/********************************
Author: Sravanthi Kota Venkata
********************************/

#include <stdio.h>
#include <stdlib.h>
#include "sdvbs_common.h"

I2D* readImage(const char* pathName)
{
    // Reading BMP image
    char signature[2];   
    int file_size;
    short int reserved1;
    short int reserved2;
    int loc_of_bitmap;

    int size_of_infoheader;
    int width;
    int height;
    short int number_of_planes;
    short int bits_per_pixel;

    int compression_method;
    int bytes_of_bitmap;
    int hori_reso;
    int vert_reso;
    int no_of_colors;
    int no_of_imp_colors;

    int nI,nJ;
    int pixSize;

    unsigned char tempb,tempg,tempr,tempjunk[12];
    int ta;
    I2D* srcImage;

    FILE *input;
    input = fopen(pathName,"rb");
    if(input == NULL)
    {
        perror("File pointer error");
        return NULL;
    }
    else
    {
        //start of header information
        fread(&signature,sizeof(signature),1,input);
        fread(&file_size,sizeof(file_size),1,input);
        fread(&reserved1,sizeof(reserved1),1,input);
        fread(&reserved2,sizeof(reserved2),1,input);
        fread(&loc_of_bitmap,sizeof(loc_of_bitmap),1,input);

        fread(&size_of_infoheader,sizeof(size_of_infoheader),1,input);
        fread(&width,sizeof(width),1,input); // Reads the width of the image
        fread(&height,sizeof(height),1,input); // Reads the height of the image
        fread(&number_of_planes,sizeof(number_of_planes),1,input);
        fread(&bits_per_pixel,sizeof(bits_per_pixel),1,input);
        fread(&compression_method,sizeof(compression_method),1,input);
        fread(&bytes_of_bitmap,sizeof(bytes_of_bitmap),1,input);

        fread(&hori_reso,sizeof(hori_reso),1,input);
        fread(&vert_reso,sizeof(vert_reso),1,input);
        fread(&no_of_colors,sizeof(no_of_colors),1,input);
        fread(&no_of_imp_colors,sizeof(no_of_imp_colors),1,input);
        //end of header information

        srcImage = iMallocHandle(height, width);
        
        // Conditions to check whether the BMP is interleaved and handling few exceptions
        if(srcImage->height <= 0 || srcImage->width <= 0 || signature[0] != 'B' || signature[1] != 'M'  || ( bits_per_pixel !=24 && bits_per_pixel !=8 ) )
        {
            printf("ERROR in BMP read: The input file is not in standard BMP format");
            return NULL;
        }
        fseek(input,loc_of_bitmap,SEEK_SET);

        if (bits_per_pixel == 8)
        {
            for(nI = (height - 1); nI >= 0 ; nI--)
            {
                for(nJ = 0;nJ < width; nJ++)
                {
                    fread(&tempg,sizeof(unsigned char),1,input);
                    subsref(srcImage,nI,nJ) = (int)tempg;
                }
            }
        }
        else if (bits_per_pixel == 24)
        {
            for(nI = (height - 1); nI >= 0 ; nI--)
            {
                for(nJ = 0;nJ < width; nJ++)
                {
                    fread(&tempb,sizeof(unsigned char),1,input);
                    fread(&tempg,sizeof(unsigned char),1,input);
                    fread(&tempr,sizeof(unsigned char),1,input);
                    ta = (3*tempr + 6*tempg + tempb)/10;
                    ta = tempg;
                    subsref(srcImage,nI,nJ) = (int)ta;
                }
            }
        }
        else
        {
            return NULL;
        }

        fclose(input);
        return srcImage;
    }
}