From 3b1118229b7ba4ae719adc13893fa9604ba18a36 Mon Sep 17 00:00:00 2001
From: Luke Street <luke@street.dev>
Date: Sat, 9 May 2026 20:22:30 -0600
Subject: [PATCH] Add Android DocumentsProvider

---
 .../android/app/src/main/AndroidManifest.xml  |  11 +
 .../dusk/DuskDocumentsProvider.java           | 373 ++++++++++++++++++
 .../app/src/main/res/values/strings.xml       |   2 +
 3 files changed, 386 insertions(+)
 create mode 100644 platforms/android/app/src/main/java/com/twilitrealm/dusk/DuskDocumentsProvider.java

diff --git a/platforms/android/app/src/main/AndroidManifest.xml b/platforms/android/app/src/main/AndroidManifest.xml
index f3e11030ca..f5a0365856 100644
--- a/platforms/android/app/src/main/AndroidManifest.xml
+++ b/platforms/android/app/src/main/AndroidManifest.xml
@@ -24,6 +24,17 @@
         <meta-data android:name="android.game_mode_config"
             android:resource="@xml/game_mode_config" />
 
+        <provider
+            android:name="dev.twilitrealm.dusk.DuskDocumentsProvider"
+            android:authorities="dev.twilitrealm.dusk.documents"
+            android:exported="true"
+            android:grantUriPermissions="true"
+            android:permission="android.permission.MANAGE_DOCUMENTS">
+            <intent-filter>
+                <action android:name="android.content.action.DOCUMENTS_PROVIDER" />
+            </intent-filter>
+        </provider>
+
         <activity
             android:name="dev.twilitrealm.dusk.DuskActivity"
             android:alwaysRetainTaskState="true"
diff --git a/platforms/android/app/src/main/java/com/twilitrealm/dusk/DuskDocumentsProvider.java b/platforms/android/app/src/main/java/com/twilitrealm/dusk/DuskDocumentsProvider.java
new file mode 100644
index 0000000000..edab8d9bc1
--- /dev/null
+++ b/platforms/android/app/src/main/java/com/twilitrealm/dusk/DuskDocumentsProvider.java
@@ -0,0 +1,373 @@
+package dev.twilitrealm.dusk;
+
+import android.content.res.AssetFileDescriptor;
+import android.database.Cursor;
+import android.database.MatrixCursor;
+import android.os.CancellationSignal;
+import android.os.ParcelFileDescriptor;
+import android.provider.DocumentsContract.Document;
+import android.provider.DocumentsContract.Root;
+import android.provider.DocumentsProvider;
+import android.webkit.MimeTypeMap;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
+public class DuskDocumentsProvider extends DocumentsProvider {
+    public static final String AUTHORITY = "dev.twilitrealm.dusk.documents";
+
+    private static final String ROOT_ID = "dusk";
+    private static final String ROOT_DOCUMENT_ID = "root";
+    private static final String DIRECTORY_MIME_TYPE = Document.MIME_TYPE_DIR;
+
+    private static final String[] DEFAULT_ROOT_PROJECTION = new String[] {
+        Root.COLUMN_ROOT_ID,
+        Root.COLUMN_FLAGS,
+        Root.COLUMN_TITLE,
+        Root.COLUMN_DOCUMENT_ID,
+        Root.COLUMN_ICON,
+        Root.COLUMN_AVAILABLE_BYTES,
+        Root.COLUMN_SUMMARY
+    };
+
+    private static final String[] DEFAULT_DOCUMENT_PROJECTION = new String[] {
+        Document.COLUMN_DOCUMENT_ID,
+        Document.COLUMN_DISPLAY_NAME,
+        Document.COLUMN_FLAGS,
+        Document.COLUMN_MIME_TYPE,
+        Document.COLUMN_LAST_MODIFIED,
+        Document.COLUMN_SIZE
+    };
+
+    @Override
+    public boolean onCreate() {
+        ensureUserDirectories();
+        return true;
+    }
+
+    @Override
+    public Cursor queryRoots(String[] projection) throws FileNotFoundException {
+        final MatrixCursor result = new MatrixCursor(resolveRootProjection(projection));
+        final File root = getRootDirectory();
+        final MatrixCursor.RowBuilder row = result.newRow();
+
+        row.add(Root.COLUMN_ROOT_ID, ROOT_ID);
+        row.add(Root.COLUMN_FLAGS,
+            Root.FLAG_LOCAL_ONLY |
+            Root.FLAG_SUPPORTS_CREATE |
+            Root.FLAG_SUPPORTS_IS_CHILD);
+        row.add(Root.COLUMN_TITLE, getContext().getString(R.string.app_name));
+        row.add(Root.COLUMN_DOCUMENT_ID, ROOT_DOCUMENT_ID);
+        row.add(Root.COLUMN_ICON, R.mipmap.icon);
+        row.add(Root.COLUMN_AVAILABLE_BYTES, root.getFreeSpace());
+        row.add(Root.COLUMN_SUMMARY, getContext().getString(R.string.documents_provider_summary));
+
+        return result;
+    }
+
+    @Override
+    public Cursor queryDocument(String documentId, String[] projection) throws FileNotFoundException {
+        final MatrixCursor result = new MatrixCursor(resolveDocumentProjection(projection));
+        includeDocument(result, documentId, getFileForDocumentId(documentId));
+        return result;
+    }
+
+    @Override
+    public Cursor queryChildDocuments(String parentDocumentId, String[] projection, String sortOrder)
+        throws FileNotFoundException
+    {
+        final MatrixCursor result = new MatrixCursor(resolveDocumentProjection(projection));
+        final File parent = getFileForDocumentId(parentDocumentId);
+        final File[] files = parent.listFiles();
+
+        if (files == null) {
+            return result;
+        }
+
+        for (File file : files) {
+            includeDocument(result, getDocumentIdForFile(file), file);
+        }
+
+        return result;
+    }
+
+    @Override
+    public boolean isChildDocument(String parentDocumentId, String documentId) {
+        try {
+            final File parent = getFileForDocumentId(parentDocumentId);
+            final File child = getFileForDocumentId(documentId);
+            return isInside(parent, child);
+        } catch (FileNotFoundException e) {
+            return false;
+        }
+    }
+
+    @Override
+    public String createDocument(String parentDocumentId, String mimeType, String displayName)
+        throws FileNotFoundException
+    {
+        final File parent = getFileForDocumentId(parentDocumentId);
+        if (!parent.isDirectory()) {
+            throw new FileNotFoundException("Parent is not a directory: " + parentDocumentId);
+        }
+
+        final String safeDisplayName = sanitizeDisplayName(displayName);
+        final File file = buildUniqueFile(parent, safeDisplayName);
+        final boolean created;
+        if (DIRECTORY_MIME_TYPE.equals(mimeType)) {
+            created = file.mkdir();
+        } else {
+            try {
+                created = file.createNewFile();
+            } catch (IOException e) {
+                throw asFileNotFound("Unable to create document", e);
+            }
+        }
+
+        if (!created) {
+            throw new FileNotFoundException("Unable to create document: " + displayName);
+        }
+
+        return getDocumentIdForFile(file);
+    }
+
+    @Override
+    public String renameDocument(String documentId, String displayName) throws FileNotFoundException {
+        final File file = getFileForDocumentId(documentId);
+        if (ROOT_DOCUMENT_ID.equals(documentId)) {
+            throw new FileNotFoundException("Cannot rename root document");
+        }
+
+        final File target = buildUniqueFile(file.getParentFile(), sanitizeDisplayName(displayName));
+        if (!file.renameTo(target)) {
+            throw new FileNotFoundException("Unable to rename document: " + documentId);
+        }
+        return getDocumentIdForFile(target);
+    }
+
+    @Override
+    public void deleteDocument(String documentId) throws FileNotFoundException {
+        if (ROOT_DOCUMENT_ID.equals(documentId)) {
+            throw new FileNotFoundException("Cannot delete root document");
+        }
+
+        final File file = getFileForDocumentId(documentId);
+        deleteRecursively(file);
+    }
+
+    @Override
+    public ParcelFileDescriptor openDocument(String documentId, String mode, CancellationSignal signal)
+        throws FileNotFoundException
+    {
+        return ParcelFileDescriptor.open(getFileForDocumentId(documentId), modeToParcelMode(mode));
+    }
+
+    @Override
+    public AssetFileDescriptor openDocumentThumbnail(String documentId, android.graphics.Point sizeHint,
+        CancellationSignal signal) throws FileNotFoundException
+    {
+        throw new FileNotFoundException("Thumbnails are not supported");
+    }
+
+    private void includeDocument(MatrixCursor result, String documentId, File file) throws FileNotFoundException {
+        final MatrixCursor.RowBuilder row = result.newRow();
+        final boolean isDirectory = file.isDirectory();
+        final String displayName = ROOT_DOCUMENT_ID.equals(documentId)
+            ? getContext().getString(R.string.documents_provider_root_name)
+            : file.getName();
+
+        int flags = Document.FLAG_SUPPORTS_DELETE | Document.FLAG_SUPPORTS_RENAME;
+        if (isDirectory) {
+            flags |= Document.FLAG_DIR_SUPPORTS_CREATE;
+        } else if (file.canWrite()) {
+            flags |= Document.FLAG_SUPPORTS_WRITE;
+        }
+        if (ROOT_DOCUMENT_ID.equals(documentId)) {
+            flags &= ~(Document.FLAG_SUPPORTS_DELETE | Document.FLAG_SUPPORTS_RENAME);
+        }
+
+        row.add(Document.COLUMN_DOCUMENT_ID, documentId);
+        row.add(Document.COLUMN_DISPLAY_NAME, displayName);
+        row.add(Document.COLUMN_FLAGS, flags);
+        row.add(Document.COLUMN_MIME_TYPE, isDirectory ? DIRECTORY_MIME_TYPE : getMimeType(file));
+        row.add(Document.COLUMN_LAST_MODIFIED, file.lastModified());
+        row.add(Document.COLUMN_SIZE, isDirectory ? null : file.length());
+    }
+
+    private File getRootDirectory() throws FileNotFoundException {
+        final File root = getContext().getFilesDir();
+        if (root == null) {
+            throw new FileNotFoundException("Dusk files directory is unavailable");
+        }
+        return root;
+    }
+
+    private File getFileForDocumentId(String documentId) throws FileNotFoundException {
+        final File root = getRootDirectory();
+        if (ROOT_DOCUMENT_ID.equals(documentId)) {
+            return root;
+        }
+        if (!documentId.startsWith(ROOT_DOCUMENT_ID + "/")) {
+            throw new FileNotFoundException("Invalid document id: " + documentId);
+        }
+
+        final String relativePath = documentId.substring(ROOT_DOCUMENT_ID.length() + 1);
+        final File file = new File(root, relativePath);
+        if (!isInside(root, file)) {
+            throw new FileNotFoundException("Document escapes Dusk files directory: " + documentId);
+        }
+        if (!file.exists()) {
+            throw new FileNotFoundException("Document does not exist: " + documentId);
+        }
+        return file;
+    }
+
+    private String getDocumentIdForFile(File file) throws FileNotFoundException {
+        final File root = getRootDirectory();
+        if (sameFile(root, file)) {
+            return ROOT_DOCUMENT_ID;
+        }
+        if (!isInside(root, file)) {
+            throw new FileNotFoundException("File escapes Dusk files directory: " + file);
+        }
+
+        final String rootPath = canonicalPath(root);
+        final String filePath = canonicalPath(file);
+        return ROOT_DOCUMENT_ID + "/" + filePath.substring(rootPath.length() + 1);
+    }
+
+    private void ensureUserDirectories() {
+        final File root = getContext().getFilesDir();
+        if (root == null) {
+            return;
+        }
+        new File(root, "texture_replacements").mkdirs();
+        new File(root, "USA/Card A").mkdirs();
+        new File(root, "EUR/Card A").mkdirs();
+    }
+
+    private static String[] resolveRootProjection(String[] projection) {
+        return projection != null ? projection : DEFAULT_ROOT_PROJECTION;
+    }
+
+    private static String[] resolveDocumentProjection(String[] projection) {
+        return projection != null ? projection : DEFAULT_DOCUMENT_PROJECTION;
+    }
+
+    private static String sanitizeDisplayName(String displayName) throws FileNotFoundException {
+        if (displayName == null) {
+            throw new FileNotFoundException("Document name is empty");
+        }
+
+        final String sanitized = displayName.trim();
+        if (sanitized.isEmpty() || ".".equals(sanitized) || "..".equals(sanitized) ||
+            sanitized.contains("/") || sanitized.contains("\\"))
+        {
+            throw new FileNotFoundException("Invalid document name: " + displayName);
+        }
+        return sanitized;
+    }
+
+    private static File buildUniqueFile(File parent, String displayName) {
+        File file = new File(parent, displayName);
+        if (!file.exists()) {
+            return file;
+        }
+
+        final int dot = displayName.lastIndexOf('.');
+        final String baseName = dot > 0 ? displayName.substring(0, dot) : displayName;
+        final String extension = dot > 0 ? displayName.substring(dot) : "";
+        for (int i = 1; i < 100; ++i) {
+            file = new File(parent, baseName + " (" + i + ")" + extension);
+            if (!file.exists()) {
+                return file;
+            }
+        }
+        return new File(parent, baseName + " (" + System.currentTimeMillis() + ")" + extension);
+    }
+
+    private static int modeToParcelMode(String mode) {
+        if ("r".equals(mode)) {
+            return ParcelFileDescriptor.MODE_READ_ONLY;
+        }
+        if ("w".equals(mode) || "wt".equals(mode)) {
+            return ParcelFileDescriptor.MODE_WRITE_ONLY |
+                ParcelFileDescriptor.MODE_CREATE |
+                ParcelFileDescriptor.MODE_TRUNCATE;
+        }
+        if ("wa".equals(mode)) {
+            return ParcelFileDescriptor.MODE_WRITE_ONLY |
+                ParcelFileDescriptor.MODE_CREATE |
+                ParcelFileDescriptor.MODE_APPEND;
+        }
+        if ("rw".equals(mode)) {
+            return ParcelFileDescriptor.MODE_READ_WRITE |
+                ParcelFileDescriptor.MODE_CREATE;
+        }
+        if ("rwt".equals(mode)) {
+            return ParcelFileDescriptor.MODE_READ_WRITE |
+                ParcelFileDescriptor.MODE_CREATE |
+                ParcelFileDescriptor.MODE_TRUNCATE;
+        }
+        return ParcelFileDescriptor.MODE_READ_ONLY;
+    }
+
+    private static String getMimeType(File file) {
+        final int dot = file.getName().lastIndexOf('.');
+        if (dot >= 0) {
+            final String extension = file.getName().substring(dot + 1).toLowerCase();
+            final String mimeType = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
+            if (mimeType != null) {
+                return mimeType;
+            }
+        }
+        return "application/octet-stream";
+    }
+
+    private static void deleteRecursively(File file) throws FileNotFoundException {
+        if (file.isDirectory()) {
+            final File[] children = file.listFiles();
+            if (children != null) {
+                for (File child : children) {
+                    deleteRecursively(child);
+                }
+            }
+        }
+        if (!file.delete()) {
+            throw new FileNotFoundException("Unable to delete document: " + file);
+        }
+    }
+
+    private static boolean isInside(File parent, File child) {
+        try {
+            final String parentPath = canonicalPath(parent);
+            final String childPath = canonicalPath(child);
+            return childPath.equals(parentPath) || childPath.startsWith(parentPath + File.separator);
+        } catch (FileNotFoundException e) {
+            return false;
+        }
+    }
+
+    private static boolean sameFile(File a, File b) {
+        try {
+            return canonicalPath(a).equals(canonicalPath(b));
+        } catch (FileNotFoundException e) {
+            return false;
+        }
+    }
+
+    private static String canonicalPath(File file) throws FileNotFoundException {
+        try {
+            return file.getCanonicalPath();
+        } catch (IOException e) {
+            throw asFileNotFound("Unable to resolve path", e);
+        }
+    }
+
+    private static FileNotFoundException asFileNotFound(String message, IOException cause) {
+        final FileNotFoundException exception = new FileNotFoundException(message + ": " + cause.getMessage());
+        exception.initCause(cause);
+        return exception;
+    }
+}
diff --git a/platforms/android/app/src/main/res/values/strings.xml b/platforms/android/app/src/main/res/values/strings.xml
index 79d8812b82..752dae76bf 100644
--- a/platforms/android/app/src/main/res/values/strings.xml
+++ b/platforms/android/app/src/main/res/values/strings.xml
@@ -1,4 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
     <string name="app_name">Dusk</string>
+    <string name="documents_provider_root_name">Dusk Data</string>
+    <string name="documents_provider_summary">Saves, texture packs, settings, and logs</string>
 </resources>