// (c) 2012 Timothy Pearson
// (c) 2012 Raptor Engineering
// ALL RIGHTS RESERVED

#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <limits.h>

#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <pwd.h>
#include <grp.h>
#include <time.h>

#include <mysql/mysql.h>

#include "libraptorsmiface.h"

MYSQL *conn = 0;

char *server = "localhost";
char *user = "remotelab";
char *password = "rlpass123"; /* set me first */
char *database = "remotelab_sm";

void dprint(const char *fmt, ...)
{
	va_list argp;
	va_start(argp, fmt);

#if 0
	vprintf(fmt, argp);
#else
	char debug[1024];
	vsprintf(debug, fmt, argp);
	FILE *fp = fopen("/raptorsmiface.debug", "a");
	if (fp != NULL)
	{
		fputs(debug, fp);
		fclose(fp);
	}
#endif

	va_end(argp);
}

void connect_if_needed() {
	if (!conn) {
		conn = mysql_init(NULL);
		if (!mysql_real_connect(conn, server, user, password, database, 0, NULL, 0)) {
			dprint("[ERROR] MySQL connection FAILED [%s]\n\r", mysql_error(conn));
			conn = 0;
		}
	}
}

char* get_mysql_escaped_string(MYSQL *sqlcn, char* rawstr) {
	unsigned int minlen = strlen(rawstr);
	unsigned int maxlen = ((minlen*2)+1);
	char* escstr = malloc(maxlen*sizeof(char));
	mysql_real_escape_string(sqlcn, escstr, rawstr, minlen);
	return escstr;
}

char* get_group_for_user(char* username) {
	struct passwd* pwd;
	pwd = getpwnam(username);
	if (!pwd) {
		return true;
	}
	gid_t groupid = pwd->pw_gid;
	struct group* primarygroup;
	primarygroup = getgrgid(groupid);
	if (!primarygroup) {
		return true;
	}

	return strdup(primarygroup->gr_name);
}

char raptor_sm_deallocate_session(char* username) {
	MYSQL_RES *res;
	MYSQL_ROW row;
	MYSQL_RES *svr_res;
	MYSQL_ROW svr_row;
	MYSQL_RES *cnt_res;
	MYSQL_ROW cnt_row;
	char* query;

	connect_if_needed();
	if (!conn) {
		return 1;
	}

	// Remove the user from the system
	char* safe_username = get_mysql_escaped_string(conn, username);
	asprintf(&query, "DELETE FROM sessions WHERE username='%s'", safe_username);
	free(safe_username);
	if (mysql_query(conn, query)) {
		// Server error
		free(query);
		return 2;
	}
	else {
		free(query);
		return 0;
	}
}

char* raptor_sm_allocate_session(char* username) {
	MYSQL_RES *res;
	MYSQL_ROW row;
	MYSQL_RES *svr_res;
	MYSQL_ROW svr_row;
	MYSQL_RES *cnt_res;
	MYSQL_ROW cnt_row;
	char* query;

	connect_if_needed();
	if (!conn) {
		return strdup("SQLERR001");
	}

	// Verify that this user is not already on the system
	char* safe_username = get_mysql_escaped_string(conn, username);
	asprintf(&query, "SELECT servername FROM sessions WHERE username='%s'", safe_username);
	free(safe_username);
	if (mysql_query(conn, query)) {
		// Server error
		free(query);
		return strdup("SQLERR002");
	}
	else {
		free(query);
		res = mysql_store_result(conn);
		if ((row = mysql_fetch_row(res)) == NULL) {
			// User is not on a system
			// Find the least utilized node
			if (mysql_query(conn, "SELECT name FROM servers")) {
				// Server error
				mysql_free_result(res);
				return strdup("SQLERR003");
			}
			else {
				svr_res = mysql_store_result(conn);
				char* bestserver = strdup("");
				int bestusage = INT_MAX;
				while ((svr_row = mysql_fetch_row(svr_res)) != NULL) {
					char* safe_servername = get_mysql_escaped_string(conn, svr_row[0]);
					asprintf(&query, "SELECT username FROM sessions WHERE servername='%s'", safe_servername);
					free(safe_servername);
					if (mysql_query(conn, query)) {
						// Server error
						free(query);
						free(bestserver);
						mysql_free_result(res);
						mysql_free_result(svr_res);
						return strdup("SQLERR004");
					}
					else {
						free(query);
						cnt_res = mysql_store_result(conn);
						int usagecount = 0;
						while ((cnt_row = mysql_fetch_row(cnt_res)) != NULL) {
							usagecount++;
						}
						mysql_free_result(cnt_res);
						if (usagecount < bestusage) {
							free(bestserver);
							bestserver = strdup(svr_row[0]);
							bestusage = usagecount;
						}
					}
				}
				mysql_free_result(res);
				mysql_free_result(svr_res);

				// Insert new information into the sessions database and set status to ALLOCATED
				char* safe_servername = get_mysql_escaped_string(conn, bestserver);
				char* safe_username = get_mysql_escaped_string(conn, username);
				asprintf(&query, "INSERT INTO sessions (username, servername, state) VALUES ('%s', '%s', '%d')", safe_username, safe_servername, SM_STATUS_ALLOCATED);
				free(safe_servername);
				free(safe_username);
				if (mysql_query(conn, query)) {
					// Server error
					free(query);
					return strdup("SQLERR005");
				}
				else {
					free(query);
					return strdup(bestserver);
				}
			}
		}
		else {
			char* ret = strdup(row[0]);
			mysql_free_result(res);
			return ret;
		}
	}
}

char* raptor_sm_get_ip_for_hostname(char* hostname, char* error) {
	struct addrinfo hints, *res;
	struct in_addr addr;
	int err;
	
	memset(&hints, 0, sizeof(hints));
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_family = AF_INET;
	
	if ((err = getaddrinfo(hostname, NULL, &hints, &res)) != 0) {
		if (error) *error = 1;
		return strdup("");
	}
	
	addr.s_addr = ((struct sockaddr_in *)(res->ai_addr))->sin_addr.s_addr;
	
	char* ret = strdup(inet_ntoa(addr));
	freeaddrinfo(res);
	if (error) *error = 0;
	return ret;
}

char* raptor_sm_get_hostname_for_username(char* username, bool create) {
	MYSQL_RES *res;
	MYSQL_ROW row;
	char* query;

	connect_if_needed();
	if (!conn) {
		return strdup("SQLERR100");
	}

	char* safe_username = get_mysql_escaped_string(conn, username);
	asprintf(&query, "SELECT servername FROM sessions WHERE username='%s'", safe_username);
	free(safe_username);
	if (mysql_query(conn, query)) {
		// Server error
		free(query);
		return strdup("SQLERR101");
	}
	else {
		free(query);
		res = mysql_store_result(conn);
		while ((row = mysql_fetch_row(res)) != NULL) {
			char* ret = strdup(row[0]);
			mysql_free_result(res);
			return ret;
		}
		// Nothing in the DB
		mysql_free_result(res);
		if (create) {
			// Try to allocate a new session on a node
			return raptor_sm_allocate_session(username);
		}
		else {
			return strdup("");
		}
	}
}

char* raptor_sm_get_ip_for_username(char* username, bool create) {
	char* hostname = raptor_sm_get_hostname_for_username(username, create);
	char err;
	char* ip = raptor_sm_get_ip_for_hostname(hostname, &err);
	if (err) {
		raptor_sm_deallocate_session(username);
	}
	free(hostname);
	return ip;
}

bool raptor_sm_sesslimit_reached(char* username) {
	MYSQL_RES *res;
	MYSQL_ROW row;
	char* query;

	connect_if_needed();
	if (!conn) {
		return true;
	}

	// Respect maximum session number for the group for this user
	int sesslimit = 0;	// Default to denying all sessions

	// Get group for user
	char* groupname = get_group_for_user(username);
	char* safe_groupname = get_mysql_escaped_string(conn, groupname);
	free(groupname);
	asprintf(&query, "SELECT sesslimit FROM groups WHERE groupname='%s'", safe_groupname);
	free(safe_groupname);
	if (mysql_query(conn, query)) {
		// Server error
		free(query);
		return true;
	}
	else {
		free(query);
		res = mysql_store_result(conn);
		row = mysql_fetch_row(res);
		if (row[0]) {
			sesslimit = atoi(row[0]);
		}
		mysql_free_result(res);
	}

	// Figure out how many users are online from this group
	int sesscount = 0;
	asprintf(&query, "SELECT username FROM sessions WHERE state<>'%d'", SM_STATUS_ALLOCATED);
	if (mysql_query(conn, query)) {
		// Server error
		free(query);
		return true;
	}
	else {
		free(query);
		res = mysql_store_result(conn);
		while ((row = mysql_fetch_row(res)) != NULL) {
			if (row[0]) {
				char* test_groupname = get_group_for_user(row[0]);
				if (strcmp(groupname, test_groupname) == 0) {
					sesscount++;
				}
				free(test_groupname);
			}
		}
		mysql_free_result(res);

		if (sesscount < sesslimit) {
			return false;
		}
		return true;
	}

	// We should never end up here!
	return true;
}

pid_t raptor_sm_run_remote_server(char* username, char *const argv[]) {
	MYSQL_RES *res;
	MYSQL_ROW row;
	char* query;

	connect_if_needed();
	if (!conn) {
		return -1;
	}

	// Respect maximum session number for the group for this user
	if (raptor_sm_sesslimit_reached(username)) {
		return -5;
	}

	// Make sure a server is not already running for this user
	// Return the existing PID if it is
	char* safe_username = get_mysql_escaped_string(conn, username);
	asprintf(&query, "SELECT pid FROM sessions WHERE username='%s' AND state<>'%d'", safe_username, SM_STATUS_ALLOCATED);
	free(safe_username);
	if (mysql_query(conn, query)) {
		// Server error
		free(query);
		return -2;
	}
	else {
		free(query);
		res = mysql_store_result(conn);
		while ((row = mysql_fetch_row(res)) != NULL) {
			if (row[0]) {
				int ret = atoi(row[0]);
				if (ret >= 0) {
					mysql_free_result(res);
					return ret;
				}
			}
		}
		mysql_free_result(res);
	}

	int i;
	int n_commands;

	n_commands = 0;
	while (argv[n_commands] != NULL) {
		n_commands++;
	}

	char* ipaddr = raptor_sm_get_ip_for_username(username, true);

	// This is HORRIBLY inefficient
	char* command_string = strdup("");
	for (i=0; i<n_commands; i++) {
		char* origstr = command_string;
		asprintf(&command_string, "%s %s", origstr, argv[i]);
		free(origstr);
	}
	char* origstr = command_string;
	asprintf(&command_string, "ssh %s \'%s & echo $! &\'", ipaddr, origstr);
	free(origstr);
	
	FILE *fp;
	char output[1024];
	
	// Open the command for reading
	fp = popen(command_string, "r");
	if (fp == NULL) {
		return -1;
	}
	
	// Read the output a line at a time
	fgets(output, sizeof(output)-1, fp);
	
	// Close output
	pclose(fp);

	free(command_string);

	return atoi(output);
}

char* raptor_sm_server_started(char* username, pid_t pid, int display) {
	MYSQL_RES *res;
	MYSQL_ROW row;
	char* query;

	long long timestamp = time(NULL);

	connect_if_needed();
	if (!conn) {
		return -1;
	}

	// Update new information into the sessions database and set status to ALLOCATED
	char* safe_username = get_mysql_escaped_string(conn, username);
	asprintf(&query, "UPDATE sessions SET pid='%d', stamp_start='%lld', state='%d', display='%d', stamp_statechange='%lld' WHERE username='%s' AND state='%d'", pid, timestamp, SM_STATUS_RUNNING, display, timestamp, safe_username, SM_STATUS_ALLOCATED);
	free(safe_username);
	if (mysql_query(conn, query)) {
		// Server error
		free(query);
		return -2;
	}
	else {
		free(query);
		return 0;
	}
}

int raptor_sm_get_display_for_username(char* username) {
	MYSQL_RES *res;
	MYSQL_ROW row;
	char* query;

	connect_if_needed();
	if (!conn) {
		return -1;
	}

	char* safe_username = get_mysql_escaped_string(conn, username);
	asprintf(&query, "SELECT display FROM sessions WHERE username='%s'", safe_username);
	free(safe_username);
	if (mysql_query(conn, query)) {
		// Server error
		free(query);
		return -2;
	}
	else {
		free(query);
		res = mysql_store_result(conn);
		while ((row = mysql_fetch_row(res)) != NULL) {
			if (row[0]) {
				int ret = atoi(row[0]);
				mysql_free_result(res);
				return ret;
			}
			else {
				mysql_free_result(res);
				return -3;
			}
		}
		// Nothing in the DB
		mysql_free_result(res);
		return -4;
	}
}

void raptor_sm_wait_for_pid_exit(char* username, pid_t pid) {
	char* ipaddr = raptor_sm_get_ip_for_username(username, false);

	char* command_string;
	asprintf(&command_string, "ssh %s \'while [[ `ps -p %d | grep %d` != \"\" ]]; do sleep 1; done\'", ipaddr, pid, pid);
	system(command_string);
	free(command_string);
}

void raptor_sm_session_terminated(char* username) {
	raptor_sm_deallocate_session(username);
}

int raptor_sm_get_new_unique_display(int mindisplay, int maxdisplay) {
	MYSQL_RES *res;
	MYSQL_ROW row;
	char* query;

	connect_if_needed();
	if (!conn) {
		return -1;
	}

	asprintf(&query, "SELECT display FROM sessions");
	if (mysql_query(conn, query)) {
		// Server error
		free(query);
		return -2;
	}
	else {
		res = mysql_store_result(conn);
		int freedisp;
		bool dispinuse;
		for (freedisp=mindisplay; freedisp<maxdisplay; freedisp++) {
			dispinuse = false;
			mysql_data_seek(res, 0);
			while ((row = mysql_fetch_row(res)) != NULL) {
				if (row[0]) {
					if (atoi(row[0]) == freedisp) {
						dispinuse = true;
					}
				}
			}
			if (dispinuse == false) {
				break;
			}
		}
		mysql_free_result(res);
		return freedisp;
	}
}

char raptor_sm_set_session_state(int display, int state) {
	MYSQL_RES *res;
	MYSQL_ROW row;
	char* query;

	long long timestamp = time(NULL);

	connect_if_needed();
	if (!conn) {
		return -1;
	}

	// Update new state into the sessions database
	asprintf(&query, "UPDATE sessions SET state='%d', stamp_statechange='%lld' WHERE display='%d'", state, timestamp, display);
	if (mysql_query(conn, query)) {
		// Server error
		free(query);
		return -2;
	}
	else {
		free(query);
		return 0;
	}
}