// Ceres Solver - A fast non-linear least squares minimizer

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// http://ceres-solver.org/

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// Author: vitus@google.com (Michael Vitus)

//

// Reads a file in the g2o filename format that describes a pose graph problem.

#ifndef EXAMPLES_CERES_READ_G2O_H_

#define EXAMPLES_CERES_READ_G2O_H_

#include <fstream>

#include <string>

#include "glog/logging.h"

namespace ceres {

namespace examples {

// Reads a single pose from the input and inserts it into the map. Returns false

// if there is a duplicate entry.

template <typename Pose, typename Allocator>

bool ReadVertex(std::ifstream* infile,

                std::map<int, Pose, std::less<int>, Allocator>* poses) {

  int id;

  Pose pose;

  *infile >> id >> pose;

  // Ensure we don't have duplicate poses.

  if (poses->find(id) != poses->end()) {

    LOG(ERROR) << "Duplicate vertex with ID: " << id;

    return false;

  }

  (*poses)[id] = pose;

  return true;

}

// Reads the contraints between two vertices in the pose graph

template <typename Constraint, typename Allocator>

void ReadConstraint(std::ifstream* infile,

                    std::vector<Constraint, Allocator>* constraints) {

  Constraint constraint;

  *infile >> constraint;

  constraints->push_back(constraint);

}

// Reads a file in the g2o filename format that describes a pose graph

// problem. The g2o format consists of two entries, vertices and constraints.

//

// In 2D, a vertex is defined as follows:

//

// VERTEX_SE2 ID x_meters y_meters yaw_radians

//

// A constraint is defined as follows:

//

// EDGE_SE2 ID_A ID_B A_x_B A_y_B A_yaw_B I_11 I_12 I_13 I_22 I_23 I_33

//

// where I_ij is the (i, j)-th entry of the information matrix for the

// measurement.

//

//

// In 3D, a vertex is defined as follows:

//

// VERTEX_SE3:QUAT ID x y z q_x q_y q_z q_w

//

// where the quaternion is in Hamilton form.

// A constraint is defined as follows:

//

// EDGE_SE3:QUAT ID_a ID_b x_ab y_ab z_ab q_x_ab q_y_ab q_z_ab q_w_ab I_11 I_12 I_13 ... I_16 I_22 I_23 ... I_26 ... I_66 // NOLINT

//

// where I_ij is the (i, j)-th entry of the information matrix for the

// measurement. Only the upper-triangular part is stored. The measurement order

// is the delta position followed by the delta orientation.

template 

          typename VectorAllocator>

bool ReadG2oFile(const std::string& filename,

                 std::map<int, Pose, std::less<int>, MapAllocator>* poses,

                 std::vector<Constraint, VectorAllocator>* constraints) {

  CHECK(poses != NULL);

  CHECK(constraints != NULL);

  poses->clear();

  constraints->clear();

  std::ifstream infile(filename.c_str());

  if (!infile) {

    return false;

  }

  std::string data_type;

  while (infile.good()) {

    // Read whether the type is a node or a constraint.

    infile >> data_type;

    if (data_type == Pose::name()) {

      if (!ReadVertex(&infile, poses)) {

        return false;

      }

    } else if (data_type == Constraint::name()) {

      ReadConstraint(&infile, constraints);

    } else {

      LOG(ERROR) << "Unknown data type: " << data_type;

      return false;

    }

    // Clear any trailing whitespace from the line.

    infile >> std::ws;

  }

  return true;

}

}  // namespace examples

}  // namespace ceres

#endif  // EXAMPLES_CERES_READ_G2O_H_