// Copyright (C) 2010, Guy Barrand. All rights reserved.
// See the file tools.license for terms.

#ifndef tools_wroot_wbuf
#define tools_wroot_wbuf

#include <ostream>
#include "../long_out"
#include "../charp_out"
#include "../stype"

#include <cstring> //memcpy
#include <vector>

namespace tools {
namespace wroot {

class wbuf {

  /////////////////////////////////////////////////////////
  /// swap ////////////////////////////////////////////////
  /////////////////////////////////////////////////////////
  // NOTE : on most common platforms (including Android, iPad)
  //        CERN-ROOT byte swaps ! (Bad luck). We have arranged to
  //        optimize this operation. The below "_swap_" functions
  //        do not have local variables and manipulates pointers
  //        directly.

  static void write_swap_2(char* a_pos,char* a_x) {
    *a_pos = *(a_x+1);a_pos++;
    *a_pos = *a_x;a_pos++;
  }
  static void write_swap_4(char* a_pos,char* a_x) {
    a_x += 3;
    *a_pos = *a_x;a_pos++;a_x--;
    *a_pos = *a_x;a_pos++;a_x--;
    *a_pos = *a_x;a_pos++;a_x--;
    *a_pos = *a_x;a_pos++;
  }
  static void write_swap_8(char* a_pos,char* a_x) {
    a_x += 7;
    *a_pos = *a_x;a_pos++;a_x--;
    *a_pos = *a_x;a_pos++;a_x--;
    *a_pos = *a_x;a_pos++;a_x--;
    *a_pos = *a_x;a_pos++;a_x--;
    *a_pos = *a_x;a_pos++;a_x--;
    *a_pos = *a_x;a_pos++;a_x--;
    *a_pos = *a_x;a_pos++;a_x--;
    *a_pos = *a_x;a_pos++;
  }
  /////////////////////////////////////////////////////////
  /// nswp ////////////////////////////////////////////////
  /////////////////////////////////////////////////////////
  static void write_nswp_2(char* a_pos,char* a_x) {::memcpy(a_pos,a_x,2);}
  static void write_nswp_4(char* a_pos,char* a_x) {::memcpy(a_pos,a_x,4);}
  static void write_nswp_8(char* a_pos,char* a_x) {::memcpy(a_pos,a_x,8);}
  /////////////////////////////////////////////////////////
  /////////////////////////////////////////////////////////
  /////////////////////////////////////////////////////////


  static const std::string& s_class() {
    static const std::string s_v("tools::wroot::wbuf");
    return s_v;
  }
  typedef void (*w_2_func)(char*,char*);
  typedef void (*w_4_func)(char*,char*);
  typedef void (*w_8_func)(char*,char*);
public:
  wbuf(std::ostream& a_out,bool a_byte_swap,const char* a_eob,char*& a_pos)
  :m_out(a_out)
  ,m_byte_swap(a_byte_swap)
  ,m_eob(a_eob)
  ,m_pos(a_pos)

  ,m_w_2_func(0)
  ,m_w_4_func(0)
  ,m_w_8_func(0)
  {
    set_byte_swap(a_byte_swap);
  }
  virtual ~wbuf(){
  }
public:
  wbuf(const wbuf& a_from)
  :m_out(a_from.m_out) //a ref.
  ,m_byte_swap(a_from.m_byte_swap)
  ,m_eob(a_from.m_eob)
  ,m_pos(a_from.m_pos) //a ref.
  ,m_w_2_func(a_from.m_w_2_func)
  ,m_w_4_func(a_from.m_w_4_func)
  ,m_w_8_func(a_from.m_w_8_func)
  {
    set_byte_swap(a_from.m_byte_swap);
  }
  wbuf& operator=(const wbuf& a_from){
    set_byte_swap(a_from.m_byte_swap);
    m_eob = a_from.m_eob;
    //m_pos is a ref.
    m_w_2_func = a_from.m_w_2_func;
    m_w_4_func = a_from.m_w_4_func;
    m_w_8_func = a_from.m_w_8_func;
    return *this;
  }
public:
  void set_eob(const char* a_eob){m_eob = a_eob;}
  bool byte_swap() const {return m_byte_swap;}
  void set_byte_swap(bool a_value) {
    m_byte_swap = a_value;
    if(m_byte_swap) {
      m_w_2_func = write_swap_2;
      m_w_4_func = write_swap_4;
      m_w_8_func = write_swap_8;
    } else {
      m_w_2_func = write_nswp_2;
      m_w_4_func = write_nswp_4;
      m_w_8_func = write_nswp_8;
    }
  }
public:
  bool write(unsigned char a_x) {
    if(!check_eob<unsigned char>()) return false;
    *m_pos++ = a_x;
    return true;
  }

  bool write(unsigned short a_x) {
    if(!check_eob<unsigned short>()) return false;
    m_w_2_func(m_pos,(char*)&a_x);
    m_pos += sizeof(unsigned short);
    return true;
  }

  bool write(unsigned int a_x) {
    if(!check_eob<unsigned int>()) return false;
    m_w_4_func(m_pos,(char*)&a_x);
    m_pos += sizeof(unsigned int);
    return true;
  }

  bool write(uint64 a_x){
    if(!check_eob<uint64>()) return false;
    m_w_8_func(m_pos,(char*)&a_x);
    m_pos += 8;
    return true;
  }

  bool write(float a_x) {
    if(!check_eob<float>()) return false;
    m_w_4_func(m_pos,(char*)&a_x);
    m_pos += sizeof(float);
    return true;
  }

  bool write(double a_x) {
    if(!check_eob<double>()) return false;
    m_w_8_func(m_pos,(char*)&a_x);
    m_pos += sizeof(double);
    return true;
  }

  bool write(char a_x)  {return write((unsigned char)a_x);}
  bool write(short a_x) {return write((unsigned short)a_x);}
  bool write(int a_x)   {return write((unsigned int)a_x);}
  bool write(int64 a_x) {return write((uint64)a_x);}

  bool write(const std::string& a_x) {
    unsigned char nwh;
    unsigned int nchars = (unsigned int)a_x.size();
    if(nchars>254) {
      if(!check_eob(1+4,"std::string")) return false;
      nwh = 255;
      if(!write(nwh)) return false;
      if(!write(nchars)) return false;
    } else {
      if(!check_eob(1,"std::string")) return false;
      nwh = (unsigned char)nchars;
      if(!write(nwh)) return false;
    }
    if(!check_eob(nchars,"std::string")) return false;
    for (unsigned int i = 0; i < nchars; i++) m_pos[i] = a_x[i];
    m_pos += nchars;
    return true;
  }


  template <class T>
  bool write(const T* a_a,uint32 a_n) {
    if(!a_n) return true;
    uint32 l = a_n * sizeof(T);
    if(!check_eob(l,"array")) return false;
    if(m_byte_swap) {
      for(uint32 i=0;i<a_n;i++) {
        if(!write(a_a[i])) return false;
      }
    } else {
      ::memcpy(m_pos,a_a,l);
      m_pos += l;
    }
    return true;
  }

  template <class T>
  bool write(const std::vector<T>& a_v) {
    if(a_v.empty()) return true;
    uint32 n = uint32(a_v.size());
    uint32 l = n * sizeof(T);
    if(!check_eob(l,"array")) return false;
    for(uint32 i=0;i<n;i++) {
      if(!write(a_v[i])) return false;
    }
    return true;
  }

protected:
  template <class T>
  bool check_eob(){
    if((m_pos+sizeof(T))>m_eob) {
      m_out << s_class() << " : " << stype(T()) << " : "
           << " try to access out of buffer " << sizeof(T) << " bytes"
           << " (pos=" << charp_out(m_pos)
           << ", eob=" << charp_out(m_eob) << ")." << std::endl;
      return false;
    }
    return true;
  }
  bool check_eob(size_t a_n,const char* a_cmt){
    if((m_pos+a_n)>m_eob) {
      m_out << s_class() << " : " << a_cmt << " : "
           << " try to access out of buffer " << a_n << " bytes"
           << " (pos=" << charp_out(m_pos)
           << ", eob=" << charp_out(m_eob) << ")." << std::endl;
      return false;
    }
    return true;
  }

protected:
  std::ostream& m_out;
  bool m_byte_swap;
  const char* m_eob;
  char*& m_pos;

  w_2_func m_w_2_func;
  w_4_func m_w_4_func;
  w_8_func m_w_8_func;
};

}}

#endif
