/*
  Copyright 2009 Nathan Phillip Brink

  This file is a part of DistRen.

  DistRen is free software: you can redistribute it and/or modify
  it under the terms of the GNU Affero General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  DistRen 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 Affero General Public License for more details.

  You should have received a copy of the GNU Affero General Public License
  along with DistRen.  If not, see <http://www.gnu.org/licenses/>.

*/

#include "libremoteio.h"
#include "execio.h"
#include "asprintf.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

/* local */

int _remoteio_ssh_open(struct remoteio *rem, struct remoteio_server *server);
int _remoteio_ssh_read(struct remoteio *rem, void *buf, size_t len, size_t *bytesread);
int _remoteio_ssh_write(struct remoteio *rem, void *buf, size_t len, size_t *byteswritten);
int _remoteio_ssh_close(struct remoteio *rem);

/**
  lookup table for different methods of remoteio:
  the enum remoteio_method is the index of the entry to use for that method. 
  Regardless, a NULL terminator is required because the configuration function
  searches through this table for the method specified in the config file.
*/
struct remoteio_method_funcmap funcmap[] = 
  {
    /* [REMOTEIO_METHOD_SSH] */
    {&_remoteio_ssh_open, &_remoteio_ssh_read, &_remoteio_ssh_write, &_remoteio_ssh_close, "ssh"},
    {NULL, NULL, NULL, NULL, NULL}
  };

struct remoteio_server *remoteio_getserver(const struct remoteio_opts *opts, const char *servername);

int remoteio_config(cfg_t *cfg, struct remoteio_opts *opts)
{
  size_t numservers;
  size_t counter;
  static int haslisted_methods = 0;
  
  struct remoteio_server *aserver;

  opts->servers = malloc(sizeof(struct remoteio_server));
  if(!opts->servers)
    {
      fprintf(stderr, "@todo cleanup!\n");
      abort();
    }
  
  aserver = opts->servers;
  
  numservers = cfg_size(cfg, "server"); 
  for(counter = 0; counter < numservers; counter ++)
    {
      cfg_t *cfg_aserver;
      char *method;
      
      cfg_aserver = cfg_getnsec(cfg, "server", counter);
      
      if(!aserver) /*< if the malloc in the previous loop failed */
	abort();
      
      aserver->name = strdup(cfg_title(cfg_aserver));
      aserver->hostname = strdup(cfg_getstr(cfg_aserver, "hostname"));
      aserver->username = strdup(cfg_getstr(cfg_aserver, "username"));

      aserver->method = REMOTEIO_METHOD_MAX;
      method = cfg_getstr(cfg_aserver, "method");
      for(counter = 0; funcmap[counter].name; counter ++)
	if(strcmp(method, funcmap[counter].name) == 0)
	  aserver->method = REMOTEIO_METHOD_SSH;
      if(aserver->method == REMOTEIO_METHOD_MAX)
	{
	  fprintf(stderr, "No such method as %s\n", method);
	  if(!haslisted_methods)
	    {
	      fprintf(stderr, "Available methods:\n");
	      for(counter = 0; funcmap[counter].name; counter ++)
		fprintf(stderr, "\t%s\n", funcmap[counter].name);
	      
	      haslisted_methods ++;
	    }
	  abort();
	}
      
      if(counter < numservers - 1)
	{
	  aserver->next = malloc(sizeof(struct remoteio_server));
	  aserver = aserver->next;
	}
    }
  aserver->next = NULL;
  
  return 0;
}



int remoteio_open(struct remoteio **remoteio, struct remoteio_opts *opts, const char *servername)
{
  struct remoteio_server *theserver;
  struct remoteio *rem;

  int tmp;

  if(!opts)
    {
      fprintf(stderr, "%s:%d: no null opts!\n\tThis is a bug, please report it (after making sure it isn't already reported)\n", __FILE__, __LINE__);
      return 1;
    }

  theserver = remoteio_getserver(opts, servername);
  if(!theserver)
    {
      fprintf(stderr, "%s:%d: Could not find server named ``%s''\n", __FILE__, __LINE__, servername);
      return 1;
    }

  if(theserver->method >= REMOTEIO_METHOD_MAX
     || theserver->method < 0)
    {
      fprintf(stderr, "%s:%d: Unsupported remoteio method %d\n\tThis is a bug, probably indicating memory corruption. This is, of course, probably my fault (not your hardware's) ;-)\n", __FILE__, __LINE__, theserver->method);
      return 1;
    }
  rem = malloc(sizeof(struct remoteio));
  if(!rem)
    {
      fprintf(stderr, "OOM\n");
      return 2;
    }
  *remoteio = rem;

  rem->method = theserver->method;
  rem->opts = opts;

  tmp = funcmap[theserver->method].open_func(rem, theserver);
  if(tmp)
    {
      fprintf(stderr, "Error using method %s for server ``%s''", funcmap[theserver->method].name, servername);
      free(rem);
      *remoteio = NULL;
      return tmp;
    }
  
  return 0;
}

int remoteio_read(struct remoteio *rem, void *buf, size_t len, size_t *bytesread)
{
  return funcmap[rem->method].read_func(rem, buf, len, bytesread);
}

int remoteio_write(struct remoteio *rem, void *buf, size_t len, size_t *byteswritten)
{
  return funcmap[rem->method].write_func(rem, buf, len, byteswritten);
}

int remoteio_close(struct remoteio *rem)
{
  int rtn;
  
  rtn = funcmap[rem->method].close_func(rem);
  free(rem);
  
  return rtn;
}


struct remoteio_server *remoteio_getserver(const struct remoteio_opts *opts, const char *servername)
{
  struct remoteio_server *aserver;
  
  for(aserver = opts->servers;
      aserver;
      aserver = aserver->next)
    if(!strcmp(servername, aserver->name))
      return aserver;

  return (struct remoteio_server *)NULL;
}




/**
   different remoteio methods' implementations:
 */

/*
  SSH, via execio
*/

int _remoteio_ssh_open(struct remoteio *rem, struct remoteio_server *server)
{
  char *userhost;
  char *sshargs[] = {rem->opts->ssh_command, NULL /* userhost */, "distrend", "-d", (char *)NULL};

  int rtn;

  if(server->username)
    _distren_asprintf(&userhost, "%s@%s", server->username, server->hostname);
  else
    userhost = strdup(server->hostname);
  sshargs[1] = userhost;

  rtn = execio_open( &rem->execio, "ssh", sshargs);
  if(rtn)
    {
      fprintf(stderr, "error opening remoteio channel to ssh userhost ``%s''\n" , userhost);
      free(userhost);
      return 1;
    }
  free(userhost);
  
  return 0;
}

int _remoteio_ssh_read(struct remoteio *rem, void *buf, size_t len, size_t *bytesread)
{
  return execio_read(rem->execio, buf, len, bytesread);
}

int _remoteio_ssh_write(struct remoteio *rem, void *buf, size_t len, size_t *byteswritten)
{
  return execio_write(rem->execio, buf, len, byteswritten);
}

int _remoteio_ssh_close(struct remoteio *rem)
{
  int rtn;
  
  rtn = execio_close(rem->execio);
  if(rtn)
    fprintf(stderr, "%s:%d: error closing execio\n", __FILE__, __LINE__);
  
  return rtn;
}