/**********************************************************************
 *
 * sqlbrowsefilter.cpp -- 
 * Copyright (C) 2008  DL Consulting Ltd
 *
 * A component of the Greenstone digital library software
 * from the New Zealand Digital Library Project at the
 * University of Waikato, New Zealand.
 *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *********************************************************************/

#include "sqlbrowsefilter.h"
#include "fileutil.h"


sqlbrowsefilterclass::sqlbrowsefilterclass ()
{
  sql_db_ptr = NULL;
}


sqlbrowsefilterclass::~sqlbrowsefilterclass ()
{
}


void sqlbrowsefilterclass::configure (const text_t &key, const text_tarray &cfgline)
{
  filterclass::configure (key, cfgline);

  if (key == "indexstem")
  {
    indexstem = cfgline[0];
  }
}


bool sqlbrowsefilterclass::init (ostream &logout)
{
  outconvertclass text_t2ascii;

  if (!filterclass::init(logout)) return false;

  if (sql_db_ptr == NULL)
  {
    // most likely a configuration problem
    logout << text_t2ascii 
	   << "configuration error: sqlbrowsefilter contains a null sqldbclass\n\n";
    return false;
  }

  if (indexstem.empty())
  {
    indexstem = collection;
  }

  // get the filename for the database and make sure it exists
  sql_db_filename = filename_cat(dbhome, "collect", collection, "index", "text", indexstem);
  sql_db_filename += sql_db_ptr->getfileextension();
  if (!file_exists(sql_db_filename))
  {
    logout << text_t2ascii
	   << "warning: database \"" << sql_db_filename << "\" does not exist\n\n";
    return false;
  }

  return true;
}


void sqlbrowsefilterclass::filter (const FilterRequest_t &request,
				   FilterResponse_t &response,
				   comerror_t &err, ostream &logout)
{
  outconvertclass text_t2ascii;

  response.clear();
  err = noError;

  if (sql_db_ptr == NULL) {
    // most likely a configuration problem
    logout << text_t2ascii << "configuration error: sqlbrowsefilter contains a null sqldbclass\n\n";
    err = configurationError;
    return;
  }

  // open the database
  sql_db_ptr->setlogout (&logout);
  if (!sql_db_ptr->opendatabase (sql_db_filename, DB_READER, 100, false)) {
    // most likely a system problem (we have already checked that the database exists)
    logout << text_t2ascii << "system problem: open on database \"" << sql_db_filename << "\" failed\n\n";
    err = systemProblem;
    return;
  }

  // Request for the metadata values assigned to an element
  if ((request.filterResultOptions & FRmetadataValues) && !request.fields.empty())
  {
    text_t metadata_element_name = *(request.fields.begin());
    text_tarray metadata_values = sql_db_ptr->getmetadatavalues (metadata_element_name);

    // Create a map from metadata value to ResultDocInfo_t, to remove duplicate values and obtain occurrence counts
    map<text_t, ResultDocInfo_t> unique_metadata_values_map;
    text_tarray::iterator metadata_value_iterator = metadata_values.begin();
    while (metadata_value_iterator != metadata_values.end())
    {
      text_t metadata_value = *metadata_value_iterator;

      // If no ResultDocInfo_t has already been created for this metadata value, create one now
      if (unique_metadata_values_map.find(metadata_value) == unique_metadata_values_map.end())
      {
	ResultDocInfo_t metadata_value_result_doc;
	metadata_value_result_doc.OID = metadata_value;
	metadata_value_result_doc.result_num = 1;
	unique_metadata_values_map[metadata_value] = metadata_value_result_doc;
      }
      // Otherwise we've seen this value before, so just update the occurrence count
      else
      {
	unique_metadata_values_map[metadata_value].result_num++;
      }

      metadata_value_iterator++;
    }

    // Fill in response.docInfo with the ResultDocInfo_t objects we've created above
    map<text_t, ResultDocInfo_t>::iterator unique_metadata_values_iterator = unique_metadata_values_map.begin();
    while (unique_metadata_values_iterator != unique_metadata_values_map.end())
    {
      response.docInfo.push_back ((*unique_metadata_values_iterator).second);
      unique_metadata_values_iterator++;
    }
  }

  sql_db_ptr->closedatabase();  // Important that local library doesn't leave any files open
}