/*!
 *  Copyright (c) 2015 by Contributors
 * \file base.h
 * \brief Rcpp interface of MXNet
 *  All the interface is done through C API,
 *  to achieve maximum portability when we need different compiler for libmxnet.
 */
#ifndef MXNET_RCPP_BASE_H_
#define MXNET_RCPP_BASE_H_

#include <Rcpp.h>
#include <dmlc/base.h>
#include <mxnet/c_api.h>
#include <string>
#include <sstream>
#include <set>
#include <vector>
#include <algorithm>

/*! \brief namespace of mxnet */
namespace mxnet {
/*! \brief namespace of R package */
namespace R {

/*! \brief macro to be compatible with non c++11 env */
#if DMLC_USE_CXX11 == 0
#ifndef nullptr
#define nullptr NULL
#endif
#endif

/*!
 * \brief Log that enables Stop and print message to R console
 */
class RLogFatal {
 public:
  RLogFatal(const char* file, int line) {
    log_stream_ << file << ":"
                << line << ": ";
  }
  inline std::ostringstream &stream() {
    return log_stream_;
  }
  ~RLogFatal()
#if DMLC_USE_CXX11
  noexcept(false)
#endif
  {
    std::string msg = log_stream_.str() + '\n';
    throw Rcpp::exception(msg.c_str());
  }

 private:
  std::ostringstream log_stream_;
};

/*!
 * \brief LOG FATAL to report error to R console
 *  Need to append newline to it.
 */
#define RLOG_FATAL ::mxnet::R::RLogFatal(__FILE__, __LINE__).stream()

/*! \brief LOG INFO to report message to R console, need to append newline */
#define RLOG_INFO ::Rcpp::Rcout

/*!
 * \brief Checking macro for Rcpp code, report error ro R console
 * \code
 *  RCHECK(data.size() == 1) << "Data size must be 1";
 * \endcode
 */
#define RCHECK(x)                                           \
  if (!(x)) RLOG_FATAL << "RCheck failed: " #x << ' ' /* NOLINT(*) */

/*!
 * \brief protected MXNet C API call, report R error if happens.
 * \param func Expression to call.
 */
#define MX_CALL(func)                                              \
  {                                                                \
    int e = (func);                                                \
    if (e != 0) {                                                  \
      throw Rcpp::exception(MXGetLastError());                     \
    }                                                              \
  }
/*!
 * \brief set seed to the random number generator
 * \param seed the seed to set.
 */
void SetSeed(int seed);

/*!
 * \brief Base Movable class of MXNet Module object.
 *  This class will define several common functions.
 * \tparam Class The class name of subclass
 */
template<typename Class>
class MXNetMovable {
 public:
  /*! \brief The type of Class in R's side */
  typedef Rcpp::RObject RObjectType;
  /*!
   * \brief Get a pointer representation of obj.
   * \param obj The R object.
   * \return The pointer of the object.
   * \throw Rcpp::exception if the object is moved.
   */
  inline static Class* XPtr(const Rcpp::RObject& obj) {
    Class* ptr = Rcpp::as<Class*>(obj);
    bool has_been_moved = static_cast<MXNetMovable<Class>*>(ptr)->moved_;
    RCHECK(!has_been_moved)
        << "Passed in a moved " << Class::TypeName() << " as parameter."
        << " Moved parameters should no longer be used";
    return ptr;
  }

 protected:
  /*! \brief default constructor */
  MXNetMovable() : moved_(false) {}
  /*!
   * \brief Default implement to Move a existing R Class object to a new one.
   * \param src The source R Object.
   * \return A new R object containing moved information as old one.
   */
  inline static RObjectType Move(const Rcpp::RObject& src) {
    Class* old = Class::XPtr(src);
    Class* moved = old->CreateMoveObject();
    static_cast<MXNetMovable<Class>*>(old)->moved_ = true;
    return Rcpp::internal::make_new_object(moved);
  }

  /*! \brief Whether the object has been moved */
  bool moved_;
};

/*! \brief Context of device enviroment */
struct Context {
  /*! \brief The device ID of the context */
  int dev_type;
  /*! \brief The device ID of the context */
  int dev_id;
  /*! \brief The R object type of the context */
  typedef Rcpp::List RObjectType;
  /*! \brief default constructor  */
  Context() {}
  /*!
   * \brief Constructor
   * \param src source R representation.
   */
  explicit Context(const Rcpp::RObject& src) {
    Rcpp::List list(src);
    this->dev_id = list[1];
    this->dev_type = list[2];
  }
  /*! \return R object representation of the context */
  inline RObjectType RObject() const {
    const char *dev_name = "cpu";
    if (dev_type == kGPU) dev_name = "gpu";
    Rcpp::List ret = Rcpp::List::create(
        Rcpp::Named("device") = dev_name,
        Rcpp::Named("device_id") = dev_id,
        Rcpp::Named("device_typeid") = dev_type);
    ret.attr("class") = "MXContext";
    return ret;
  }
  /*!
   * Create a CPU context.
   * \param dev_id the device id.
   * \return CPU Context.
   */
  inline static RObjectType CPU(int dev_id = 0) {
    Context ctx;
    ctx.dev_type = kCPU;
    ctx.dev_id = dev_id;
    return ctx.RObject();
  }
  /*!
   * Create a GPU context.
   * \param dev_id the device id.
   * \return GPU Context.
   */
  inline static RObjectType GPU(int dev_id) {
    Context ctx;
    ctx.dev_type = kGPU;
    ctx.dev_id = dev_id;
    return ctx.RObject();
  }
  /*! \brief initialize all the Rcpp module functions */
  inline static void InitRcppModule() {
    using namespace Rcpp;  // NOLINT(*);
    function("mx.cpu", &CPU,
             List::create(_["dev.id"] = 0),
             "Create a CPU context.");
    function("mx.gpu", &GPU,
             List::create(_["dev.id"] = 0),
             "Create a GPU context with specific device_id.");
  }
  /*! \brief the device type id for CPU */
  static const int kCPU = 1;
  /*! \brief the device type id for GPU */
  static const int kGPU = 2;
};

/*!
 * \brief Get a C char pointer vector representation of keys
 * The keys must stay alive when using c_keys
 * \param keys the string vector to get keys from
 * \return the C char pointer
 */
inline std::vector<const char*> CKeys(const std::vector<std::string> &keys) {
  std::vector<const char*> c_keys(keys.size());
  for (size_t i = 0; i < keys.size(); ++i) {
    c_keys[i] = keys[i].c_str();
  }
  return c_keys;
}

/*!
 *\return whether the expression is simple arguments
 * That is not module object and can be converted to string
 */
inline const char* TypeName(const Rcpp::RObject& args) {
  switch (TYPEOF(args)) {
    case REALSXP: return "numeric";
    case VECSXP: return "list";
    case INTSXP: return "integer";
    case CPLXSXP: return "complex";
    case LGLSXP: return "logical";
    case STRSXP: return "string";
    default: return "object type";
  }
}

/*!
 * \brief A simple function to convert value of known type to string.
 * \param val the value
 * \return the corresponding string
 */
template<typename T>
inline std::string toString(const Rcpp::RObject& val) {
  std::ostringstream os;
  os << Rcpp::as<T>(val);
  return os.str();
}

/*!
 * \brief Check whether the value is simple parameter
 * \param val The value to check.
 */
inline bool isSimple(const Rcpp::RObject& val) {
  switch (TYPEOF(val)) {
    case STRSXP:
    case INTSXP:
    case REALSXP:
    case LGLSXP: return true;
    default: return false;
  }
}

/*!
 * \brief Create a API compatile string presentation of value
 * \param key The key name of the parameter
 * \param val The value of the parameter
 * \return A python string representation of val
 */
inline std::string toPyString(const std::string &key, const Rcpp::RObject& val) {
  std::ostringstream os;
  int len = Rf_length(val);
  if (len != 1  ||
      key.substr(std::max(5, static_cast<int>(key.size())) - 5) == std::string("shape")) {
    RCHECK(TYPEOF(val) == INTSXP || TYPEOF(val) == REALSXP)
        << "Only accept integer vectors or simple types";
    // Do shape convesion back to reversed shape.
    Rcpp::IntegerVector vec(val);
    os << "(";
    for (size_t i = 0; i < vec.size(); ++i) {
      int value = vec[vec.size() - i - 1];
      if (i != 0) os << ", ";
      os << value;
    }
    if (vec.size() == 1) os << ",";
    os << ")";
    return os.str();
  }
  switch (TYPEOF(val)) {
    case STRSXP: return Rcpp::as<std::string>(val);
    case INTSXP: return toString<int>(val);
    case REALSXP: return toString<double>(val);
    case LGLSXP: return toString<bool>(val);
    default: {
      RLOG_FATAL << "Unsupported parameter type " << TypeName(val)
                 << " for argument " << key
                 << ", expect integer, logical, or string.";
    }
  }
  return os.str();
}

/*!
 * \brief Convert dot . style seperator into underscore _
 *  So num_hidden -> num.hidden
 *  This allows R user to use the dot style seperators.
 * \param src the source key
 * \retunr a converted key
 */
inline std::string FormatParamKey(std::string src) {
  for (size_t i = 0; i < src.size(); ++i) {
    if (src[i] == '.') src[i] = '_';
  }
  return src;
}

/*! \return wher list has names */
inline bool HasName(const Rcpp::List& src) {
  Rcpp::RObject obj = src.names();
  return obj != R_NilValue;
}

/*!
 * \brief Get names from list, return vector of empty strings if names do not present
 * \param src the source list
 * \retunr vector of string of same length as src.
 */
inline std::vector<std::string> SafeGetListNames(const Rcpp::List& src) {
  if (!HasName(src)) {
    return std::vector<std::string>(src.size(), std::string());
  } else {
    return src.names();
  }
}

/*!
 * \brief convert Rcpp's Dimension to internal shape vector
 * This will reverse the shape layout internally
 * \param rshape The dimension in R
 * \return A internal vector representation of shapes in mxnet.
 */
inline std::vector<mx_uint> Dim2InternalShape(const Rcpp::Dimension &rshape) {
  std::vector<mx_uint> shape(rshape.size());
  for (size_t i = 0; i < rshape.size(); ++i) {
    shape[rshape.size() - i - 1] = rshape[i];
  }
  return shape;
}

class NDArray;
class Symbol;
class Executor;
class KVStore;
}  // namespace R
}  // namespace mxnet

// This is Rcpp namespace, contains patches to Rcpp
// The following section follows style of Rcpp
namespace Rcpp {
  namespace internal {  // NOLINT(*)
    inline bool is_module_object_internal_fix(SEXP obj, const char* clazz) {
      Environment env(obj);
      SEXP sexp = env.get(".cppclass");
      if (TYPEOF(sexp) != EXTPTRSXP) return false;
      XPtr<class_Base> xp(sexp);
      return xp->has_typeinfo_name(clazz);
    }
    template <typename T> bool is__module__object_fix(SEXP x) {
      typedef typename Rcpp::traits::un_pointer<T>::type CLASS;
      if (!is__simple<S4>(x)) return false;
      return is_module_object_internal_fix(x, typeid(CLASS).name());
    }
  }  // namespace internal  NOLINT(*)

  template<>
  inline bool is<mxnet::R::NDArray>(SEXP x);
  template<>
  inline bool is<mxnet::R::Symbol>(SEXP x);
  template<>
  inline bool is<mxnet::R::Executor>(SEXP x);
}  // namespace Rcpp
#endif  // MXNET_RCPP_BASE_H_