Stop save-mode exports landing as (invalid).json

app/src/main/cpp/Core/fileselector/fileselector.cpp

@@ -12,6 +12,7 @@ jclass class_FileSelector;
 jclass class_String;
 jmethodID method_nselectFile;
 jmethodID method_nselectFileMulti;
+jmethodID method_nselectFileMultiNamed;
 jmethodID method_nselectFiles;
 
 
@@ -20,6 +21,7 @@ PRIVATE_API void fsel_setup(JNIEnv* env) {
     class_String       = (jclass)env->NewGlobalRef(env->FindClass("java/lang/String"));
     method_nselectFile      = env->GetStaticMethodID(class_FileSelector, "nselectFile",      "(Ljava/lang/String;JZ)Z");
     method_nselectFileMulti = env->GetStaticMethodID(class_FileSelector, "nselectFileMulti", "([Ljava/lang/String;JZ)Z");
+    method_nselectFileMultiNamed = env->GetStaticMethodID(class_FileSelector, "nselectFileMultiNamed", "([Ljava/lang/String;JZLjava/lang/String;)Z");
     method_nselectFiles     = env->GetStaticMethodID(class_FileSelector, "nselectFiles",     "([Ljava/lang/String;J)Z");
 }
 extern "C"
@@ -91,8 +93,9 @@ static jobjectArray fsel_build_mime_array(JNIEnv* env,
     return arr;
 }
 
-bool requestFileMulti(const char* const* mime_types, size_t mime_type_count,
-                      callback_function callback, bool save) {
+bool requestFileMultiNamed(const char* const* mime_types, size_t mime_type_count,
+                           callback_function callback, bool save,
+                           const char* suggested_name) {
     if (!mime_types || mime_type_count == 0) return false;
 
     JNIEnv* env;
@@ -104,17 +107,38 @@ bool requestFileMulti(const char* const* mime_types, size_t mime_type_count,
     jobjectArray mimeArr = fsel_build_mime_array(env, mime_types, mime_type_count);
     if (!mimeArr) return false;
 
+    // Null stays null all the way into the Java side, where it means "leave the
+    // name field as it was" - the pre-EXTRA_TITLE behaviour, and what
+    // requestFileMulti below still asks for.
+    jstring nameStr = nullptr;
+    if (suggested_name && suggested_name[0] != '\0') {
+        nameStr = env->NewStringUTF(suggested_name);
+        if (!nameStr || fsel_check_exception(env, "NewStringUTF(name)")) {
+            env->DeleteLocalRef(mimeArr);
+            return false;
+        }
+    }
+
     jboolean result = env->CallStaticBooleanMethod(
-        class_FileSelector, method_nselectFileMulti,
-        mimeArr, (jlong)callback, save);
+        class_FileSelector, method_nselectFileMultiNamed,
+        mimeArr, (jlong)callback, save, nameStr);
     const bool exceptionRaised = fsel_check_exception(env, "CallStaticBooleanMethod");
 
+    if (nameStr) env->DeleteLocalRef(nameStr);
     env->DeleteLocalRef(mimeArr);
 
     if (exceptionRaised) return false;
     return result == JNI_TRUE;
 }
 
+// Kept as a delegate rather than a second copy of the body: this symbol is
+// linked by every mod already built against this header, so it has to stay -
+// but two JNI bodies to keep in step is how the two forms drift apart.
+bool requestFileMulti(const char* const* mime_types, size_t mime_type_count,
+                      callback_function callback, bool save) {
+    return requestFileMultiNamed(mime_types, mime_type_count, callback, save, nullptr);
+}
+
 bool requestFiles(const char* const* mime_types, size_t mime_type_count,
                   callback_function_files callback) {
     if (!mime_types || mime_type_count == 0) return false;

app/src/main/cpp/Core/fileselector/fileselector.h

@@ -44,6 +44,29 @@ bool requestFileMulti(const char* const* mime_types,
                       callback_function callback,
                       bool save);
 
+/**
+ * requestFileMulti, plus a proposed file name for save mode.
+ * suggested_name - initial name shown in the picker, or nullptr/"" for none.
+ *                  Ignored when save is false; the user can always change it.
+ *
+ * Pass this whenever save is true. ACTION_CREATE_DOCUMENT takes its initial
+ * name from EXTRA_TITLE, and with no name the picker's field opens empty - which
+ * the platform does not leave empty: an empty display name comes back as the
+ * literal "(invalid)" from FileUtils.buildValidFatFilename, so the file is
+ * created as "(invalid).<ext>".
+ *
+ * Include the extension. FileUtils.splitFileName keeps it when it maps back to
+ * mime_types[0] and swaps it for the type's own otherwise, so there is no
+ * double-suffix case to avoid. Illegal characters, over-long names and
+ * collisions are all handled by the provider - it appends "(1)" rather than
+ * overwriting.
+ */
+bool requestFileMultiNamed(const char* const* mime_types,
+                           size_t mime_type_count,
+                           callback_function callback,
+                           bool save,
+                           const char* suggested_name);
+
 /**
  * Callback for requestFiles.
  * count - number of file descriptors; 0 on cancel or all-failed

app/src/main/java/git/artdeell/skymodloader/FileSelector.java

@@ -46,7 +46,26 @@ public boolean selectFile(String mimeType, long callbackFunction, boolean save)
     public static boolean nselectFileMulti(String[] mimeTypes, long callbackFunction, boolean save) {
         return selector.selectFileMulti(mimeTypes, callbackFunction, save);
     }
+
+    // Save mode with a proposed file name.
+    //
+    // Kept as a SEPARATE entry point rather than a fourth argument on the one
+    // above: nselectFileMulti is resolved from native by its exact signature
+    // ([Ljava/lang/String;JZ)Z, so every mod built against the old Canvas would
+    // fail to find it the moment that changed.
+    public static boolean nselectFileMultiNamed(String[] mimeTypes, long callbackFunction,
+                                                boolean save, String suggestedName) {
+        return selector.selectFileMulti(mimeTypes, callbackFunction, save, suggestedName);
+    }
+
     public boolean selectFileMulti(String[] mimeTypes, long callbackFunction, boolean save) {
+        return selectFileMulti(mimeTypes, callbackFunction, save, null);
+    }
+
+    // suggestedName - initial name for the save picker, or null to leave the
+    //   field empty as before. May include the extension; see buildPickerIntent.
+    public boolean selectFileMulti(String[] mimeTypes, long callbackFunction, boolean save,
+                                   String suggestedName) {
         if(this.callbackFunction != 0) return false;
         if(mimeTypes == null || mimeTypes.length == 0) return false;
 
@@ -65,7 +84,7 @@ public boolean selectFileMulti(String[] mimeTypes, long callbackFunction, boolea
             this.isSaveMode = save;
             this.isMultiFilesMode = false;
             gameActivity.startActivityForResult(
-                buildPickerIntent(types, save, /*allowMultiple=*/false),
+                buildPickerIntent(types, save, /*allowMultiple=*/false, suggestedName),
                 SELECTING_FILE);
         });
         return true;
@@ -85,13 +104,15 @@ public boolean selectFiles(String[] mimeTypes, long callbackFunction) {
             this.isSaveMode = false;
             this.isMultiFilesMode = true;
             gameActivity.startActivityForResult(
-                buildPickerIntent(types, /*save=*/false, /*allowMultiple=*/true),
+                buildPickerIntent(types, /*save=*/false, /*allowMultiple=*/true,
+                                  /*suggestedName=*/null),
                 SELECTING_FILE);
         });
         return true;
     }
 
-    private static Intent buildPickerIntent(String[] types, boolean save, boolean allowMultiple) {
+    private static Intent buildPickerIntent(String[] types, boolean save, boolean allowMultiple,
+                                            String suggestedName) {
         Intent i = new Intent(save ? Intent.ACTION_CREATE_DOCUMENT : Intent.ACTION_GET_CONTENT);
         i.addCategory(Intent.CATEGORY_OPENABLE);
         if(allowMultiple) i.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);
@@ -101,6 +122,22 @@ private static Intent buildPickerIntent(String[] types, boolean save, boolean al
             i.setType("*/*");
             i.putExtra(Intent.EXTRA_MIME_TYPES, types);
         }
+        // ACTION_CREATE_DOCUMENT reads its initial file name from EXTRA_TITLE;
+        // the user can still change it before saving. Without it the name field
+        // opens empty, and an empty display name is NOT left empty by the
+        // platform - FileUtils.buildValidFatFilename substitutes the literal
+        // "(invalid)", so saved files arrive as "(invalid).json".
+        //
+        // The name may carry its extension. FileUtils.splitFileName keeps the
+        // caller's extension when it maps back to the requested MIME type and
+        // replaces it otherwise, so "sheet.json" + "application/json" stays
+        // "sheet.json" rather than gaining a second suffix. Illegal characters
+        // and over-long names are sanitized by the provider, so nothing here has
+        // to - only the empty case needs guarding, since that is the one
+        // buildValidFatFilename cannot rescue.
+        if(save && suggestedName != null && !suggestedName.isEmpty()) {
+            i.putExtra(Intent.EXTRA_TITLE, suggestedName);
+        }
         return i;
     }