examples/ledger/todo_list/lib/src/ledger_helpers.dart

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

import 'dart:convert';
import 'dart:typed_data' show Uint8List;

import 'package:fidl_fuchsia_ledger/fidl_async.dart' as ledger;
import 'package:fuchsia_logger/logger.dart';

/// Takes a Ledger status and logs an error if the
/// status is not OK.
bool validateLedgerResponse(ledger.Status status, String description) {
  if (status != ledger.Status.ok) {
    log.info('Ledger error in $description: $status');
    return false;
  }
  return true;
}

/// Retrieves all entries from a snapshot.
///
/// If the response is paginated, this method transparently makes multiple
/// Ledger calls, assemble the complete response and call [callback] exactly
/// once.
void getEntriesFromSnapshot(ledger.PageSnapshotProxy snapshot,
    void callback(Map<List<int>, String> items)) {
  _getEntriesRecursive(snapshot, <List<int>, String>{}, null, callback);
}

Future<void> _getEntriesRecursive(
    ledger.PageSnapshotProxy snapshot,
    Map<List<int>, String> items,
    ledger.Token token,
    void callback(Map<List<int>, String> items)) async {
  final response = await snapshot.getEntriesInline(Uint8List(0), token);
  final status = response.status;
  final entries = response.entries;
  final nextToken = response.nextToken;

  for (final ledger.InlinedEntry entry in entries) {
    items[entry.key] = utf8.decode(entry.inlinedValue.value);
  }
  if (status == ledger.IterationStatus.ok) {
    callback(items);
    return;
  }
  await _getEntriesRecursive(snapshot, items, nextToken, callback);
}