PDF export: ensure the file always have a pdf extension

app/src/main/java/org/fairscan/app/MainViewModel.kt

@@ -295,7 +295,8 @@ class MainViewModel(
     fun getFinalPdf(): GeneratedPdf? {
         val tempPdf = _pdfUiState.value.generatedPdf ?: return null
         val tempFile = tempPdf.file
-        val newFile = File(tempFile.parentFile, desiredFilename)
+        val fileName = PdfFileManager.addExtensionIfMissing(desiredFilename)
+        val newFile = File(tempFile.parentFile, fileName)
         if (tempFile.absolutePath != newFile.absolutePath) {
             if (newFile.exists()) newFile.delete()
             val success = tempFile.renameTo(newFile)

app/src/main/java/org/fairscan/app/PdfFileManager.kt

@@ -27,6 +27,15 @@ class PdfFileManager(
     private val externalDir: File,
     private val pdfWriter: PdfWriter
 ) {
+    companion object {
+        fun addExtensionIfMissing(fileName: String): String {
+            return if (fileName.lowercase().endsWith(".pdf"))
+                fileName
+            else
+                "$fileName.pdf"
+        }
+    }
+
     fun generatePdf(jpegs: Sequence<ByteArray>): GeneratedPdf {
         pdfDir.mkdirs()
         require(pdfDir.exists() && pdfDir.isDirectory) { "Invalid pdfDir: $pdfDir" }

app/src/main/java/org/fairscan/app/view/PdfGenerationBottomSheet.kt

@@ -260,7 +260,7 @@ private fun CloseButton(onDismiss: () -> Unit) {
 
 fun defaultFilename(): String {
     val timestamp = SimpleDateFormat("yyyyMMdd_HHmmss", Locale.getDefault()).format(Date())
-    return "scan_$timestamp.pdf"
+    return "scan_$timestamp"
 }
 
 fun formatFileSize(sizeInBytes: Long?, context: Context): String {

app/src/test/java/org/fairscan/app/PdfFileManagerTest.kt

@@ -84,4 +84,12 @@ class PdfFileManagerTest {
         assertThat(pdf.file.readBytes()).isEqualTo(byteArrayOf(0x01, 0x02, 0x11))
         assertThat(pdf.file.name).endsWith(".pdf")
     }
+
+    @Test
+    fun addExtensionIfMissing() {
+        assertThat(PdfFileManager.addExtensionIfMissing("f1.pdf")).isEqualTo("f1.pdf")
+        assertThat(PdfFileManager.addExtensionIfMissing("f2.PDF")).isEqualTo("f2.PDF")
+        assertThat(PdfFileManager.addExtensionIfMissing("f3")).isEqualTo("f3.pdf")
+        assertThat(PdfFileManager.addExtensionIfMissing("f4.txt")).isEqualTo("f4.txt.pdf")
+    }
 }