/*
 * purple - Handling of XEP-0047: In-Band Bytestreams.
 *
 * Purple is the legal property of its developers, whose names are too numerous
 * to list here.  Please refer to the COPYRIGHT file distributed with this
 * source distribution.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02111-1301  USA
 *
 */

#include <math.h>

#include <purple.h>

#include "ibb.h"

#define JABBER_IBB_SESSION_DEFAULT_BLOCK_SIZE 4096

static GHashTable *jabber_ibb_sessions = NULL;
static GList *open_handlers = NULL;

static JabberStream *jabber_ibb_session_get_js(JabberIBBSession *sess);

JabberIBBSession *
jabber_ibb_session_create(JabberStream *js, const gchar *sid, const gchar *who,
	gpointer user_data)
{
	JabberIBBSession *sess = g_new0(JabberIBBSession, 1);
	sess->js = js;
	if (sid) {
		sess->sid = g_strdup(sid);
	} else {
		sess->sid = jabber_get_next_id(js);
	}
	sess->who = g_strdup(who);
	sess->block_size = JABBER_IBB_SESSION_DEFAULT_BLOCK_SIZE;
	sess->state = JABBER_IBB_SESSION_NOT_OPENED;
	sess->user_data = user_data;

	g_hash_table_insert(jabber_ibb_sessions, sess->sid, sess);

	return sess;
}

JabberIBBSession *
jabber_ibb_session_create_from_xmlnode(JabberStream *js, const char *from,
	const char *id, PurpleXmlNode *open, gpointer user_data)
{
	JabberIBBSession *sess = NULL;
	const gchar *sid = purple_xmlnode_get_attrib(open, "sid");
	const gchar *block_size = purple_xmlnode_get_attrib(open, "block-size");

	if (!open) {
		return NULL;
	}

	if (!sid || !block_size) {
		purple_debug_error("jabber",
			"IBB session open tag requires sid and block-size attributes\n");
		return NULL;
	}

	sess = jabber_ibb_session_create(js, sid, from, user_data);
	sess->id = g_strdup(id);
	sess->block_size = atoi(block_size);
	/* if we create a session from an incoming <open/> request, it means the
	  session is immediately open... */
	sess->state = JABBER_IBB_SESSION_OPENED;

	return sess;
}

void
jabber_ibb_session_destroy(JabberIBBSession *sess)
{
	purple_debug_info("jabber", "IBB: destroying session %p %s\n", sess,
		sess->sid);

	if (jabber_ibb_session_get_state(sess) == JABBER_IBB_SESSION_OPENED) {
		jabber_ibb_session_close(sess);
	}

	if (sess->last_iq_id) {
		purple_debug_info("jabber", "IBB: removing callback for <iq/> %s\n",
			sess->last_iq_id);
		jabber_iq_remove_callback_by_id(jabber_ibb_session_get_js(sess),
			sess->last_iq_id);
		g_free(sess->last_iq_id);
		sess->last_iq_id = NULL;
	}

	g_hash_table_remove(jabber_ibb_sessions, sess->sid);
	g_free(sess->id);
	g_free(sess->sid);
	g_free(sess->who);
	g_free(sess);
}

static const gchar *
jabber_ibb_session_get_sid(const JabberIBBSession *sess)
{
	return sess->sid;
}

static JabberStream *
jabber_ibb_session_get_js(JabberIBBSession *sess)
{
	return sess->js;
}

static const gchar *
jabber_ibb_session_get_who(const JabberIBBSession *sess)
{
	return sess->who;
}

static guint16
jabber_ibb_session_get_send_seq(const JabberIBBSession *sess)
{
	return sess->send_seq;
}

static guint16
jabber_ibb_session_get_recv_seq(const JabberIBBSession *sess)
{
	return sess->recv_seq;
}

JabberIBBSessionState
jabber_ibb_session_get_state(const JabberIBBSession *sess)
{
	return sess->state;
}

gsize
jabber_ibb_session_get_block_size(const JabberIBBSession *sess)
{
	return sess->block_size;
}

gsize
jabber_ibb_session_get_max_data_size(const JabberIBBSession *sess)
{
	return (gsize) floor((sess->block_size - 2) * (float) 3 / 4);
}

gpointer
jabber_ibb_session_get_user_data(JabberIBBSession *sess)
{
	return sess->user_data;
}

void
jabber_ibb_session_set_opened_callback(JabberIBBSession *sess,
	JabberIBBOpenedCallback *cb)
{
	sess->opened_cb = cb;
}

void
jabber_ibb_session_set_data_sent_callback(JabberIBBSession *sess,
	JabberIBBSentCallback *cb)
{
	sess->data_sent_cb = cb;
}

void
jabber_ibb_session_set_closed_callback(JabberIBBSession *sess,
	JabberIBBClosedCallback *cb)
{
	sess->closed_cb = cb;
}

void
jabber_ibb_session_set_data_received_callback(JabberIBBSession *sess,
	JabberIBBDataCallback *cb)
{
	sess->data_received_cb = cb;
}

void
jabber_ibb_session_set_error_callback(JabberIBBSession *sess,
	JabberIBBErrorCallback *cb)
{
	sess->error_cb = cb;
}

static void
jabber_ibb_session_opened_cb(G_GNUC_UNUSED JabberStream *js,
                             G_GNUC_UNUSED const char *from,
                             JabberIqType type, G_GNUC_UNUSED const char *id,
                             G_GNUC_UNUSED PurpleXmlNode *packet,
                             gpointer data)
{
	JabberIBBSession *sess = (JabberIBBSession *) data;

	if (type == JABBER_IQ_ERROR) {
		sess->state = JABBER_IBB_SESSION_ERROR;
	} else {
		sess->state = JABBER_IBB_SESSION_OPENED;
	}

	if (sess->opened_cb) {
		sess->opened_cb(sess);
	}
}

void
jabber_ibb_session_open(JabberIBBSession *sess)
{
	if (jabber_ibb_session_get_state(sess) != JABBER_IBB_SESSION_NOT_OPENED) {
		purple_debug_error("jabber",
			"jabber_ibb_session called on an already open stream\n");
	} else {
		JabberIq *set = jabber_iq_new(sess->js, JABBER_IQ_SET);
		PurpleXmlNode *open = purple_xmlnode_new("open");
		gchar block_size[10];

		purple_xmlnode_set_attrib(set->node, "to", jabber_ibb_session_get_who(sess));
		purple_xmlnode_set_namespace(open, NS_IBB);
		purple_xmlnode_set_attrib(open, "sid", jabber_ibb_session_get_sid(sess));
		g_snprintf(block_size, sizeof(block_size), "%" G_GSIZE_FORMAT,
			jabber_ibb_session_get_block_size(sess));
		purple_xmlnode_set_attrib(open, "block-size", block_size);
		purple_xmlnode_insert_child(set->node, open);

		jabber_iq_set_callback(set, jabber_ibb_session_opened_cb, sess);

		jabber_iq_send(set);
	}
}

void
jabber_ibb_session_close(JabberIBBSession *sess)
{
	JabberIBBSessionState state = jabber_ibb_session_get_state(sess);

	if (state != JABBER_IBB_SESSION_OPENED && state != JABBER_IBB_SESSION_ERROR) {
		purple_debug_error("jabber",
			"jabber_ibb_session_close called on a session that has not been"
			"opened\n");
	} else {
		JabberIq *set = jabber_iq_new(jabber_ibb_session_get_js(sess),
			JABBER_IQ_SET);
		PurpleXmlNode *close = purple_xmlnode_new("close");

		purple_xmlnode_set_attrib(set->node, "to", jabber_ibb_session_get_who(sess));
		purple_xmlnode_set_namespace(close, NS_IBB);
		purple_xmlnode_set_attrib(close, "sid", jabber_ibb_session_get_sid(sess));
		purple_xmlnode_insert_child(set->node, close);
		jabber_iq_send(set);
		sess->state = JABBER_IBB_SESSION_CLOSED;
	}
}

static void
jabber_ibb_session_send_acknowledge_cb(G_GNUC_UNUSED JabberStream *js,
                                       G_GNUC_UNUSED const char *from,
                                       JabberIqType type,
                                       G_GNUC_UNUSED const char *id,
                                       G_GNUC_UNUSED PurpleXmlNode *packet,
                                       gpointer data)
{
	JabberIBBSession *sess = (JabberIBBSession *) data;

	if (sess) {
		/* reset callback */
		g_free(sess->last_iq_id);
		sess->last_iq_id = NULL;

		if (type == JABBER_IQ_ERROR) {
			jabber_ibb_session_close(sess);
			sess->state = JABBER_IBB_SESSION_ERROR;

			if (sess->error_cb) {
				sess->error_cb(sess);
			}
		} else {
			if (sess->data_sent_cb) {
				sess->data_sent_cb(sess);
			}
		}
	} else {
		/* the session has gone away, it was probably cancelled */
		purple_debug_info("jabber",
			"got response from send data, but IBB session is no longer active\n");
	}
}

void
jabber_ibb_session_send_data(JabberIBBSession *sess, gconstpointer data,
                             gsize size)
{
	JabberIBBSessionState state = jabber_ibb_session_get_state(sess);

	purple_debug_info("jabber", "sending data block of %" G_GSIZE_FORMAT " bytes on IBB stream\n",
		size);

	if (state != JABBER_IBB_SESSION_OPENED) {
		purple_debug_error("jabber",
			"trying to send data on a non-open IBB session\n");
	} else if (size > jabber_ibb_session_get_max_data_size(sess)) {
		purple_debug_error("jabber",
			"trying to send a too large packet in the IBB session\n");
	} else {
		JabberIq *set = jabber_iq_new(jabber_ibb_session_get_js(sess),
			JABBER_IQ_SET);
		PurpleXmlNode *data_element = purple_xmlnode_new("data");
		char *base64 = g_base64_encode(data, size);
		char seq[10];
		g_snprintf(seq, sizeof(seq), "%u", jabber_ibb_session_get_send_seq(sess));

		purple_xmlnode_set_attrib(set->node, "to", jabber_ibb_session_get_who(sess));
		purple_xmlnode_set_namespace(data_element, NS_IBB);
		purple_xmlnode_set_attrib(data_element, "sid", jabber_ibb_session_get_sid(sess));
		purple_xmlnode_set_attrib(data_element, "seq", seq);
		purple_xmlnode_insert_data(data_element, base64, -1);

		purple_xmlnode_insert_child(set->node, data_element);

		purple_debug_info("jabber",
			"IBB: setting send <iq/> callback for session %p %s\n", sess,
			sess->sid);
		jabber_iq_set_callback(set, jabber_ibb_session_send_acknowledge_cb, sess);
		sess->last_iq_id = g_strdup(purple_xmlnode_get_attrib(set->node, "id"));
		purple_debug_info("jabber", "IBB: set sess->last_iq_id: %s\n",
			sess->last_iq_id);
		jabber_iq_send(set);

		g_free(base64);
		(sess->send_seq)++;
	}
}

static void
jabber_ibb_send_error_response(JabberStream *js, const char *to, const char *id)
{
	JabberIq *result = jabber_iq_new(js, JABBER_IQ_ERROR);
	PurpleXmlNode *error = purple_xmlnode_new("error");
	PurpleXmlNode *item_not_found = purple_xmlnode_new("item-not-found");

	purple_xmlnode_set_namespace(item_not_found, NS_XMPP_STANZAS);
	purple_xmlnode_set_attrib(error, "code", "440");
	purple_xmlnode_set_attrib(error, "type", "cancel");
	jabber_iq_set_id(result, id);
	purple_xmlnode_set_attrib(result->node, "to", to);
	purple_xmlnode_insert_child(error, item_not_found);
	purple_xmlnode_insert_child(result->node, error);

	jabber_iq_send(result);
}

/* Handle incoming packet. */
static void
jabber_ibb_parse(JabberStream *js, const char *who,
                 G_GNUC_UNUSED JabberIqType type, const char *id,
                 PurpleXmlNode *child)
{
	const char *name = child->name;
	gboolean data  = purple_strequal(name, "data");
	gboolean close = purple_strequal(name, "close");
	gboolean open  = purple_strequal(name, "open");
	const gchar *sid = (data || close) ?
		purple_xmlnode_get_attrib(child, "sid") : NULL;
	JabberIBBSession *sess =
		sid ? g_hash_table_lookup(jabber_ibb_sessions, sid) : NULL;

	if (sess) {

		if (!purple_strequal(who, jabber_ibb_session_get_who(sess))) {
			/* the iq comes from a different JID than the remote JID of the
			  session, ignore it */
			purple_debug_error("jabber",
				"Got IBB iq from wrong JID, ignoring\n");
		} else if (data) {
			const gchar *seq_attr = purple_xmlnode_get_attrib(child, "seq");
			guint16 seq = (seq_attr ? atoi(seq_attr) : 0);

			/* reject the data, and set the session in error if we get an
			  out-of-order packet */
			if (seq_attr && seq == jabber_ibb_session_get_recv_seq(sess)) {
				/* sequence # is the expected... */
				JabberIq *result = jabber_iq_new(js, JABBER_IQ_RESULT);

				jabber_iq_set_id(result, id);
				purple_xmlnode_set_attrib(result->node, "to", who);

				if (sess->data_received_cb) {
					gchar *base64 = purple_xmlnode_get_data(child);
					gsize size;
					gpointer rawdata = g_base64_decode(base64, &size);

					g_free(base64);

					if (rawdata) {
						purple_debug_info("jabber",
							"got %" G_GSIZE_FORMAT " bytes of data on IBB stream\n",
							size);
						/* we accept other clients to send up to block-size
						 of _unencoded_ data, since there's been some confusions
						 regarding the interpretation of this attribute
						 (including previous versions of libpurple) */
						if (size > jabber_ibb_session_get_block_size(sess)) {
							purple_debug_error("jabber",
								"IBB: received a too large packet\n");
							if (sess->error_cb)
								sess->error_cb(sess);
							g_free(rawdata);
							return;
						} else {
							purple_debug_info("jabber",
								"calling IBB callback for received data\n");
							sess->data_received_cb(sess, rawdata, size);
						}
						g_free(rawdata);
					} else {
						purple_debug_error("jabber",
							"IBB: invalid BASE64 data received\n");
						if (sess->error_cb)
							sess->error_cb(sess);
						return;

					}
				}

				(sess->recv_seq)++;
				jabber_iq_send(result);

			} else {
				purple_debug_error("jabber",
					"Received an out-of-order/invalid IBB packet\n");
				sess->state = JABBER_IBB_SESSION_ERROR;

				if (sess->error_cb) {
					sess->error_cb(sess);
				}
			}
		} else if (close) {
			sess->state = JABBER_IBB_SESSION_CLOSED;
			purple_debug_info("jabber", "IBB: received close\n");

			if (sess->closed_cb) {
				purple_debug_info("jabber", "IBB: calling closed handler\n");
				sess->closed_cb(sess);
			}
		}
	} else if (open) {
		JabberIq *result;
		const GList *iterator;

		/* run all open handlers registered until one returns true */
		for (iterator = open_handlers ; iterator ;
			 iterator = g_list_next(iterator)) {
			JabberIBBOpenHandler *handler = iterator->data;

			if (handler(js, who, id, child)) {
				result = jabber_iq_new(js, JABBER_IQ_RESULT);
				purple_xmlnode_set_attrib(result->node, "to", who);
				jabber_iq_set_id(result, id);
				jabber_iq_send(result);
				return;
			}
		}
		/* no open callback returned success, reject */
		jabber_ibb_send_error_response(js, who, id);
	} else {
		/* send error reply */
		jabber_ibb_send_error_response(js, who, id);
	}
}

void
jabber_ibb_register_open_handler(JabberIBBOpenHandler *cb)
{
	open_handlers = g_list_append(open_handlers, cb);
}

void
jabber_ibb_unregister_open_handler(JabberIBBOpenHandler *cb)
{
	open_handlers = g_list_remove(open_handlers, cb);
}

void
jabber_ibb_init(void)
{
	jabber_ibb_sessions = g_hash_table_new(g_str_hash, g_str_equal);

	jabber_add_feature(NS_IBB, NULL);

	jabber_iq_register_handler("close", NS_IBB, jabber_ibb_parse);
	jabber_iq_register_handler("data", NS_IBB, jabber_ibb_parse);
	jabber_iq_register_handler("open", NS_IBB, jabber_ibb_parse);
}

void
jabber_ibb_uninit(void)
{
	g_clear_pointer(&jabber_ibb_sessions, g_hash_table_destroy);
	g_clear_list(&open_handlers, NULL);
}