/*
 * Copyright 2016 The Cartographer Authors
 *
 * 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 CARTOGRAPHER_MAPPING_INTERNAL_2D_LOCAL_TRAJECTORY_BUILDER_2D_H_
#define CARTOGRAPHER_MAPPING_INTERNAL_2D_LOCAL_TRAJECTORY_BUILDER_2D_H_

#include <chrono>
#include <memory>

#include "cartographer/common/time.h"
#include "cartographer/mapping/2d/submap_2d.h"
#include "cartographer/mapping/internal/2d/scan_matching/ceres_scan_matcher_2d.h"
#include "cartographer/mapping/internal/2d/scan_matching/real_time_correlative_scan_matcher_2d.h"
#include "cartographer/mapping/internal/motion_filter.h"
#include "cartographer/mapping/internal/range_data_collator.h"
#include "cartographer/mapping/pose_extrapolator.h"
#include "cartographer/mapping/proto/2d/local_trajectory_builder_options_2d.pb.h"
#include "cartographer/metrics/family_factory.h"
#include "cartographer/sensor/imu_data.h"
#include "cartographer/sensor/internal/voxel_filter.h"
#include "cartographer/sensor/odometry_data.h"
#include "cartographer/sensor/range_data.h"
#include "cartographer/transform/rigid_transform.h"

namespace cartographer {
namespace mapping {

// Wires up the local SLAM stack (i.e. pose extrapolator, scan matching, etc.)
// without loop closure.
// TODO(gaschler): Add test for this class similar to the 3D test.
class LocalTrajectoryBuilder2D {
 public:
  struct InsertionResult {
    std::shared_ptr<const TrajectoryNode::Data> constant_data;
    std::vector<std::shared_ptr<const Submap2D>> insertion_submaps;
  };
  struct MatchingResult {
    common::Time time;
    transform::Rigid3d local_pose;
    sensor::RangeData range_data_in_local;
    // 'nullptr' if dropped by the motion filter.
    std::unique_ptr<const InsertionResult> insertion_result;
  };

  explicit LocalTrajectoryBuilder2D(
      const proto::LocalTrajectoryBuilderOptions2D& options,
      const std::vector<std::string>& expected_range_sensor_ids);
  ~LocalTrajectoryBuilder2D();

  LocalTrajectoryBuilder2D(const LocalTrajectoryBuilder2D&) = delete;
  LocalTrajectoryBuilder2D& operator=(const LocalTrajectoryBuilder2D&) = delete;

  // Returns 'MatchingResult' when range data accumulation completed,
  // otherwise 'nullptr'. Range data must be approximately horizontal
  // for 2D SLAM. `TimedPointCloudData::time` is when the last point in
  // `range_data` was acquired, `TimedPointCloudData::ranges` contains the
  // relative time of point with respect to `TimedPointCloudData::time`.
  std::unique_ptr<MatchingResult> AddRangeData(
      const std::string& sensor_id,
      const sensor::TimedPointCloudData& range_data);
  void AddImuData(const sensor::ImuData& imu_data);
  void AddOdometryData(const sensor::OdometryData& odometry_data);

  static void RegisterMetrics(metrics::FamilyFactory* family_factory);

 private:
  std::unique_ptr<MatchingResult> AddAccumulatedRangeData(
      common::Time time, const sensor::RangeData& gravity_aligned_range_data,
      const transform::Rigid3d& gravity_alignment);
  sensor::RangeData TransformToGravityAlignedFrameAndFilter(
      const transform::Rigid3f& transform_to_gravity_aligned_frame,
      const sensor::RangeData& range_data) const;

  std::unique_ptr<InsertionResult> InsertIntoSubmap(
      common::Time time, const sensor::RangeData& range_data_in_local,
      const sensor::RangeData& gravity_aligned_range_data,
      const transform::Rigid3d& pose_estimate,
      const Eigen::Quaterniond& gravity_alignment);

  // Scan matches 'gravity_aligned_range_data' and returns the observed pose,
  // or nullptr on failure.
  std::unique_ptr<transform::Rigid2d> ScanMatch(
      common::Time time, const transform::Rigid2d& pose_prediction,
      const sensor::RangeData& gravity_aligned_range_data);

  // Lazily constructs a PoseExtrapolator.
  void InitializeExtrapolator(common::Time time);

  const proto::LocalTrajectoryBuilderOptions2D options_;
  ActiveSubmaps2D active_submaps_;

  MotionFilter motion_filter_;
  scan_matching::RealTimeCorrelativeScanMatcher2D
      real_time_correlative_scan_matcher_;
  scan_matching::CeresScanMatcher2D ceres_scan_matcher_;

  std::unique_ptr<PoseExtrapolator> extrapolator_;

  int num_accumulated_ = 0;
  sensor::RangeData accumulated_range_data_;
  std::chrono::steady_clock::time_point accumulation_started_;

  RangeDataCollator range_data_collator_;
};

}  // namespace mapping
}  // namespace cartographer

#endif  // CARTOGRAPHER_MAPPING_INTERNAL_2D_LOCAL_TRAJECTORY_BUILDER_2D_H_
