feat: complete DataViewModel with DataRepository integration and export/delete functionality

android/app/src/main/java/com/senstools/presentation/ui/data/DataFragment.kt

@@ -7,8 +7,10 @@ import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.viewModels
 import androidx.recyclerview.widget.LinearLayoutManager
+import com.google.android.material.dialog.MaterialAlertDialogBuilder
 import com.senstools.databinding.FragmentDataBinding
 import com.senstools.presentation.adapter.DataFileAdapter
+import com.senstools.presentation.viewmodel.DataFile
 import com.senstools.presentation.viewmodel.DataViewModel
 
 class DataFragment : Fragment() {
@@ -38,8 +40,8 @@ class DataFragment : Fragment() {
     private fun setupRecyclerView() {
         adapter = DataFileAdapter(
             onItemClick = { file -> viewModel.openFile(file) },
-            onExportClick = { file -> viewModel.exportFile(file) },
-            onDeleteClick = { file -> viewModel.deleteFile(file) }
+            onExportClick = { file -> showExportDialog(file) },
+            onDeleteClick = { file -> showDeleteConfirmDialog(file) }
         )
         binding.recyclerView.layoutManager = LinearLayoutManager(requireContext())
         binding.recyclerView.adapter = adapter
@@ -49,6 +51,17 @@ class DataFragment : Fragment() {
         viewModel.dataFiles.observe(viewLifecycleOwner) { files ->
             adapter.submitList(files)
         }
+
+        viewModel.isExporting.observe(viewLifecycleOwner) { exporting ->
+            binding.swipeRefresh.isEnabled = !exporting
+        }
+
+        viewModel.exportResult.observe(viewLifecycleOwner) { result ->
+            result?.let {
+                showToast(it)
+                viewModel.clearExportResult()
+            }
+        }
     }
 
     private fun setupListeners() {
@@ -58,6 +71,34 @@ class DataFragment : Fragment() {
         }
     }
 
+    private fun showExportDialog(file: DataFile) {
+        val options = arrayOf("Export to CSV", "Export to JSON")
+        MaterialAlertDialogBuilder(requireContext())
+            .setTitle("Export: " + file.name)
+            .setItems(options) { _, which ->
+                when (which) {
+                    0 -> viewModel.exportToCSV(file)
+                    1 -> viewModel.exportToJSON(file)
+                }
+            }
+            .show()
+    }
+
+    private fun showDeleteConfirmDialog(file: DataFile) {
+        MaterialAlertDialogBuilder(requireContext())
+            .setTitle("Delete File")
+            .setMessage("Delete " + file.name + "?")
+            .setPositiveButton("Delete") { _, _ ->
+                viewModel.deleteFile(file)
+            }
+            .setNegativeButton("Cancel", null)
+            .show()
+    }
+
+    private fun showToast(message: String) {
+        android.widget.Toast.makeText(requireContext(), message, android.widget.Toast.LENGTH_SHORT).show()
+    }
+
     override fun onDestroyView() {
         super.onDestroyView()
         _binding = null

android/app/src/main/java/com/senstools/presentation/viewmodel/DataViewModel.kt

@@ -1,37 +1,117 @@
 package com.senstools.presentation.viewmodel
 
+import android.app.Application
+import androidx.lifecycle.AndroidViewModel
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
-import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.senstools.domain.repository.DataRepository
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import java.io.File
 
-class DataViewModel : ViewModel() {
+class DataViewModel(application: Application) : AndroidViewModel(application) {
 
     private val _dataFiles = MutableLiveData<List<DataFile>>()
     val dataFiles: LiveData<List<DataFile>> = _dataFiles
 
+    private val _isExporting = MutableLiveData(false)
+    val isExporting: LiveData<Boolean> = _isExporting
+
+    private val _exportResult = MutableLiveData<String?>()
+    val exportResult: LiveData<String?> = _exportResult
+
+    private val dataRepository: DataRepository
+
     init {
+        dataRepository = DataRepository(application.filesDir)
         loadFiles()
     }
 
     private fun loadFiles() {
-        // Load files from storage
-        _dataFiles.value = emptyList()
+        val files = dataRepository.listDataFiles().map { info ->
+            DataFile(
+                name = info.name,
+                path = info.path,
+                size = info.size,
+                date = info.lastModified
+            )
+        }
+        _dataFiles.value = files
     }
 
     fun refreshFiles() {
         loadFiles()
     }
 
-    fun openFile(file: DataFile) {
-        // Open file for viewing
+    fun openFile(file: DataFile) { // placeholder
     }
 
-    fun exportFile(file: DataFile) {
-        // Export file to CSV/JSON
+    fun exportToCSV(file: DataFile) {
+        viewModelScope.launch {
+            _isExporting.value = true
+            val result = withContext(Dispatchers.IO) {
+                val exportDir = File(
+                    getApplication<Application>().filesDir,
+                    "senstools_export"
+                )
+                exportDir.mkdirs()
+                val csvPath = File(exportDir, file.name.replace(".bin", ".csv")).absolutePath
+                val success = dataRepository.exportToCSV(file.path, csvPath)
+                success to csvPath
+            }
+            _exportResult.value = if (result.first) {
+                "CSV exported to: " + result.second
+            } else {
+                "CSV export failed"
+            }
+            _isExporting.value = false
+        }
+    }
+
+    fun exportToJSON(file: DataFile) {
+        viewModelScope.launch {
+            _isExporting.value = true
+            val result = withContext(Dispatchers.IO) {
+                val exportDir = File(
+                    getApplication<Application>().filesDir,
+                    "senstools_export"
+                )
+                exportDir.mkdirs()
+                val jsonPath = File(exportDir, file.name.replace(".bin", ".json")).absolutePath
+                val success = dataRepository.exportToJSON(file.path, jsonPath)
+                success to jsonPath
+            }
+            _exportResult.value = if (result.first) {
+                "JSON exported to: " + result.second
+            } else {
+                "JSON export failed"
+            }
+            _isExporting.value = false
+        }
     }
 
     fun deleteFile(file: DataFile) {
-        // Delete file
+        viewModelScope.launch {
+            withContext(Dispatchers.IO) {
+                dataRepository.deleteFile(file.name)
+            }
+            loadFiles()
+        }
+    }
+
+    fun deleteAll() {
+        viewModelScope.launch {
+            withContext(Dispatchers.IO) {
+                dataRepository.deleteAll()
+            }
+            loadFiles()
+        }
+    }
+
+    fun clearExportResult() {
+        _exportResult.value = null
     }
 }