///////////////////////////////////////////////////////////////////////////////

// BSD 3-Clause License

//

// Copyright (C) 2021-2023, University of Edinburgh, Heriot-Watt University

// Copyright note valid unless otherwise stated in individual files.

// All rights reserved.

///////////////////////////////////////////////////////////////////////////////

#ifndef CROCODDYL_CORE_RESIDUAL_BASE_HPP_

#define CROCODDYL_CORE_RESIDUAL_BASE_HPP_

#include <boost/make_shared.hpp>

#include <boost/shared_ptr.hpp>

#include "crocoddyl/core/activation-base.hpp"

#include "crocoddyl/core/cost-base.hpp"

#include "crocoddyl/core/data-collector-base.hpp"

#include "crocoddyl/core/fwd.hpp"

#include "crocoddyl/core/state-base.hpp"

namespace crocoddyl {

/**

 * @brief Abstract class for residual models

 *

 * A residual model defines a vector function \f$\mathbf{r}(\mathbf{x},

 * \mathbf{u})\mathbb{R}^{nr}\f$ where `nr` describes its dimension in the

 * Euclidean space. This function depends on the state point

 * \f$\mathbf{x}\in\mathcal{X}\f$, which lies in the state manifold described

 * with a `nq`-tuple, its velocity \f$\dot{\mathbf{x}}\in

 * T_{\mathbf{x}}\mathcal{X}\f$ that belongs to the tangent space with `nv`

 * dimension, and the control input \f$\mathbf{u}\in\mathbb{R}^{nu}\f$. The

 * residual function can used across cost and constraint models.

 *

 * The main computations are carring out in `calc` and `calcDiff` routines.

 * `calc` computes the residual vector and `calcDiff` computes the Jacobians of

 * the residual function. Additionally, it is important to note that

 * `calcDiff()` computes the Jacobians using the latest stored values by

 * `calc()`. Thus, we need to first run `calc()`.

 *

 * \sa `StateAbstractTpl`, `calc()`, `calcDiff()`, `createData()`

 */

template <typename _Scalar>

class ResidualModelAbstractTpl {

 public:

  typedef _Scalar Scalar;

  typedef MathBaseTpl<Scalar> MathBase;

  typedef ResidualDataAbstractTpl<Scalar> ResidualDataAbstract;

  typedef CostDataAbstractTpl<Scalar> CostDataAbstract;

  typedef ActivationDataAbstractTpl<Scalar> ActivationDataAbstract;

  typedef StateAbstractTpl<Scalar> StateAbstract;

  typedef DataCollectorAbstractTpl<Scalar> DataCollectorAbstract;

  typedef typename MathBase::VectorXs VectorXs;

  typedef typename MathBase::MatrixXs MatrixXs;

  typedef typename MathBase::DiagonalMatrixXs DiagonalMatrixXs;

  /**

   * @brief Initialize the residual model

   *

   * @param[in] state        State of the system

   * @param[in] nr           Dimension of residual vector

   * @param[in] nu           Dimension of control vector

   * @param[in] q_dependent  Define if the residual function depends on q

   * (default true)

   * @param[in] v_dependent  Define if the residual function depends on v

   * (default true)

   * @param[in] u_dependent  Define if the residual function depends on u

   * (default true)

   */

  ResidualModelAbstractTpl(boost::shared_ptr<StateAbstract> state,

                           const std::size_t nr, const std::size_t nu,

                           const bool q_dependent = true,

                           const bool v_dependent = true,

                           const bool u_dependent = true);

  /**

   * @copybrief ResidualModelAbstractTpl()

   *

   * The default `nu` value is obtained from `StateAbstractTpl::get_nv()`.

   *

   * @param[in] state        State of the system

   * @param[in] nr           Dimension of residual vector

   * @param[in] q_dependent  Define if the residual function depends on q

   * (default true)

   * @param[in] v_dependent  Define if the residual function depends on v

   * (default true)

   * @param[in] u_dependent  Define if the residual function depends on u

   * (default true)

   */

  ResidualModelAbstractTpl(boost::shared_ptr<StateAbstract> state,

                           const std::size_t nr, const bool q_dependent = true,

                           const bool v_dependent = true,

                           const bool u_dependent = true);

  virtual ~ResidualModelAbstractTpl();

  /**

   * @brief Compute the residual vector

   *

   * @param[in] data  Residual data

   * @param[in] x     State point \f$\mathbf{x}\in\mathbb{R}^{ndx}\f$

   * @param[in] u     Control input \f$\mathbf{u}\in\mathbb{R}^{nu}\f$

   */

  virtual void calc(const boost::shared_ptr<ResidualDataAbstract>& data,

                    const Eigen::Ref<const VectorXs>& x,

                    const Eigen::Ref<const VectorXs>& u);

  /**

   * @brief Compute the residual vector for nodes that depends only on the state

   *

   * It updates the residual vector based on the state only. This function is

   * used in the terminal nodes of an optimal control problem.

   *

   * @param[in] data  Residual data

   * @param[in] x     State point \f$\mathbf{x}\in\mathbb{R}^{ndx}\f$

   */

  virtual void calc(const boost::shared_ptr<ResidualDataAbstract>& data,

                    const Eigen::Ref<const VectorXs>& x);

  /**

   * @brief Compute the Jacobian of the residual vector

   *

   * It computes the Jacobian the residual function. It assumes that `calc()`

   * has been run first.

   *

   * @param[in] data  Residual data

   * @param[in] x     State point \f$\mathbf{x}\in\mathbb{R}^{ndx}\f$

   * @param[in] u     Control input \f$\mathbf{u}\in\mathbb{R}^{nu}\f$

   */

  virtual void calcDiff(const boost::shared_ptr<ResidualDataAbstract>& data,

                        const Eigen::Ref<const VectorXs>& x,

                        const Eigen::Ref<const VectorXs>& u);

  /**

   * @brief Compute the Jacobian of the residual functions with respect to the

   * state only

   *

   * It updates the Jacobian of the residual function based on the state only.

   * This function is used in the terminal nodes of an optimal control problem.

   *

   * @param[in] data  Residual data

   * @param[in] x     State point \f$\mathbf{x}\in\mathbb{R}^{ndx}\f$

   */

  virtual void calcDiff(const boost::shared_ptr<ResidualDataAbstract>& data,

                        const Eigen::Ref<const VectorXs>& x);

  /**

   * @brief Create the residual data

   *

   * The default data contains objects to store the values of the residual

   * vector and their Jacobians. However, it is possible to specialize this

   * function if we need to create additional data, for instance, to avoid

   * dynamic memory allocation.

   *

   * @param data  Data collector

   * @return the residual data

   */

  virtual boost::shared_ptr<ResidualDataAbstract> createData(

      DataCollectorAbstract* const data);

  /**

   * @brief Compute the derivative of the cost function

   *

   * This function assumes that the derivatives of the activation and residual

   * are computed via calcDiff functions.

   *

   * @param cdata     Cost data

   * @param rdata     Residual data

   * @param adata     Activation data

   * @param update_u  Update the derivative of the cost function w.r.t. to the

   * control if True.

   */

  virtual void calcCostDiff(

      const boost::shared_ptr<CostDataAbstract>& cdata,

      const boost::shared_ptr<ResidualDataAbstract>& rdata,

      const boost::shared_ptr<ActivationDataAbstract>& adata,

      const bool update_u = true);

  /**

   * @brief Return the state

   */

  const boost::shared_ptr<StateAbstract>& get_state() const;

  /**

   * @brief Return the dimension of the residual vector

   */

  std::size_t get_nr() const;

  /**

   * @brief Return the dimension of the control input

   */

  std::size_t get_nu() const;

  /**

   * @brief Return true if the residual function depends on q

   */

  bool get_q_dependent() const;

  /**

   * @brief Return true if the residual function depends on v

   */

  bool get_v_dependent() const;

  /**

   * @brief Return true if the residual function depends on u

   */

  bool get_u_dependent() const;

  /**

   * @brief Print information on the residual model

   */

  template <class Scalar>

  friend std::ostream& operator<<(

      std::ostream& os, const ResidualModelAbstractTpl<Scalar>& model);

  /**

   * @brief Print relevant information of the residual model

   *

   * @param[out] os  Output stream object

   */

  virtual void print(std::ostream& os) const;

 protected:

  boost::shared_ptr<StateAbstract> state_;  //!< State description

  std::size_t nr_;                          //!< Residual vector dimension

  std::size_t nu_;                          //!< Control dimension

  VectorXs unone_;                          //!< No control vector

  bool q_dependent_;  //!< Label that indicates if the residual function depends

                      //!< on q

  bool v_dependent_;  //!< Label that indicates if the residual function depends

                      //!< on v

  bool u_dependent_;  //!< Label that indicates if the residual function depends

                      //!< on u

};

template <typename _Scalar>

struct ResidualDataAbstractTpl {

  typedef _Scalar Scalar;

  typedef MathBaseTpl<Scalar> MathBase;

  typedef DataCollectorAbstractTpl<Scalar> DataCollectorAbstract;

  typedef typename MathBase::VectorXs VectorXs;

  typedef typename MathBase::MatrixXs MatrixXs;

  template <template <typename Scalar> class Model>

                          DataCollectorAbstract* const data)

      : shared(data),

        r(model->get_nr()),

        Ru(model->get_nr(), model->get_nu()),

  DataCollectorAbstract* shared;  //!< Shared data allocated by the action model

  VectorXs r;                     //!< Residual vector

  MatrixXs Rx;  //!< Jacobian of the residual vector with respect the state

  MatrixXs Ru;  //!< Jacobian of the residual vector with respect the control

  MatrixXs Arr_Rx;

  MatrixXs Arr_Ru;

};

}  // namespace crocoddyl

/* --- Details -------------------------------------------------------------- */

/* --- Details -------------------------------------------------------------- */

/* --- Details -------------------------------------------------------------- */

#include "crocoddyl/core/residual-base.hxx"

#endif  // CROCODDYL_CORE_RESIDUAL_BASE_HPP_