#include <iostream>
#include <fcntl.h>
#include <vector>
#include <unistd.h>
#include <omp.h>
#include <iomanip>

using namespace std;

using ColorT = unsigned char;

struct PixelT {
    ColorT color[3];
};

using ImageT = vector <vector <PixelT>>;

void WriteImage(string  baseFileName, const ImageT &  image);

int main(int argc, char * argv[]) {
    double startTime, 
           loopTime, 
           writeTime;

    int xdim{100};
    int ydim{100};
    int threads{1};
    bool doWrite{true};
    bool verbose{false};
    string fileName{"foo"};

    int opt;
    while((opt = getopt(argc, argv, "w:h:t:f:xv")) != -1) {
        switch(opt) {
            case 'w':
                xdim = atoi(optarg);
                if (xdim < 100) {
                   xdim = 100;
                }
                break;
            case 'h':
                ydim = atoi(optarg);
                if (ydim < 100) {
                   ydim = 100;
                }
                break;
            case 'f':
                fileName = optarg;
                break;
            case 't':
                threads = atoi(optarg);
                if (threads < 1) {
                   threads = 1;
                }
                break;
            case 'v':
                verbose = true;
                break;
            case 'x':
                doWrite = false;
                break;
        }
    }

    omp_set_num_threads(threads);

    if(verbose) {
       cout << "\tCreating a " << xdim << " x " << ydim << " image." << endl;
       cout << "\tUsing " << threads << " threads. " << endl;
       if (doWrite) {
           cout << "\tWriting the output file to " << fileName << endl;
       } else {
           cout << "\tNot writing the output file." << endl;
       }
    }

    vector<vector<PixelT>> image(xdim,vector<PixelT>(ydim));

    startTime = omp_get_wtime();

    #pragma omp parallel 
    {
        int id = omp_get_thread_num()+1;
        unsigned int  seed;

        #pragma omp for
        for(int i = 0; i < xdim; ++i) {
           for(int j = 0; j < ydim; ++j) {
               for(int k =0; k < 3; ++k) {
                   image[i][j].color[k] = rand_r(&seed)%255;
                   //image[i][j].color[k] = 255/id;
               }
           }
        }
    } 
      
    loopTime = omp_get_wtime();

    if (doWrite) {
         WriteImage(fileName, image);
    }

    writeTime = omp_get_wtime();

    if (verbose) {
        cout << fixed;
        cout << endl;
        cout << "Total time: "<< setprecision(2)
            << writeTime - startTime << " sec " << endl;

        cout << "Loop time:  " << setprecision(2) 
                       << loopTime - startTime << " sec " << endl;
        if (doWrite) {
            cout << "Write time: " << setprecision(2)
                 << writeTime - loopTime << " sec " << endl;
        }
    }

    return 0;
}

void WriteImage(string  baseFileName, const ImageT &  image){

    string pngName {baseFileName + ".ppm"};

    // open a file for writing
    int flags = O_CREAT | O_WRONLY | O_TRUNC;
    int mode {S_IRUSR | S_IRGRP | S_IROTH | S_IWUSR};
    int fd {open(pngName.c_str(), flags, mode)};

    if (-1 == fd) {
       perror("Error Open:");
    }

    string tmp;
    tmp = "P6\n";

    // write the PBM header
    // the magic number P6  (in ascii) followed by a newline 
    write(fd, tmp.c_str(), sizeof(char) * tmp.size());

    // width space height newline in ascii
    tmp = to_string(image.size()) + " " + to_string(image[0].size()) + "\n";
    write(fd, tmp.c_str(), sizeof(char) * tmp.size());

    // the maximum value (255) newline in ascii
    tmp = "255\n";
    write(fd, tmp.c_str(), sizeof(char) * tmp.size());


    // write the rgb values row by row in binary format
    for(int i = 0; i < image.size(); ++i) {
       for(int j = 0; j < image[0].size(); ++j) {
           write(fd, image[i][j].color, sizeof(ColorT) * 3);
       }
    }

    // close the file
    close(fd);
    // run ppmtogif or ppmtojpeg 
    string jpegName{baseFileName + ".jpeg"};
    string cmd { "ppmtojpeg  < " + pngName  + " > " + jpegName};
    system(cmd.c_str());
    unlink(pngName.c_str());
}