/*
 *     hacha.c: Une archivos con el Hacha de Windows en Linux.
 * Copyright  (c) BatchDrake 2006 <BatchDrake@gmail.com>
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */
 
 
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

inline char *xstrdup (char *str)
{
  register char *r;

  if ((r = strdup (str)) == NULL)
    abort ();

  return r;
}

inline void *xmalloc (int size)
{
  register void *r;

  if ((r = malloc (size)) == NULL)
    abort ();

  return r;
}

static int __expect_hacha_boundary (FILE *fp)
{
  char buf [5];
  
  if (fread (buf, 5, 1, fp) < 1)
    return -1;
  
  if (memcmp (buf, "?????", 5) == 0)
    return 1;
  
  return 0;
}

void expect_hacha_marker (char *file, FILE *fp)
{
  int i;
  
  if ((i = __expect_hacha_boundary (fp)) == -1)
  {
    fprintf (stderr, "%s: Final de fichero inesperado. Archivo incompleto.\n", file);
    exit (1);
  }
  else if (i == 0)
  {
    fprintf (stderr, "%s: Separador interno no encontrado (¿formato no reconocido?). Se aborta.\n", file);
    exit (1);
  }
}

int string_end (FILE *fp)
{
  int r;
  
  r = __expect_hacha_boundary (fp);
  
  fseek (fp, -5, SEEK_CUR);
  
  return r;
}

char *get_hacha_string (FILE *fp)
{
  char buffer [256];
  char *result;
  int i;
  
  for (i = 0; i < 256 && !string_end (fp); i++)
    fread (&buffer[i], 1, 1, fp);
  
  buffer[i] = '\0';
  
  return xstrdup (buffer);
}

int main (int argc, char **argv)
{
  FILE *fp;
  FILE *out;
  FILE *this_input;
  
  char b;
  char *out_file, *tmp;
  char *in_files, *template;
  
  char buffer [4096];
  int size;
  int frag_size;
  int chunk_size;
  int version;
  
  register int frsize;
  register int i, p;
  register int total_amount;
  
  if (argc != 2)
  {
    fprintf (stderr, "Forma de uso: %s archivo.0\n", argv[0]);
    return 0;
  }
  
  fp = fopen (argv[1], "rb");
  if (fp == NULL)
  {
    perror (argv[1]);
    exit (2);
  }
  
  expect_hacha_marker (argv[1], fp);
  
  printf ("\n");
  
  fread (&version, sizeof (int), 1, fp);
  printf ("\tHacha version 0.%d\n", version);
  expect_hacha_marker (argv[1], fp);
  out_file = get_hacha_string (fp);
  expect_hacha_marker (argv[1], fp);
  printf ("\tArchivo de salida: %s\n", out_file);
  tmp = get_hacha_string (fp);
  
  if (!sscanf (tmp, "%i", &size))
  {
    fprintf (stderr, "%s: Error en formato de tamaño total.\n", argv[1]);
    exit (3);
  }
  
  free (tmp);
  
  expect_hacha_marker (argv[1], fp);
  
  tmp = get_hacha_string (fp);
  
  if (!sscanf (tmp, "%i", &frag_size))
  {
    fprintf (stderr, "%s: Error en formato de tamaño total.\n", argv[1]);
    exit (3);
  }
  
  free (tmp);
  
  expect_hacha_marker (argv[1], fp);
  
  
  printf ("\tTamaño total: %g MiB\n", (float) size / (1024.0 * 1024.0));
  printf ("\tTamaño por fragmento: %g MiB\n", (float) frag_size / (1024.0 * 1024.0));
  printf ("\nSe espera que el archivo se haya dividido en %d partes.\n\n", size / frag_size + ((size % frag_size) ? 1 : 0));

  
  
  frsize = frag_size;
  out = fopen (out_file, "wb");
  if (out == NULL)
  {
    perror (out_file);
    exit (4);
  }
  
  template = xstrdup (argv[1]);
  in_files = xmalloc (strlen (argv[1]) + 5);
  
  strcpy (in_files, argv[1]);
  template [strlen (template) - 1] = '\0';
  
  for (i = 0, total_amount = 0; total_amount < size; i++)
  {
    printf ("Ligando fichero nº %d... ", i + 1);
    fflush (stdout);
    
    if (i)
    {
      sprintf (in_files, "%s%d", template, i);
      this_input = fopen (in_files, "rb");
      if (this_input == NULL)
      {
        perror (in_files);
        fprintf (stderr, "El archivo es necesario para la recomposición pero no se ha podido abrir. Se aborta.\n");
        unlink (out_file);
        
        exit (1);
      }
    }
    else
      this_input = fp;
    
    if (total_amount + frsize > size)
      frsize = size - total_amount;
    
    for (p = 0; p < frsize; )
    {
      chunk_size = ((p + 4096) <= frsize) ? 4096 : frsize - p;
      
      if ((p % 4096) == 0 || chunk_size < 4096)
        fprintf (stderr, "%3d%%\033[4D", ((p + chunk_size)) / (frsize / 100));
      if (fread (buffer, chunk_size, 1, this_input) < 1)
      {
        fprintf (stderr, "%s: fatal: El fichero está incompleto (¿descarga interrumpida?). Se aborta.\n", in_files);
        unlink (out_file);
        
        exit (1);
      }
      
      if (fwrite (buffer, chunk_size, 1, out) < 1)
      {
        perror (out_file);
        
        fprintf (stderr, "%s: fatal: Ha ocurrido un problema al escribir el fichero resultante. Se aborta.\n", in_files);
        unlink (out_file);
      }
      
      p += chunk_size;
    }
    
    total_amount += p;
    
    printf ("Ok  \n");
  }
  
  
  printf ("\nTodo bien.\n");
  
  return 0;
}