/*
 * Computer Science 50
* Problem Set 4
 *
* Copies a BMP piece by piece, just because.
*/

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

#include "bmp.h"

int main(int argc, char* argv[])
{
// ensure proper usage
if (argc != 4)
{
    printf("Usage: ./resize n infile outfile\n");
    return 1;
}

// remember filenames
char* infile = argv[2];
char* outfile = argv[3];
int n = atoi(argv[1]);
// tests n
if (n < 1 || n > 100)
    {

        printf("n must between 1 and 100\n");
        return 1;
    }

// open input file
FILE* inptr = fopen(infile, "r");
if (inptr == NULL)
{
    printf("Could not open %s.\n", infile);
    return 2;
}

// open output file
FILE* outptr = fopen(outfile, "w");
if (outptr == NULL)
{
    fclose(inptr);
    fprintf(stderr, "Could not create %s.\n", outfile);
    return 3;
}

// read infile's BITMAPFILEHEADER
BITMAPFILEHEADER bf;
fread(&bf, sizeof(BITMAPFILEHEADER), 1, inptr);

// read infile's BITMAPINFOHEADER
BITMAPINFOHEADER bi;
fread(&bi, sizeof(BITMAPINFOHEADER), 1, inptr);

// ensure infile is (likely) a 24-bit uncompressed BMP 4.0
if (bf.bfType != 0x4d42 || bf.bfOffBits != 54 || bi.biSize != 40 ||
    bi.biBitCount != 24 || bi.biCompression != 0)
{
    fclose(outptr);
    fclose(inptr);
    fprintf(stderr, "Unsupported file format.\n");
    return 4;
}

// update header
BITMAPFILEHEADER new_bf = bf;
BITMAPINFOHEADER new_bi = bi;

new_bi.biHeight  = bi.biHeight * n;
new_bi.biWidth = bi.biWidth * n;

// determine padding for scanlines
int padding =  (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
int new_padding = (4 - (new_bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;

new_bi.biSizeImage = (new_bi.biWidth * sizeof(RGBTRIPLE) + new_padding) * abs(new_bi.biHeight);
new_bf.bfSize = 54 + new_bi.biSizeImage;



// write outfile's BITMAPFILEHEADER
fwrite(&new_bf, sizeof(BITMAPFILEHEADER), 1, outptr);

// write outfile's BITMAPINFOHEADER
fwrite(&new_bi, sizeof(BITMAPINFOHEADER), 1, outptr);


// iterate over infile's scanlines
for (int i = 0, biHeight = abs(bi.biHeight); i < biHeight; i++)
{
   // Perform the horizontal resize many times to get a vertical one.
    for (int h = 0; h < n; h++)
    {

        // iterate over pixels in scanline
        for (int j = 0; j < bi.biWidth; j++)
        {
            // temporary storage
            RGBTRIPLE triple;

            // read RGB triple from infile
            fread(&triple, sizeof(RGBTRIPLE), 1, inptr);


            // write RGB triple to outfile
            for (int t = 0; t < n; t++)
            {
            fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
            }

        }


    // skip over padding, if any
    fseek(inptr, padding, SEEK_CUR);

    // then add it back (to demonstrate how)
            for (int k = 0; k < new_padding; k++)
            {
               fputc(0x00, outptr);
            }
    //go back to beginning of scanline
    if(h < n-1)
        {
        fseek(inptr, -1 * ((3 * bi.biWidth) + (padding)), SEEK_CUR);
        }
    else
        {
        fseek(inptr, 0 , SEEK_CUR);
        }
    }


}

// close infile
fclose(inptr);

// close outfile
fclose(outptr);

// that's all folks
return 0;
}