// Copies 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: copy infile outfile\n");
        return 1;
    }

    // remember filenames
    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;
    }

    float size = atof(argv[1]);
    if (size == 0)
    {
        fprintf(stderr, "Wrong float number for size\n");
        return 1;
    }

    // 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;
    }

    //copying bitmapfileheader & bitmapinfoheader into new variables to change its values
    BITMAPFILEHEADER new_bf = bf;
    BITMAPINFOHEADER new_bi = bi;
    //declarations of padding
    float padding, new_padding;

    //declaration for step that will be used in case of size < 0
    float step;

    //changing value of width & height & size at make image larger case
    if (size >= 1)
    {
        //giving width & height new values according to new size
        new_bi.biWidth *= size;
        new_bi.biHeight *= size;
        // determine padding for scanlines
        padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
        new_padding = (4 - (new_bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
        new_bi.biSizeImage = (sizeof(RGBTRIPLE) * new_bi.biWidth + new_padding) * abs(new_bi.biHeight);
        new_bf.bfSize = new_bi.biSizeImage + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);

        // 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++)
        {
            // resize image vertically by repeating ntimes according to the new size
            for (int repeat = 0; repeat < size; repeat++)
            {
                // 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);

                    //loop through the new width of new image, to write the byte multiple times according to new size
                    for (int k = 0; k < size; k++)
                    {
                        // write RGB triple to outfile
                        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);
                }

                //getting the cursor back to the start of line, to repeat vertically
                if (repeat < size -1)
                {
                    fseek(inptr, -(bi.biWidth * 3 + padding), SEEK_CUR);
                }
            }
        }
    }

    else if (size < 1)
    {
        //step is float number
        step = 1 / size;
        //giving width & height new values according to new size
        new_bi.biWidth /= step;
        new_bi.biHeight /= step;
        // determine padding for scanlines
        padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
        new_padding = (4 - (new_bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
        new_bi.biSizeImage = (sizeof(RGBTRIPLE) * new_bi.biWidth + new_padding) * abs(new_bi.biHeight);
        new_bf.bfSize = new_bi.biSizeImage + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);

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

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

                // write RGB triple to outfile
                fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);

                //moving to the next place according to the step size
                fseek(inptr, step , SEEK_CUR);
            }

            // 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);
            }

            //getting the cursor reading another line without writing, to repeat vertically
            for (int repeat = 0; repeat < step - 1; repeat++)
            {
                fseek(inptr, (bi.biWidth * sizeof(RGBTRIPLE)) + padding, SEEK_CUR);
            }

        }
    }

    // close infile
    fclose(inptr);

    // close outfile
    fclose(outptr);

    // success
    return 0;
}