documents: Create DocumentTreeTestHelper

For future tests

2 files changed, 443 insertions, 426 deletions

diff --git a/libs/documents/src/test/java/org/the_jk/cleversync/documents/DocumentTreeTest.kt b/libs/documents/src/test/java/org/the_jk/cleversync/documents/DocumentTreeTest.kt
index f116f0e..ad6abfa 100644
--- a/libs/documents/src/test/java/org/the_jk/cleversync/documents/DocumentTreeTest.kt
+++ b/libs/documents/src/test/java/org/the_jk/cleversync/documents/DocumentTreeTest.kt
@@ -1,34 +1,14 @@
 package org.the_jk.cleversync.documents
 
-import android.Manifest.permission.MANAGE_DOCUMENTS
-import android.content.Context
-import android.content.pm.ProviderInfo
-import android.database.Cursor
-import android.database.MatrixCursor
-import android.os.Build
-import android.os.CancellationSignal
-import android.os.ParcelFileDescriptor
-import android.provider.DocumentsContract
-import android.provider.DocumentsProvider
-import android.webkit.MimeTypeMap
-import androidx.test.core.app.ApplicationProvider
-import com.google.common.truth.Truth.assertThat
 import org.junit.After
 import org.junit.Before
 import org.junit.Rule
 import org.junit.rules.TemporaryFolder
 import org.junit.runner.RunWith
-import org.robolectric.Robolectric
 import org.robolectric.RobolectricTestRunner
-import org.robolectric.android.controller.ContentProviderController
 import org.robolectric.annotation.Config
 import org.robolectric.shadows.ShadowLooper
 import org.the_jk.cleversync.TreeAbstractTest
-import java.io.File
-import java.io.FileInputStream
-import java.io.FileNotFoundException
-import java.io.FileOutputStream
-import java.io.IOException
 import java.util.concurrent.TimeUnit
 
 @Config(manifest=Config.NONE)
@@ -37,36 +17,16 @@ class DocumentTreeTest : TreeAbstractTest() {
     @get:Rule
     val folder = TemporaryFolder()
 
-    private lateinit var controller: ContentProviderController<FakeProvider>
+    private val helper = DocumentTreeTestHelper()
 
     @Before
     fun setUp() {
-        val context = ApplicationProvider.getApplicationContext<Context>()
-        val contentResolver = context.contentResolver
-        val providerInfo = ProviderInfo()
-        providerInfo.authority = "org.the_jk.cleversync.documents.test"
-        providerInfo.grantUriPermissions = true
-        providerInfo.exported = true
-        providerInfo.readPermission = MANAGE_DOCUMENTS
-        providerInfo.writePermission = MANAGE_DOCUMENTS
-        controller = Robolectric
-                .buildContentProvider(FakeProvider::class.java)
-
-        controller.get().setBaseDir(folder.root)
-        controller.create(providerInfo)
-
-        val treeUri = DocumentsContract.buildTreeDocumentUri(providerInfo.authority, ROOT)
-        assertThat(DocumentsContract.isTreeUri(treeUri)).isTrue()
-
-        tree = DocumentTreeFactory.modifiableTree(
-            contentResolver,
-            treeUri,
-        )
+       tree = helper.openTree(folder)
     }
 
     @After
     fun tearDown() {
-        controller.shutdown()
+        helper.closeTree(tree)
     }
 
     override fun idle() {
@@ -74,387 +34,4 @@ class DocumentTreeTest : TreeAbstractTest() {
     }
 
     override fun supportSymlinks() = false
-
-    private class FakeProvider : DocumentsProvider() {
-        private lateinit var baseDir: File
-
-        fun setBaseDir(file: File) {
-            baseDir = file
-        }
-
-        override fun onCreate(): Boolean {
-            return true
-        }
-
-        override fun queryRoots(projection: Array<String>?): Cursor {
-            val result = MatrixCursor(resolveRootProjection(projection))
-            val row = result.newRow()
-            row.add(DocumentsContract.Root.COLUMN_ROOT_ID, ROOT)
-            row.add(DocumentsContract.Root.COLUMN_SUMMARY, "")
-            row.add(DocumentsContract.Root.COLUMN_FLAGS,
-                DocumentsContract.Root.FLAG_SUPPORTS_CREATE or
-                        DocumentsContract.Root.FLAG_SUPPORTS_IS_CHILD)
-            row.add(DocumentsContract.Root.COLUMN_TITLE, "fake")
-            row.add(DocumentsContract.Root.COLUMN_DOCUMENT_ID, getDocIdForFile(baseDir))
-            row.add(DocumentsContract.Root.COLUMN_MIME_TYPES, getChildMimeTypes())
-            row.add(DocumentsContract.Root.COLUMN_AVAILABLE_BYTES, baseDir.freeSpace)
-            row.add(DocumentsContract.Root.COLUMN_ICON, null)
-            return result
-        }
-
-        override fun queryDocument(
-            documentId: String?,
-            projection: Array<String>?
-        ): Cursor {
-            val result = MatrixCursor(resolveDocumentProjection(projection))
-            includeFile(result, documentId, null)
-            return result
-        }
-
-        override fun queryChildDocuments(
-            parentDocumentId: String,
-            projection: Array<String>?,
-            sortOrder: String?
-        ): Cursor {
-            val result = MatrixCursor(resolveDocumentProjection(projection))
-            val parent = getFileForDocId(parentDocumentId)
-            parent.listFiles()?.forEach { file ->
-                includeFile(result, null, file)
-            }
-            return result
-        }
-
-        override fun openDocument(
-            documentId: String,
-            mode: String?,
-            signal: CancellationSignal?
-        ): ParcelFileDescriptor {
-            val file = getFileForDocId(documentId)
-            val accessMode = ParcelFileDescriptor.parseMode(mode)
-            return ParcelFileDescriptor.open(file, accessMode)
-        }
-
-        override fun isChildDocument(
-            parentDocumentId: String,
-            documentId: String
-        ): Boolean {
-            try {
-                val parentFile = getFileForDocId(parentDocumentId)
-                var childFile: File? = getFileForDocId(documentId)
-                // childFile can be any level of descendant of parentFile
-                // to return true.
-                do {
-                    if (isChildFile(parentFile, childFile!!)) return true
-                    childFile = childFile.parentFile
-                } while (childFile != null)
-                return false
-            } catch (_: FileNotFoundException) {
-            }
-            return false
-        }
-
-        override fun createDocument(
-            parentDocumentId: String,
-            mimeType: String?,
-            displayName: String,
-        ): String {
-            val parent = getFileForDocId(parentDocumentId)
-            val file = File(parent.path, displayName)
-            try {
-                var documentWasCreated = false
-                if (mimeType == DocumentsContract.Document.MIME_TYPE_DIR) {
-                    if (file.mkdir()) {
-                        if (file.setWritable(true) && file.setWritable(true) && file.setExecutable(true)) {
-                            documentWasCreated = true
-                        }
-                    }
-                } else {
-                    if (file.createNewFile()) {
-                        if (file.setWritable(true) && file.setReadable(true)) {
-                            documentWasCreated = true
-                        }
-                    }
-                }
-
-                if (!documentWasCreated) {
-                    throw IOException("Failed to create document with name " +
-                            displayName +" and documentId " + parentDocumentId)
-                }
-            } catch (e: IOException) {
-                throw IOException("Failed to create document with name " +
-                        displayName +" and documentId " + parentDocumentId, e)
-            }
-            return getDocIdForFile(file)
-        }
-
-        override fun renameDocument(
-            documentId: String,
-            displayName: String?
-        ): String {
-            if (displayName == null) {
-                throw IOException("Failed to rename document, new name is null")
-            }
-
-            val sourceFile = getFileForDocId(documentId)
-            val sourceParentFile = sourceFile.parentFile
-                ?: throw IOException("Failed to rename document. File has no parent.")
-            val destFile = File(sourceParentFile.path, displayName)
-
-            try {
-                if (!sourceFile.renameTo(destFile)) {
-                    throw IOException("Failed to rename document. Renamed failed.")
-                }
-            } catch (e: Exception) {
-                throw IOException("Failed to rename document.", e)
-            }
-
-            return getDocIdForFile(destFile)
-        }
-
-        override fun deleteDocument(documentId: String) {
-            val file = getFileForDocId(documentId)
-            if (!file.delete()) {
-                throw IOException("Failed to delete document with id $documentId")
-            }
-        }
-
-        override fun removeDocument(
-            documentId: String,
-            parentDocumentId: String,
-        ) {
-            val parent = getFileForDocId(parentDocumentId)
-            val file = getFileForDocId(documentId)
-
-            val doesFileParentMatch = isChildFile(parent, file)
-
-            if (parent == file || doesFileParentMatch) {
-                if (!file.delete()) {
-                    throw IOException("Failed to delete document with id $documentId")
-                }
-            } else {
-                throw IOException("Failed to delete document with id $documentId")
-            }
-        }
-
-        override fun copyDocument(
-            sourceDocumentId: String,
-            targetParentDocumentId: String
-        ): String {
-            val parent = getFileForDocId(targetParentDocumentId)
-            val oldFile = getFileForDocId(sourceDocumentId)
-            val newFile = File(parent.path, oldFile.name)
-
-            try {
-                var wasNewFileCreated = false
-                if (newFile.createNewFile()) {
-                    if (newFile.setWritable(true) && newFile.setReadable(true)) {
-                        wasNewFileCreated = true
-                    }
-                }
-
-                if (!wasNewFileCreated) {
-                    throw IOException("Failed to copy document " + sourceDocumentId +
-                            ". Could not create new file.")
-                }
-
-                FileInputStream(oldFile).use { inStream ->
-                    FileOutputStream(newFile).use { outStream ->
-                        // Transfer bytes from in to out
-                        val buf = ByteArray(65536)
-                        var len: Int
-                        while ((inStream.read(buf).also { len = it }) > 0) {
-                            outStream.write(buf, 0, len)
-                        }
-                    }
-                }
-            } catch (e: IOException) {
-                throw IOException("Failed to copy document: $sourceDocumentId", e)
-            }
-            return getDocIdForFile(newFile)
-        }
-
-        override fun moveDocument(
-            sourceDocumentId: String,
-            sourceParentDocumentId: String,
-            targetParentDocumentId: String,
-        ): String {
-            try {
-                // Copy document, insisting that the parent is correct
-                val newDocumentId = copyDocument(sourceDocumentId, sourceParentDocumentId,
-                    targetParentDocumentId)
-                // Remove old document
-                removeDocument(sourceDocumentId,sourceParentDocumentId)
-                return newDocumentId
-            } catch (e: IOException) {
-                throw IOException("Failed to move document $sourceDocumentId", e)
-            }
-        }
-
-        override fun getDocumentType(documentId: String): String {
-            val file = getFileForDocId(documentId)
-            return getTypeForFile(file)
-        }
-
-        private fun copyDocument(
-            sourceDocumentId: String,
-            sourceParentDocumentId: String,
-            targetParentDocumentId: String,
-        ): String {
-            if (!isChildDocument(sourceParentDocumentId, sourceDocumentId)) {
-                throw IOException(
-                    "Failed to copy document with id " +
-                            sourceDocumentId + ". Parent is not: " + sourceParentDocumentId
-                )
-            }
-            return copyDocument(sourceDocumentId, targetParentDocumentId)
-        }
-
-        private fun isChildFile(parentFile: File, childFile: File): Boolean {
-            return parentFile == childFile.parentFile
-        }
-
-        private fun getDocIdForFile(file: File): String {
-            var path = file.absolutePath
-
-            // Start at first char of path under root
-            val rootPath = baseDir.path
-            path = if (rootPath.equals(path)) {
-                ""
-            } else if (rootPath.endsWith("/")) {
-                path.substring(rootPath.length)
-            } else {
-                path.substring(rootPath.length + 1)
-            }
-
-            return "$ROOT:$path"
-        }
-
-        private fun getFileForDocId(docId: String): File {
-            var target = baseDir
-            if (docId == ROOT) {
-                return target
-            }
-            val splitIndex = docId.indexOf(':', 1)
-            if (splitIndex < 0) {
-                throw FileNotFoundException("Missing root for $docId")
-            } else {
-                val path = docId.substring(splitIndex + 1)
-                target = File(target, path)
-                if (!target.exists()) {
-                    throw FileNotFoundException("Missing file for $docId at $target")
-                }
-                return target
-            }
-        }
-
-        private fun includeFile(result: MatrixCursor, inDocId: String?, inFile: File?) {
-            val (docId, file) = if (inDocId == null) {
-                getDocIdForFile(inFile!!) to inFile
-            } else {
-                inDocId to getFileForDocId(inDocId)
-            }
-
-            var flags = 0
-
-            if (file.isDirectory) {
-                // Add FLAG_DIR_SUPPORTS_CREATE if the file is a writable directory.
-                if (file.canWrite()) {
-                    flags = flags or DocumentsContract.Document.FLAG_DIR_SUPPORTS_CREATE
-                }
-            }
-            if (file.canWrite()) {
-                // If the file is writable set FLAG_SUPPORTS_WRITE and
-                // FLAG_SUPPORTS_DELETE
-                flags = flags or DocumentsContract.Document.FLAG_SUPPORTS_WRITE
-                flags = flags or DocumentsContract.Document.FLAG_SUPPORTS_DELETE
-                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
-                    flags =
-                        flags or DocumentsContract.Document.FLAG_SUPPORTS_RENAME
-                }
-                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
-                    flags =
-                        flags or DocumentsContract.Document.FLAG_SUPPORTS_REMOVE
-                    flags =
-                        flags or DocumentsContract.Document.FLAG_SUPPORTS_MOVE
-                    flags =
-                        flags or DocumentsContract.Document.FLAG_SUPPORTS_COPY
-                }
-            }
-
-            val displayName = file.name
-            val mimeType = getTypeForFile(file)
-
-            val row = result.newRow()
-            row.add(DocumentsContract.Document.COLUMN_DOCUMENT_ID, docId)
-            row.add(DocumentsContract.Document.COLUMN_DISPLAY_NAME, displayName)
-            row.add(DocumentsContract.Document.COLUMN_SIZE, file.length())
-            row.add(DocumentsContract.Document.COLUMN_MIME_TYPE, mimeType)
-            row.add(DocumentsContract.Document.COLUMN_LAST_MODIFIED, file.lastModified())
-            row.add(DocumentsContract.Document.COLUMN_FLAGS, flags)
-            row.add(DocumentsContract.Document.COLUMN_ICON, null)
-        }
-    }
-
-    private companion object {
-        val DEFAULT_ROOT_PROJECTION = 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
-        )
-
-        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: String = "root"
-
-        fun resolveRootProjection(projection: Array<String>?): Array<String> {
-            return projection ?: DEFAULT_ROOT_PROJECTION
-        }
-
-        fun resolveDocumentProjection(projection: Array<String>?): Array<String> {
-            return projection ?: DEFAULT_DOCUMENT_PROJECTION
-        }
-
-        fun getTypeForFile(file: File): String {
-            return if (file.isDirectory) {
-                DocumentsContract.Document.MIME_TYPE_DIR
-            } else {
-                getTypeForName(file.name)
-            }
-        }
-
-        fun getTypeForName(name: String): String {
-            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/octet-stream"
-        }
-
-        fun getChildMimeTypes(): String {
-            val mimeTypes = setOf(
-                "image/*",
-                "text/*",
-                "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
-                DocumentsContract.Document.MIME_TYPE_DIR,
-                "application/octet-stream",
-            )
-            return mimeTypes.joinToString("\n")
-        }
-    }
 }
diff --git a/libs/documents/src/test/java/org/the_jk/cleversync/documents/DocumentTreeTestHelper.kt b/libs/documents/src/test/java/org/the_jk/cleversync/documents/DocumentTreeTestHelper.kt
new file mode 100644
index 0000000..5358920
--- /dev/null
+++ b/libs/documents/src/test/java/org/the_jk/cleversync/documents/DocumentTreeTestHelper.kt
@@ -0,0 +1,440 @@
+package org.the_jk.cleversync.documents
+
+import android.Manifest.permission.MANAGE_DOCUMENTS
+import android.content.Context
+import android.content.pm.ProviderInfo
+import android.database.Cursor
+import android.database.MatrixCursor
+import android.os.Build
+import android.os.CancellationSignal
+import android.os.ParcelFileDescriptor
+import android.provider.DocumentsContract
+import android.provider.DocumentsProvider
+import android.webkit.MimeTypeMap
+import androidx.test.core.app.ApplicationProvider
+import com.google.common.truth.Truth.assertThat
+import org.junit.rules.TemporaryFolder
+import org.robolectric.Robolectric
+import org.robolectric.android.controller.ContentProviderController
+import org.the_jk.cleversync.io.ModifiableTree
+import java.io.File
+import java.io.FileInputStream
+import java.io.FileNotFoundException
+import java.io.FileOutputStream
+import java.io.IOException
+
+class DocumentTreeTestHelper {
+    private lateinit var controller: ContentProviderController<FakeProvider>
+
+    fun openTree(folder: TemporaryFolder): ModifiableTree {
+        val context = ApplicationProvider.getApplicationContext<Context>()
+        val contentResolver = context.contentResolver
+        val providerInfo = ProviderInfo()
+        providerInfo.authority = "org.the_jk.cleversync.documents.test"
+        providerInfo.grantUriPermissions = true
+        providerInfo.exported = true
+        providerInfo.readPermission = MANAGE_DOCUMENTS
+        providerInfo.writePermission = MANAGE_DOCUMENTS
+        controller = Robolectric
+            .buildContentProvider(FakeProvider::class.java)
+
+        controller.get().setBaseDir(folder.root)
+        controller.create(providerInfo)
+
+        val treeUri = DocumentsContract.buildTreeDocumentUri(providerInfo.authority, ROOT)
+        assertThat(DocumentsContract.isTreeUri(treeUri)).isTrue()
+
+        return DocumentTreeFactory.modifiableTree(
+            contentResolver,
+            treeUri,
+        )
+    }
+
+    @Suppress("UNUSED_PARAMETER")
+    fun closeTree(tree: ModifiableTree) {
+        controller.shutdown()
+    }
+
+    private class FakeProvider : DocumentsProvider() {
+        private lateinit var baseDir: File
+
+        fun setBaseDir(file: File) {
+            baseDir = file
+        }
+
+        override fun onCreate(): Boolean {
+            return true
+        }
+
+        override fun queryRoots(projection: Array<String>?): Cursor {
+            val result = MatrixCursor(resolveRootProjection(projection))
+            val row = result.newRow()
+            row.add(DocumentsContract.Root.COLUMN_ROOT_ID, ROOT)
+            row.add(DocumentsContract.Root.COLUMN_SUMMARY, "")
+            row.add(DocumentsContract.Root.COLUMN_FLAGS,
+                DocumentsContract.Root.FLAG_SUPPORTS_CREATE or
+                        DocumentsContract.Root.FLAG_SUPPORTS_IS_CHILD)
+            row.add(DocumentsContract.Root.COLUMN_TITLE, "fake")
+            row.add(DocumentsContract.Root.COLUMN_DOCUMENT_ID, getDocIdForFile(baseDir))
+            row.add(DocumentsContract.Root.COLUMN_MIME_TYPES, getChildMimeTypes())
+            row.add(DocumentsContract.Root.COLUMN_AVAILABLE_BYTES, baseDir.freeSpace)
+            row.add(DocumentsContract.Root.COLUMN_ICON, null)
+            return result
+        }
+
+        override fun queryDocument(
+            documentId: String?,
+            projection: Array<String>?
+        ): Cursor {
+            val result = MatrixCursor(resolveDocumentProjection(projection))
+            includeFile(result, documentId, null)
+            return result
+        }
+
+        override fun queryChildDocuments(
+            parentDocumentId: String,
+            projection: Array<String>?,
+            sortOrder: String?
+        ): Cursor {
+            val result = MatrixCursor(resolveDocumentProjection(projection))
+            val parent = getFileForDocId(parentDocumentId)
+            parent.listFiles()?.forEach { file ->
+                includeFile(result, null, file)
+            }
+            return result
+        }
+
+        override fun openDocument(
+            documentId: String,
+            mode: String?,
+            signal: CancellationSignal?
+        ): ParcelFileDescriptor {
+            val file = getFileForDocId(documentId)
+            val accessMode = ParcelFileDescriptor.parseMode(mode)
+            return ParcelFileDescriptor.open(file, accessMode)
+        }
+
+        override fun isChildDocument(
+            parentDocumentId: String,
+            documentId: String
+        ): Boolean {
+            try {
+                val parentFile = getFileForDocId(parentDocumentId)
+                var childFile: File? = getFileForDocId(documentId)
+                // childFile can be any level of descendant of parentFile
+                // to return true.
+                do {
+                    if (isChildFile(parentFile, childFile!!)) return true
+                    childFile = childFile.parentFile
+                } while (childFile != null)
+                return false
+            } catch (_: FileNotFoundException) {
+            }
+            return false
+        }
+
+        override fun createDocument(
+            parentDocumentId: String,
+            mimeType: String?,
+            displayName: String,
+        ): String {
+            val parent = getFileForDocId(parentDocumentId)
+            val file = File(parent.path, displayName)
+            try {
+                var documentWasCreated = false
+                if (mimeType == DocumentsContract.Document.MIME_TYPE_DIR) {
+                    if (file.mkdir()) {
+                        if (file.setWritable(true) && file.setWritable(true) && file.setExecutable(true)) {
+                            documentWasCreated = true
+                        }
+                    }
+                } else {
+                    if (file.createNewFile()) {
+                        if (file.setWritable(true) && file.setReadable(true)) {
+                            documentWasCreated = true
+                        }
+                    }
+                }
+
+                if (!documentWasCreated) {
+                    throw IOException("Failed to create document with name " +
+                            displayName +" and documentId " + parentDocumentId)
+                }
+            } catch (e: IOException) {
+                throw IOException("Failed to create document with name " +
+                        displayName +" and documentId " + parentDocumentId, e)
+            }
+            return getDocIdForFile(file)
+        }
+
+        override fun renameDocument(
+            documentId: String,
+            displayName: String?
+        ): String {
+            if (displayName == null) {
+                throw IOException("Failed to rename document, new name is null")
+            }
+
+            val sourceFile = getFileForDocId(documentId)
+            val sourceParentFile = sourceFile.parentFile
+                ?: throw IOException("Failed to rename document. File has no parent.")
+            val destFile = File(sourceParentFile.path, displayName)
+
+            try {
+                if (!sourceFile.renameTo(destFile)) {
+                    throw IOException("Failed to rename document. Renamed failed.")
+                }
+            } catch (e: Exception) {
+                throw IOException("Failed to rename document.", e)
+            }
+
+            return getDocIdForFile(destFile)
+        }
+
+        override fun deleteDocument(documentId: String) {
+            val file = getFileForDocId(documentId)
+            if (!file.delete()) {
+                throw IOException("Failed to delete document with id $documentId")
+            }
+        }
+
+        override fun removeDocument(
+            documentId: String,
+            parentDocumentId: String,
+        ) {
+            val parent = getFileForDocId(parentDocumentId)
+            val file = getFileForDocId(documentId)
+
+            val doesFileParentMatch = isChildFile(parent, file)
+
+            if (parent == file || doesFileParentMatch) {
+                if (!file.delete()) {
+                    throw IOException("Failed to delete document with id $documentId")
+                }
+            } else {
+                throw IOException("Failed to delete document with id $documentId")
+            }
+        }
+
+        override fun copyDocument(
+            sourceDocumentId: String,
+            targetParentDocumentId: String
+        ): String {
+            val parent = getFileForDocId(targetParentDocumentId)
+            val oldFile = getFileForDocId(sourceDocumentId)
+            val newFile = File(parent.path, oldFile.name)
+
+            try {
+                var wasNewFileCreated = false
+                if (newFile.createNewFile()) {
+                    if (newFile.setWritable(true) && newFile.setReadable(true)) {
+                        wasNewFileCreated = true
+                    }
+                }
+
+                if (!wasNewFileCreated) {
+                    throw IOException("Failed to copy document " + sourceDocumentId +
+                            ". Could not create new file.")
+                }
+
+                FileInputStream(oldFile).use { inStream ->
+                    FileOutputStream(newFile).use { outStream ->
+                        // Transfer bytes from in to out
+                        val buf = ByteArray(65536)
+                        var len: Int
+                        while ((inStream.read(buf).also { len = it }) > 0) {
+                            outStream.write(buf, 0, len)
+                        }
+                    }
+                }
+            } catch (e: IOException) {
+                throw IOException("Failed to copy document: $sourceDocumentId", e)
+            }
+            return getDocIdForFile(newFile)
+        }
+
+        override fun moveDocument(
+            sourceDocumentId: String,
+            sourceParentDocumentId: String,
+            targetParentDocumentId: String,
+        ): String {
+            try {
+                // Copy document, insisting that the parent is correct
+                val newDocumentId = copyDocument(sourceDocumentId, sourceParentDocumentId,
+                    targetParentDocumentId)
+                // Remove old document
+                removeDocument(sourceDocumentId,sourceParentDocumentId)
+                return newDocumentId
+            } catch (e: IOException) {
+                throw IOException("Failed to move document $sourceDocumentId", e)
+            }
+        }
+
+        override fun getDocumentType(documentId: String): String {
+            val file = getFileForDocId(documentId)
+            return getTypeForFile(file)
+        }
+
+        private fun copyDocument(
+            sourceDocumentId: String,
+            sourceParentDocumentId: String,
+            targetParentDocumentId: String,
+        ): String {
+            if (!isChildDocument(sourceParentDocumentId, sourceDocumentId)) {
+                throw IOException(
+                    "Failed to copy document with id " +
+                            sourceDocumentId + ". Parent is not: " + sourceParentDocumentId
+                )
+            }
+            return copyDocument(sourceDocumentId, targetParentDocumentId)
+        }
+
+        private fun isChildFile(parentFile: File, childFile: File): Boolean {
+            return parentFile == childFile.parentFile
+        }
+
+        private fun getDocIdForFile(file: File): String {
+            var path = file.absolutePath
+
+            // Start at first char of path under root
+            val rootPath = baseDir.path
+            path = if (rootPath.equals(path)) {
+                ""
+            } else if (rootPath.endsWith("/")) {
+                path.substring(rootPath.length)
+            } else {
+                path.substring(rootPath.length + 1)
+            }
+
+            return "$ROOT:$path"
+        }
+
+        private fun getFileForDocId(docId: String): File {
+            var target = baseDir
+            if (docId == ROOT) {
+                return target
+            }
+            val splitIndex = docId.indexOf(':', 1)
+            if (splitIndex < 0) {
+                throw FileNotFoundException("Missing root for $docId")
+            } else {
+                val path = docId.substring(splitIndex + 1)
+                target = File(target, path)
+                if (!target.exists()) {
+                    throw FileNotFoundException("Missing file for $docId at $target")
+                }
+                return target
+            }
+        }
+
+        private fun includeFile(result: MatrixCursor, inDocId: String?, inFile: File?) {
+            val (docId, file) = if (inDocId == null) {
+                getDocIdForFile(inFile!!) to inFile
+            } else {
+                inDocId to getFileForDocId(inDocId)
+            }
+
+            var flags = 0
+
+            if (file.isDirectory) {
+                // Add FLAG_DIR_SUPPORTS_CREATE if the file is a writable directory.
+                if (file.canWrite()) {
+                    flags = flags or DocumentsContract.Document.FLAG_DIR_SUPPORTS_CREATE
+                }
+            }
+            if (file.canWrite()) {
+                // If the file is writable set FLAG_SUPPORTS_WRITE and
+                // FLAG_SUPPORTS_DELETE
+                flags = flags or DocumentsContract.Document.FLAG_SUPPORTS_WRITE
+                flags = flags or DocumentsContract.Document.FLAG_SUPPORTS_DELETE
+                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+                    flags =
+                        flags or DocumentsContract.Document.FLAG_SUPPORTS_RENAME
+                }
+                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
+                    flags =
+                        flags or DocumentsContract.Document.FLAG_SUPPORTS_REMOVE
+                    flags =
+                        flags or DocumentsContract.Document.FLAG_SUPPORTS_MOVE
+                    flags =
+                        flags or DocumentsContract.Document.FLAG_SUPPORTS_COPY
+                }
+            }
+
+            val displayName = file.name
+            val mimeType = getTypeForFile(file)
+
+            val row = result.newRow()
+            row.add(DocumentsContract.Document.COLUMN_DOCUMENT_ID, docId)
+            row.add(DocumentsContract.Document.COLUMN_DISPLAY_NAME, displayName)
+            row.add(DocumentsContract.Document.COLUMN_SIZE, file.length())
+            row.add(DocumentsContract.Document.COLUMN_MIME_TYPE, mimeType)
+            row.add(DocumentsContract.Document.COLUMN_LAST_MODIFIED, file.lastModified())
+            row.add(DocumentsContract.Document.COLUMN_FLAGS, flags)
+            row.add(DocumentsContract.Document.COLUMN_ICON, null)
+        }
+    }
+
+    private companion object {
+        val DEFAULT_ROOT_PROJECTION = 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
+        )
+
+        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: String = "root"
+
+        fun resolveRootProjection(projection: Array<String>?): Array<String> {
+            return projection ?: DEFAULT_ROOT_PROJECTION
+        }
+
+        fun resolveDocumentProjection(projection: Array<String>?): Array<String> {
+            return projection ?: DEFAULT_DOCUMENT_PROJECTION
+        }
+
+        fun getTypeForFile(file: File): String {
+            return if (file.isDirectory) {
+                DocumentsContract.Document.MIME_TYPE_DIR
+            } else {
+                getTypeForName(file.name)
+            }
+        }
+
+        fun getTypeForName(name: String): String {
+            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/octet-stream"
+        }
+
+        fun getChildMimeTypes(): String {
+            val mimeTypes = setOf(
+                "image/*",
+                "text/*",
+                "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+                DocumentsContract.Document.MIME_TYPE_DIR,
+                "application/octet-stream",
+            )
+            return mimeTypes.joinToString("\n")
+        }
+    }
+}