3 files changed, 319 insertions, 4 deletions

diff --git a/src/android/app/src/main/AndroidManifest.xml b/src/android/app/src/main/AndroidManifest.xml
index 7d3eccc5c..c37559b47 100644
--- a/src/android/app/src/main/AndroidManifest.xml
+++ b/src/android/app/src/main/AndroidManifest.xml
@@ -74,6 +74,18 @@
                 android:name="android.support.FILE_PROVIDER_PATHS"
                 android:resource="@xml/nnf_provider_paths" />
         </provider>
+
+        <provider
+            android:name=".features.DocumentProvider"
+            android:authorities="${applicationId}.user"
+            android:grantUriPermissions="true"
+            android:exported="true"
+            android:permission="android.permission.MANAGE_DOCUMENTS">
+            <intent-filter>
+                <action android:name="android.content.action.DOCUMENTS_PROVIDER" />
+            </intent-filter>
+        </provider>
+
     </application>
 
 </manifest>
diff --git a/src/android/app/src/main/java/org/yuzu/yuzu_emu/YuzuApplication.kt b/src/android/app/src/main/java/org/yuzu/yuzu_emu/YuzuApplication.kt
index 273d4951a..a0c5c5c25 100644
--- a/src/android/app/src/main/java/org/yuzu/yuzu_emu/YuzuApplication.kt
+++ b/src/android/app/src/main/java/org/yuzu/yuzu_emu/YuzuApplication.kt
@@ -8,9 +8,12 @@ import android.app.NotificationChannel
 import android.app.NotificationManager
 import android.content.Context
 import org.yuzu.yuzu_emu.model.GameDatabase
-import org.yuzu.yuzu_emu.utils.DirectoryInitialization.start
+import org.yuzu.yuzu_emu.utils.DirectoryInitialization
 import org.yuzu.yuzu_emu.utils.DocumentsTree
 import org.yuzu.yuzu_emu.utils.GpuDriverHelper
+import java.io.File
+
+fun Context.getPublicFilesDir() : File = getExternalFilesDir(null) ?: filesDir
 
 class YuzuApplication : Application() {
     private fun createNotificationChannel() {
@@ -36,7 +39,7 @@ class YuzuApplication : Application() {
         super.onCreate()
         application = this
         documentsTree = DocumentsTree()
-        start(applicationContext)
+        DirectoryInitialization.start(applicationContext)
         GpuDriverHelper.initializeDriverParameters(applicationContext)
         NativeLibrary.LogDeviceInfo()
 
@@ -50,10 +53,10 @@ class YuzuApplication : Application() {
 
         @JvmField
         var documentsTree: DocumentsTree? = null
-        private var application: YuzuApplication? = null
+        lateinit var application: YuzuApplication
 
         @JvmStatic
         val appContext: Context
-            get() = application!!.applicationContext
+            get() = application.applicationContext
     }
 }
diff --git a/src/android/app/src/main/java/org/yuzu/yuzu_emu/features/DocumentProvider.kt b/src/android/app/src/main/java/org/yuzu/yuzu_emu/features/DocumentProvider.kt
new file mode 100644
index 000000000..e6e9a6fe8
--- /dev/null
+++ b/src/android/app/src/main/java/org/yuzu/yuzu_emu/features/DocumentProvider.kt
@@ -0,0 +1,300 @@
+// SPDX-FileCopyrightText: 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+// SPDX-License-Identifier: MPL-2.0
+// Copyright © 2023 Skyline Team and Contributors (https://github.com/skyline-emu/)
+
+package org.yuzu.yuzu_emu.features
+
+import android.database.Cursor
+import android.database.MatrixCursor
+import android.os.CancellationSignal
+import android.os.ParcelFileDescriptor
+import android.provider.DocumentsContract
+import android.provider.DocumentsProvider
+import android.webkit.MimeTypeMap
+import org.yuzu.yuzu_emu.R
+import org.yuzu.yuzu_emu.YuzuApplication
+import org.yuzu.yuzu_emu.getPublicFilesDir
+import java.io.*
+
+class DocumentProvider : DocumentsProvider() {
+    private val baseDirectory: File
+        get() = File(YuzuApplication.application.getPublicFilesDir().canonicalPath)
+
+    companion object {
+        private val DEFAULT_ROOT_PROJECTION: Array<String> = arrayOf(
+            DocumentsContract.Root.COLUMN_ROOT_ID,
+            DocumentsContract.Root.COLUMN_MIME_TYPES,
+            DocumentsContract.Root.COLUMN_FLAGS,
+            DocumentsContract.Root.COLUMN_ICON,
+            DocumentsContract.Root.COLUMN_TITLE,
+            DocumentsContract.Root.COLUMN_SUMMARY,
+            DocumentsContract.Root.COLUMN_DOCUMENT_ID,
+            DocumentsContract.Root.COLUMN_AVAILABLE_BYTES
+        )
+
+        private val DEFAULT_DOCUMENT_PROJECTION: Array<String> = arrayOf(
+            DocumentsContract.Document.COLUMN_DOCUMENT_ID,
+            DocumentsContract.Document.COLUMN_MIME_TYPE,
+            DocumentsContract.Document.COLUMN_DISPLAY_NAME,
+            DocumentsContract.Document.COLUMN_LAST_MODIFIED,
+            DocumentsContract.Document.COLUMN_FLAGS,
+            DocumentsContract.Document.COLUMN_SIZE
+        )
+
+        const val ROOT_ID: String = "root"
+    }
+
+    override fun onCreate(): Boolean {
+        return true
+    }
+
+    /**
+     * @return The [File] that corresponds to the document ID supplied by [getDocumentId]
+     */
+    private fun getFile(documentId: String): File {
+        if (documentId.startsWith(ROOT_ID)) {
+            val file = baseDirectory.resolve(documentId.drop(ROOT_ID.length + 1))
+            if (!file.exists()) throw FileNotFoundException("${file.absolutePath} ($documentId) not found")
+            return file
+        } else {
+            throw FileNotFoundException("'$documentId' is not in any known root")
+        }
+    }
+
+    /**
+     * @return A unique ID for the provided [File]
+     */
+    private fun getDocumentId(file: File): String {
+        return "$ROOT_ID/${file.toRelativeString(baseDirectory)}"
+    }
+
+    override fun queryRoots(projection: Array<out String>?): Cursor {
+        val cursor = MatrixCursor(projection ?: DEFAULT_ROOT_PROJECTION)
+
+        cursor.newRow().apply {
+            add(DocumentsContract.Root.COLUMN_ROOT_ID, ROOT_ID)
+            add(DocumentsContract.Root.COLUMN_SUMMARY, null)
+            add(
+                DocumentsContract.Root.COLUMN_FLAGS,
+                DocumentsContract.Root.FLAG_SUPPORTS_CREATE or DocumentsContract.Root.FLAG_SUPPORTS_IS_CHILD
+            )
+            add(DocumentsContract.Root.COLUMN_TITLE, context!!.getString(R.string.app_name))
+            add(DocumentsContract.Root.COLUMN_DOCUMENT_ID, getDocumentId(baseDirectory))
+            add(DocumentsContract.Root.COLUMN_MIME_TYPES, "*/*")
+            add(DocumentsContract.Root.COLUMN_AVAILABLE_BYTES, baseDirectory.freeSpace)
+            add(DocumentsContract.Root.COLUMN_ICON, R.drawable.ic_yuzu)
+        }
+
+        return cursor
+    }
+
+    override fun queryDocument(documentId: String?, projection: Array<out String>?): Cursor {
+        val cursor = MatrixCursor(projection ?: DEFAULT_DOCUMENT_PROJECTION)
+        return includeFile(cursor, documentId, null)
+    }
+
+    override fun isChildDocument(parentDocumentId: String?, documentId: String?): Boolean {
+        return documentId?.startsWith(parentDocumentId!!) ?: false
+    }
+
+    /**
+     * @return A new [File] with a unique name based off the supplied [name], not conflicting with any existing file
+     */
+    private fun File.resolveWithoutConflict(name: String): File {
+        var file = resolve(name)
+        if (file.exists()) {
+            var noConflictId =
+                1 // Makes sure two files don't have the same name by adding a number to the end
+            val extension = name.substringAfterLast('.')
+            val baseName = name.substringBeforeLast('.')
+            while (file.exists())
+                file = resolve("$baseName (${noConflictId++}).$extension")
+        }
+        return file
+    }
+
+    override fun createDocument(
+        parentDocumentId: String?,
+        mimeType: String?,
+        displayName: String
+    ): String {
+        val parentFile = getFile(parentDocumentId!!)
+        val newFile = parentFile.resolveWithoutConflict(displayName)
+
+        try {
+            if (DocumentsContract.Document.MIME_TYPE_DIR == mimeType) {
+                if (!newFile.mkdir())
+                    throw IOException("Failed to create directory")
+            } else {
+                if (!newFile.createNewFile())
+                    throw IOException("Failed to create file")
+            }
+        } catch (e: IOException) {
+            throw FileNotFoundException("Couldn't create document '${newFile.path}': ${e.message}")
+        }
+
+        return getDocumentId(newFile)
+    }
+
+    override fun deleteDocument(documentId: String?) {
+        val file = getFile(documentId!!)
+        if (!file.delete())
+            throw FileNotFoundException("Couldn't delete document with ID '$documentId'")
+    }
+
+    override fun removeDocument(documentId: String, parentDocumentId: String?) {
+        val parent = getFile(parentDocumentId!!)
+        val file = getFile(documentId)
+
+        if (parent == file || file.parentFile == null || file.parentFile!! == parent) {
+            if (!file.delete())
+                throw FileNotFoundException("Couldn't delete document with ID '$documentId'")
+        } else {
+            throw FileNotFoundException("Couldn't delete document with ID '$documentId'")
+        }
+    }
+
+    override fun renameDocument(documentId: String?, displayName: String?): String {
+        if (displayName == null)
+            throw FileNotFoundException("Couldn't rename document '$documentId' as the new name is null")
+
+        val sourceFile = getFile(documentId!!)
+        val sourceParentFile = sourceFile.parentFile
+            ?: throw FileNotFoundException("Couldn't rename document '$documentId' as it has no parent")
+        val destFile = sourceParentFile.resolve(displayName)
+
+        try {
+            if (!sourceFile.renameTo(destFile))
+                throw FileNotFoundException("Couldn't rename document from '${sourceFile.name}' to '${destFile.name}'")
+        } catch (e: Exception) {
+            throw FileNotFoundException("Couldn't rename document from '${sourceFile.name}' to '${destFile.name}': ${e.message}")
+        }
+
+        return getDocumentId(destFile)
+    }
+
+    private fun copyDocument(
+        sourceDocumentId: String, sourceParentDocumentId: String,
+        targetParentDocumentId: String?
+    ): String {
+        if (!isChildDocument(sourceParentDocumentId, sourceDocumentId))
+            throw FileNotFoundException("Couldn't copy document '$sourceDocumentId' as its parent is not '$sourceParentDocumentId'")
+
+        return copyDocument(sourceDocumentId, targetParentDocumentId)
+    }
+
+    override fun copyDocument(sourceDocumentId: String, targetParentDocumentId: String?): String {
+        val parent = getFile(targetParentDocumentId!!)
+        val oldFile = getFile(sourceDocumentId)
+        val newFile = parent.resolveWithoutConflict(oldFile.name)
+
+        try {
+            if (!(newFile.createNewFile() && newFile.setWritable(true) && newFile.setReadable(true)))
+                throw IOException("Couldn't create new file")
+
+            FileInputStream(oldFile).use { inStream ->
+                FileOutputStream(newFile).use { outStream ->
+                    inStream.copyTo(outStream)
+                }
+            }
+        } catch (e: IOException) {
+            throw FileNotFoundException("Couldn't copy document '$sourceDocumentId': ${e.message}")
+        }
+
+        return getDocumentId(newFile)
+    }
+
+    override fun moveDocument(
+        sourceDocumentId: String, sourceParentDocumentId: String?,
+        targetParentDocumentId: String?
+    ): String {
+        try {
+            val newDocumentId = copyDocument(
+                sourceDocumentId, sourceParentDocumentId!!,
+                targetParentDocumentId
+            )
+            removeDocument(sourceDocumentId, sourceParentDocumentId)
+            return newDocumentId
+        } catch (e: FileNotFoundException) {
+            throw FileNotFoundException("Couldn't move document '$sourceDocumentId'")
+        }
+    }
+
+    private fun includeFile(cursor: MatrixCursor, documentId: String?, file: File?): MatrixCursor {
+        val localDocumentId = documentId ?: file?.let { getDocumentId(it) }
+        val localFile = file ?: getFile(documentId!!)
+
+        var flags = 0
+        if (localFile.isDirectory && localFile.canWrite()) {
+            flags = DocumentsContract.Document.FLAG_DIR_SUPPORTS_CREATE
+        } else if (localFile.canWrite()) {
+            flags = DocumentsContract.Document.FLAG_SUPPORTS_WRITE
+            flags = flags or DocumentsContract.Document.FLAG_SUPPORTS_DELETE
+
+            flags = flags or DocumentsContract.Document.FLAG_SUPPORTS_REMOVE
+            flags = flags or DocumentsContract.Document.FLAG_SUPPORTS_MOVE
+            flags = flags or DocumentsContract.Document.FLAG_SUPPORTS_COPY
+            flags = flags or DocumentsContract.Document.FLAG_SUPPORTS_RENAME
+        }
+
+        cursor.newRow().apply {
+            add(DocumentsContract.Document.COLUMN_DOCUMENT_ID, localDocumentId)
+            add(
+                DocumentsContract.Document.COLUMN_DISPLAY_NAME,
+                if (localFile == baseDirectory) context!!.getString(R.string.app_name) else localFile.name
+            )
+            add(DocumentsContract.Document.COLUMN_SIZE, localFile.length())
+            add(DocumentsContract.Document.COLUMN_MIME_TYPE, getTypeForFile(localFile))
+            add(DocumentsContract.Document.COLUMN_LAST_MODIFIED, localFile.lastModified())
+            add(DocumentsContract.Document.COLUMN_FLAGS, flags)
+            if (localFile == baseDirectory)
+                add(DocumentsContract.Root.COLUMN_ICON, R.drawable.ic_yuzu)
+        }
+
+        return cursor
+    }
+
+    private fun getTypeForFile(file: File): Any {
+        return if (file.isDirectory)
+            DocumentsContract.Document.MIME_TYPE_DIR
+        else
+            getTypeForName(file.name)
+    }
+
+    private fun getTypeForName(name: String): Any {
+        val lastDot = name.lastIndexOf('.')
+        if (lastDot >= 0) {
+            val extension = name.substring(lastDot + 1)
+            val mime = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension)
+            if (mime != null)
+                return mime
+        }
+        return "application/octect-stream"
+    }
+
+    override fun queryChildDocuments(
+        parentDocumentId: String?,
+        projection: Array<out String>?,
+        sortOrder: String?
+    ): Cursor {
+        var cursor = MatrixCursor(projection ?: DEFAULT_DOCUMENT_PROJECTION)
+
+        val parent = getFile(parentDocumentId!!)
+        for (file in parent.listFiles()!!)
+            cursor = includeFile(cursor, null, file)
+
+        return cursor
+    }
+
+    override fun openDocument(
+        documentId: String?,
+        mode: String?,
+        signal: CancellationSignal?
+    ): ParcelFileDescriptor {
+        val file = documentId?.let { getFile(it) }
+        val accessMode = ParcelFileDescriptor.parseMode(mode)
+        return ParcelFileDescriptor.open(file, accessMode)
+    }
+}