Fix handling file names with spaces for mime type detection (#134)

This fixes https://github.com/syncthing/syncthing-lite/issues/133

app/src/main/kotlin/net/syncthing/lite/dialogs/FileMenuDialogFragment.kt

@@ -47,7 +47,7 @@ class FileMenuDialogFragment: BottomSheetDialogFragment() {
                     Intent(Intent.ACTION_CREATE_DOCUMENT).apply {
                         addCategory(Intent.CATEGORY_OPENABLE)
 
-                        type = MimeType.getFromUrl(fileSpec.fileName)
+                        type = MimeType.getFromFilename(fileSpec.fileName)
 
                         putExtra(Intent.EXTRA_TITLE, fileSpec.fileName)
                     },

app/src/main/kotlin/net/syncthing/lite/dialogs/downloadfile/DownloadFileDialogFragment.kt

@@ -88,7 +88,7 @@ class DownloadFileDialogFragment : DialogFragment() {
                     dismissAllowingStateLoss()
 
                     if (outputUri == null) {
-                        val mimeType = MimeType.getFromUrl(fileSpec.fileName)
+                        val mimeType = MimeType.getFromFilename(fileSpec.fileName)
 
                         try {
                             context!!.startActivity(

app/src/main/kotlin/net/syncthing/lite/library/SyncthingProvider.kt

@@ -159,7 +159,7 @@ class SyncthingProvider : DocumentsProvider() {
                     if (fileInfo.isDirectory())
                         Document.MIME_TYPE_DIR
                     else
-                        MimeType.getFromUrl(fileInfo.fileName)
+                        MimeType.getFromFilename(fileInfo.fileName)
             )
             add(Document.COLUMN_LAST_MODIFIED, fileInfo.lastModified)
             add(Document.COLUMN_FLAGS, 0)

app/src/main/kotlin/net/syncthing/lite/utils/MimeType.kt

@@ -1,6 +1,7 @@
 package net.syncthing.lite.utils
 
 import android.webkit.MimeTypeMap
+import net.syncthing.java.core.utils.PathUtils
 
 object MimeType {
     private const val DEFAULT_MIME_TYPE = "application/octet-stream"
@@ -11,7 +12,7 @@ object MimeType {
         return mimeType ?: DEFAULT_MIME_TYPE
     }
 
-    fun getFromUrl(url: String) = getFromExtension(
-            MimeTypeMap.getFileExtensionFromUrl(url).toLowerCase()
+    fun getFromFilename(path: String) = getFromExtension(
+            PathUtils.getFileExtensionFromFilename(path).toLowerCase()
     )
 }

syncthing-core/src/main/kotlin/net/syncthing/java/core/utils/PathUtils.kt

@@ -130,4 +130,12 @@ object PathUtils {
 
         return dir.removeSuffix(PATH_SEPARATOR) + file
     }
+
+    fun getFileExtensionFromFilename(filename: String): String {
+        assertFilenameValid(filename)
+
+        val dotIndex = filename.lastIndexOf(".")
+
+        return if (dotIndex != 0) filename.substring(dotIndex + 1) else ""
+    }
 }