groundplatform.android.model.submission.SkippedTaskData
 import org.groundplatform.android.model.submission.TaskData
+import org.groundplatform.android.model.submission.isNotNullOrEmpty
 import org.groundplatform.android.model.submission.isNullOrEmpty
 import org.groundplatform.android.model.task.Task
 import org.groundplatform.android.ui.common.AbstractViewModel
+import org.groundplatform.android.ui.datacollection.components.ButtonAction
+import org.groundplatform.android.ui.datacollection.components.refactor.ButtonActionState
 
 /** Defines the state of an inflated [Task] and controls its UI. */
-open class AbstractTaskViewModel internal constructor() : AbstractViewModel() {
+abstract class AbstractTaskViewModel internal constructor() : AbstractViewModel() {
 
   /** Current value. */
   private val _taskDataFlow: MutableStateFlow<TaskData?> = MutableStateFlow(null)
   val taskTaskData: StateFlow<TaskData?> = _taskDataFlow.asStateFlow()
 
+  abstract val taskActionButtonStates: StateFlow<List<ButtonActionState>>
+
   lateinit var task: Task
+  private lateinit var isFirstPosition: () -> Boolean
+  private lateinit var isLastPositionWithValue: (TaskData?) -> Boolean
 
-  open fun initialize(job: Job, task: Task, taskData: TaskData?) {
+  open fun initialize(
+    job: Job,
+    task: Task,
+    taskData: TaskData?,
+    isFirstPosition: () -> Boolean,
+    isLastPosition: (TaskData?) -> Boolean,
+  ) {
     this.task = task
+    this.isFirstPosition = isFirstPosition
+    this.isLastPositionWithValue = isLastPosition
     setValue(taskData)
   }
 
@@ -74,4 +89,50 @@ open class AbstractTaskViewModel internal constructor() : AbstractViewModel() {
   fun isTaskOptional(): Boolean = !task.isRequired
 
   fun hasNoData(): Boolean = taskTaskData.value.isNullOrEmpty()
+
+  fun getPreviousButtonState(): ButtonActionState =
+    ButtonActionState(
+      action = ButtonAction.PREVIOUS,
+      isEnabled = !isFirstPosition(),
+      isVisible = true,
+    )
+
+  fun getNextButtonState(taskData: TaskData?, hideIfEmpty: Boolean = false): ButtonActionState {
+    val isVisible = if (hideIfEmpty) taskData.isNotNullOrEmpty() else true
+    return if (isLastPositionWithValue(taskData)) {
+      ButtonActionState(
+        action = ButtonAction.DONE,
+        isEnabled = taskData.isNotNullOrEmpty(),
+        isVisible = isVisible,
+      )
+    } else {
+      ButtonActionState(
+        action = ButtonAction.NEXT,
+        isEnabled = taskData.isNotNullOrEmpty(),
+        isVisible = isVisible,
+      )
+    }
+  }
+
+  fun getSkipButtonState(taskData: TaskData?): ButtonActionState =
+    ButtonActionState(
+      action = ButtonAction.SKIP,
+      isEnabled = isTaskOptional(),
+      isVisible = isTaskOptional() && taskData.isNullOrEmpty(),
+    )
+
+  fun getUndoButtonState(taskData: TaskData?): ButtonActionState =
+    ButtonActionState(
+      action = ButtonAction.UNDO,
+      isEnabled = taskData.isNotNullOrEmpty(),
+      isVisible = taskData.isNotNullOrEmpty(),
+    )
+
+  open fun onButtonClick(action: ButtonAction) {
+    if (action == ButtonAction.UNDO) {
+      clearResponse()
+    } else {
+      // Subclasses handle other actions
+    }
+  }
 }

app/src/main/java/org/groundplatform/android/ui/datacollection/tasks/date/DateTaskViewModel.kt

@@ -15,12 +15,23 @@
  */
 package org.groundplatform.android.ui.datacollection.tasks.date
 
+import androidx.lifecycle.viewModelScope
 import java.util.Date
 import javax.inject.Inject
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.stateIn
 import org.groundplatform.android.model.submission.DateTimeTaskData.Companion.fromMillis
+import org.groundplatform.android.ui.datacollection.components.refactor.ButtonActionState
 import org.groundplatform.android.ui.datacollection.tasks.AbstractTaskViewModel
 
 class DateTaskViewModel @Inject constructor() : AbstractTaskViewModel() {
+  override val taskActionButtonStates: StateFlow<List<ButtonActionState>> by lazy {
+    taskTaskData
+      .map { listOf(getPreviousButtonState(), getSkipButtonState(it), getNextButtonState(it)) }
+      .stateIn(viewModelScope, SharingStarted.Lazily, emptyList())
+  }
 
   fun updateResponse(date: Date) {
     setValue(fromMillis(date.time))

app/src/main/java/org/groundplatform/android/ui/datacollection/tasks/instruction/InstructionTaskViewModel.kt

@@ -15,8 +15,20 @@
  */
 package org.groundplatform.android.ui.datacollection.tasks.instruction
 
+import androidx.lifecycle.viewModelScope
 import javax.inject.Inject
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.stateIn
+import org.groundplatform.android.ui.datacollection.components.refactor.ButtonActionState
 import org.groundplatform.android.ui.datacollection.tasks.AbstractTaskViewModel
 
 @Suppress("EmptyClassBlock")
-class InstructionTaskViewModel @Inject constructor() : AbstractTaskViewModel() {}
+class InstructionTaskViewModel @Inject constructor() : AbstractTaskViewModel() {
+  override val taskActionButtonStates: StateFlow<List<ButtonActionState>> by lazy {
+    taskTaskData
+      .map { listOf(getPreviousButtonState(), getNextButtonState(it)) }
+      .stateIn(viewModelScope, SharingStarted.Lazily, emptyList())
+  }
+}