// Copies a BMP file

#include <stdio.h>
#include <stdlib.h>
#include <string.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
    char *N = argv[1];
    char *infile = argv[2];
    char *outfile = argv[3];

    // convert string to integer
    int n = atoi(N);


    if(n < 0 || n > 100)
    {
        fprintf(stderr, "Usage: ./resize n infile outfile\n");
        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);

    // 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 new dimensions
    int oldWidth = bi.biWidth;
    int oldHeight = bi.biHeight;
    int newWidth = oldWidth * n;
    int newHeight = oldHeight * n;

    // determine padding for scanlines
    int inPadding  = (4 - (oldWidth * sizeof(RGBTRIPLE)) % 4) % 4;
    int outPadding  = (4 - (newWidth * sizeof(RGBTRIPLE)) % 4) % 4;

    printf("oldwidth is %i\n", oldWidth);
    printf("newwidth is %i\n", newWidth);
    printf("oldheight is %i\n", oldHeight);
    printf("newheight is %i\n", newHeight);
    printf("oldpadding value is %i\n", inPadding);
    printf("newpadding value is %i\n ", outPadding);

    // reconfigure headers
    bi.biHeight = newHeight;
    bi.biWidth = newWidth;
    bi.biSizeImage = ((sizeof(RGBTRIPLE) * newWidth) + outPadding) * abs(newHeight);
    bf.bfSize = bi.biSizeImage + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);

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

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


    // iterate over infile's scanlines
    for (int i = 0, biHeight = abs(oldHeight); i < biHeight; i++)
    {
        RGBTRIPLE buffer[newWidth];
        RGBTRIPLE* current = &buffer[0]; //current starts pointing to buffer[0]

        // iterate over pixels in scanline (Horizontally)
        for (int j = 0; j < oldWidth; j++)
        {
            RGBTRIPLE triple;

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

            // write RGB triple to ARRAY
            for (int k = 0; k < n; k++)
            {
                *current = triple; // triple will store into *current address
                current++; // the pointer will point to the next address in buffer
            }
        }

        // Write scanline n times to output
        for (int l=0; l<n; l++){

            fwrite(&buffer, sizeof(buffer), 1, outptr);  // Write array to outfile

            for (int k = 0; k < outPadding; k++)
            {
                fputc(0x00, outptr);
            }

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

    }

    // close infile
    fclose(inptr);

    // close outfile
    fclose(outptr);

    // success
    return 0;
}