🐛 Fix duplicate file extension when saving on macOS

filekit-dialogs/src/commonMain/kotlin/io/github/vinceglb/filekit/dialogs/FileSaverName.kt

@@ -20,3 +20,15 @@ internal fun buildFileSaverSuggestedName(
         else -> "$suggestedName.$normalizedExtension"
     }
 }
+
+internal fun buildFileSaverAllowedFileTypes(
+    defaultExtension: String?,
+    allowedExtensions: Set<String>?,
+): List<String>? {
+    val normalizedDefault = normalizeFileSaverExtension(defaultExtension)
+    val normalizedAllowed = normalizeFileSaverExtensions(allowedExtensions).orEmpty()
+    return buildList {
+        normalizedDefault?.let { add(it) }
+        normalizedAllowed.forEach { if (it != normalizedDefault) add(it) }
+    }.takeIf { it.isNotEmpty() }
+}

filekit-dialogs/src/commonTest/kotlin/io/github/vinceglb/filekit/dialogs/FileSaverNameTest.kt

@@ -55,4 +55,28 @@ class FileSaverNameTest {
         assertEquals("document.pdf", buildFileSaverSuggestedName("document", ".pdf"))
         assertEquals("document.pdf", buildFileSaverSuggestedName("document", " .pdf "))
     }
+
+    @Test
+    fun buildFileSaverAllowedFileTypes_whenNoExtensions_returnsNull() {
+        assertNull(buildFileSaverAllowedFileTypes(null, null))
+        assertNull(buildFileSaverAllowedFileTypes("", setOf("", ".")))
+    }
+
+    @Test
+    fun buildFileSaverAllowedFileTypes_whenOnlyDefaultExtension_returnsSingleNormalizedType() {
+        assertEquals(listOf("pdf"), buildFileSaverAllowedFileTypes(".pdf", null))
+    }
+
+    @Test
+    fun buildFileSaverAllowedFileTypes_whenNoDefault_returnsNormalizedAllowedExtensions() {
+        assertEquals(listOf("md", "txt"), buildFileSaverAllowedFileTypes(null, setOf("md", "txt")))
+    }
+
+    @Test
+    fun buildFileSaverAllowedFileTypes_putsDefaultExtensionFirstAndDeduplicates() {
+        assertEquals(
+            listOf("pdf", "md", "txt"),
+            buildFileSaverAllowedFileTypes("pdf", setOf("md", "pdf", "txt")),
+        )
+    }
 }

filekit-dialogs/src/jvmMain/kotlin/io/github/vinceglb/filekit/dialogs/platform/mac/MacOSFilePicker.kt

@@ -3,7 +3,7 @@ package io.github.vinceglb.filekit.dialogs.platform.mac
 import io.github.vinceglb.filekit.PlatformFile
 import io.github.vinceglb.filekit.dialogs.FileKitDialogSettings
 import io.github.vinceglb.filekit.dialogs.FileKitMacOSSettings
-import io.github.vinceglb.filekit.dialogs.buildFileSaverSuggestedName
+import io.github.vinceglb.filekit.dialogs.buildFileSaverAllowedFileTypes
 import io.github.vinceglb.filekit.dialogs.platform.PlatformFilePicker
 import io.github.vinceglb.filekit.dialogs.platform.mac.foundation.Foundation
 import io.github.vinceglb.filekit.dialogs.platform.mac.foundation.ID
@@ -73,18 +73,15 @@ internal class MacOSFilePicker : PlatformFilePicker {
                     Foundation.invoke(savePanel, "setDirectoryURL:", Foundation.nsURL(it.path))
                 }
 
+                // Set the file name without extension, NSSavePanel appends it from allowedFileTypes
                 Foundation.invoke(
                     savePanel,
                     "setNameFieldStringValue:",
-                    Foundation.nsString(
-                        buildFileSaverSuggestedName(
-                            suggestedName = suggestedName,
-                            extension = defaultExtension,
-                        ),
-                    ),
+                    Foundation.nsString(suggestedName),
                 )
 
-                val fileTypes = allowedExtensions ?: defaultExtension?.let { setOf(it) }
+                // Default extension first so it is the one appended
+                val fileTypes = buildFileSaverAllowedFileTypes(defaultExtension, allowedExtensions)
                 savePanel.setAllowedFileTypes(fileTypes)
 
                 Foundation.invoke(

filekit-dialogs/src/macosMain/kotlin/io/github/vinceglb/filekit/dialogs/FileKit.macos.kt

@@ -74,21 +74,16 @@ internal actual suspend fun FileKit.platformOpenFileSaver(
 ): PlatformFile? {
     // Create an NSSavePanel
     val nsSavePanel = NSSavePanel()
-    val normalizedDefaultExtension = normalizeFileSaverExtension(defaultExtension)
-    val normalizedAllowedExtensions = normalizeFileSaverExtensions(allowedExtensions)
 
     // Set the initial directory
     directory?.let { nsSavePanel.directoryURL = NSURL.fileURLWithPath(it.path) }
 
-    // Set the file name
-    nsSavePanel.nameFieldStringValue = buildFileSaverSuggestedName(
-        suggestedName = suggestedName,
-        extension = normalizedDefaultExtension,
-    )
+    // Set the file name without extension, NSSavePanel appends it from allowedFileTypes
+    nsSavePanel.nameFieldStringValue = suggestedName
 
-    // Set the file extension filters
-    val fileTypes = normalizedAllowedExtensions ?: normalizedDefaultExtension?.let { setOf(it) }
-    fileTypes?.let { nsSavePanel.allowedFileTypes = it.toList() }
+    // Set the file extension filters, default extension first so it is the one appended
+    buildFileSaverAllowedFileTypes(defaultExtension, allowedExtensions)
+        ?.let { nsSavePanel.allowedFileTypes = it }
 
     // Accept the creation of directories
     nsSavePanel.canCreateDirectories = dialogSettings.canCreateDirectories