Clean up old PDF files at startup

app/src/main/java/org/mydomain/myscan/FileUtils.kt

@@ -28,3 +28,10 @@ fun getAvailableFilename(desiredFile: File): File {
     }
     return file
 }
+
+fun cleanUpOldFiles(dir: File, thresholdInMillis: Int) {
+    val now = System.currentTimeMillis()
+    dir.listFiles { file -> now - file.lastModified() > thresholdInMillis }
+        ?.forEach { file -> file.delete() }
+}
+

app/src/main/java/org/mydomain/myscan/MainActivity.kt

@@ -32,6 +32,7 @@ import androidx.core.content.FileProvider
 import androidx.core.net.toFile
 import androidx.core.net.toUri
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import androidx.lifecycle.lifecycleScope
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
@@ -52,6 +53,9 @@ class MainActivity : ComponentActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         initLibraries()
+        lifecycleScope.launch(Dispatchers.IO) {
+            cleanUpOldFiles(File(cacheDir, "pdfs"), 1000 * 3600)
+        }
         val viewModel: MainViewModel by viewModels { MainViewModel.getFactory(this) }
         enableEdgeToEdge()
         setContent {

app/src/test/java/org/mydomain/myscan/FileUtilsTest.kt

@@ -28,17 +28,38 @@ class FileUtilsTest {
         val f1 = File(dir, "f_1.pdf")
         val f2 = File(dir, "f_2.pdf")
 
-        assertThat(f.exists()).isFalse
-        assertThat(f1.exists()).isFalse
+        assertThat(f).doesNotExist()
+        assertThat(f1).doesNotExist()
         assertThat(getAvailableFilename(f)).isEqualTo(f)
 
         f.apply { writeText("dummy") }
-        assertThat(f.exists()).isTrue
+        assertThat(f).exists()
         assertThat(getAvailableFilename(f)).isEqualTo(f1)
 
         f1.apply { writeText("dummy") }
-        assertThat(f1.exists()).isTrue
+        assertThat(f1).exists()
         assertThat(getAvailableFilename(f)).isEqualTo(f2)
     }
 
+    @Test
+    fun cleanUpOldFiles() {
+        val dir = createTempDirectory().toFile()
+        val subDir = File(dir,"subDir")
+        cleanUpOldFiles(subDir, 10)
+        assertThat(subDir).doesNotExist()
+
+        subDir.mkdirs()
+        assertThat(subDir).exists()
+        val file1 = File(subDir, "file1")
+        file1.createNewFile()
+        val file2 = File(subDir, "file2")
+        file2.createNewFile()
+
+        val now = System.currentTimeMillis()
+        file1.setLastModified(now - 10_000)
+        file2.setLastModified(now - 11_000)
+        cleanUpOldFiles(subDir, 10_500)
+        assertThat(file1).exists()
+        assertThat(file2).doesNotExist()
+    }
 }