//This program reads in a 24-bit bmp image file named test.tns in the directory bmpviewer

#include <os.h>
#include "utils.h"
#include "screen.h"
#include "dirlist.h"
#include "string.h"
#define CONTRAST (*(volatile unsigned*) 0x900F0020)

asm(".string \"PRG\"\n");

int main(void) 
{
  //bitmap header
  char* header = (char*) malloc(0x36);
  //screen buffer
  char* scrbuf = (char*) malloc(SCREEN_BYTES_SIZE);
  clearBuf(scrbuf);
  //image file
  FILE* img;
  //loop indices
  int i, x, y;
  //list the files
  int numfiles;
  char** filenames = (char**) malloc(1024);
  numfiles = dirlist("/documents/bmpviewer/", "*.bmp.tns", filenames);
  y = 0;
  for (i = 0; i < numfiles; i++) {
    drawStr(scrbuf, 8, y, filenames[i]);
    y += 12;
  } 
  refresh(scrbuf);
  i = 0;
  while (!isKeyPressed(KEY_NSPIRE_CLICK)) {
    if (isKeyPressed(KEY_NSPIRE_UP)) {
      putChar(scrbuf, 0, 12 * i, 0);
      i--;
      if (i < 0) i = 0;
    }
    if (isKeyPressed(KEY_NSPIRE_DOWN)) {
      putChar(scrbuf, 0, 12 * i, 0);
      i++;
      if (i >= numfiles) i = numfiles - 1;
    }
    if (isKeyPressed(KEY_NSPIRE_ESC)) {
      return;
    }
    drawStr(scrbuf, 0, 12 * i, ">");
    //refresh 3x to delay keypresses
    for (y = 0; y < 3; y++) {
      refresh(scrbuf);
    }
  }
  char* selected = filenames[i]; 
  char* path = "/documents/bmpviewer/";
  char* fullname = (char*) malloc(strlen(path) + strlen(selected));
  strcpy(fullname, path);
  strcpy(fullname + strlen(path), selected);
  clearBuf(scrbuf);
  //read the header
  //img = fopen("/documents/bmpviewer/test.tns", "rb");
  img = fopen(fullname, "rb");
  fread(header, 1, 0x36, img);
  //compute some ints (image data size, width, and height) from the header
  int bmpsize = header[34] + 
                256 * header[35] + 
                65536 * header[36] + 
                65536 * 256 * header[37]; 
  int w = header[18] + 
          256 * header[19] + 
          65536 * header[20] + 
          65536 * 256 * header[21]; 
  int h = header[22] + 
          256 * header[23] + 
          65536 * header[24] + 
          65536 * 256 * header[25]; 
  //number of pixels
  int pxsize = bmpsize / 3;
  //allocate byte data and pixel (grayscale) data
  char* data = (char*) malloc(bmpsize);
  char* pxdata = (char*) malloc(pxsize);
  //read in data and close image
  fread(data, 1, bmpsize, img);
  fclose(img);
  //convert RGB to grayscale
  for (i = 0; i < pxsize; i++) {
    pxdata[i] = (data[3 * i] + data[3 * i + 1] + data[3 * i + 2]) / 48;
  }
  //draw to the buffer and display it
  for (x = 0; x < w; x++) {
    for (y = 0; y < h; y++) {
      setPixelBuf(scrbuf, x, h - 1 - y, pxdata[w * y + x]);
    }
  }
  while (!isKeyPressed(KEY_NSPIRE_ESC)) {
    if (isKeyPressed(KEY_NSPIRE_PLUS)) {
      CONTRAST++;
      if (CONTRAST > 0x95) CONTRAST = 0x95;
    }

    if (isKeyPressed(KEY_NSPIRE_MINUS)) {
      CONTRAST--;
      if (CONTRAST < 0x6B) CONTRAST = 0x6B;
    }

    for (i = 0; i < 3; i++) {
      refresh(scrbuf);
    }
  }  
  free(fullname);
  free(filenames);
  free(header);
  free(scrbuf);
  free(data);
  free(pxdata);
  return 0;
}