/* SNMP-like status interface
 *
 * (C) 2010-2011 by Daniel Willmann <daniel@totalueberwachung.de>
 * (C) 2010-2011 by On-Waves
 *
 * All Rights Reserved
 *
 * 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 02110-1301 USA.
 *
 */

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include <arpa/inet.h>

#include <netinet/tcp.h>

#include <sys/fcntl.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/types.h>

#include <openbsc/control_cmd.h>
#include <openbsc/debug.h>
#include <openbsc/e1_input.h>
#include <openbsc/gsm_data.h>
#include <openbsc/ipaccess.h>
#include <openbsc/socket.h>
#include <openbsc/subchan_demux.h>

#include <openbsc/abis_rsl.h>
#include <openbsc/abis_nm.h>

#include <osmocom/core/msgb.h>
#include <osmocom/core/select.h>
#include <osmocom/core/talloc.h>

#include <osmocom/gsm/tlv.h>

#include <osmocom/vty/command.h>
#include <osmocom/vty/vector.h>

struct ctrl_handle {
	struct osmo_fd listen_fd;
	struct gsm_network *gsmnet;
};

vector ctrl_node_vec;

int ctrl_cmd_send(struct osmo_wqueue *queue, struct ctrl_cmd *cmd)
{
	int ret;
	struct msgb *msg;

	msg = ctrl_cmd_make(cmd);
	if (!msg) {
		LOGP(DINP, LOGL_ERROR, "Could not generate msg\n");
		return -1;
	}

	ipaccess_prepend_header_ext(msg, IPAC_PROTO_EXT_CTRL);
	ipaccess_prepend_header(msg, IPAC_PROTO_OSMO);

	ret = osmo_wqueue_enqueue(queue, msg);
	if (ret != 0) {
		LOGP(DINP, LOGL_ERROR, "Failed to enqueue the command.\n");
		msgb_free(msg);
	}
	return ret;
}

int ctrl_cmd_handle(struct ctrl_cmd *cmd, void *data)
{
	char *token, *request;
	int num, i, j, ret, node;
	struct gsm_network *gsmnet = data;

	struct gsm_network *net = NULL;
	struct gsm_bts *bts = NULL;
	struct gsm_bts_trx *trx = NULL;
	struct gsm_bts_trx_ts *ts = NULL;
	vector vline, cmdvec, cmds_vec;

	ret = CTRL_CMD_ERROR;
	cmd->reply = "Someone forgot to fill in the reply.";
	cmd->node = NULL;
	node = CTRL_NODE_ROOT;

	request = talloc_strdup(tall_bsc_ctx, cmd->variable);
	if (!request)
		goto err;

	for (i=0;i<strlen(request);i++) {
		if (request[i] == '.')
			request[i] = ' ';
	}

	vline = cmd_make_strvec(request);
	talloc_free(request);
	if (!vline)
		goto err;

	for (i=0;i<vector_active(vline);i++) {
		token = vector_slot(vline, i);
		/* TODO: We need to make sure that the following chars are digits
		 * and/or use strtol to check if number conversion was successful
		 * Right now something like net.bts_stats will not work */
		if (!strcmp(token, "net")) {
			net = gsmnet;
			if (!net)
				break;
			cmd->node = net;
			node = CTRL_NODE_NET;
		} else if (!strncmp(token, "bts", 3)) {
			if (!net)
				break;
			num = atoi(&token[3]);
			bts = gsm_bts_num(net, num);
			if (!bts)
				break;
			cmd->node = bts;
			node = CTRL_NODE_BTS;
		} else if (!strncmp(token, "trx", 3)) {
			if (!bts)
				break;
			num = atoi(&token[3]);
			trx = gsm_bts_trx_num(bts, num);
			if (!trx)
				break;
			cmd->node = trx;
			node = CTRL_NODE_TRX;
		} else if (!strncmp(token, "ts", 2)) {
			if (!trx)
				break;
			num = atoi(&token[2]);
			if ((num >= 0) && (num < TRX_NR_TS))
				ts = &trx->ts[num];
			if (!ts)
				break;
			cmd->node = ts;
			node = CTRL_NODE_TS;
		} else {
			/* If we're here the rest must be the command */
			cmdvec = vector_init(vector_active(vline)-i);
			for (j=i; j<vector_active(vline); j++) {
				vector_set(cmdvec, vector_slot(vline, j));
			}

			/* Get the command vector of the right node */
			cmds_vec = vector_lookup(ctrl_node_vec, node);

			if (!cmds_vec) {
				cmd->reply = "Command not found";
				vector_free(cmdvec);
				break;
			}

			ret = ctrl_cmd_exec(cmdvec, cmd, cmds_vec, data);

			vector_free(cmdvec);
			break;
		}
	}

	cmd_free_strvec(vline);

err:
	if (ret == CTRL_CMD_ERROR)
		cmd->type = CTRL_TYPE_ERROR;
	return ret;
}

static void control_close_conn(struct ctrl_connection *ccon)
{
	close(ccon->write_queue.bfd.fd);
	osmo_fd_unregister(&ccon->write_queue.bfd);
	if (ccon->closed_cb)
		ccon->closed_cb(ccon);
	talloc_free(ccon);
}

static int handle_control_read(struct osmo_fd * bfd)
{
	int ret = -1, error;
	struct osmo_wqueue *queue;
	struct ctrl_connection *ccon;
	struct ipaccess_head *iph;
	struct ipaccess_head_ext *iph_ext;
	struct msgb *msg;
	struct ctrl_cmd *cmd;
	struct ctrl_handle *ctrl = bfd->data;

	queue = container_of(bfd, struct osmo_wqueue, bfd);
	ccon = container_of(queue, struct ctrl_connection, write_queue);

	msg = ipaccess_read_msg(bfd, &error);

	if (!msg) {
		if (error == 0)
			LOGP(DINP, LOGL_INFO, "The control connection was closed\n");
		else
			LOGP(DINP, LOGL_ERROR, "Failed to parse ip access message: %d\n", error);

		goto err;
	}

	if (msg->len < sizeof(*iph) + sizeof(*iph_ext)) {
		LOGP(DINP, LOGL_ERROR, "The message is too short.\n");
		goto err;
	}

	iph = (struct ipaccess_head *) msg->data;
	if (iph->proto != IPAC_PROTO_OSMO) {
		LOGP(DINP, LOGL_ERROR, "Protocol mismatch. We got 0x%x\n", iph->proto);
		goto err;
	}

	iph_ext = (struct ipaccess_head_ext *) iph->data;
	if (iph_ext->proto != IPAC_PROTO_EXT_CTRL) {
		LOGP(DINP, LOGL_ERROR, "Extended protocol mismatch. We got 0x%x\n", iph_ext->proto);
		goto err;
	}

	msg->l2h = iph_ext->data;

	cmd = ctrl_cmd_parse(ccon, msg);

	if (cmd) {
		cmd->ccon = ccon;
		if (ctrl_cmd_handle(cmd, ctrl->gsmnet) != CTRL_CMD_HANDLED) {
			ctrl_cmd_send(queue, cmd);
			talloc_free(cmd);
		}
	} else {
		cmd = talloc_zero(ccon, struct ctrl_cmd);
		if (!cmd)
			goto err;
		LOGP(DINP, LOGL_ERROR, "Command parser error.\n");
		cmd->type = CTRL_TYPE_ERROR;
		cmd->id = "err";
		cmd->reply = "Command parser error.";
		ctrl_cmd_send(queue, cmd);
		talloc_free(cmd);
	}

	msgb_free(msg);
	return 0;

err:
	control_close_conn(ccon);
	msgb_free(msg);
	return ret;
}

static int control_write_cb(struct osmo_fd *bfd, struct msgb *msg)
{
	int rc;

	rc = write(bfd->fd, msg->data, msg->len);
	if (rc != msg->len)
		LOGP(DINP, LOGL_ERROR, "Failed to write message to the control connection.\n");

	return rc;
}

static struct ctrl_connection *ctrl_connection_alloc(void *ctx)
{
	struct ctrl_connection *ccon = talloc_zero(ctx, struct ctrl_connection);
	if (!ccon)
		return NULL;

	osmo_wqueue_init(&ccon->write_queue, 100);
	/* Error handling here? */

	INIT_LLIST_HEAD(&ccon->cmds);
	return ccon;
}

static int listen_fd_cb(struct osmo_fd *listen_bfd, unsigned int what)
{
	int ret, fd, on;
	struct ctrl_connection *ccon;
	struct sockaddr_in sa;
	socklen_t sa_len = sizeof(sa);


	if (!(what & BSC_FD_READ))
		return 0;

	fd = accept(listen_bfd->fd, (struct sockaddr *) &sa, &sa_len);
	if (fd < 0) {
		perror("accept");
		return fd;
	}
	LOGP(DINP, LOGL_INFO, "accept()ed new control connection from %s\n",
		inet_ntoa(sa.sin_addr));

	on = 1;
	ret = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on));
	if (ret != 0) {
		LOGP(DNAT, LOGL_ERROR, "Failed to set TCP_NODELAY: %s\n", strerror(errno));
		close(fd);
		return ret;
	}
	ccon = ctrl_connection_alloc(listen_bfd->data);
	if (!ccon) {
		LOGP(DINP, LOGL_ERROR, "Failed to allocate.\n");
		close(fd);
		return -1;
	}

	ccon->write_queue.bfd.data = listen_bfd->data;
	ccon->write_queue.bfd.fd = fd;
	ccon->write_queue.bfd.when = BSC_FD_READ;
	ccon->write_queue.read_cb = handle_control_read;
	ccon->write_queue.write_cb = control_write_cb;

	ret = osmo_fd_register(&ccon->write_queue.bfd);
	if (ret < 0) {
		LOGP(DINP, LOGL_ERROR, "Could not register FD.\n");
		close(ccon->write_queue.bfd.fd);
		talloc_free(ccon);
	}

	return ret;
}

int controlif_setup(struct gsm_network *gsmnet, uint16_t port)
{
	int ret;
	struct ctrl_handle *ctrl;

	ctrl = talloc_zero(tall_bsc_ctx, struct ctrl_handle);
	if (!ctrl)
		return -ENOMEM;

	ctrl->gsmnet = gsmnet;

	ctrl_node_vec = vector_init(5);
	if (!ctrl_node_vec)
		return -ENOMEM;

	/* Listen for control connections */
	ret = make_sock(&ctrl->listen_fd, IPPROTO_TCP, 0, port,
			0, listen_fd_cb, ctrl);
	if (ret < 0) {
		talloc_free(ctrl);
		return ret;
	}

	return ret;
}