#ifndef XGBOOST_TREE_UPDATER_H_
#define XGBOOST_TREE_UPDATER_H_
/*!
 * \file updater.h
 * \brief interface to update the tree
 * \author Tianqi Chen
 */
#include <vector>

#include "../data.h"
#include "./model.h"

namespace xgboost {
namespace tree {
/*! 
 * \brief interface of tree update module, that performs update of a tree
 * \tparam FMatrix the data type updater taking
 */
template<typename FMatrix>
class IUpdater {
 public:
  /*!
   * \brief set parameters from outside
   * \param name name of the parameter
   * \param val  value of the parameter
   */  
  virtual void SetParam(const char *name, const char *val) = 0;
  /*!
   * \brief peform update to the tree models
   * \param gpair the gradient pair statistics of the data
   * \param fmat feature matrix that provide access to features
   * \param root_index pre-partitioned root_index of each instance,
   *          root_index.size() can be 0 which indicates that no pre-partition involved
   * \param trees pointer to the trese to be updated, upater will change the content of the tree
   *   note: all the trees in the vector are updated, with the same statistics, 
   *         but maybe different random seeds, usually one tree is passed in at a time, 
   *         there can be multiple trees when we train random forest style model
   */
  virtual void Update(const std::vector<bst_gpair> &gpair,
                      FMatrix &fmat,
                      const std::vector<unsigned> &root_index,
                      const std::vector<RegTree*> &trees) = 0;
  // destructor
  virtual ~IUpdater(void) {}
};

}  // namespace tree
}  // namespace xgboost

#include "./updater_prune-inl.hpp"
#include "./updater_colmaker-inl.hpp"

namespace xgboost {
namespace tree {
/*! 
 * \brief create a updater based on name 
 * \param name name of updater
 * \return return the updater instance
 */
template<typename FMatrix>
inline IUpdater<FMatrix>* CreateUpdater(const char *name) {
  if (!strcmp(name, "prune")) return new TreePruner<FMatrix>();
  if (!strcmp(name, "grow_colmaker")) return new ColMaker<FMatrix, GradStats>();
  utils::Error("unknown updater:%s", name);
  return NULL;
}

}  // namespace tree
}  // namespace xgboost
#endif  // XGBOOST_TREE_UPDATER_H_