content: /*
   * Copyright (C) 2013 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  
  package com.example.android.storageprovider;
  
  import static android.os.Build.VERSION.SDK_INT;
  
  import android.content.Context;
  import android.content.SharedPreferences;
  import android.content.res.AssetFileDescriptor;
  import android.content.res.TypedArray;
  import android.database.Cursor;
  import android.database.MatrixCursor;
  import android.graphics.Point;
  import android.os.Build;
  import android.os.CancellationSignal;
  import android.os.Handler;
  import android.os.ParcelFileDescriptor;
  import android.provider.DocumentsContract.Document;
  import android.provider.DocumentsContract.Root;
  import android.provider.DocumentsProvider;
  import android.webkit.MimeTypeMap;
  
  import com.example.android.common.logger.Log;
  
  import java.io.ByteArrayOutputStream;
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.HashSet;
  import java.util.LinkedList;
  import java.util.PriorityQueue;
  import java.util.Set;
  
  /**
   * Manages documents and exposes them to the Android system for sharing.
   */
  public class MyCloudProvider extends DocumentsProvider {
      private static final String TAG = "MyCloudProvider";
  
      // Use these as the default columns to return information about a root if no specific
      // columns are requested in a query.
      private static final String[] DEFAULT_ROOT_PROJECTION = new String[]{
              Root.COLUMN_ROOT_ID,
              Root.COLUMN_MIME_TYPES,
              Root.COLUMN_FLAGS,
              Root.COLUMN_ICON,
              Root.COLUMN_TITLE,
              Root.COLUMN_SUMMARY,
              Root.COLUMN_DOCUMENT_ID,
              Root.COLUMN_AVAILABLE_BYTES
      };
  
      // Use these as the default columns to return information about a document if no specific
      // columns are requested in a query.
      private static final String[] DEFAULT_DOCUMENT_PROJECTION = new String[]{
              Document.COLUMN_DOCUMENT_ID,
              Document.COLUMN_MIME_TYPE,
              Document.COLUMN_DISPLAY_NAME,
              Document.COLUMN_LAST_MODIFIED,
              Document.COLUMN_FLAGS,
              Document.COLUMN_SIZE
      };
  
      // No official policy on how many to return, but make sure you do limit the number of recent
      // and search results.
      private static final int MAX_SEARCH_RESULTS = 20;
      private static final int MAX_LAST_MODIFIED = 5;
  
      private static final String ROOT = "root";
  
      // A file object at the root of the file hierarchy.  Depending on your implementation, the root
      // does not need to be an existing file system directory.  For example, a tag-based document
      // provider might return a directory containing all tags, represented as child directories.
      private File mBaseDir;
  
      @Override
      public boolean onCreate() {
          Log.v(TAG, "onCreate");
  
          mBaseDir = getContext().getFilesDir();
  
          writeTestFilesToStorage();
  
          return true;
      }
  
      // BEGIN_INCLUDE(query_roots)
      @Override
      public Cursor queryRoots(String[] projection) throws FileNotFoundException {
          Log.v(TAG, "queryRoots");
  
          // Create a cursor with either the requested fields, or the default projection.  This
          // cursor is returned to the Android system picker UI and used to display all roots from
          // this provider.
          final MatrixCursor result = new MatrixCursor(resolveRootProjection(projection));
  
          // If user is not logged in, return an empty root cursor.  This removes our provider from
          // the list entirely.
          if (!isUserLoggedIn()) {
              return result;
          }
  
          // It's possible to have multiple roots (e.g. for multiple accounts in the same app) -
          // just add multiple cursor rows.
          // Construct one row for a root called "MyCloud".
          final MatrixCursor.RowBuilder row = result.newRow();
  
          row.add(Root.COLUMN_ROOT_ID, ROOT);
          row.add(Root.COLUMN_SUMMARY, getContext().getString(R.string.root_summary));
  
          // FLAG_SUPPORTS_CREATE means at least one directory under the root supports creating
          // documents.  FLAG_SUPPORTS_RECENTS means your application's most recently used
          // documents will show up in the "Recents" category.  FLAG_SUPPORTS_SEARCH allows users
          // to search all documents the application shares. FLAG_SUPPORTS_IS_CHILD allows
          // testing parent child relationships, available after SDK 21 (Lollipop).
          if (SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
              row.add(Root.COLUMN_FLAGS, Root.FLAG_SUPPORTS_CREATE |
                      Root.FLAG_SUPPORTS_RECENTS |
                      Root.FLAG_SUPPORTS_SEARCH );
          } else {
              row.add(Root.COLUMN_FLAGS, Root.FLAG_SUPPORTS_CREATE |
                      Root.FLAG_SUPPORTS_RECENTS |
                      Root.FLAG_SUPPORTS_SEARCH |
                      Root.FLAG_SUPPORTS_IS_CHILD);
          }
  
          // COLUMN_TITLE is the root title (e.g. what will be displayed to identify your provider).
          row.add(Root.COLUMN_TITLE, getContext().getString(R.string.app_name));
  
          // This document id must be unique within this provider and consistent across time.  The
          // system picker UI may save it and refer to it later.
          row.add(Root.COLUMN_DOCUMENT_ID, getDocIdForFile(mBaseDir));
  
          // The child MIME types are used to filter the roots and only present to the user roots
          // that contain the desired type somewhere in their file hierarchy.
          row.add(Root.COLUMN_MIME_TYPES, getChildMimeTypes(mBaseDir));
          row.add(Root.COLUMN_AVAILABLE_BYTES, mBaseDir.getFreeSpace());
          row.add(Root.COLUMN_ICON, R.drawable.ic_launcher);
  
          return result;
      }
      // END_INCLUDE(query_roots)
  
      // BEGIN_INCLUDE(query_recent_documents)
      @Override
      public Cursor queryRecentDocuments(String rootId, String[] projection)
              throws FileNotFoundException {
          Log.v(TAG, "queryRecentDocuments");
  
          // This example implementation walks a local file structure to find the most recently
          // modified files.  Other implementations might include making a network call to query a
          // server.
  
          // Create a cursor with the requested projection, or the default projection.
          final MatrixCursor result = new MatrixCursor(resolveDocumentProjection(projection));
  
          final File parent = getFileForDocId(rootId);
  
          // Create a queue to store the most recent documents, which orders by last modified.
          PriorityQueue<File> lastModifiedFiles = new PriorityQueue<File>(5, new Comparator<File>() {
              public int compare(File i, File j) {
                  return Long.compare(i.lastModified(), j.lastModified());
              }
          });
  
          // Iterate through all files and directories in the file structure under the root.  If
          // the file is more recent than the least recently modified, add it to the queue,
          // limiting the number of results.
          final LinkedList<File> pending = new LinkedList<File>();
  
          // Start by adding the parent to the list of files to be processed
          pending.add(parent);
  
          // Do while we still have unexamined files
          while (!pending.isEmpty()) {
              // Take a file from the list of unprocessed files
              final File file = pending.removeFirst();
              if (file.isDirectory()) {
                  // If it's a directory, add all its children to the unprocessed list
                  Collections.addAll(pending, file.listFiles());
              } else {
                  // If it's a file, add it to the ordered queue.
                  lastModifiedFiles.add(file);
              }
          }
  
          // Add the most recent files to the cursor, not exceeding the max number of results.
          int includedCount = 0;
          while (includedCount < MAX_LAST_MODIFIED + 1 && !lastModifiedFiles.isEmpty()) {
              final File file = lastModifiedFiles.remove();
              includeFile(result, null, file);
              includedCount++;
          }
          return result;
      }
      // END_INCLUDE(query_recent_documents)
  
      // BEGIN_INCLUDE(query_search_documents)
      @Override
      public Cursor querySearchDocuments(String rootId, String query, String[] projection)
              throws FileNotFoundException {
          Log.v(TAG, "querySearchDocuments");
  
          // Create a cursor with the requested projection, or the default projection.
          final MatrixCursor result = new MatrixCursor(resolveDocumentProjection(projection));
          final File parent = getFileForDocId(rootId);
  
          // This example implementation searches file names for the query and doesn't rank search
          // results, so we can stop as soon as we find a sufficient number of matches.  Other
          // implementations might use other data about files, rather than the file name, to
          // produce a match; it might also require a network call to query a remote server.
  
          // Iterate through all files in the file structure under the root until we reach the
          // desired number of matches.
          final LinkedList<File> pending = new LinkedList<File>();
  
          // Start by adding the parent to the list of files to be processed
          pending.add(parent);
  
          // Do while we still have unexamined files, and fewer than the max search results
          while (!pending.isEmpty() && result.getCount() < MAX_SEARCH_RESULTS) {
              // Take a file from the list of unprocessed files
              final File file = pending.removeFirst();
              if (file.isDirectory()) {
                  // If it's a directory, add all its children to the unprocessed list
                  Collections.addAll(pending, file.listFiles());
              } else {
                  // If it's a file and it matches, add it to the result cursor.
                  if (file.getName().toLowerCase().contains(query)) {
                      includeFile(result, null, file);
                  }
              }
          }
          return result;
      }
      // END_INCLUDE(query_search_documents)
  
      // BEGIN_INCLUDE(open_document_thumbnail)
      @Override
      public AssetFileDescriptor openDocumentThumbnail(String documentId, Point sizeHint,
                                                       CancellationSignal signal)
              throws FileNotFoundException {
          Log.v(TAG, "openDocumentThumbnail");
  
          final File file = getFileForDocId(documentId);
          final ParcelFileDescriptor pfd =
                  ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY);
          return new AssetFileDescriptor(pfd, 0, AssetFileDescriptor.UNKNOWN_LENGTH);
      }
      // END_INCLUDE(open_document_thumbnail)
  
      // BEGIN_INCLUDE(query_document)
      @Override
      public Cursor queryDocument(String documentId, String[] projection)
              throws FileNotFoundException {
          Log.v(TAG, "queryDocument");
  
          // Create a cursor with the requested projection, or the default projection.
          final MatrixCursor result = new MatrixCursor(resolveDocumentProjection(projection));
          includeFile(result, documentId, null);
          return result;
      }
      // END_INCLUDE(query_document)
  
      // BEGIN_INCLUDE(query_child_documents)
      @Override
      public Cursor queryChildDocuments(String parentDocumentId, String[] projection,
                                        String sortOrder) throws FileNotFoundException {
          Log.v(TAG, "queryChildDocuments, parentDocumentId: " +
                  parentDocumentId +
                  " sortOrder: " +
                  sortOrder);
  
          final MatrixCursor result = new MatrixCursor(resolveDocumentProjection(projection));
          final File parent = getFileForDocId(parentDocumentId);
          for (File file : parent.listFiles()) {
              includeFile(result, null, file);
          }
          return result;
      }
      // END_INCLUDE(query_child_documents)
  
  
      // BEGIN_INCLUDE(open_document)
      @Override
      public ParcelFileDescriptor openDocument(final String documentId, final String mode,
                                               CancellationSignal signal)
              throws FileNotFoundException {
          Log.v(TAG, "openDocument, mode: " + mode);
          // It's OK to do network operations in this method to download the document, as long as you
          // periodically check the CancellationSignal.  If you have an extremely large file to
          // transfer from the network, a better solution may be pipes or sockets
          // (see ParcelFileDescriptor for helper methods).
  
          final File file = getFileForDocId(documentId);
          final int accessMode = ParcelFileDescriptor.parseMode(mode);
  
          final boolean isWrite = (mode.indexOf('w') != -1);
          if (isWrite) {
              // Attach a close listener if the document is opened in write mode.
              try {
                  Handler handler = new Handler(getContext().getMainLooper());
                  return ParcelFileDescriptor.open(file, accessMode, handler,
                          new ParcelFileDescriptor.OnCloseListener() {
                      @Override
                      public void onClose(IOException e) {
  
                          // Update the file with the cloud server.  The client is done writing.
                          Log.i(TAG, "A file with id " + documentId + " has been closed!  Time to " +
                                  "update the server.");
                      }
  
                  });
              } catch (IOException e) {
                  throw new FileNotFoundException("Failed to open document with id " + documentId +
                          " and mode " + mode);
              }
          } else {
              return ParcelFileDescriptor.open(file, accessMode);
          }
      }
      // END_INCLUDE(open_document)
  
  
      public boolean isChildFile(File parentFile, File childFile){
          File realFileParent = childFile.getParentFile();
          return realFileParent == null || realFileParent.equals(parentFile);
      }
  
      // BEGIN_INCLUDE(is_child_document)
      @Override
      public boolean isChildDocument(String parentDocumentId, String documentId) {
          Log.v(TAG, "isChildDocument");
          try {
              File parentFile = getFileForDocId(parentDocumentId);
              File childFile = getFileForDocId(documentId);
              return isChildFile(parentFile, childFile);
          } catch (FileNotFoundException e) {
              Log.e(TAG, "FileNotFound in isChildDocument: " + e.getMessage());
              e.printStackTrace();
          }
          return false;
      }
      // END_INCLUDE(is_child_document)
  
      // BEGIN_INCLUDE(create_document)
      @Override
      public String createDocument(String documentId, String mimeType, String displayName)
              throws FileNotFoundException {
          Log.v(TAG, "createDocument");
  
          File parent = getFileForDocId(documentId);
          File file = new File(parent.getPath(), displayName);
          try {
              // Create the new File to copy into
              boolean wasNewFileCreated = false;
              if (file.createNewFile()) {
                  if (file.setWritable(true) && file.setReadable(true)) {
                      wasNewFileCreated = true;
                  }
              }
  
              if (!wasNewFileCreated) {
                  throw new FileNotFoundException("Failed to create document with name " +
                          displayName +" and documentId " + documentId);
              }
          } catch (IOException e) {
              throw new FileNotFoundException("Failed to create document with name " +
                      displayName +" and documentId " + documentId);
          }
          return getDocIdForFile(file);
      }
      // END_INCLUDE(create_document)
  
      // BEGIN_INCLUDE(rename_document)
      @Override
      public String renameDocument(String documentId, String displayName)
              throws FileNotFoundException {
          Log.v(TAG, "renameDocument");
          if (displayName == null) {
              throw new FileNotFoundException("Failed to rename document, new name is null");
          }
  
          // Create the destination file in the same directory as the source file
          File sourceFile = getFileForDocId(documentId);
          File sourceParentFile = sourceFile.getParentFile();
          if (sourceParentFile == null) {
              throw new FileNotFoundException("Failed to rename document. File has no parent.");
          }
          File destFile = new File(sourceParentFile.getPath(), displayName);
  
          // Try to do the rename
          try {
              boolean renameSucceeded = sourceFile.renameTo(destFile);
              if (!renameSucceeded) {
                  throw new FileNotFoundException("Failed to rename document. Renamed failed.");
              }
          } catch (Exception e) {
              Log.w(TAG, "Rename exception : " + e.getLocalizedMessage() + e.getCause());
              throw new FileNotFoundException("Failed to rename document. Error: " + e.getMessage());
          }
  
          return getDocIdForFile(destFile);
      }
      // END_INCLUDE(rename_document)
  
      // BEGIN_INCLUDE(delete_document)
      @Override
      public void deleteDocument(String documentId) throws FileNotFoundException {
          Log.v(TAG, "deleteDocument");
          File file = getFileForDocId(documentId);
          if (file.delete()) {
              Log.i(TAG, "Deleted file with id " + documentId);
          } else {
              throw new FileNotFoundException("Failed to delete document with id " + documentId);
          }
      }
      // END_INCLUDE(delete_document)
  
      // BEGIN_INCLUDE(remove_document)
      @Override
      public void removeDocument(String documentId, String parentDocumentId)
              throws FileNotFoundException {
          Log.v(TAG, "removeDocument");
          File parent = getFileForDocId(parentDocumentId);
          File file = getFileForDocId(documentId);
  
          if (file == null) {
              throw new FileNotFoundException("Failed to delete document with id " + documentId);
          }
  
          // removeDocument is the same as deleteDocument but allows the parent to be specified
          // Check here if the specified parentDocumentId matches the true parent of documentId
          boolean doesFileParentMatch = false;
          File fileParent = file.getParentFile();
  
          if (fileParent == null || fileParent.equals(parent)) {
              doesFileParentMatch = true;
          }
  
          // Remove the file if parent matches or file and parent are equal
          if (parent.equals(file) || doesFileParentMatch) {
              if (file.delete()) {
                  Log.i(TAG, "Deleted file with id " + documentId);
              } else {
                  throw new FileNotFoundException("Failed to delete document with id " + documentId);
              }
          } else {
              throw new FileNotFoundException("Failed to delete document with id " + documentId);
          }
      }
      // END_INCLUDE(remove_document)
  
      /**
       * overload copyDocument to insist that the parent matches
       */
      public String copyDocument(String sourceDocumentId, String sourceParentDocumentId,
                                 String targetParentDocumentId) throws FileNotFoundException {
          Log.v(TAG, "copyDocument with document parent");
          if (!isChildDocument(sourceParentDocumentId, sourceDocumentId)) {
              throw new FileNotFoundException("Failed to copy document with id " +
                      sourceDocumentId + ". Parent is not: " + sourceParentDocumentId);
          }
          return copyDocument(sourceDocumentId, targetParentDocumentId);
      }
  
      // BEGIN_INCLUDE(copyDocument)
      @Override
      public String copyDocument(String sourceDocumentId, String targetParentDocumentId)
              throws FileNotFoundException {
          Log.v(TAG, "copyDocument");
  
          File parent = getFileForDocId(targetParentDocumentId);
          File oldFile = getFileForDocId(sourceDocumentId);
          File newFile = new File(parent.getPath(), oldFile.getName());
          try {
              // Create the new File to copy into
              boolean wasNewFileCreated = false;
              if (newFile.createNewFile()) {
                  if (newFile.setWritable(true) && newFile.setReadable(true)) {
                      wasNewFileCreated = true;
                  }
              }
  
              if (!wasNewFileCreated) {
                  throw new FileNotFoundException("Failed to copy document " + sourceDocumentId +
                          ". Could not create new file.");
              }
  
              // Copy the bytes into the new file
              try (InputStream inStream = new FileInputStream(oldFile)) {
                  try (OutputStream outStream = new FileOutputStream(newFile)) {
                      // Transfer bytes from in to out
                      byte[] buf = new byte[4096]; // ideal range for network: 2-8k, disk: 8-64k
                      int len;
                      while ((len = inStream.read(buf)) > 0) {
                          outStream.write(buf, 0, len);
                      }
                  }
              }
          } catch (IOException e) {
              throw new FileNotFoundException("Failed to copy document: " + sourceDocumentId +
                      ". " + e.getMessage());
          }
          return getDocIdForFile(newFile);
      }
      // END_INCLUDE(copyDocument)
  
      // BEGIN_INCLUDE(moveDocument)
      @Override
      public String moveDocument(String sourceDocumentId, String sourceParentDocumentId,
                                 String targetParentDocumentId) throws FileNotFoundException {
          Log.v(TAG, "moveDocument");
          try {
              // Copy document, insisting that the parent is correct
              String newDocumentId = copyDocument(sourceDocumentId, sourceParentDocumentId,
                      targetParentDocumentId);
              // Remove old document
              removeDocument(sourceDocumentId,sourceParentDocumentId);
              return newDocumentId;
          } catch (FileNotFoundException e) {
              throw new FileNotFoundException("Failed to move document " + sourceDocumentId);
          }
      }
      // END_INCLUDE(moveDocument)
  
  
      @Override
      public String getDocumentType(String documentId) throws FileNotFoundException {
          File file = getFileForDocId(documentId);
          return getTypeForFile(file);
      }
  
      /**
       * @param projection the requested root column projection
       * @return either the requested root column projection, or the default projection if the
       * requested projection is null.
       */
      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;
      }
  
      /**
       * Get a file's MIME type
       *
       * @param file the File object whose type we want
       * @return the MIME type of the file
       */
      private static String getTypeForFile(File file) {
          if (file.isDirectory()) {
              return Document.MIME_TYPE_DIR;
          } else {
              return getTypeForName(file.getName());
          }
      }
  
      /**
       * Get the MIME data type of a document, given its filename.
       *
       * @param name the filename of the document
       * @return the MIME data type of a document
       */
      private static String getTypeForName(String name) {
          final int lastDot = name.lastIndexOf('.');
          if (lastDot >= 0) {
              final String extension = name.substring(lastDot + 1);
              final String mime = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
              if (mime != null) {
                  return mime;
              }
          }
          return "application/octet-stream";
      }
  
      /**
       * Gets a string of unique MIME data types a directory supports, separated by newlines.  This
       * should not change.
       *
       * @param parent the File for the parent directory
       * @return a string of the unique MIME data types the parent directory supports
       */
      private String getChildMimeTypes(File parent) {
          Set<String> mimeTypes = new HashSet<String>();
          mimeTypes.add("image/*");
          mimeTypes.add("text/*");
          mimeTypes.add("application/vnd.openxmlformats-officedocument.wordprocessingml.document");
  
          // Flatten the list into a string and insert newlines between the MIME type strings.
          StringBuilder mimeTypesString = new StringBuilder();
          for (String mimeType : mimeTypes) {
              mimeTypesString.append(mimeType).append("\n");
          }
  
          return mimeTypesString.toString();
      }
  
      /**
       * Get the document ID given a File.  The document id must be consistent across time.  Other
       * applications may save the ID and use it to reference documents later.
       * <p/>
       * This implementation is specific to this demo.  It assumes only one root and is built
       * directly from the file structure.  However, it is possible for a document to be a child of
       * multiple directories (for example "android" and "images"), in which case the file must have
       * the same consistent, unique document ID in both cases.
       *
       * @param file the File whose document ID you want
       * @return the corresponding document ID
       */
      private String getDocIdForFile(File file) {
          String path = file.getAbsolutePath();
  
          // Start at first char of path under root
          final String rootPath = mBaseDir.getPath();
          if (rootPath.equals(path)) {
              path = "";
          } else if (rootPath.endsWith("/")) {
              path = path.substring(rootPath.length());
          } else {
              path = path.substring(rootPath.length() + 1);
          }
  
          return "root" + ':' + path;
      }
  
      /**
       * Add a representation of a file to a cursor.
       *
       * @param result the cursor to modify
       * @param docId  the document ID representing the desired file (may be null if given file)
       * @param file   the File object representing the desired file (may be null if given docID)
       * @throws FileNotFoundException
       */
      private void includeFile(MatrixCursor result, String docId, File file)
              throws FileNotFoundException {
          if (docId == null) {
              docId = getDocIdForFile(file);
          } else {
              file = getFileForDocId(docId);
          }
  
          int flags = 0;
  
          if (file.isDirectory()) {
              // Request the folder to lay out as a grid rather than a list. This also allows a larger
              // thumbnail to be displayed for each image.
              //            flags |= Document.FLAG_DIR_PREFERS_GRID;
  
              // Add FLAG_DIR_SUPPORTS_CREATE if the file is a writable directory.
              if (file.isDirectory() && file.canWrite()) {
                  flags |= Document.FLAG_DIR_SUPPORTS_CREATE;
              }
          } else if (file.canWrite()) {
              // If the file is writable set FLAG_SUPPORTS_WRITE and
              // FLAG_SUPPORTS_DELETE
              flags |= Document.FLAG_SUPPORTS_WRITE;
              flags |= Document.FLAG_SUPPORTS_DELETE;
  
              // Add SDK specific flags if appropriate
              if (SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                  flags |= Document.FLAG_SUPPORTS_RENAME;
              }
              if (SDK_INT >= Build.VERSION_CODES.N) {
                  flags |= Document.FLAG_SUPPORTS_REMOVE;
                  flags |= Document.FLAG_SUPPORTS_MOVE;
                  flags |= Document.FLAG_SUPPORTS_COPY;
              }
          }
  
          final String displayName = file.getName();
          final String mimeType = getTypeForFile(file);
  
          if (mimeType.startsWith("image/")) {
              // Allow the image to be represented by a thumbnail rather than an icon
              flags |= Document.FLAG_SUPPORTS_THUMBNAIL;
          }
  
          final MatrixCursor.RowBuilder row = result.newRow();
          row.add(Document.COLUMN_DOCUMENT_ID, docId);
          row.add(Document.COLUMN_DISPLAY_NAME, displayName);
          row.add(Document.COLUMN_SIZE, file.length());
          row.add(Document.COLUMN_MIME_TYPE, mimeType);
          row.add(Document.COLUMN_LAST_MODIFIED, file.lastModified());
          row.add(Document.COLUMN_FLAGS, flags);
  
          // Add a custom icon
          row.add(Document.COLUMN_ICON, R.drawable.ic_launcher);
      }
  
      /**
       * Translate your custom URI scheme into a File object.
       *
       * @param docId the document ID representing the desired file
       * @return a File represented by the given document ID
       * @throws java.io.FileNotFoundException
       */
      private File getFileForDocId(String docId) throws FileNotFoundException {
          File target = mBaseDir;
          if (docId.equals(ROOT)) {
              return target;
          }
          final int splitIndex = docId.indexOf(':', 1);
          if (splitIndex < 0) {
              throw new FileNotFoundException("Missing root for " + docId);
          } else {
              final String path = docId.substring(splitIndex + 1);
              target = new File(target, path);
              if (!target.exists()) {
                  throw new FileNotFoundException("Missing file for " + docId + " at " + target);
              }
              return target;
          }
      }
  
      /**
       * Preload sample files packaged in the apk into the internal storage directory.  This is a
       * test function specific to this demo.  The MyCloud mock cloud service doesn't actually
       * have a backend, so it simulates by reading content from the device's internal storage.
       */
      private void writeTestFilesToStorage() {
          if (mBaseDir.list().length > 0) {
              return;
          }
  
          int[] imageResIds = getResourceIdArray(R.array.image_res_ids);
          for (int resId : imageResIds) {
              writeFileToInternalStorage(resId, ".jpeg");
          }
  
          int[] textResIds = getResourceIdArray(R.array.text_res_ids);
          for (int resId : textResIds) {
              writeFileToInternalStorage(resId, ".txt");
          }
  
          int[] docxResIds = getResourceIdArray(R.array.docx_res_ids);
          for (int resId : docxResIds) {
              writeFileToInternalStorage(resId, ".docx");
          }
      }
  
      /**
       * Write a file to internal storage.  Used to set up our simple "cloud server".
       *
       * @param resId     the resource ID of the file to write to internal storage
       * @param extension the file extension (ex. .png, .mp3)
       */
      private void writeFileToInternalStorage(int resId, String extension) {
          InputStream ins = getContext().getResources().openRawResource(resId);
          ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
          int size;
          byte[] buffer = new byte[1024];
          try {
              while ((size = ins.read(buffer, 0, 1024)) >= 0) {
                  outputStream.write(buffer, 0, size);
              }
              ins.close();
              buffer = outputStream.toByteArray();
              String filename = getContext().getResources().getResourceEntryName(resId) + extension;
              FileOutputStream fos = getContext().openFileOutput(filename, Context.MODE_PRIVATE);
              fos.write(buffer);
              fos.close();
  
          } catch (IOException e) {
              e.printStackTrace();
          }
      }
  
      private int[] getResourceIdArray(int arrayResId) {
          TypedArray ar = getContext().getResources().obtainTypedArray(arrayResId);
          int len = ar.length();
          int[] resIds = new int[len];
          for (int i = 0; i < len; i++) {
              resIds[i] = ar.getResourceId(i, 0);
          }
          ar.recycle();
          return resIds;
      }
  
      /**
       * Placeholder function to determine whether the user is logged in.
       */
      private boolean isUserLoggedIn() {
          final SharedPreferences sharedPreferences =
                  getContext().getSharedPreferences(getContext().getString(R.string.app_name),
                          Context.MODE_PRIVATE);
          return sharedPreferences.getBoolean(getContext().getString(R.string.key_logged_in), false);
      }
  }
  