/**
 * 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)
    {
        fprintf(stderr, "Usage: ./resize n infile outfile\n");
        return 1;
    }

    // remember filenames
    int n = atoi(argv[1]);
    char *infile = argv[2];
    char *outfile = argv[3];

    // open input file
    FILE *inptr = fopen(infile, "r");
    if (inptr == NULL)
    {
        fprintf(stderr, "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;
    }

        // determine padding for scanlines


    BITMAPINFOHEADER nbi = bi;
    nbi.biWidth = n * bi.biWidth;
    nbi.biHeight = n * bi.biHeight;
    int padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
    int npadding = (4 - (nbi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;

    nbi.biSizeImage = (nbi.biWidth * sizeof(RGBTRIPLE) + npadding) * abs(nbi.biHeight);

    BITMAPFILEHEADER nbf = bf;
    nbf.bfSize = nbi.biSizeImage + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);


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

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

    // iterate over infile's scanlines
    for (int i = 0, biHeight = abs(bi.biHeight); i < biHeight; i++)
    {
        //save the row
        RGBTRIPLE row[nbi.biWidth];
        int index=0;
        // 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);

            for (int k=0; k<n; k++)
            {
                row[index] = triple;
                index++;
            }
        }

                    // skip over padding, if any
            fseek(inptr, padding, SEEK_CUR);
            for (int l=0; l<n; l++){
                // then add it back (to demonstrate how)
                fwrite(&row, sizeof(RGBTRIPLE)*nbi.biWidth,1,outptr);
                for (int k = 0; k < npadding; k++)
                {
                    fputc(0x00, outptr);
                }

             }

        }



    // close infile
    fclose(inptr);

    // close outfile
    fclose(outptr);
    // success
    return 0;
}