#include <types.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <drivers/ide.h>

#include <fs/ssfs.h>



#define SSFS_START_LBA 16
#define SSFS_FILE_HEADER_SIZE_BYTES 32


int ssfs_read_file(const char* name, void* buffer, int size)
{
  if (strlen(name) > 15)
  {
    return -1;
  }
  
  uint8_t header_buf[512];
  int r = read_sector(16, header_buf);
  
  if (r != 0)
  {
    return -2;
  }

  ssfs_file_header_t f;
  memcpy(&f, header_buf, sizeof(f));

  if (strncmp(f.filename, name, 15) != 0)
  {
    return -3;
  }

  /* Clamp read size to actual file size */
  if (size > (int)f.num_bytes)
      size = (int)f.num_bytes;

  int total_read = 0;
  int sector_count = div_round_up(size, 512);
  uint8_t sector_data[512];

  for (int k = 0; k < sector_count; k++)
  {
    r = read_sector(f.start_sector + k, sector_data);
    
    if (r != 0)
    {
      return -4; /* I/O error */
    }

    int to_copy = size - total_read;
    
    if (to_copy > 512)
    {
      to_copy = 512;
    }

    memcpy((uint8_t*)buffer + total_read, sector_data, to_copy);
    total_read += to_copy;
  }

  return 0;
}


/* size is number of bytes */
int ssfs_write_file(const char* name, void* data, int size)
{
  ssfs_file_header_t* f = (ssfs_file_header_t*) malloc(sizeof(ssfs_file_header_t));
  memset(f, 0, sizeof(ssfs_file_header_t));
  
  if (strlen(name) > 15)
  {
    return -1;
  }
  
  strcpy(f->filename, name);
  f->num_sectors = 0;
  
  int sector_count = div_round_up(size, 512);
  
  uint8_t* buffer = (uint8_t*) malloc(sector_count * 512);
  
  memset(buffer, 0, sector_count * 512);
  memcpy(buffer, data, (size_t) size);
  
  int r = 0;
  
  f->start_sector = 32;
  
  for (int k = 0; k < sector_count; k++)
  {
    r = write_sector(f->start_sector + k, buffer + (k * 512));
    
    if (r != 0)
    {
      break;
    }
  }
  
  f->num_sectors = sector_count;
  f->num_bytes = (uint32_t) size;
  
  uint8_t header_buf[512];
  memset(header_buf, 0, 512);
  memcpy(header_buf, f, sizeof(*f));
  write_sector(16, header_buf);
  
  free(buffer);
  free(f);
  
  return 0;
}