/*
 * Copyright (c) 2012 Vojtech Horky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup remcons
 * @{
 */
/** @file
 */

#include <async.h>
#include <stdio.h>
#include <adt/prodcons.h>
#include <ipc/input.h>
#include <ipc/console.h>
#include <ipc/vfs.h>
#include <errno.h>
#include <str_error.h>
#include <loc.h>
#include <event.h>
#include <io/keycode.h>
#include <align.h>
#include <malloc.h>
#include <as.h>
#include <fibril_synch.h>
#include <task.h>
#include <net/in.h>
#include <net/inet.h>
#include <net/socket.h>
#include <io/console.h>
#include <inttypes.h>
#include "telnet.h"
#include "user.h"

#define APP_GETTERM  "/app/getterm"
#define APP_SHELL "/app/bdsh"

/** Telnet commands to force character mode
 * (redundant to be on the safe side).
 * See
 * http://stackoverflow.com/questions/273261/force-telnet-user-into-character-mode
 * for discussion.
 */
static const telnet_cmd_t telnet_force_character_mode_command[] = {
	TELNET_IAC, TELNET_WILL, TELNET_ECHO,
	TELNET_IAC, TELNET_WILL, TELNET_SUPPRESS_GO_AHEAD,
	TELNET_IAC, TELNET_WONT, TELNET_LINEMODE
};
static const size_t telnet_force_character_mode_command_count =
    sizeof(telnet_force_character_mode_command) / sizeof(telnet_cmd_t);


/** Handling client requests (VFS and console interface).
 *
 * @param user Telnet user the requests belong to.
 */
static void client_connection_message_loop(telnet_user_t *user)
{
	while (true) {
		ipc_call_t call;
		ipc_callid_t callid = 0;

		/*
		 * The getterm task might terminate while we are here,
		 * waiting for a call. Also, the socket might be closed
		 * meanwhile.
		 * We want to detect this situation early, so we use a
		 * timeout variant of async_get_call().
		 */
		while (callid == 0) {
			callid = async_get_call_timeout(&call, 1000);

			if (telnet_user_is_zombie(user)) {
				if (callid != 0) {
					async_answer_0(callid, EINTR);
				}
				return;
			}
		}
		
		if (!IPC_GET_IMETHOD(call)) {
			return;
		}

		switch (IPC_GET_IMETHOD(call)) {
		case CONSOLE_GET_SIZE:
			async_answer_2(callid, EOK, 100, 1);
			break;
		case CONSOLE_GET_POS:
			fibril_mutex_lock(&user->guard);
			async_answer_2(callid, EOK, user->cursor_x, 0);
			fibril_mutex_unlock(&user->guard);
			break;
		case CONSOLE_GET_EVENT: {
			kbd_event_t event;
			int rc = telnet_user_get_next_keyboard_event(user, &event);
			if (rc != EOK) {
				/* Silently ignore. */
				async_answer_0(callid, EOK);
				break;
			}
			async_answer_4(callid, EOK, event.type, event.key, event.mods, event.c);
			break;
		}
		case CONSOLE_GOTO: {
			int new_x = IPC_GET_ARG1(call);
			telnet_user_update_cursor_x(user, new_x);
			async_answer_0(callid, ENOTSUP);
			break;
		}
		case VFS_OUT_READ:
			async_answer_0(callid, ENOTSUP);
			break;
		case VFS_OUT_WRITE: {
			uint8_t *buf;
			size_t size;
			int rc = async_data_write_accept((void **)&buf, false, 0, 0, 0, &size);

			if (rc != EOK) {
				async_answer_0(callid, rc);
				break;
			}

			rc = telnet_user_send_data(user, buf, size);
			free(buf);

			if (rc != EOK) {
				async_answer_0(callid, rc);
				break;
			}

			async_answer_1(callid, EOK, size);
			break;
		}
		case VFS_OUT_SYNC:
			async_answer_0(callid, EOK);
			break;
		case CONSOLE_CLEAR:
			async_answer_0(callid, EOK);
			break;

		case CONSOLE_GET_COLOR_CAP:
			async_answer_1(callid, EOK, CONSOLE_CAP_NONE);
			break;
		case CONSOLE_SET_STYLE:
			async_answer_0(callid, ENOTSUP);
			break;
		case CONSOLE_SET_COLOR:
			async_answer_0(callid, ENOTSUP);
			break;
		case CONSOLE_SET_RGB_COLOR:
			async_answer_0(callid, ENOTSUP);
			break;

		case CONSOLE_CURSOR_VISIBILITY:
			async_answer_0(callid, ENOTSUP);
			break;

		default:
			async_answer_0(callid, EINVAL);
			break;
		}
	}
}

/** Callback when client connects to a telnet terminal. */
static void client_connection(ipc_callid_t iid, ipc_call_t *icall, void *arg)
{
	/* Find the user. */
	telnet_user_t *user = telnet_user_get_for_client_connection(IPC_GET_ARG1(*icall));
	if (user == NULL) {
		async_answer_0(iid, ENOENT);
		return;
	}
	async_answer_0(iid, EOK);

	telnet_user_log(user, "New client connected (%" PRIxn").", iid);

	/* Force character mode. */
	send(user->socket, (void *)telnet_force_character_mode_command,
	    telnet_force_character_mode_command_count, 0);

	/* Handle messages. */
	client_connection_message_loop(user);

	telnet_user_notify_client_disconnected(user);
	telnet_user_log(user, "Client disconnected (%" PRIxn").", iid);
}

/** Fibril for spawning the task running after user connects.
 *
 * @param arg Corresponding @c telnet_user_t structure.
 */
static int spawn_task_fibril(void *arg)
{
	telnet_user_t *user = arg;
	int rc;

	char term[LOC_NAME_MAXLEN];
	snprintf(term, LOC_NAME_MAXLEN, "%s/%s", "/loc", user->service_name);

	task_id_t task;
	rc = task_spawnl(&task, APP_GETTERM, APP_GETTERM, "-w", term, APP_SHELL, NULL);
	if (rc != EOK) {
		telnet_user_error(user, "Spawning `%s -w %s %s' failed: %s.",
		    APP_GETTERM, term, APP_SHELL, str_error(rc));
		fibril_mutex_lock(&user->guard);
		user->task_finished = true;
		fibril_condvar_signal(&user->refcount_cv);
		fibril_mutex_unlock(&user->guard);
		return EOK;
	}

	fibril_mutex_lock(&user->guard);
	user->task_id = task;
	fibril_mutex_unlock(&user->guard);

	task_exit_t task_exit;
	int task_retval;
	task_wait(task, &task_exit, &task_retval);
	telnet_user_log(user, "%s terminated %s, exit code %d.", APP_GETTERM,
	    task_exit == TASK_EXIT_NORMAL ? "normally" : "unexpectedly",
	    task_retval);

	/* Announce destruction. */
	fibril_mutex_lock(&user->guard);
	user->task_finished = true;
	fibril_condvar_signal(&user->refcount_cv);
	fibril_mutex_unlock(&user->guard);

	return EOK;
}

/** Tell whether given user can be destroyed (has no active clients).
 *
 * @param user The telnet user in question.
 */
static bool user_can_be_destroyed_no_lock(telnet_user_t *user)
{
	return user->task_finished && user->socket_closed &&
	    (user->locsrv_connection_count == 0);
}

/** Fibril for each accepted socket.
 *
 * @param arg Corresponding @c telnet_user_t structure.
 */
static int network_user_fibril(void *arg)
{
	int rc;
	telnet_user_t *user = arg;

	rc = loc_service_register(user->service_name, &user->service_id);
	if (rc != EOK) {
		telnet_user_error(user, "Unable to register %s with loc: %s.",
		    user->service_name, str_error(rc));
		return EOK;
	}

	telnet_user_log(user, "Service %s registerd with id %" PRIun ".",
	    user->service_name, user->service_id);

	fid_t spawn_fibril = fibril_create(spawn_task_fibril, user);
	assert(spawn_fibril);
	fibril_add_ready(spawn_fibril);

	/* Wait for all clients to exit. */
	fibril_mutex_lock(&user->guard);
	while (!user_can_be_destroyed_no_lock(user)) {
		if (user->task_finished) {
			closesocket(user->socket);
			user->socket_closed = true;
			continue;
		} else if (user->socket_closed) {
			if (user->task_id != 0) {
				task_kill(user->task_id);
			}
		}
		fibril_condvar_wait_timeout(&user->refcount_cv, &user->guard, 1000);
	}
	fibril_mutex_unlock(&user->guard);

	rc = loc_service_unregister(user->service_id);
	if (rc != EOK) {
		telnet_user_error(user,
		    "Unable to unregister %s from loc: %s (ignored).",
		    user->service_name, str_error(rc));
	}

	telnet_user_log(user, "Destroying...");
	telnet_user_destroy(user);

	return EOK;
}

int main(int argc, char *argv[])
{
	int port = 2223;
	
	async_set_client_connection(client_connection);
	int rc = loc_server_register(NAME);
	if (rc < 0) {
		fprintf(stderr, NAME ": Unable to register server: %s.\n",
		    str_error(rc));
		return 1;
	}

	struct sockaddr_in addr;

	addr.sin_family = AF_INET;
	addr.sin_port = htons(port);

	rc = inet_pton(AF_INET, "127.0.0.1", (void *)
	    &addr.sin_addr.s_addr);
	if (rc != EOK) {
		fprintf(stderr, "Error parsing network address: %s.\n",
		    str_error(rc));
		return 2;
	}

	int listen_sd = socket(PF_INET, SOCK_STREAM, 0);
	if (listen_sd < 0) {
		fprintf(stderr, "Error creating listening socket: %s.\n",
		    str_error(listen_sd));
		return 3;
	}

	rc = bind(listen_sd, (struct sockaddr *) &addr, sizeof(addr));
	if (rc != EOK) {
		fprintf(stderr, "Error binding socket: %s.\n",
		    str_error(rc));
		return 4;
	}

	rc = listen(listen_sd, BACKLOG_SIZE);
	if (rc != EOK) {
		fprintf(stderr, "listen() failed: %s.\n", str_error(rc));
		return 5;
	}

	printf("%s: HelenOS Remote console service\n", NAME);

	while (true) {
		struct sockaddr_in raddr;
		socklen_t raddr_len = sizeof(raddr);
		int conn_sd = accept(listen_sd, (struct sockaddr *) &raddr,
		    &raddr_len);

		if (conn_sd < 0) {
			fprintf(stderr, "accept() failed: %s.\n",
			    str_error(rc));
			continue;
		}

		telnet_user_t *user = telnet_user_create(conn_sd);
		assert(user);

		fid_t fid = fibril_create(network_user_fibril, user);
		assert(fid);
		fibril_add_ready(fid);
	}

	return 0;
}

/** @}
 */