// Copyright (c) 2017 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

'use strict';

nassh.sftp.fsp = {};

/**
 * @fileoverview: This file manages the File System Provider API requests and
 *                currently active SFTP instances. File system requests are
 *                handled by their respective SFTP clients.
 */

// Map of file system ids to their SFTP instances
nassh.sftp.fsp.sftpInstances = {};

// Maximum amount of bytes of data transferred in read/write data packets.
// SFTP v3 supports a max of 32768 bytes.
nassh.sftp.fsp.DATA_LIMIT = 32768;

/**
 * Creates a new SFTP CommandInstance in the background page and connects to
 * the provided connection. Utilizes the same hterm.Terminal.IO as the
 * foreground page to authenticate the user before commencing SFTP communication.
 */
nassh.sftp.fsp.createSftpInstance = function(args) {
  var sftpInstance = new nassh.CommandInstance(args.argv);
  return sftpInstance.connectTo(args.connectOptions);
};

/**
 * Sanitizes the provided file's metadata to the requirements specified in
 * 'options'.
 */
nassh.sftp.fsp.sanitizeMetadata = function(file, options) {
  var metadata = {};
  if (options.name) {
    if (file.filename) {
      metadata.name = file.filename;
    } else if (options.directoryPath) {
      metadata.name = options.directoryPath.split('/').pop();
    } else {
      metadata.name = options.entryPath.split('/').pop();
    }
  }
  if (options.isDirectory) {
    metadata.isDirectory = (file.permissions & 0x4000) == 0x4000;
  }
  if (options.size) {
    metadata.size = file.size;
  }
  if (options.modificationTime) {
    metadata.modificationTime = new Date(file.last_modified*1000);
  }
  return metadata;
};

/**
 * Metadata Requested handler. Retrieves the file attributes of the requested
 * file path.
 */
nassh.sftp.fsp.onGetMetadataRequested = function(options, onSuccess, onError) {
  if (!nassh.sftp.fsp.checkInstanceExists(options.fileSystemId, onError)) {
    return;
  }

  var client = nassh.sftp.fsp.sftpInstances[options.fileSystemId].sftpClient;
  var path = '.' + options.entryPath; // relative path
  client.fileStatus(path)
    .then(metadata => nassh.sftp.fsp.sanitizeMetadata(metadata, options))
    .then(onSuccess)
    .catch(response => {
        // If file not found
      if (response instanceof nassh.sftp.StatusError && response.code == 2) {
        onError('NOT_FOUND');
        return;
      }
      console.warn(response.name + ': ' + response.message);
      onError('FAILED');
    });
};

/**
 * Reads the remote directory handle and returns a list of metadata entries,
 * which are sanitized if applicable.
 */
nassh.sftp.fsp.readDirectory = function(directoryHandle, client, sanitizeOptions) {
  var metadataEntries = []; // directory entries
  function nextRead() {
    return client.readDirectory(directoryHandle)
      .then(response => {
        // If EOF, return all the directory entries
        if (response instanceof nassh.sftp.packets.StatusPacket
            && response.code == 1) {
          return metadataEntries;
        }

        for(var i = 0; i < response.fileCount; i++) {
          var file = response.files[i];
          // Skip over the file if it's a '.', '..' or link file
          if (file.filename == '.' || file.filename == '..' ||
              file.permissions & 0x2000) {
            continue;
          }

          if (sanitizeOptions) {
            file = nassh.sftp.fsp.sanitizeMetadata(file, sanitizeOptions);
          }
          metadataEntries.push(file);
        }

        return nextRead();
      });
  }
  return nextRead();
};

/**
 * Read Directory Requested handler. Retrieves the entries of the requested
 * directory.
 */
nassh.sftp.fsp.onReadDirectoryRequested = function(options, onSuccess, onError) {
  if (!nassh.sftp.fsp.checkInstanceExists(options.fileSystemId, onError)) {
    return;
  }

  var client = nassh.sftp.fsp.sftpInstances[options.fileSystemId].sftpClient;
  var directoryHandle;
  var path = '.' + options.directoryPath; // relative path
  client.openDirectory(path)
    .then(handle => { directoryHandle = handle; })
    .then(() => nassh.sftp.fsp.readDirectory(directoryHandle, client, options))
    .then(entries => { onSuccess(entries, false); })
    .catch(response => {
      console.warn(response.name + ': ' + response.message);
      onError('FAILED');
    })
    .then(() => client.closeFile(directoryHandle));
};

/**
 * Write File Requested handler. Writes to the requested file.
 */
nassh.sftp.fsp.onWriteFileRequested = function(options, onSuccess, onError) {
  if (!nassh.sftp.fsp.checkInstanceExists(options.fileSystemId, onError)) {
    return;
  }

  var client = nassh.sftp.fsp.sftpInstances[options.fileSystemId].sftpClient;
  var fileHandle = client.openedFiles[options.openRequestId];
  if (!fileHandle) {
    onError('INVALID_OPERATION');
    return;
  }

  var writePromises = [];
  // Splits up the data to be written into nassh.sftp.fsp.DATA_LIMIT sized chunks
  // and places them into multiple promises which will be resolved asynchronously.
  for (var i = 0; i < options.data.byteLength; i += nassh.sftp.fsp.DATA_LIMIT) {

    var endSlice = i + nassh.sftp.fsp.DATA_LIMIT;
    var array = new Uint8Array(options.data.slice(i, endSlice));
    var dataChunk = String.fromCharCode.apply(null, array);
    var offset = options.offset + i;

    var writePromise = client.writeFile(fileHandle, offset, dataChunk);
    writePromises.push(writePromise);
  }

  Promise.all(writePromises)
    .then(onSuccess)
    .catch(response => {
      console.warn(response.name + ': ' + response.message);
      onError('FAILED');
    });
};

/**
 * Open File Requested handler. Opens the requested file and saves its handle.
 */
nassh.sftp.fsp.onOpenFileRequested = function(options, onSuccess, onError) {
  if (!nassh.sftp.fsp.checkInstanceExists(options.fileSystemId, onError)) {
    return;
  }

  var client = nassh.sftp.fsp.sftpInstances[options.fileSystemId].sftpClient;
  var pflags = 0x00000000;
  if (options.mode == "READ") {
    pflags |= 0x00000001; // read flag
  } else if (options.mode == "WRITE") {
    pflags |= 0x00000002; // write flag
  }

  var path = '.' + options.filePath; // relative path
  client.openFile(path, pflags)
    .then(handle => { client.openedFiles[options.requestId] = handle; })
    .then(onSuccess)
    .catch(response => {
      console.warn(response.name + ': ' + response.message);
      onError('FAILED');
    });
};

/**
 * Create File Requested handler. Creates a file at the requested file path and
 * saves its handle.
 */
nassh.sftp.fsp.onCreateFileRequested = function(options, onSuccess, onError) {
  if (!nassh.sftp.fsp.checkInstanceExists(options.fileSystemId, onError)) {
    return;
  }

  var client = nassh.sftp.fsp.sftpInstances[options.fileSystemId].sftpClient;
  var pflags = 0x00000008 | 0x00000020; // create | exclusive flag

  var path = '.' + options.filePath; // relative path
  client.openFile(path, pflags)
    .then(handle => { client.openedFiles[options.requestId] = handle; })
    .then(onSuccess)
    .catch(response => {
      console.warn(response.name + ': ' + response.message);
      onError('FAILED');
    });
};

/**
 * Truncate File Requested handler. Truncates the requested file path to 0
 * length and then closes it.
 */
nassh.sftp.fsp.onTruncateRequested = function(options, onSuccess, onError) {
  if (!nassh.sftp.fsp.checkInstanceExists(options.fileSystemId, onError)) {
    return;
  }

  var client = nassh.sftp.fsp.sftpInstances[options.fileSystemId].sftpClient;
  var pflags = 0x00000008 | 0x00000010; // create | truncate flag

  var path = '.' + options.filePath; // relative path
  client.openFile(path, pflags)
    .then(handle => { client.closeFile(handle); })
    .then(onSuccess)
    .catch(response => {
      console.warn(response.name + ': ' + response.message);
      onError('FAILED');
    });
};

/**
 * Delete Entry Requested handler. Deletes the entry of the requested file path.
 * If the entry is a directory, deletes all sub-entries recursively.
 */
nassh.sftp.fsp.onDeleteEntryRequested = function(options, onSuccess, onError) {
  if (!nassh.sftp.fsp.checkInstanceExists(options.fileSystemId, onError)) {
    return;
  }

  var client = nassh.sftp.fsp.sftpInstances[options.fileSystemId].sftpClient;
  var path = '.' + options.entryPath; // relative path
  if (options.recursive) {
    nassh.sftp.fsp.removeDirectory(path, client)
      .then(onSuccess)
      .catch(response => {
        // If file not found
        if (response instanceof nassh.sftp.StatusError && response.code == 2) {
          onError('NOT_FOUND');
          return;
        }
        console.warn(response.name + ': ' + response.message);
        onError('FAILED');
      });

  } else {
    client.removeFile(path)
      .then(onSuccess)
      .catch(response => {
        // If file not found
        if (response instanceof nassh.sftp.StatusError && response.code == 2) {
          onError('NOT_FOUND');
          return;
        }
        console.warn(response.name + ': ' + response.message);
        onError('FAILED');
      });
  }
};

/**
 * Reads the remote directory and removes all of its entries before removing
 * itself.
 */
nassh.sftp.fsp.removeDirectory = function(path, client) {
  var directoryHandle;
  return client.openDirectory(path)
    .then(handle => { directoryHandle = handle; })
    .then(() => readDirectory(directoryHandle, client))
    .then(entries => {
      var removePromises = [];

      // Recursively delete contents
      for(var i = 0; i < entries.length; i++) {

        var file = entries[i];
        var filename = file.filename;
        if (filename == '.' || filename == '..') {
          continue;
        }

        filename = path + '/' + filename;
        if (file.permissions & 0x4000) {
          removePromises.push(removeDirectory(filename, client));
        } else {
          removePromises.push(client.removeFile(filename));
        }
      }

      return Promise.all(removePromises);
    })
    .then(() => client.closeFile(directoryHandle))
    .then(() => client.removeDirectory(path));
};

/**
 * Close File Requested handler. Closes the requested file and removes its
 * handle.
 */
nassh.sftp.fsp.onCloseFileRequested = function(options, onSuccess, onError) {
  if (!nassh.sftp.fsp.checkInstanceExists(options.fileSystemId, onError)) {
    return;
  }

  var client = nassh.sftp.fsp.sftpInstances[options.fileSystemId].sftpClient;
  if (!client.openedFiles[options.openRequestId]) {
    console.warn('File handle not found');
    onError('INVALID_OPERATION');
    return;
  }

  client.closeFile(client.openedFiles[options.openRequestId])
    .then(() => { delete client.openedFiles[options.openRequestId]; })
    .then(onSuccess)
    .catch(response => {
      console.warn(response.name + ': ' + response.message);
      onError('FAILED');
    });
};

/**
 * Create Directory Requested handler. Creates a directory at the requested
 * file path.
 */
nassh.sftp.fsp.onCreateDirectoryRequested = function(options, onSuccess, onError) {
  if (!nassh.sftp.fsp.checkInstanceExists(options.fileSystemId, onError)) {
    return;
  }

  var client = nassh.sftp.fsp.sftpInstances[options.fileSystemId].sftpClient;
  if (options.recursive) { // Not supported/implemented.
    onError('INVALID_OPERATION');
    return;
  }

  var path = '.' + options.directoryPath; // relative path
  client.makeDirectory(path)
    .then(onSuccess)
    .catch(response => {
      console.warn(response.name + ': ' + response.message);
      onError('FAILED');
    });
};

/**
 * Move Requested handler. Moves (renames) the requested source file path to the
 * target file path.
 */
nassh.sftp.fsp.onMoveEntryRequested = function(options, onSuccess, onError) {
  if (!nassh.sftp.fsp.checkInstanceExists(options.fileSystemId, onError)) {
    return;
  }

  var client = nassh.sftp.fsp.sftpInstances[options.fileSystemId].sftpClient;
  var sourcePath = '.' + options.sourcePath; // relative path
  var targetPath = '.' + options.targetPath; // relative path
  client.renameFile(sourcePath, targetPath)
    .then(onSuccess)
    .catch(response => {
      console.warn(response.name + ': ' + response.message);
      onError('FAILED');
    });
};

/**
 * Read File Requested handler. Reads the requested file and returns its data.
 */
nassh.sftp.fsp.onReadFileRequested = function(options, onSuccess, onError) {
  if (!nassh.sftp.fsp.checkInstanceExists(options.fileSystemId, onError)) {
    return;
  }

  var client = nassh.sftp.fsp.sftpInstances[options.fileSystemId].sftpClient;
  var fileHandle = client.openedFiles[options.openRequestId];
  if (!fileHandle) {
    onError('INVALID_OPERATION');
    return;
  }

  var readPromises = [];
  var readLimit = options.offset + options.length;
  // Splits up the data to be read into nassh.sftp.fsp.DATA_LIMIT sized chunks
  // and places them into multiple promises which will be resolved asynchronously.
  for (var i = options.offset; i < readLimit; i += nassh.sftp.fsp.DATA_LIMIT) {
    readPromises.push(client.readFile(fileHandle, i, nassh.sftp.fsp.DATA_LIMIT));
  }

  Promise.all(readPromises)
    .then(dataChunks => {
      // join all resolved data chunks together and return them as an ArrayBuffer
      var data = dataChunks.join('');
      var array = new Uint8Array(data.length);
      for (var i = 0; i < array.length; i++) {
        array[i] = data.charCodeAt(i);
      }
      return array.buffer;
    })
    .then(data => { onSuccess(data, false); } )
    .catch(response => {
      console.warn(response.name + ': ' + response.message);
      onError('FAILED');
    });
};

/**
 * Copy Entry Requested handler. Copies the entry of the requested file path.
 * If the entry is a directory, copies all sub-entries recursively.
 */
nassh.sftp.fsp.onCopyEntryRequested = function(options, onSuccess, onError) {
  if (!nassh.sftp.fsp.checkInstanceExists(options.fileSystemId, onError)) {
    return;
  }

  var client = nassh.sftp.fsp.sftpInstances[options.fileSystemId].sftpClient;
  var sourcePath = '.' + options.sourcePath; // relative path
  var targetPath = '.' + options.targetPath; // relative path
  client.fileStatus(sourcePath)
    .then(metadata => {
      // if the file has the 0x4000 permission flag set, it's a directory
      if (metadata.permissions & 0x4000) {
        return nassh.sftp.fsp.copyDirectory(sourcePath, targetPath, client);
      } else {
        return nassh.sftp.fsp.copyFile(sourcePath, targetPath, metadata.size, client);
      }
    })
    .then(onSuccess)
    .catch(response => {
      console.warn(response.name + ': ' + response.message);
      onError('FAILED');
    });
};

/**
 * Copies the file at the remote source path to the remote target path.
 */
nassh.sftp.fsp.copyFile = function(sourcePath, targetPath, size, client) {
  var sourceHandle;
  var targetHandle;
  return client.openFile(sourcePath)
    .then(handle => {

      sourceHandle = handle;
      // write | append | create | exclusive flags
      var pflags = 0x00000002 | 0x00000004 | 0x00000008 | 0x00000020;
      return client.openFile(targetPath, pflags);

    })
    .then(handle => {

      targetHandle = handle;
      var readWritePromises = [];
      // Splits up the data to be read and written into nassh.sftp.fsp.DATA_LIMIT
      // sized chunks and places them into multiple promises which will be
      // resolved asynchronously.
      for (var i = 0; i < size; i += nassh.sftp.fsp.DATA_LIMIT) {
        var offset = i;
        var readWritePromise = client.readFile(sourceHandle,
                                               offset, nassh.sftp.fsp.DATA_LIMIT)
          .then(data => client.writeFile(targetHandle, offset, data));

        readWritePromises.push(readWritePromise);
      }
      return Promise.all(readWritePromises);

    })
    .then(() => client.closeFile(sourceHandle))
    .then(() => client.closeFile(targetHandle));
};

/**
 * Reads the remote directory and copies all of its entries before copying
 * itself.
 */
nassh.sftp.fsp.copyDirectory = function(sourcePath, targetPath, client) {
  var sourceHandle;
  return client.openDirectory(sourcePath)
    .then(handle => { sourceHandle = handle; })
    .then(() => client.makeDirectory(targetPath))
    .then(() => readDirectory(sourceHandle, client))
    .then(entries => {

      var copyPromises = [];
      for(var i = 0; i < entries.length; i++) {
        var file = entries[i];
        if (file.filename == '.' || file.filename == '..') {
          continue;
        }

        var fileSourcePath = sourcePath + '/' + file.filename;
        var fileTargetPath = targetPath + '/' + file.filename;
        if (file.permissions & 0x4000) {
          copyPromises.push(nassh.sftp.fsp.copyDirectory(fileSourcePath,
                                               fileTargetPath, client));
        } else {
          copyPromises.push(nassh.sftp.fsp.copyFile(fileSourcePath, fileTargetPath,
                                          file.size, client));
        }
      }

      return Promise.all(copyPromises);
    })
    .then(() => client.closeFile(sourceHandle));
};

/**
 * Mount Requested handler. Opens the Secure Shell main page which prompts the
 * user to mount a remote connection.
 *
 * Note: This is only called upon first installation of Secure Shell and when
 * the user clicks "Add New Service" from the File App.
 */
nassh.sftp.fsp.onMountRequested = function(options, onSuccess, onError) {
  window.open('html/nassh.html');
};

/**
 * Unmount Requested handler. Closes the SFTP connection and removes the SFTP
 * instance before unmounting the file system.
 */
nassh.sftp.fsp.onUnmountRequested = function(options, onSuccess, onError) {
  // We don't return immediately on errors.  If the caller is trying to unmount
  // us, then usually it means they think we're mounted even if we don't think
  // we are.  This can happen if the Secure Shell background page is killed, but
  // the Files app remembers all the connections.  Either way, it's more robust
  // for us to always unmount with the FSP layer.
  if (nassh.sftp.fsp.checkInstanceExists(options.fileSystemId, onError)) {
    // Only clear local state if we know about the mount.
    var sftpInstance = nassh.sftp.fsp.sftpInstances[options.fileSystemId];
    sftpInstance.exit(0); // exit NaCl plugin
    delete nassh.sftp.fsp.sftpInstances[options.fileSystemId];
  }

  chrome.fileSystemProvider.unmount(
    {fileSystemId: options.fileSystemId}, () => {
      if (chrome.runtime.lastError) {
        console.warn(chrome.runtime.lastError.message);
        onError('FAILED');
      } else {
        onSuccess();
        if (chrome.runtime.lastError) {} //HACK: catches silly lastError (bug?)
                                         //TODO(mcdermottm): talk to mtomasz@
      }
    });
};

/**
 * Checks if the file system id has an associated SFTP instance.
 */
nassh.sftp.fsp.checkInstanceExists = function(fsId, onError) {
  if (!nassh.sftp.fsp.sftpInstances[fsId]) {
    console.warn('SFTP Instance for file system id "' + fsId + '" not found!');
    onError('FAILED');
    return false;
  }
  return true;
};

/**
 * Object containing all supported File System Provider API methods.
 */
nassh.sftp.fsp.providerMethods = [
  'onGetMetadataRequested',
  'onReadDirectoryRequested',
  'onOpenFileRequested',
  'onCloseFileRequested',
  'onReadFileRequested',
  'onMountRequested',
  'onUnmountRequested',
  'onMoveEntryRequested',
  'onDeleteEntryRequested',
  'onWriteFileRequested',
  'onCreateFileRequested',
  'onTruncateRequested',
  'onCopyEntryRequested',
  'onCreateDirectoryRequested'
];

// Loop over the provider methods and link them to their handlers.
if (chrome.fileSystemProvider) {
  nassh.sftp.fsp.providerMethods.forEach(function(provider) {
    chrome.fileSystemProvider[provider].addListener(nassh.sftp.fsp[provider]);
  });
}