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

// save 24-bits bmp file, buffer must be in bmp format: upside-down
void savebmp(char *name, uchar *buffer, int x, int y) {
  FILE *f = fopen(name, "wb");
  if (!f) {
    printf("Error writing image to disk.\n");
    return;
  }
  unsigned int size = x * y * 3 + 54;
  uchar header[54] = {
    'B', 'M', size & 255, (size >> 8) & 255, (size >> 16) & 255, size >> 24, //
    0, 0, 0, 0, 54, 0, 0, 0, 40, 0, 0, 0, x & 255, x >> 8, 0, 0, y & 255,    //
    y >> 8, 0, 0, 1, 0, 24, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  //
    0, 0, 0, 0, 0, 0, 0, 0,                                                  //
  };
  fwrite(header, 1, 54, f);
  fwrite(buffer, 1, x * y * 3, f);
  fclose(f);
}

// read bmp file and store image in contiguous array
void readbmp(char *filename, uchar *array) {
  FILE *img = fopen(filename, "rb"); // read the file
  uchar header[54];
  size_t result =
      fread(header, sizeof(uchar), 54, img); // read the 54-byte header

  if (result != 54) {
    perror("Error reading file.\n");
    return;
  }

  // extract image height and width from header
  int width = *(int *)&header[18];
  int height = *(int *)&header[22];
  int padding = 0;
  while ((width * 3 + padding) % 4 != 0)
    padding++;

  int widthnew = width * 3 + padding;
  uchar *data = calloc(widthnew, sizeof(uchar));

  for (int i = 0; i < height; i++) {
    result = fread(data, sizeof(uchar), widthnew, img);

    if (result != (size_t)widthnew) {
      perror("Error reading file.\n");
    }

    for (int j = 0; j < width * 3; j += 3) {
      array[3 * i * width + j + 0] = data[j + 0];
      array[3 * i * width + j + 1] = data[j + 1];
      array[3 * i * width + j + 2] = data[j + 2];
    }
  }
  fclose(img); // close the file
}