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

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

#include "bmp.h"

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

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

    if (factor <= 1 || factor >= 100)
    {
        printf("Please enter a factor between 1 and 100.\n");
    }

    // 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 BITMxAPINFOHEADER
    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;
    }


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

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

    // determine new height
    int oldWidth = bi.biWidth;
    int newWidth = oldWidth * factor;

    // determine new width
    int oldHeight = bi.biHeight;
    int newHeight = oldHeight * factor;

    // determine new padding
    //int oldPadding =  (4 - (oldWidth * sizeof(RGBTRIPLE)) % 4) % 4;
    int newPadding =  (4 - (newWidth * sizeof(RGBTRIPLE)) % 4) % 4;

    // image size
    bi.biSizeImage = (newWidth * sizeof(RGBTRIPLE) + abs(newPadding)) * abs(newHeight);
    bf.bfSize = (bi.biSizeImage) + 54;

    // 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, oldHeight = abs(newHeight); i < oldHeight; i++)

    {
        // iterate over scanline factor times
        for (int j = 0; j < factor; j++)
        {
            // iterate over pixels of scanline
            for (int k = 0; k < newWidth; k++)
            {
                // temporary storage
                RGBTRIPLE triple;

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

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

            // update padding
            for (int l = 0; l < newPadding; l++)
                fputc(0x00, outptr);

            // go back to the beginning of the line
            if (j < factor - 1)
                fseek(inptr, (-oldWidth * sizeof(RGBTRIPLE)), SEEK_CUR);
        }

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


    // close infile
    fclose(inptr);

    // close outfile
    fclose(outptr);

    // that's all folks
    return 0;
}