// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

module content;

import "components/leveldb/public/interfaces/leveldb.mojom";

// Gives information about changes to a LevelDB database.
// The reason this is a parameter to DeleteAll and GetAll below, instead of
// being specified when opening a LevelDBWrapper, is to avoid the client getting
// callbacks for changes that have already been applied to its database that
// it's fetching via GetAll or it's clearing via DeleteAll.
// In the methods below, |source| is a user-defined string which was passed to
// the various LevelDBWrapper methods.
// Note that observer methods are called before the callbacks for the
// LevelDBWrapper methods are run.
interface LevelDBObserver {
  KeyChanged(array<uint8> key, array<uint8> new_value, array<uint8> old_value,
             string source);
  KeyDeleted(array<uint8> key, array<uint8> old_value, string source);
  AllDeleted(string source);
};

struct KeyValue {
  array<uint8> key;
  array<uint8> value;
};

// A wrapper around leveldb that supports giving notifications when values
// change.
interface LevelDBWrapper {
  // Sets the database entry for |key| to |value|. Returns OK on success.
  Put(array<uint8> key, array<uint8> value, string source)
    => (leveldb.DatabaseError status);

  // Remove the database entry (if any) for |key|.  Returns OK on success, and a
  // non-OK status on error.  It is not an error if |key| did not exist in the
  // database.
  Delete(array<uint8> key, string source) => (leveldb.DatabaseError status);

  // Removes all the entries.
  DeleteAll(LevelDBObserver observer, string source)
    => (leveldb.DatabaseError status);

  // Returns the value of the |key|.
  Get(array<uint8> key) => (leveldb.DatabaseError status, array<uint8> value);

  // Only used with small databases. Returns all key/value pairs.
  [Sync]
  GetAll(LevelDBObserver observer)
    => (leveldb.DatabaseError status, array<KeyValue> data);
};