/********************************************************************\
  * BitlBee -- An IRC to other IM-networks gateway                     *
  *                                                                    *
  * Copyright 2002-2012 Wilmer van der Gaast and others                *
  \********************************************************************/

/* Storage backend that uses an XMLish format for all data. */

/*
  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 with
  the Debian GNU/Linux distribution in /usr/share/common-licenses/GPL;
  if not, write to the Free Software Foundation, Inc., 59 Temple Place,
  Suite 330, Boston, MA  02111-1307  USA
*/

#define BITLBEE_CORE
#include "bitlbee.h"
#include "base64.h"
#include "arc.h"
#include "md5.h"
#include "xmltree.h"

#include <glib/gstdio.h>

typedef enum
{
	XML_PASS_CHECK_ONLY = -1,
	XML_PASS_UNKNOWN = 0,
	XML_PASS_WRONG,
	XML_PASS_OK
} xml_pass_st;

/* To make it easier later when extending the format: */
#define XML_FORMAT_VERSION "1"

struct xml_parsedata
{
	irc_t *irc;
	char given_nick[MAX_NICK_LENGTH+1];
	char *given_pass;
};

static void xml_init( void )
{
	if( g_access( global.conf->configdir, F_OK ) != 0 )
		log_message( LOGLVL_WARNING, "The configuration directory `%s' does not exist. Configuration won't be saved.", global.conf->configdir );
	else if( g_access( global.conf->configdir, F_OK ) != 0 || 
	         g_access( global.conf->configdir, W_OK ) != 0 )
		log_message( LOGLVL_WARNING, "Permission problem: Can't read/write from/to `%s'.", global.conf->configdir );
}

static void handle_settings( struct xt_node *node, set_t **head )
{
	struct xt_node *c;
	
	for( c = node->children; ( c = xt_find_node( c, "setting" ) ); c = c->next )
	{
		char *name = xt_find_attr( c, "name" );
		
		if( !name )
			continue;
		
		if( strcmp( node->name, "account" ) == 0 )
		{
			set_t *s = set_find( head, name );
			if( s && ( s->flags & ACC_SET_ONLINE_ONLY ) )
				continue; /* U can't touch this! */
		}
		set_setstr( head, name, c->text );
	}
}

static xt_status handle_account( struct xt_node *node, gpointer data )
{
	struct xml_parsedata *xd = data;
	char *protocol, *handle, *server, *password = NULL, *autoconnect, *tag;
	char *pass_b64 = NULL;
	unsigned char *pass_cr = NULL;
	int pass_len;
	struct prpl *prpl = NULL;
	account_t *acc;
	struct xt_node *c;
	
	handle = xt_find_attr( node, "handle" );
	pass_b64 = xt_find_attr( node, "password" );
	server = xt_find_attr( node, "server" );
	autoconnect = xt_find_attr( node, "autoconnect" );
	tag = xt_find_attr( node, "tag" );
	
	protocol = xt_find_attr( node, "protocol" );
	if( protocol )
		prpl = find_protocol( protocol );
	
	if( !handle || !pass_b64 || !protocol || !prpl )
		return XT_ABORT;
	else if( ( pass_len = base64_decode( pass_b64, (unsigned char**) &pass_cr ) ) &&
	         arc_decode( pass_cr, pass_len, &password, xd->given_pass ) >= 0 )
	{
		acc = account_add( xd->irc->b, prpl, handle, password );
		if( server )
			set_setstr( &acc->set, "server", server );
		if( autoconnect )
			set_setstr( &acc->set, "auto_connect", autoconnect );
		if( tag )
			set_setstr( &acc->set, "tag", tag );
	}
	else
		return XT_ABORT;
	
	g_free( pass_cr );
	g_free( password );
	
	handle_settings( node, &acc->set );
	
	for( c = node->children; ( c = xt_find_node( c, "buddy" ) ); c = c->next )
	{
		char *handle, *nick;
		
		handle = xt_find_attr( c, "handle" );
		nick = xt_find_attr( c, "nick" );
		
		if( handle && nick )
			nick_set_raw( acc, handle, nick );
		else
			return XT_ABORT;
	}	
	return XT_HANDLED;
}

static xt_status handle_channel( struct xt_node *node, gpointer data )
{
	struct xml_parsedata *xd = data;
	irc_channel_t *ic;
	char *name, *type;
	
	name = xt_find_attr( node, "name" );
	type = xt_find_attr( node, "type" );
	
	if( !name || !type )
		return XT_ABORT;
	
	/* The channel may exist already, for example if it's &bitlbee.
	   Also, it's possible that the user just reconnected and the
	   IRC client already rejoined all channels it was in. They
	   should still get the right settings. */
	if( ( ic = irc_channel_by_name( xd->irc, name ) ) ||
	    ( ic = irc_channel_new( xd->irc, name ) ) )
		set_setstr( &ic->set, "type", type );
	
	handle_settings( node, &ic->set );
	
	return XT_HANDLED;
}

static const struct xt_handler_entry handlers[] = {
	{ "account", "user", handle_account, },
	{ "channel", "user", handle_channel, },
	{ NULL,      NULL,   NULL, },
};

static storage_status_t xml_load_real( irc_t *irc, const char *my_nick, const char *password, xml_pass_st action )
{
	struct xml_parsedata xd[1];
	char *fn, buf[2048];
	int fd, st;
	struct xt_parser *xp;
	struct xt_node *node;
	storage_status_t ret = STORAGE_OTHER_ERROR;
	
	xd->irc = irc;
	strncpy( xd->given_nick, my_nick, MAX_NICK_LENGTH );
	xd->given_nick[MAX_NICK_LENGTH] = '\0';
	nick_lc( xd->given_nick );
	xd->given_pass = password;
	
	fn = g_strconcat( global.conf->configdir, xd->given_nick, ".xml", NULL );
	if( ( fd = open( fn, O_RDONLY ) ) < 0 )
	{
		ret = STORAGE_NO_SUCH_USER;
		goto error;
	}
	
	xp = xt_new( handlers, xd );
	while( ( st = read( fd, buf, sizeof( buf ) ) ) > 0 )
	{
		st = xt_feed( xp, buf, st );
		if( st != 1 )
			break;
	}
	close( fd );
	if( st != 0 )
		goto error;
	
	node = xp->root;
	if( node == NULL || node->next != NULL || strcmp( node->name, "user" ) != 0 )
		goto error;
	
	{
		char *nick = xt_find_attr( node, "nick" );
		char *pass = xt_find_attr( node, "password" );
		
		if( !nick || !pass )
		{
			goto error;
		}
		else if( ( st = md5_verify_password( xd->given_pass, pass ) ) != 0 )
		{
			ret = STORAGE_INVALID_PASSWORD;
			goto error;
		}
	}
	
	if( action == XML_PASS_CHECK_ONLY )
	{
		ret = STORAGE_OK;
		goto error;
	}
	
	/* DO NOT call xt_handle() before verifying the password! */
	if( xt_handle( xp, NULL, 1 ) == XT_HANDLED )
		ret = STORAGE_OK;
	
	handle_settings( node, &xd->irc->b->set );
	
error:
	xt_free( xp );
	g_free( fn );
	return ret;
}

static storage_status_t xml_load( irc_t *irc, const char *password )
{
	return xml_load_real( irc, irc->user->nick, password, XML_PASS_UNKNOWN );
}

static storage_status_t xml_check_pass( const char *my_nick, const char *password )
{
	return xml_load_real( NULL, my_nick, password, XML_PASS_CHECK_ONLY );
}


static gboolean xml_generate_nick( gpointer key, gpointer value, gpointer data );

struct xt_node *xml_generate( irc_t *irc )
{
	char *pass_buf = NULL;
	set_t *set;
	account_t *acc;
	md5_byte_t pass_md5[21];
	md5_state_t md5_state;
	GSList *l;
	struct xt_node *root, *cur;
	
	/* Generate a salted md5sum of the password. Use 5 bytes for the salt
	   (to prevent dictionary lookups of passwords) to end up with a 21-
	   byte password hash, more convenient for base64 encoding. */
	random_bytes( pass_md5 + 16, 5 );
	md5_init( &md5_state );
	md5_append( &md5_state, (md5_byte_t*) irc->password, strlen( irc->password ) );
	md5_append( &md5_state, pass_md5 + 16, 5 ); /* Add the salt. */
	md5_finish( &md5_state, pass_md5 );
	/* Save the hash in base64-encoded form. */
	pass_buf = base64_encode( pass_md5, 21 );
	
	root = cur = xt_new_node( "user", NULL, NULL );
	xt_add_attr( cur, "nick", irc->user->nick );
	xt_add_attr( cur, "password", pass_buf );
	xt_add_attr( cur, "version", XML_FORMAT_VERSION );
	
	g_free( pass_buf );
	
	for( set = irc->b->set; set; set = set->next )
		if( set->value && !( set->flags & SET_NOSAVE ) )
		{
			struct xt_node *xset;
			xt_add_child( cur, xset = xt_new_node( "setting", set->value, NULL ) );
			xt_add_attr( xset, "name", set->key );
		}
	
	for( acc = irc->b->accounts; acc; acc = acc->next )
	{
		unsigned char *pass_cr;
		char *pass_b64;
		int pass_len;
		
		pass_len = arc_encode( acc->pass, strlen( acc->pass ), (unsigned char**) &pass_cr, irc->password, 12 );
		pass_b64 = base64_encode( pass_cr, pass_len );
		g_free( pass_cr );
		
		cur = xt_new_node( "account", NULL, NULL );
		xt_add_attr( cur, "protocol", acc->prpl->name );
		xt_add_attr( cur, "handle", acc->user );
		xt_add_attr( cur, "password", pass_b64 );
		xt_add_attr( cur, "autoconnect", acc->auto_connect ? "true" : "false" );
		xt_add_attr( cur, "tag", acc->tag );
		if( acc->server && acc->server[0] )
			xt_add_attr( cur, "server", acc->server );
		
		g_free( pass_b64 );
		
		for( set = acc->set; set; set = set->next )
			if( set->value && !( set->flags & ACC_SET_NOSAVE ) )
			{
				struct xt_node *xset;
				xt_add_child( cur, xset = xt_new_node( "setting", set->value, NULL ) );
				xt_add_attr( xset, "name", set->key );
			}
		
		/* This probably looks pretty strange. g_hash_table_foreach
		   is quite a PITA already (but it can't get much better in
		   C without using #define, I'm afraid), and since it
		   doesn't seem to be possible to abort the foreach on write
		   errors, so instead let's use the _find function and
		   return TRUE on write errors. Which means, if we found
		   something, there was an error. :-) */
		g_hash_table_find( acc->nicks, xml_generate_nick, cur );
		
		xt_add_child( root, cur );
	}
	
	for( l = irc->channels; l; l = l->next )
	{
		irc_channel_t *ic = l->data;
		
		if( ic->flags & IRC_CHANNEL_TEMP )
			continue;
		
		cur = xt_new_node( "channel", NULL, NULL );
		xt_add_attr( cur, "name", ic->name );
		xt_add_attr( cur, "type", set_getstr( &ic->set, "type" ) );
		
		for( set = ic->set; set; set = set->next )
			if( set->value && strcmp( set->key, "type" ) != 0 )
			{
				struct xt_node *xset;
				xt_add_child( cur, xset = xt_new_node( "setting", set->value, NULL ) );
				xt_add_attr( xset, "name", set->key );
			}
		
		xt_add_child( root, cur );
	}
	
	return root;
}

static gboolean xml_generate_nick( gpointer key, gpointer value, gpointer data )
{
	struct xt_node *node = xt_new_node( "buddy", NULL, NULL );
	xt_add_attr( node, "handle", key );
	xt_add_attr( node, "nick", value );
	xt_add_child( (struct xt_node *) data, node );
	
	return FALSE;
}

static storage_status_t xml_save( irc_t *irc, int overwrite )
{
	storage_status_t ret = STORAGE_OK;
	char path[512], *path2 = NULL, *xml = NULL;
	struct xt_node *tree = NULL;
	size_t len;
	int fd;
	
	path2 = g_strdup( irc->user->nick );
	nick_lc( path2 );
	g_snprintf( path, sizeof( path ) - 20, "%s%s%s", global.conf->configdir, path2, ".xml" );
	g_free( path2 );
	
	if( !overwrite && g_access( path, F_OK ) == 0 )
		return STORAGE_ALREADY_EXISTS;
	
	strcat( path, ".XXXXXX" );
	if( ( fd = mkstemp( path ) ) < 0 )
	{
		irc_rootmsg( irc, "Error while opening configuration file." );
		return STORAGE_OTHER_ERROR;
	}
	
	tree = xml_generate( irc );
	xml = xt_to_string_i( tree );
	len = strlen( xml );
	if( write( fd, xml, len ) != len ||
	    fsync( fd ) != 0 || /* #559 */
	    close( fd ) != 0 )
		goto error;
	
	path2 = g_strndup( path, strlen( path ) - 7 );
	if( rename( path, path2 ) != 0 )
	{
		g_free( path2 );
		goto error;
	}
	g_free( path2 );
	
	goto finish;

error:
	irc_rootmsg( irc, "Write error. Disk full?" );
	ret = STORAGE_OTHER_ERROR;

finish:	
	close( fd );
	unlink( path );
	g_free( xml );
	xt_free_node( tree );
	
	return ret;
}


static storage_status_t xml_remove( const char *nick, const char *password )
{
	char s[512], *lc;
	storage_status_t status;

	status = xml_check_pass( nick, password );
	if( status != STORAGE_OK )
		return status;

	lc = g_strdup( nick );
	nick_lc( lc );
	g_snprintf( s, 511, "%s%s%s", global.conf->configdir, lc, ".xml" );
	g_free( lc );
	
	if( unlink( s ) == -1 )
		return STORAGE_OTHER_ERROR;
	
	return STORAGE_OK;
}

storage_t storage_xml = {
	.name = "xml",
	.init = xml_init,
	.check_pass = xml_check_pass,
	.remove = xml_remove,
	.load = xml_load,
	.save = xml_save
};