/* 
** Copyright (C) 2010 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
**
** 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 3 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  
**  
*/

#include <stdlib.h>
#include <xapian.h>
#include <glib/gstdio.h>
#include <string.h>
#include <string>

#include "mu-query-xapian.h"

#include "mu-msg-xapian.h"
#include "mu-msg-xapian-priv.hh"

static void add_prefix (const MuMsgField* field, Xapian::QueryParser* qparser);

struct _MuQueryXapian {
	Xapian::Database*         _db;
	Xapian::QueryParser*	  _qparser;
	Xapian::Sorter*           _sorters[MU_MSG_FIELD_TYPE_NUM];
};

gboolean
_init_mu_query_xapian (MuQueryXapian *mqx, const char* dbpath)
{
	mqx->_db = 0;
	mqx->_qparser = 0;
	
	try {
		mqx->_db = new Xapian::Database(dbpath);
		mqx->_qparser = new Xapian::QueryParser;
		
		mqx->_qparser->set_database(*mqx->_db);
		mqx->_qparser->set_default_op(Xapian::Query::OP_OR);
		mqx->_qparser->set_stemming_strategy (Xapian::QueryParser::STEM_SOME);

		memset (mqx->_sorters, 0, sizeof(mqx->_sorters));
		mu_msg_field_foreach ((MuMsgFieldForEachFunc)add_prefix,
				      (gpointer)mqx->_qparser);
		
	} catch (...) {

		g_warning ("%s: caught exception", __FUNCTION__);
		
		delete mqx->_db;
		delete mqx->_qparser;
		
		return FALSE;
	}
	return TRUE;
}

	
static void
_uninit_mu_query_xapian (MuQueryXapian *mqx)
{
	try {
		delete mqx->_db;
		delete mqx->_qparser;

		for (int i = 0; i != MU_MSG_FIELD_TYPE_NUM; ++i) 
			delete mqx->_sorters[i];
		
	} catch (...) {
		
		g_warning ("%s: caught exception", __FUNCTION__);
	}
}

static Xapian::Query
_get_query  (MuQueryXapian * mqx, const char* searchexpr, int *err = 0)  {
	
	try {
		return mqx->_qparser->parse_query
			(searchexpr,
			 Xapian::QueryParser::FLAG_BOOLEAN          | 
			 Xapian::QueryParser::FLAG_PHRASE           |
			 Xapian::QueryParser::FLAG_LOVEHATE         |
			 Xapian::QueryParser::FLAG_BOOLEAN_ANY_CASE |
			 Xapian::QueryParser::FLAG_WILDCARD         |
			 Xapian::QueryParser::FLAG_PURE_NOT         |
			 Xapian::QueryParser::FLAG_PARTIAL);

	} catch (const Xapian::Error& ex) {

		g_warning ("error in query: %s (\"%s\")",
			   ex.get_msg().c_str(), searchexpr);
	} catch (...) {

		g_warning ("%s: caught exception", __FUNCTION__);
	}	
	if (err)
		*err  = 1;
	
	return Xapian::Query();
}

static void
add_prefix (const MuMsgField* field, Xapian::QueryParser* qparser)
{
	if (!mu_msg_field_is_xapian_enabled(field)) 
		return;

	const std::string prefix (mu_msg_field_xapian_prefix(field));
	
	qparser->add_boolean_prefix(std::string(mu_msg_field_name(field)),
				   prefix);
	qparser->add_boolean_prefix(std::string(mu_msg_field_shortcut(field)),
				    prefix);

	/* make the empty string match this field too*/
	qparser->add_prefix ("", prefix);
}

MuQueryXapian*
mu_query_xapian_new (const char* path)
{
	char *xpath;	
	MuQueryXapian *mqx;
	
	g_return_val_if_fail (path, NULL);
	
	xpath = g_strdup_printf ("%s%c%s", path, G_DIR_SEPARATOR, "xapian");
	if (!g_file_test (xpath, G_FILE_TEST_IS_DIR) ||
	    g_access(xpath, R_OK) != 0) { 
		g_warning ("'%s' is not a readable xapian dir", xpath);
		g_free (xpath);
		return NULL;
	}

	mqx = g_new (MuQueryXapian, 1);
	_init_mu_query_xapian (mqx, xpath);
	g_free (xpath);

	return mqx;
}


void
mu_query_xapian_destroy (MuQueryXapian *self)
{
	if (!self)
		return;

	_uninit_mu_query_xapian (self);
	g_free (self);
}




MuMsgXapian*
mu_query_xapian_run (MuQueryXapian *self, const char* searchexpr,
		     const MuMsgField* sortfield, gboolean ascending)  
{
	g_return_val_if_fail (self, NULL);
	g_return_val_if_fail (searchexpr, NULL);
		
	try {
		Xapian::Query q(_get_query(self, searchexpr));
		Xapian::Enquire enq (*self->_db);
		
		if (sortfield) 
			enq.set_sort_by_value (
				(Xapian::valueno)mu_msg_field_id(sortfield),
				ascending);

		enq.set_query  (q);
		enq.set_cutoff (0,0);

		return mu_msg_xapian_new (enq, 10000);
		
	} catch (const Xapian::Error &err) {
		g_warning ("%s: caught xapian exception '%s' for expr '%s' (%s)", 
			   __FUNCTION__, err.get_msg().c_str(),
			   searchexpr, err.get_error_string());
	} catch (...) {
		g_warning ("%s: caught exception", __FUNCTION__);
	}

	return NULL;
}

char*
mu_query_xapian_as_string  (MuQueryXapian *self, const char* searchexpr) 
{
	g_return_val_if_fail (self, NULL);
	g_return_val_if_fail (searchexpr, NULL);
		
	try {
		Xapian::Query q(_get_query(self, searchexpr));
		return g_strdup(q.get_description().c_str());
		
	} catch (const Xapian::Error &err) {
		g_warning ("%s: caught xapian exception '%s' (%s)", 
			   __FUNCTION__, err.get_msg().c_str(), 
			   err.get_error_string());
	} catch (...) {
		g_warning ("%s: caught exception", __FUNCTION__);
	}

	return NULL;
}


char*
mu_query_xapian_combine (const gchar **params, gboolean connect_or)
{
	GString *str;
	int i;
	
	g_return_val_if_fail (params && params[0], NULL);
	
	str = g_string_sized_new (64); /* just a guess */
	
	for (i = 0; params && params[i]; ++i) { 

		const char* elm;
		const char* cnx = "";
		gboolean do_quote;

		elm = (const gchar*)params[i];
		if (!elm) /* shouldn't happen */
			break;  
		
		if (params[i + 1])
			cnx = connect_or ? " OR " : " AND ";

		do_quote = (strcasecmp (elm, "OR") == 0  ||
			    strcasecmp (elm, "AND") == 0 ||
			    strcasecmp (elm, "NOT") == 0);
		
		g_string_append_printf (str, "%s%s%s%s",
					do_quote ? "\"" : "",
					elm,
					do_quote ? "\"" : "",
					cnx);	
	}
	return g_string_free (str, FALSE);
}