/*  FlexNBD server (C) Bytemark Hosting 2012

    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, see <http://www.gnu.org/licenses/>.
*/

/** The control server responds on a UNIX socket and services our "remote"
 *  commands which are used for changing the access control list, initiating
 *  a mirror process, or asking for status.  The protocol is pretty simple -
 *  after connecting the client sends a series of LF-terminated lines, followed
 *  by a blank line (i.e. double LF).  The first line is taken to be the command
 *  name to invoke, and the lines before the double LF are its arguments.
 *
 *  These commands can be invoked remotely from the command line, with the 
 *  client code to be found in remote.c
 */

#include "control.h"
#include "mirror.h"
#include "serve.h"
#include "util.h"
#include "ioutil.h"
#include "parse.h"
#include "readwrite.h"
#include "bitset.h"
#include "self_pipe.h"
#include "acl.h"
#include "status.h"
#include "mbox.h"

#include <stdlib.h>
#include <string.h>
#include <sys/un.h>
#include <unistd.h>


struct control * control_create(struct flexnbd * flexnbd, const char * csn)
{
	struct control * control = xmalloc( sizeof( struct control ) );

	NULLCHECK( csn );

	control->flexnbd = flexnbd;
	control->socket_name = csn;
	control->close_signal = self_pipe_create();
	
	return control;
}


void control_signal_close( struct control * control)
{

	NULLCHECK( control );
	self_pipe_signal( control->close_signal );
}


void control_destroy( struct control * control )
{
	NULLCHECK( control );

	self_pipe_destroy( control->close_signal );
	free( control );
}

struct control_client * control_client_create( struct flexnbd * flexnbd, int client_fd )
{
	NULLCHECK( flexnbd );

	struct control_client * control_client = 
		xmalloc( sizeof( struct control_client ) );

	control_client->socket = client_fd;
	control_client->flexnbd = flexnbd; 
	return control_client;
}



void control_client_destroy( struct control_client * client )
{
	NULLCHECK( client );
	free( client );
}


void control_respond(struct control_client * client);

void control_handle_client( struct control * control, int client_fd )
{
	NULLCHECK( control );
	NULLCHECK( control->flexnbd );
	struct control_client * control_client =
		control_client_create( control->flexnbd, client_fd );

	/* We intentionally don't spawn a thread for the client here.
	 * This is to avoid having more than one thread potentially
	 * waiting on the migration commit status.
	 */
	control_respond( control_client );
}


void control_accept_client( struct control * control )
{

	int client_fd;
	union mysockaddr client_address;
	socklen_t addrlen = sizeof( union mysockaddr );

	client_fd = accept( control->control_fd, &client_address.generic, &addrlen );
	FATAL_IF( -1 == client_fd, "control accept failed" );

	control_handle_client( control, client_fd );
}

int control_accept( struct control * control )
{
	NULLCHECK( control );

	fd_set fds;

	FD_ZERO( &fds );
	FD_SET( control->control_fd, &fds );
	self_pipe_fd_set( control->close_signal, &fds );
	debug("Control thread selecting");
	FATAL_UNLESS( 0 < select( FD_SETSIZE, &fds, NULL, NULL, NULL ),
			"Control select failed." );

	if ( self_pipe_fd_isset( control->close_signal, &fds ) ){
		return 0;
	}
	
	if ( FD_ISSET( control->control_fd, &fds ) ) {
		control_accept_client( control );
	}
	return 1;
}


void control_accept_loop( struct control * control )
{
	while( control_accept( control ) );
}


int open_control_socket( const char * socket_name )
{
	struct sockaddr_un bind_address;
	int control_fd;
	
	if (!socket_name) { 
		fatal( "Tried to open a control socket without a socket name" );
	}

	control_fd = socket(AF_UNIX, SOCK_STREAM, 0);
	FATAL_IF_NEGATIVE(control_fd ,
	  "Couldn't create control socket");
	
	memset(&bind_address, 0, sizeof(struct sockaddr_un));
	bind_address.sun_family = AF_UNIX;
	strncpy(bind_address.sun_path, socket_name, sizeof(bind_address.sun_path)-1);
	
	unlink(socket_name); /* ignore failure */
	
	FATAL_IF_NEGATIVE(
		bind(control_fd , &bind_address, sizeof(bind_address)),
		"Couldn't bind control socket to %s",
		socket_name
	);
	
	FATAL_IF_NEGATIVE(
		listen(control_fd , 5),
		"Couldn't listen on control socket"
	);
	return control_fd;
}


void control_listen(struct control* control)
{
	NULLCHECK( control );
	control->control_fd = open_control_socket( control->socket_name );
}


void control_serve( struct control * control )
{
	NULLCHECK( control );
	control_listen( control );
	while( control_accept( control ) );
}


void * control_runner( void * control_uncast )
{
	debug("Control thread");
	NULLCHECK( control_uncast );
	struct control * control = (struct control *)control_uncast;

	control_serve( control );
	return NULL;
}


#define write_socket(msg) write(client_fd, (msg "\n"), strlen((msg))+1)

void control_write_mirror_response( enum mirror_state mirror_state, int client_fd )
{
	switch (mirror_state) {
		case MS_INIT:
		case MS_UNKNOWN:
			write_socket( "1: Mirror failed to initialise" );
			fatal( "Impossible mirror state: %d", mirror_state );
		case MS_FAIL_CONNECT:
			write_socket( "1: Mirror failed to connect");
			break;
		case MS_FAIL_REJECTED:
			write_socket( "1: Mirror was rejected" );
			break;
		case MS_FAIL_NO_HELLO:
			write_socket( "1: Remote server failed to respond");
			break;
		case MS_FAIL_SIZE_MISMATCH:
			write_socket( "1: Remote size does not match local size" );
			break;
		case MS_GO:
		case MS_FINALISE:
		case MS_DONE: /* Yes, I know we know better, but it's simpler this way */
			write_socket( "0: Mirror started" );
			break;
		default:
			fatal( "Unhandled mirror state: %d", mirror_state );
	}
}
#undef write_socket


#define write_socket(msg) write(client->socket, (msg "\n"), strlen((msg))+1)
/** Command parser to start mirror process from socket input */
int control_mirror(struct control_client* client, int linesc, char** lines)
{
	NULLCHECK( client );

	struct flexnbd * flexnbd = client->flexnbd;
	union mysockaddr *connect_to = xmalloc( sizeof( union mysockaddr ) );
	union mysockaddr *connect_from = NULL;
	uint64_t max_Bps = 0;
	int action_at_finish;
	int raw_port;
	
	
	if (linesc < 2) {
		write_socket("1: mirror takes at least two parameters");
		return -1;
	}

	if (parse_ip_to_sockaddr(&connect_to->generic, lines[0]) == 0) {
		write_socket("1: bad IP address");
		return -1;
	}
	
	raw_port = atoi(lines[1]);
	if (raw_port < 0 || raw_port > 65535) {
		write_socket("1: bad IP port number");
		return -1;
	}
	connect_to->v4.sin_port = htobe16(raw_port);

	if (linesc > 2) {
		connect_from = xmalloc( sizeof( union mysockaddr ) );
		if (parse_ip_to_sockaddr(&connect_from->generic, lines[2]) == 0) {
			write_socket("1: bad bind address");
			return -1;
		}
	}

	if (linesc > 3) { max_Bps = atoi(lines[2]); }
	
	action_at_finish = ACTION_EXIT;
	if (linesc > 4) {
		if (strcmp("exit", lines[3]) == 0) {
			action_at_finish = ACTION_EXIT;
		}
		else if (strcmp("nothing", lines[3]) == 0) {
			action_at_finish = ACTION_NOTHING;
		}
		else {
			write_socket("1: action must be 'exit' or 'nothing'");
			return -1;
		}
	}
	
	if (linesc > 5) {
		write_socket("1: unrecognised parameters to mirror");
		return -1;
	}

	/* In theory, we should never have to worry about the switch
	 * lock here, since we should never be able to start more than
	 * one mirror at a time.  This is enforced by only accepting a
	 * single client at a time on the control socket.
	 */
	flexnbd_lock_switch( flexnbd );
	{
		struct server * serve = flexnbd_server(flexnbd);
		serve->mirror_super = mirror_super_create( 
				serve->filename,
				connect_to,
				connect_from,
				max_Bps ,
				action_at_finish);
		serve->mirror = serve->mirror_super->mirror;

		FATAL_IF( 0 != pthread_create(
					&serve->mirror_super->thread, 
					NULL, 
					mirror_super_runner, 
					serve
					),
				"Failed to create mirror thread"
			);

		debug("Control thread mirror super waiting");
		enum mirror_state state = mirror_super_wait( serve->mirror_super );
		debug("Control thread writing response");
		control_write_mirror_response( state, client->socket );
	}
	debug( "Control thread unlocking switch" );
	flexnbd_unlock_switch( flexnbd );
	debug( "Control thread going away." );
	
	return 0;
}

#undef write_socket


/** Command parser to alter access control list from socket input */
int control_acl(struct control_client* client, int linesc, char** lines)
{
	NULLCHECK( client );
	NULLCHECK( client->flexnbd );
	struct flexnbd * flexnbd = client->flexnbd;

	int default_deny = flexnbd_default_deny( flexnbd );
	struct acl * new_acl = acl_create( linesc, lines, default_deny );

	if (new_acl->len != linesc) {
		write(client->socket, "1: bad spec: ", 13);
		write(client->socket, lines[new_acl->len], 
				strlen(lines[new_acl->len]));
		write(client->socket, "\n", 1);
		acl_destroy( new_acl );
	}
	else {
		flexnbd_replace_acl( flexnbd, new_acl );
		write( client->socket, "0: updated", 10);
	}

	return 0;
}

/** FIXME: add some useful statistics */
int control_status(
		struct control_client* client, 
		int linesc __attribute__ ((unused)), 
		char** lines __attribute__((unused))
		)
{
	NULLCHECK( client );
	NULLCHECK( client->flexnbd );
	struct status * status = flexnbd_status_create( client->flexnbd );
	
	write( client->socket, "0: ", 3 );
	status_write( status, client->socket );
	status_destroy( status );

	return 0;
}

void control_cleanup(struct control_client* client, 
		int fatal __attribute__ ((unused)) )
{
	if (client->socket) { close(client->socket); }

	/* This is wrongness */
	if ( server_io_locked( client->flexnbd->serve ) ) { server_unlock_io( client->flexnbd->serve ); }
	if ( server_acl_locked( client->flexnbd->serve ) ) { server_unlock_acl( client->flexnbd->serve ); }
	if ( flexnbd_switch_locked( client->flexnbd ) ) { flexnbd_unlock_switch( client->flexnbd ); }

	control_client_destroy( client );
}

/** Master command parser for control socket connections, delegates quickly */
void control_respond(struct control_client * client)
{
	char **lines = NULL;

	error_set_handler((cleanup_handler*) control_cleanup, client);

	int i, linesc;		
	linesc = read_lines_until_blankline(client->socket, 256, &lines);

	if (linesc < 1)
	{
		write(client->socket, "9: missing command\n", 19);
		/* ignore failure */
	}
	else if (strcmp(lines[0], "acl") == 0) {
		info("acl command received" );
		if (control_acl(client, linesc-1, lines+1) < 0) {
			debug("acl command failed");
		}
	}
	else if (strcmp(lines[0], "mirror") == 0) {
		info("mirror command received" );
		if (control_mirror(client, linesc-1, lines+1) < 0) {
			debug("mirror command failed");
		}
	}
	else if (strcmp(lines[0], "status") == 0) {
		info("status command received" );
		if (control_status(client, linesc-1, lines+1) < 0) {
			debug("status command failed");
		}
	}
	else {
		write(client->socket, "10: unknown command\n", 23);
	}

	for (i=0; i<linesc; i++) {
		free(lines[i]);
	}
	free(lines);

	control_cleanup(client, 0);
	debug("control command handled" );
}