/*
 * Copyright (C) 2014 Open Source Robotics Foundation
 *
 * 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.
 *
*/

#ifndef GZ_TRANSPORT_TOPICUTILS_HH_
#define GZ_TRANSPORT_TOPICUTILS_HH_

#include <cstdint>
#include <string>

#include "gz/transport/config.hh"
#include "gz/transport/Export.hh"

namespace gz
{
  namespace transport
  {
    // Inline bracket to help doxygen filtering.
    inline namespace GZ_TRANSPORT_VERSION_NAMESPACE {
    //
    /// \class TopicUtils TopicUtils.hh gz/transport/TopicUtils.hh
    /// \brief This class provides different utilities related with topics.
    class GZ_TRANSPORT_VISIBLE TopicUtils
    {
      /// \brief Determines if a namespace is valid. A namespace's length must
      /// not exceed kMaxNameLength.
      /// The following symbols are not allowed as part of the
      /// namespace:  '@', ':=', '~'.
      /// \param[in] _ns Namespace to be checked.
      /// \return true if the namespace is valid.
      public: static bool IsValidNamespace(const std::string &_ns);

      /// \brief Determines if a partition is valid.
      /// The same rules to validate a topic name applies to a partition with
      /// the addition of the empty string, which is a valid partition (meaning
      /// no partition is used). A partition name's length must not exceed
      /// kMaxNameLength.
      /// \param[in] _partition Partition to be checked.
      /// \return true if the partition is valid.
      public: static bool IsValidPartition(const std::string &_partition);

      /// \brief Determines if a topic name is valid. A topic name is any
      /// non-empty alphanumeric string. The symbol '/' is also allowed as part
      /// of a topic name.
      /// The following symbols are not allowed as part of the
      /// topic name:  '@', ':=', '~'.
      /// A topic name's length must not exceed kMaxNameLength.
      /// Examples of valid topics: abc, /abc, /abc/de, /abc/de/
      /// \param[in] _topic Topic name to be checked.
      /// \return true if the topic name is valid.
      public: static bool IsValidTopic(const std::string &_topic);

      /// \brief Get the full topic path given a namespace and a topic name.
      /// A fully qualified topic name's length must not exceed kMaxNameLength.
      /// The fully qualified name follows the next syntax:
      /// \@\<PARTITION\>\@\<NAMESPACE\>/\<TOPIC\>
      /// where:
      /// \<PARTITION\>: The name of the partition or empty string.
      ///              A "/" will be prefixed to the partition name unless is
      ///              empty or it already starts with slash. A trailing slash
      ///              will always be removed.
      /// \<NAMESPACE\>: The namespace or empty string. A namespace is a prefix
      ///              applied to the topic name. If not empty, it will always
      ///              start with a "/". A trailing slash will always be
      ///              removed
      /// \<TOPIC\>: The topic name. A trailing slash will always be removed.
      ///
      /// Note: Intuitively, you can imagine the fully qualified name as a
      /// UNIX absolute path, where the partition is always sorrounded by "@".
      /// A namespace, if present, corresponds with the directories of the
      /// path, and you can imagine the topic as the filename.
      ///
      /// E.g.:
      ///   Only topic:                @@/topic
      ///   No partition:              @@/namespace/topic1
      ///   No namespace:              @/partition@/topic1
      ///   Partition+namespace+topic: @/my_partition@/name/space/topic
      ///
      /// \param[in] _partition Partition name.
      /// \param[in] _ns Namespace.
      /// \param[in] _topic Topic name.
      /// \param[out] _name Fully qualified topic name.
      /// \return True if the fully qualified name is valid
      /// (if partition, namespace and topic are correct).
      /// \sa IsValidPartition
      /// \sa IsValidNamespace
      /// \sa IsValidTopic
      /// \sa DecomposeFullyQualifiedTopic
      public: static bool FullyQualifiedName(const std::string &_partition,
                                             const std::string &_ns,
                                             const std::string &_topic,
                                             std::string &_name);

      /// \brief Decompose a fully qualified topic name into its partition and
      /// topic strings. Note that if the topic is preceded by a namespace, then
      /// the namespace and topic name will remain together as one string.
      ///
      /// Given a fully qualified topic name with the following syntax:
      ///
      /// \@\<PARTITION\>\@\<NAMESPACE\>/\<TOPIC\>
      ///
      /// The _partition output argument will be set to \<PARTITION\>, and the
      /// _namespaceAndTopic output argument will be set to
      /// \<NAMESPACE\>/\<TOPIC\>.
      ///
      /// \param[in] _fullyQualifiedName The fully qualified topic name.
      /// \param[out] _partition The partition component of the fully qualified
      /// topic name.
      /// \param[out] _namespaceAndTopic The namespace and topic name component.
      /// Note that there is no way to distinguish between where a namespace
      /// ends and a topic name begins, since topic names may contain slashes.
      /// \return True if the topic and partition were set.
      /// \sa FullyQualifiedName
      public: static bool DecomposeFullyQualifiedTopic(
        const std::string &_fullyQualifiedName,
        std::string &_partition,
        std::string &_namespaceAndTopic);

      /// \brief Convert a topic name to a valid topic. The input topic is
      /// modified by:
      /// * turning white space into `_`.
      /// * removing special characters and combinations.
      /// \param[in] _topic Input topic, which may be invalid.
      /// \return A valid topic, or empty string if not possible to convert.
      public: static std::string AsValidTopic(const std::string &_topic);

      /// \brief The kMaxNameLength specifies the maximum number of characters
      /// allowed in a namespace, a partition name, a topic name, and a fully
      /// qualified topic name.
      public: static const uint16_t kMaxNameLength = 65535;
    };
    }
  }
}

#endif
