#ifndef _FAT16_H
#define _FAT16_H

#include <stdint.h>
#include <string.h>
#include <ctype.h>

#define FAT16_MAX_FILENAME 12 /* 8.3 + null */
#define SECTOR_SIZE 512

typedef struct {
  uint16_t bytes_per_sector;
  uint8_t sectors_per_cluster;
  uint16_t reserved_sector_count;
  uint8_t num_fats;
  uint16_t root_entry_count;
  uint16_t total_sectors_16;
  uint16_t sectors_per_fat;
  uint32_t fat_start_lba;
  uint32_t root_dir_lba;
  uint32_t data_start_lba;
  uint32_t total_sectors;
} fat16_fs_t;

typedef struct {
  char name[FAT16_MAX_FILENAME]; /* 8.3 format */
  uint8_t attr;
  uint16_t first_cluster;
  uint32_t size;
} fat16_file_t;

int fat16_mount(uint8_t drive);

int fat16_find_file(const char* name, fat16_file_t* out_file);

int fat16_create_file(const char* name, fat16_file_t* out_file);
int fat16_delete_file(const char* filename);

int fat16_read_file(fat16_file_t* file, void* buffer);
int fat16_write_file(fat16_file_t* file, const void* buffer, uint32_t size);


/*
  Small helper function that converts a normal filename like "test.txt" into FAT16 8.3 uppercase format padded with spaces.
  This makes creating and writing files much easier.
*/
static void filename_to_83(const char* input, char out[12])
{
  memset(out, ' ', 11);
  out[11] = '\0';

  /* Find dot */
  const char* dot = strchr(input, '.');
  size_t name_len = dot ? (size_t) (dot - input) : strlen(input);
  
  if (name_len > 8)
  {
    name_len = 8;
  }
  
  for (size_t i = 0; i < name_len; i++)
  {
    out[i] = toupper((unsigned char)input[i]);
  }

  if (dot)
  {
    size_t ext_len = strlen(dot + 1);
    if (ext_len > 3) ext_len = 3;
    for (size_t i = 0; i < ext_len; i++)
    {
      out[8 + i] = toupper((unsigned char)dot[1 + i]);
    }
  }
}


#endif