/*
     This file is part of GNUnet.
     (C) 2009, 2010 Christian Grothoff (and other contributing authors)

     GNUnet 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 3, or (at your
     option) any later version.

     GNUnet 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 GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/

/**
 * @file fs/gnunet-service-fs_indexing.c
 * @brief program that provides indexing functions of the file-sharing service
 * @author Christian Grothoff
 */
#include "platform.h"
#include <float.h>
#include "gnunet_core_service.h"
#include "gnunet_datastore_service.h"
#include "gnunet_peer_lib.h"
#include "gnunet_protocols.h"
#include "gnunet_signatures.h"
#include "gnunet_util_lib.h"
#include "gnunet-service-fs.h"
#include "gnunet-service-fs_indexing.h"
#include "fs.h"

/**
 * In-memory information about indexed files (also available
 * on-disk).
 */
struct IndexInfo
{
  
  /**
   * This is a linked list.
   */
  struct IndexInfo *next;

  /**
   * Name of the indexed file.  Memory allocated
   * at the end of this struct (do not free).
   */
  const char *filename;

  /**
   * Context for transmitting confirmation to client,
   * NULL if we've done this already.
   */
  struct GNUNET_SERVER_TransmitContext *tc;

  /**
   * Context for hashing of the file.
   */
  struct GNUNET_CRYPTO_FileHashContext *fhc;
  
  /**
   * Hash of the contents of the file.
   */
  GNUNET_HashCode file_id;

};


/**
 * Linked list of indexed files.
 */
static struct IndexInfo *indexed_files;

/**
 * Maps hash over content of indexed files to the respective filename.
 * The filenames are pointers into the indexed_files linked list and
 * do not need to be freed.
 */
static struct GNUNET_CONTAINER_MultiHashMap *ifm;

/**
 * Our configuration.
 */
static const struct GNUNET_CONFIGURATION_Handle *cfg;

/**
 * Datastore handle.  Created and destroyed by code in
 * gnunet-service-fs (this is an alias).
 */
static struct GNUNET_DATASTORE_Handle *dsh;


/**
 * Write the current index information list to disk.
 */ 
static void
write_index_list ()
{
  struct GNUNET_BIO_WriteHandle *wh;
  char *fn;
  struct IndexInfo *pos;  

  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_filename (cfg,
					       "FS",
					       "INDEXDB",
					       &fn))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
		  _("Configuration option `%s' in section `%s' missing.\n"),
		  "INDEXDB",
		  "FS");
      return;
    }
  wh = GNUNET_BIO_write_open (fn);
  if (NULL == wh)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
		  _("Could not open `%s'.\n"),
		  fn);
      GNUNET_free (fn);
      return;
    }
  pos = indexed_files;
  while (pos != NULL)
    {
      if ( (GNUNET_OK !=
	    GNUNET_BIO_write (wh,
			      &pos->file_id,
			      sizeof (GNUNET_HashCode))) ||
	   (GNUNET_OK !=
	    GNUNET_BIO_write_string (wh,
				     pos->filename)) )
	break;
      pos = pos->next;
    }
  if (GNUNET_OK != 
      GNUNET_BIO_write_close (wh))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
		  _("Error writing `%s'.\n"),
		  fn);
      GNUNET_free (fn);
      return;
    }
  GNUNET_free (fn);
}


/**
 * Read index information from disk.
 */
static void
read_index_list ()
{
  struct GNUNET_BIO_ReadHandle *rh;
  char *fn;
  struct IndexInfo *pos;  
  char *fname;
  GNUNET_HashCode hc;
  size_t slen;
  char *emsg;

  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_filename (cfg,
					       "FS",
					       "INDEXDB",
					       &fn))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
		  _("Configuration option `%s' in section `%s' missing.\n"),
		  "INDEXDB",
		  "FS");
      return;
    }
  if (GNUNET_NO == GNUNET_DISK_file_test (fn))
    {
      /* no index info yet */
      GNUNET_free (fn);
      return;
    }
  rh = GNUNET_BIO_read_open (fn);
  if (NULL == rh)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
		  _("Could not open `%s'.\n"),
		  fn);
      GNUNET_free (fn);
      return;
    }
  while ( (GNUNET_OK ==
	   GNUNET_BIO_read (rh,
			    "Hash of indexed file",
			    &hc,
			    sizeof (GNUNET_HashCode))) &&
	  (GNUNET_OK ==
	   GNUNET_BIO_read_string (rh, 
				   "Name of indexed file",
				   &fname,
				   1024 * 16)) &&
	  (fname != NULL) )
    {
      slen = strlen (fname) + 1;
      pos = GNUNET_malloc (sizeof (struct IndexInfo) + slen);
      pos->file_id = hc;
      pos->filename = (const char *) &pos[1];
      memcpy (&pos[1], fname, slen);
      if (GNUNET_SYSERR ==
	  GNUNET_CONTAINER_multihashmap_put (ifm,
					     &hc,
					     (void*) pos->filename,
					     GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY))
	{
	  GNUNET_free (pos);
	}
      else
	{
	  pos->next = indexed_files;
	  indexed_files = pos;
	}
      GNUNET_free (fname);
    }
  if (GNUNET_OK != 
      GNUNET_BIO_read_close (rh, &emsg))
    GNUNET_free (emsg);
  GNUNET_free (fn);
}


/**
 * We've validated the hash of the file we're about to index.  Signal
 * success to the client and update our internal data structures.
 *
 * @param ii the index info entry for the request
 */
static void
signal_index_ok (struct IndexInfo *ii)
{
  if (GNUNET_SYSERR ==
      GNUNET_CONTAINER_multihashmap_put (ifm,
					 &ii->file_id,
					 (void*) ii->filename,
					 GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
		  _("Index request received for file `%s' is already indexed as `%s'.  Permitting anyway.\n"),
		  ii->filename,
		  (const char*) GNUNET_CONTAINER_multihashmap_get (ifm,
								   &ii->file_id));
      GNUNET_SERVER_transmit_context_append_data (ii->tc,
						  NULL, 0,
						  GNUNET_MESSAGE_TYPE_FS_INDEX_START_OK);
      GNUNET_SERVER_transmit_context_run (ii->tc,
					  GNUNET_TIME_UNIT_MINUTES);
      GNUNET_free (ii);
      return;
    }
  ii->next = indexed_files;
  indexed_files = ii;
  write_index_list ();
  GNUNET_SERVER_transmit_context_append_data (ii->tc,
					      NULL, 0,
					      GNUNET_MESSAGE_TYPE_FS_INDEX_START_OK);
  GNUNET_SERVER_transmit_context_run (ii->tc,
				      GNUNET_TIME_UNIT_MINUTES);
  ii->tc = NULL;
}


/**
 * Function called once the hash computation over an
 * indexed file has completed.
 *
 * @param cls closure, our publishing context
 * @param res resulting hash, NULL on error
 */
static void 
hash_for_index_val (void *cls,
		    const GNUNET_HashCode *
		    res)
{
  struct IndexInfo *ii = cls;

  ii->fhc = NULL;
  if ( (res == NULL) ||
       (0 != memcmp (res,
		     &ii->file_id,
		     sizeof(GNUNET_HashCode))) )
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
		  _("Hash mismatch trying to index file `%s' which has hash `%s'\n"),
		  ii->filename,
		  GNUNET_h2s (res));
#if DEBUG_FS
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
		  "Wanted `%s'\n",
		  GNUNET_h2s (&ii->file_id));
#endif
      GNUNET_SERVER_transmit_context_append_data (ii->tc,
						  NULL, 0,
						  GNUNET_MESSAGE_TYPE_FS_INDEX_START_FAILED);
      GNUNET_SERVER_transmit_context_run (ii->tc,
					  GNUNET_TIME_UNIT_MINUTES);
      GNUNET_free (ii);
      return;
    }
  signal_index_ok (ii);
}


/**
 * Handle INDEX_START-message.
 *
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message
 */
void
GNUNET_FS_handle_index_start (void *cls,
			      struct GNUNET_SERVER_Client *client,
			      const struct GNUNET_MessageHeader *message)
{
  const struct IndexStartMessage *ism;
  char *fn;
  uint16_t msize;
  struct IndexInfo *ii;
  size_t slen;
  uint64_t dev;
  uint64_t ino;
  uint64_t mydev;
  uint64_t myino;

  msize = ntohs(message->size);
  if ( (msize <= sizeof (struct IndexStartMessage)) ||
       ( ((const char *)message)[msize-1] != '\0') )
    {
      GNUNET_break (0);
      GNUNET_SERVER_receive_done (client,
				  GNUNET_SYSERR);
      return;
    }
  ism = (const struct IndexStartMessage*) message;
  if (0 != ism->reserved)
    {
      GNUNET_break (0);
      GNUNET_SERVER_receive_done (client,
				  GNUNET_SYSERR);
      return;
    }
  fn = GNUNET_STRINGS_filename_expand ((const char*) &ism[1]);
  if (fn == NULL)
    {
      GNUNET_SERVER_receive_done (client,
				  GNUNET_SYSERR);
      return;
    }
  dev = GNUNET_ntohll (ism->device);
  ino = GNUNET_ntohll (ism->inode);
  ism = (const struct IndexStartMessage*) message;
  slen = strlen (fn) + 1;
  ii = GNUNET_malloc (sizeof (struct IndexInfo) + slen);
  ii->filename = (const char*) &ii[1];
  memcpy (&ii[1], fn, slen);
  ii->file_id = ism->file_id;  
#if DEBUG_FS
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Received `%s' message for file `%s'\n",
	      "START_INDEX",
	      ii->filename);
#endif

  ii->tc = GNUNET_SERVER_transmit_context_create (client);
  mydev = 0;
  myino = 0;
  if ( ( (dev != 0) ||
	 (ino != 0) ) &&
       (GNUNET_OK == GNUNET_DISK_file_get_identifiers (fn,
						       &mydev,
						       &myino)) &&
       ( (dev == mydev) &&
	 (ino == myino) ) )
    {      
      /* fast validation OK! */
      signal_index_ok (ii);
      GNUNET_free (fn);
      return;
    }
#if DEBUG_FS
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Mismatch in file identifiers (%llu != %llu or %u != %u), need to hash.\n",
	      (unsigned long long) ino,
	      (unsigned long long) myino,
	      (unsigned int) dev,
	      (unsigned int) mydev);
#endif
  /* slow validation, need to hash full file (again) */
  ii->fhc = GNUNET_CRYPTO_hash_file (GNUNET_SCHEDULER_PRIORITY_IDLE,
				     fn,
				     HASHING_BLOCKSIZE,
				     &hash_for_index_val,
				     ii);
  if (ii->fhc == NULL)    
    hash_for_index_val (ii, NULL);    
  GNUNET_free (fn);
}


/**
 * Handle INDEX_LIST_GET-message.
 *
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message
 */
void
GNUNET_FS_handle_index_list_get (void *cls,
				 struct GNUNET_SERVER_Client *client,
				 const struct GNUNET_MessageHeader *message)
{
  struct GNUNET_SERVER_TransmitContext *tc;
  struct IndexInfoMessage *iim;
  char buf[GNUNET_SERVER_MAX_MESSAGE_SIZE - 1];
  size_t slen;
  const char *fn;
  struct IndexInfo *pos;

  tc = GNUNET_SERVER_transmit_context_create (client);
  iim = (struct IndexInfoMessage*) buf;
  pos = indexed_files;
  while (NULL != pos)
    {
      fn = pos->filename;
      slen = strlen (fn) + 1;
      if (slen + sizeof (struct IndexInfoMessage) >= GNUNET_SERVER_MAX_MESSAGE_SIZE)
	{
	  GNUNET_break (0);
	  break;
	}
      iim->header.type = htons (GNUNET_MESSAGE_TYPE_FS_INDEX_LIST_ENTRY);
      iim->header.size = htons (slen + sizeof (struct IndexInfoMessage));
      iim->reserved = 0;
      iim->file_id = pos->file_id;
      memcpy (&iim[1], fn, slen);
      GNUNET_SERVER_transmit_context_append_message (tc,
						     &iim->header);
      pos = pos->next;
    }
  GNUNET_SERVER_transmit_context_append_data (tc,
					      NULL, 0,
					      GNUNET_MESSAGE_TYPE_FS_INDEX_LIST_END);
  GNUNET_SERVER_transmit_context_run (tc,
				      GNUNET_TIME_UNIT_MINUTES);
}


/**
 * Handle UNINDEX-message.
 *
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message
 */
void
GNUNET_FS_handle_unindex (void *cls,
			  struct GNUNET_SERVER_Client *client,
			  const struct GNUNET_MessageHeader *message)
{
  const struct UnindexMessage *um;
  struct IndexInfo *pos;
  struct IndexInfo *prev;
  struct IndexInfo *next;
  struct GNUNET_SERVER_TransmitContext *tc;
  int found;

  um = (const struct UnindexMessage*) message;
  if (0 != um->reserved)
    {
      GNUNET_break (0);
      GNUNET_SERVER_receive_done (client,
				  GNUNET_SYSERR);
      return;
    }
  found = GNUNET_NO;
  prev = NULL;
  pos = indexed_files;
  while (NULL != pos)
    {
      next = pos->next;
      if (0 == memcmp (&pos->file_id,
		       &um->file_id,
		       sizeof (GNUNET_HashCode)))
	{
	  if (prev == NULL)
	    indexed_files = next;
	  else
	    prev->next = next;
	  GNUNET_break (GNUNET_OK ==
			GNUNET_CONTAINER_multihashmap_remove (ifm,
							      &pos->file_id,
							      (void*) pos->filename));
	  GNUNET_free (pos);
	  found = GNUNET_YES;
	}
      else
	{
	  prev = pos;
	}
      pos = next;
    }
#if DEBUG_FS
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Client requested unindexing of file `%s': %s\n",
	      GNUNET_h2s (&um->file_id),
	      found ? "found" : "not found");
#endif
  if (GNUNET_YES == found)    
    write_index_list ();
  tc = GNUNET_SERVER_transmit_context_create (client);
  GNUNET_SERVER_transmit_context_append_data (tc,
					      NULL, 0,
					      GNUNET_MESSAGE_TYPE_FS_UNINDEX_OK);
  GNUNET_SERVER_transmit_context_run (tc,
				      GNUNET_TIME_UNIT_MINUTES);
}


/**
 * Continuation called from datastore's remove
 * function.
 *
 * @param cls unused
 * @param success did the deletion work?
 * @param msg error message
 */
static void
remove_cont (void *cls,
	     int success,
	     const char *msg)
{
  if (GNUNET_OK != success)
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
		_("Failed to delete bogus block: %s\n"),
		msg);
}


/**
 * We've received an on-demand encoded block from the datastore.
 * Attempt to do on-demand encoding and (if successful), call the
 * continuation with the resulting block.  On error, clean up and ask
 * the datastore for more results.
 *
 * @param key key for the content
 * @param size number of bytes in data
 * @param data content stored
 * @param type type of the content
 * @param priority priority of the content
 * @param anonymity anonymity-level for the content
 * @param expiration expiration time for the content
 * @param uid unique identifier for the datum;
 *        maybe 0 if no unique identifier is available
 * @param cont function to call with the actual block (at most once, on success)
 * @param cont_cls closure for cont
 * @return GNUNET_OK on success
 */
int
GNUNET_FS_handle_on_demand_block (const GNUNET_HashCode * key,
				  uint32_t size,
				  const void *data,
				  enum GNUNET_BLOCK_Type type,
				  uint32_t priority,
				  uint32_t anonymity,
				  struct GNUNET_TIME_Absolute
				  expiration, uint64_t uid,
				  GNUNET_DATASTORE_DatumProcessor cont,
				  void *cont_cls)
{
  const struct OnDemandBlock *odb;
  GNUNET_HashCode nkey;
  struct GNUNET_CRYPTO_AesSessionKey skey;
  struct GNUNET_CRYPTO_AesInitializationVector iv;
  GNUNET_HashCode query;
  ssize_t nsize;
  char ndata[DBLOCK_SIZE];
  char edata[DBLOCK_SIZE];
  const char *fn;
  struct GNUNET_DISK_FileHandle *fh;
  uint64_t off;

  if (size != sizeof (struct OnDemandBlock))
    {
      GNUNET_break (0);
      GNUNET_DATASTORE_remove (dsh,
			       key,
			       size,
			       data,
			       -1, -1,
			       GNUNET_TIME_UNIT_FOREVER_REL,
			       &remove_cont,
			       NULL);
      return GNUNET_SYSERR;
    }
  odb = (const struct OnDemandBlock*) data;
  off = GNUNET_ntohll (odb->offset);
  fn = (const char*) GNUNET_CONTAINER_multihashmap_get (ifm,
							&odb->file_id);
  fh = NULL;
  if ( (NULL == fn) ||
       (NULL == (fh = GNUNET_DISK_file_open (fn, 
					     GNUNET_DISK_OPEN_READ,
					     GNUNET_DISK_PERM_NONE))) ||
       (off !=
	GNUNET_DISK_file_seek (fh,
			       off,
			       GNUNET_DISK_SEEK_SET)) ||
       (-1 ==
	(nsize = GNUNET_DISK_file_read (fh,
					ndata,
					sizeof (ndata)))) )
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
		  _("Could not access indexed file `%s' (%s) at offset %llu: %s\n"),
		  GNUNET_h2s (&odb->file_id),
		  fn,
		  (unsigned long long) off,
		  (fn == NULL) ? _("not indexed") : STRERROR (errno));
      if (fh != NULL)
	GNUNET_DISK_file_close (fh);
      GNUNET_DATASTORE_remove (dsh,
			       key,
			       size,
			       data,
			       -1, -1,
			       GNUNET_TIME_UNIT_FOREVER_REL,
			       &remove_cont,
			       NULL);
      return GNUNET_SYSERR;
    }
  GNUNET_DISK_file_close (fh);
  GNUNET_CRYPTO_hash (ndata,
		      nsize,
		      &nkey);
  GNUNET_CRYPTO_hash_to_aes_key (&nkey, &skey, &iv);
  GNUNET_CRYPTO_aes_encrypt (ndata,
			     nsize,
			     &skey,
			     &iv,
			     edata);
  GNUNET_CRYPTO_hash (edata,
		      nsize,
		      &query);
  if (0 != memcmp (&query, 
		   key,
		   sizeof (GNUNET_HashCode)))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
		  _("Indexed file `%s' changed at offset %llu\n"),
		  fn,
		  (unsigned long long) off);
      GNUNET_DATASTORE_remove (dsh,
			       key,
			       size,
			       data,
			       -1, -1,
			       GNUNET_TIME_UNIT_FOREVER_REL,
			       &remove_cont,
			       NULL);
      return GNUNET_SYSERR;
    }
#if DEBUG_FS
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
		  "On-demand encoded block for query `%s'\n",
		  GNUNET_h2s (key));
#endif  
  cont (cont_cls,
	key,
	nsize,
	edata,
	GNUNET_BLOCK_TYPE_FS_DBLOCK,
	priority,
	anonymity,
	expiration,
	uid);
  return GNUNET_OK;
}


/**
 * Shutdown the module.
 */
void
GNUNET_FS_indexing_done ()
{
  struct IndexInfo *pos;  

  GNUNET_CONTAINER_multihashmap_destroy (ifm);
  ifm = NULL;
  while (NULL != (pos = indexed_files))
    {
      indexed_files = pos->next;
      if (pos->fhc != NULL)
	GNUNET_CRYPTO_hash_file_cancel (pos->fhc);
      GNUNET_free (pos);
    }
  cfg = NULL;
}


/**
 * Initialize the indexing submodule.
 *
 * @param c configuration to use
 * @param d datastore to use
 */
int
GNUNET_FS_indexing_init (const struct GNUNET_CONFIGURATION_Handle *c,
			 struct GNUNET_DATASTORE_Handle *d)
{
  cfg = c;
  dsh = d;
  ifm = GNUNET_CONTAINER_multihashmap_create (128);
  read_index_list ();
  return GNUNET_OK;
}

/* end of gnunet-service-fs_indexing.c */