// Resizes a bmp file

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

int main(int argc, char* argv[])
{
    // ensure proper usage
    if (argc != 4)
    {
        fprintf(stderr, "Usage: number copy infile outfile\n");
        return 1;
    }
     // remember filenames

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

    if (n < 0 || n > 100) //making sure n is in specification
    {
        printf("positive integer please");
        return 1;
    }

    // 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);
    int input_padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4; //setting the padding

    // 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;
    }

    // write outfile's BITMAPFILEHEADER
    bi.biWidth *= n;
    bi.biHeight *= n;
    int padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4; //setting the padding
    int paddingOutput = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4; //setting the padding
    bi.biSizeImage = ((sizeof(RGBTRIPLE) * bi.biWidth) + paddingOutput) * abs(bi.biHeight);
    bf.bfSize = (bi.biSizeImage + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER));// setting the file size


    fwrite(&bf, sizeof(BITMAPFILEHEADER), 1, outptr);

    // write outfile's BITMAPINFOHEADER

    fwrite(&bi, sizeof(BITMAPINFOHEADER), 1, outptr);

    // determine padding for scanlines


    // iterate over infile's scanlines
    for (int i = 0, biHeight = abs(bi.biHeight); i < bi.biHeight; i++)
    {
        // iterate over pixels in scanline
        for (int j = 0; j < bi.biWidth; j++)
        {
            // temporary storage
            RGBTRIPLE triple;
            bi.biSizeImage = (bi.biWidth * sizeof(RGBTRIPLE) + padding) * abs(bi.biHeight);
            bf.bfSize = (bi.biSizeImage + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER));

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

            // write RGB triple to outfile
            fwrite(&triple, sizeof(BITMAPFILEHEADER), 1, outptr);
        }
        // resizing the image horizontally

        for (long offset = 0; offset < bi.biSizeImage; offset++)
        {
            if (offset == 0) //making the file pointer 0
            {
                fseek(outptr, -1 * (offset), SEEK_SET);
            }
            if (SEEK_CUR == 0x00)
            {
                fseek(outptr, 1, SEEK_CUR);
            }
            fwrite(&outptr, 1, n, outptr);//writing each byte 1 by 1 using the for loop
        //checking if file pointer is at end of the width
        for (int c = 0; c < bi.biWidth; c++)
        {
            if (bi.biSizeImage % bi.biWidth == 0) //checking each row
            {
                for(int p = 0; p < padding; p++) //actually printing the padding
                {
                    fputc(0x00,outptr);
                }
            }
        }
        }

        //resizing the image vertically

        for(int b = 0; b < n; b++)
        {
            fseek(outptr, bi.biWidth, SEEK_END);
            fwrite(&outptr, 1, n, outptr);//writing each byte 1 by 1 using the for loop
        }

    }

    // close infile
    fclose(inptr);

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