Update load/clear buttons on data availability change

app/src/main/java/com/mirenkov/ktheightmap/SettingsActivity.kt

@@ -18,8 +18,10 @@ import androidx.compose.material3.Scaffold
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
@@ -67,16 +69,25 @@ fun SettingsMain(vm: TileViewModel, launcher: ActivityResultLauncher<DocumentFil
 
     val coroutineScope = rememberCoroutineScope()
     val filePath by remember { FileLoader.filePath }
+    val pathIsNotNull = filePath != null
     val ctx = LocalContext.current
+
+    var enableClearTiles by remember { mutableStateOf(vm.repository.containsTiles()) }
+    var enableClearHeight by remember { mutableStateOf(KhmParser.fileExists(ctx)) }
+
     val loadToast = Toast.makeText(ctx, "File successfully loaded.", Toast.LENGTH_LONG)
     val clearTilesToast = Toast.makeText(ctx, "Tiles removed from database.", Toast.LENGTH_LONG)
     val clearHeightToast = Toast.makeText(ctx, "Height data removed.", Toast.LENGTH_LONG)
+
+    val selectedFileText = if (pathIsNotNull) filePath!!.split('/').last() else "none"
+
     val fileSelectorRow = @Composable () {
             Row(Modifier.fillMaxWidth()) {
                 Button({ launcher.launch(null) }) { Text("Select") }
-                Text("Selected file: none", Modifier.padding(8.dp, 0.dp).align(Alignment.CenterVertically))
+                Text("Selected file: $selectedFileText", Modifier.padding(8.dp, 0.dp).align(Alignment.CenterVertically))
             }
     }
+
     KtHeightMapTheme {
         Scaffold { paddingValues ->
             Column(Modifier.padding(paddingValues)) {
@@ -87,29 +98,34 @@ fun SettingsMain(vm: TileViewModel, launcher: ActivityResultLauncher<DocumentFil
                     Button({ filePath?.let {
                         coroutineScope.launch(Dispatchers.IO) {
                             SasSQLiteParser.processZip(it, vm.repository, ctx)
+                            enableClearTiles = true
                             coroutineScope.launch(Dispatchers.Main) { loadToast.show() }
                         }
-                    } }) { Text("SQLite (.zip)") }
+                    } }, enabled = pathIsNotNull) { Text("SQLite (.zip)") }
                     Button({ filePath?.let {
                         coroutineScope.launch(Dispatchers.IO) {
                             SasJPEGParser.processZip(it, vm.repository)
+                            enableClearTiles = true
                             coroutineScope.launch(Dispatchers.Main) { loadToast.show() }
                         }
-                    } }) { Text("JPEG (.zip)") }
+                    } }, enabled = pathIsNotNull) { Text("JPEG (.zip)") }
                     Button({ filePath?.let {
                         KhmParser.load(it, ctx)
+                        enableClearHeight = true
                         loadToast.show()
-                    } }) { Text("Height data (.khm)") }
+                    } }, enabled = pathIsNotNull) { Text("Height data (.khm)") }
                 }
                 LabeledSection("Clear...", Modifier.padding(24.dp, 8.dp)) {
                     Button({ coroutineScope.launch {
                         vm.repository.clearTiles()
+                        enableClearTiles = false
                         clearTilesToast.show()
-                    } }) { Text("Tile data") }
+                    } }, enabled = enableClearTiles) { Text("Tile data") }
                     Button({
                         KhmParser.clear(ctx)
+                        enableClearHeight = false
                         clearHeightToast.show()
-                    }) { Text("Height data") }
+                    }, enabled = enableClearHeight) { Text("Height data") }
                 }
             }
         }

app/src/main/java/com/mirenkov/ktheightmap/TileRepository.kt

@@ -25,4 +25,8 @@ class TileRepository(private val tileDao: TileDao) {
     fun getMaxLevel(): Int {
         return coroutineScope.future(Dispatchers.IO){ tileDao.maxLevel() }.join() ?: 2
     }
+
+    fun containsTiles(): Boolean {
+        return coroutineScope.future(Dispatchers.IO){ tileDao.maxLevel() }.join() != null
+    }
 }

app/src/main/java/com/mirenkov/ktheightmap/parser/KhmParser.kt

@@ -21,7 +21,7 @@ class KhmParser {
         const val HEIGHT_FILE: String = "height.khm"
 
         fun load(filePath: String, ctx: Context) {
-            if (ctx.getFileStreamPath(HEIGHT_FILE).exists()) {
+            if (fileExists(ctx)) {
                 return
             }
 
@@ -33,11 +33,15 @@ class KhmParser {
         }
 
         fun clear(ctx: Context) {
-            if (ctx.getFileStreamPath(HEIGHT_FILE).exists()) {
+            if (fileExists(ctx)) {
                 assert(ctx.deleteFile(HEIGHT_FILE))
             }
         }
 
+        fun fileExists(ctx: Context): Boolean {
+            return (ctx.getFileStreamPath(HEIGHT_FILE).exists())
+        }
+
         private fun getOffset(header: HeightInfo, x: Int, y: Int): Int {
             return (x * header.width + y) * 2
         }
@@ -70,7 +74,7 @@ class KhmParser {
         }
 
         fun getHeight(lon: Float, lat: Float, ctx: Context): UShort {
-            if (!ctx.getFileStreamPath(HEIGHT_FILE).exists())
+            if (!fileExists(ctx))
                 return 0u.toUShort()
             val dis = DataInputStream(ctx.openFileInput(HEIGHT_FILE))
             dis.use {