/*!
 * \file    utils.h
 * \brief   Utilities to handle matrix files, chrono, etc...
 *
 * \author
 *    Christos Choutouridis AEM:8997
 *    <cchoutou@ece.auth.gr>
 */
#ifndef UTILS_H_
#define UTILS_H_

#include <string>
#include <sstream>
#include <iostream>
#include <chrono>
#include <random>
#include <impl.hpp>
#include <config.h>

template <typename T>
struct buffer_t {
   buffer_t(size_t s) { p = new T[s]; }
   ~buffer_t()        { delete[] p; }
   buffer_t()                           = default;
   buffer_t(buffer_t&&)                 = default;
   buffer_t& operator=(buffer_t&&)      = default;
   buffer_t(const buffer_t&)            = delete;
   buffer_t& operator=(const buffer_t&) = delete;

   T* allocate(size_t s)   { return p = new T[s]; }
   T* operator() ()        { return p; }
   T& operator[] (size_t i){ return p[i]; }
private:
   T* p{nullptr};
};

struct Mtx {

   template<typename I>
   static void coo2csc(I *row, I *col, I const* row_coo, I const* col_coo, I nnz, I n, I isOneBased) {
      // ----- cannot assume that input is already 0!
      for (I l = 0; l < n+1; l++) col[l] = 0;

      // ----- find the correct column sizes
      for (I l = 0; l < nnz; l++)
        col[col_coo[l] - isOneBased]++;

      // ----- cumulative sum
      for (I i = 0, cumsum = 0; i < n; i++) {
        I temp = col[i];
        col[i] = cumsum;
        cumsum += temp;
      }
      col[n] = nnz;
      // ----- copy the row indices to the correct place
      for (I l = 0; l < nnz; l++) {
         I col_l;
        col_l = col_coo[l] - isOneBased;

        I dst = col[col_l];
        row[dst] = row_coo[l] - isOneBased;

        col[col_l]++;
      }
      // ----- revert the column pointers
      for (I i = 0, last = 0; i < n; i++) {
         I temp = col[i];
        col[i] = last;
        last = temp;
      }
   }

   template<typename I>
   static bool is_triangular (std::ifstream& file) {
      std::string line, token;
      enum state_en {HEADER, SIZE, DATA} state = HEADER;
      enum LU_t {Z, LOWER, UPPER} LU = Z;

      while (std::getline (file, line, '\n')) {
         std::stringstream ss(line);
         switch (state) {
         case HEADER:
            ss >> token;
            if (token != "%%MatrixMarket")   return false;
            else                             state = SIZE;
            break;
         case SIZE:
            if (line[0] == '%')  continue;
            else                 state = DATA;
            break;
         case DATA:
            if (line[0] == '%')  continue;
            I i, j;
            ss >> i >> j;
            switch (LU) {
               case Z:     LU = (i<j) ? UPPER: LOWER; break;
               case LOWER: if (i<=j)   return false;  break;
               case UPPER: if (j<=i)   return false;  break;
            }
            break;
         }
      }
      file.clear();  // rewind
      file.seekg(0);
      return true;
   }

   template<typename DataT, typename IndexT, MatrixType MatrixT>
   static bool load (SpMat<DataT, IndexT, MatrixT>& M, std::ifstream& file) {
      std::string line, token;
      enum state_en {HEADER, SIZE, DATA} state = HEADER;
      enum LU_t {Z, LOWER, UPPER} LU = Z;
      IndexT n1, n2, nnz;
      buffer_t<IndexT> col{}, row{}, coo_col{}, coo_row{};

      IndexT cnt{};
      while (std::getline (file, line, '\n')) {
         std::stringstream ss(line);
         switch (state) {
         case HEADER:
            ss >> token;
            if (token != "%%MatrixMarket")   return false;
            else                             state = SIZE;
            break;
         case SIZE:
            if (line[0] == '%')  continue;
            else {
               ss >> n1 >> n2 >> nnz;
               if (session.makeSymmetric)
                  nnz *= 2;
               col.allocate(nnz);
               row.allocate(nnz);
               coo_col.allocate(nnz);
               coo_row.allocate(nnz);
               state = DATA;
            }
            break;
         case DATA:
            if (line[0] == '%')  continue;
            IndexT i, j;
            ss >> i >> j;
            if (session.makeSymmetric) {
               if (LU == Z) {
                  LU = (i<j) ? UPPER: LOWER;
               }
               if ((LU==LOWER && j<i) || (LU==UPPER && i<j)) {
                  coo_row[cnt]   = i;
                  coo_col[cnt++] = j;
                  coo_row[cnt]   = j;
                  coo_col[cnt++] = i;
               }
            }
            else {
               coo_row[cnt]   = i;
               coo_col[cnt++] = j;
            }
            break;
         }
      }
      coo2csc(&row[0], &col[0], &coo_row[0], &coo_col[0], cnt, n1, 1);
      M = SpMat<DataT, IndexT, MatrixT>(n1, cnt, &row[0], &col[0]);
      return true;
   }
};

struct Timing{
   using Tpoint = std::chrono::steady_clock::time_point;
   using microseconds = std::chrono::microseconds;
   using milliseconds = std::chrono::milliseconds;
   using seconds = std::chrono::seconds;


   Tpoint start () noexcept { return start_ = std::chrono::steady_clock::now(); }
   Tpoint stop ()  noexcept { return stop_ = std::chrono::steady_clock::now(); }

   auto dt () noexcept {
      return std::chrono::duration_cast<std::chrono::microseconds>(stop_ - start_).count();
   }
   void print_dt () noexcept {
      auto t = stop_ - start_;
      if       (std::chrono::duration_cast<microseconds>(t).count() < 10000)
         std::cout << "time: " << std::to_string(std::chrono::duration_cast<microseconds>(t).count()) << " [usec]\n";
      else if (std::chrono::duration_cast<milliseconds>(t).count() < 10000)
         std::cout << "time: " << std::to_string(std::chrono::duration_cast<milliseconds>(t).count()) << " [msec]\n";
      else
         std::cout << "time: " << std::to_string(std::chrono::duration_cast<seconds>(t).count()) << " [sec]\n";

   }
private:
   Tpoint start_;
   Tpoint stop_;
};


void init_ER_graph (matrix& A, double p);
void print_ER_graph (matrix& A);

#endif /* UTILS_H_ */