/*
 * Copyright (C) OpenTX
 *
 * Based on code named
 *   th9x - http://code.google.com/p/th9x
 *   er9x - http://code.google.com/p/er9x
 *   gruvin9x - http://code.google.com/p/gruvin9x
 *
 * License GPLv2: http://www.gnu.org/licenses/gpl-2.0.html
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include "opentx.h"

uint8_t * lcdLoadBitmap(uint8_t * bmp, const char * filename, uint8_t width, uint8_t height)
{
  FIL bmpFile;
  UINT read;
  uint8_t bmpBuf[LCD_W]; /* maximum with LCD_W */
  uint8_t * buf = &bmpBuf[0];

  if (width > LCD_W) {
    return NULL;
  }

  FRESULT result = f_open(&bmpFile, filename, FA_OPEN_EXISTING | FA_READ);
  if (result != FR_OK) {
    return NULL;
  }

  if (f_size(&bmpFile) < 14) {
    f_close(&bmpFile);
    return NULL;
  }

  result = f_read(&bmpFile, buf, 14, &read);
  if (result != FR_OK || read != 14) {
    f_close(&bmpFile);
    return NULL;
  }

  if (buf[0] != 'B' || buf[1] != 'M') {
    f_close(&bmpFile);
    return NULL;
  }

  uint32_t fsize  = *((uint32_t *)&buf[2]);
  uint32_t hsize  = *((uint32_t *)&buf[10]); /* header size */

  uint32_t len = limit((uint32_t)4, (uint32_t)(hsize-14), (uint32_t)32);
  result = f_read(&bmpFile, buf, len, &read);
  if (result != FR_OK || read != len) {
    f_close(&bmpFile);
    return NULL;
  }

  uint32_t ihsize = *((uint32_t *)&buf[0]); /* more header size */

  /* invalid header size */
  if (ihsize + 14 > hsize) {
    f_close(&bmpFile);
    return NULL;
  }

  /* sometimes file size is set to some headers size, set a real size in that case */
  if (fsize == 14 || fsize == ihsize + 14) {
    fsize = f_size(&bmpFile) - 2;
  }

  /* declared file size less than header size */
  if (fsize <= hsize) {
    f_close(&bmpFile);
    return NULL;
  }

  uint32_t w, h;

  switch (ihsize){
    case  40: // windib
    case  56: // windib v3
    case  64: // OS/2 v2
    case 108: // windib v4
    case 124: // windib v5
      w  = *((uint32_t *)&buf[4]);
      h = *((uint32_t *)&buf[8]);
      buf += 12;
      break;
    case  12: // OS/2 v1
      w  = *((uint16_t *)&buf[4]);
      h = *((uint16_t *)&buf[6]);
      buf += 8;
      break;
    default:
      f_close(&bmpFile);
      return NULL;
  }

  if (*((uint16_t *)&buf[0]) != 1) { /* planes */
    f_close(&bmpFile);
    return NULL;
  }

  if (w > width || h > height) {
    f_close(&bmpFile);
    return NULL;
  }

  uint16_t depth = *((uint16_t *)&buf[2]);

  buf = &bmpBuf[0];

  if (f_lseek(&bmpFile, hsize) != FR_OK) {
    f_close(&bmpFile);
    return NULL;
  }

  uint8_t * dest = bmp;

  *dest++ = w;
  *dest++ = h;

  memset(dest, 0, BITMAP_BUFFER_SIZE(w, h) - 2);

  uint8_t rowSize = (w + 7) / 8;

  switch (depth) {
    case 1:
      for (int8_t i=h-1; i>=0; i--) {
        result = f_read(&bmpFile, buf, rowSize, &read);
        if (result != FR_OK || read != rowSize) {
          f_close(&bmpFile);
          return NULL;
        }

        for (uint8_t j=0; j<w; j++) {
          if (!(buf[j/8] & (1<<(7-(j%8))))) {
            uint8_t *dst = dest + i / 8 * w + j;
            *dst |= (0x01 << (i & 0x07));
          }
        }
      }
      break;

    default:
      f_close(&bmpFile);
      return NULL;
  }

  f_close(&bmpFile);
  return bmp;
}