// build:
// cc -Wall $(pkg-config --cflags --libs libssh plplot) -lm -o remote_plot_old_no_gtk remote_plot_old_no_gtk.c

// references:
// https://api.libssh.org/stable/libssh_tutorial.html
// https://api.libssh.org/stable/libssh_tutor_guided_tour.html
// plplot example 17

#include <libssh/libssh.h>
#include <stdlib.h>
#include <stdio.h>
#include <libssh/sftp.h>

// verify_knownhost()
#include <errno.h>
#include <string.h>

#include <fcntl.h> // open()

// plplot
#include <plplot/plConfig.h>
#include <plplot/plplot.h>
#include <math.h>
//#include <stdlib.h>
#include <time.h>
#include <unistd.h>

// very small also works, just transfter delays, I test accelerometer data is
// like 15782 which is 7 bytes consider newline and \0?
#define MAX_XFER_BUF_SIZE 7

// Variables for holding error return info from PLplot
static PLINT pl_errcode;
static char  errmsg[160];

int sftp_read_sync(ssh_session session, sftp_session sftp)
{
	int access_type;
	sftp_file file;
	char buffer[MAX_XFER_BUF_SIZE];
	int nbytes, rc;
	access_type = O_RDONLY;

	PLINT           id1, autoy, acc;
	PLFLT           ymin, ymax, xlab, ylab;
	PLFLT           t, tmin, tmax, tjump;
	PLINT           colbox, collab, colline[4], styline[4];
	PLCHAR_VECTOR   legline[4];

	// If db is used the plot is much more smooth. However, because of the
	// async X behaviour, one does not have a real-time scripcharter.
	// This is now disabled since it does not significantly improve the
	// performance on new machines and makes it difficult to use this
	// example non-interactively since it requires an extra pleop call after
	// each call to plstripa.
	//
	//plsetopt("db", "");
	//plsetopt("np", "");

	// User sets up plot completely except for window and data
	// Eventually settings in place when strip chart is created will be
	// remembered so that multiple strip charts can be used simultaneously.
	//

	// Specify some reasonable defaults for ymin and ymax
	// The plot will grow automatically if needed (but not shrink)

	ymin = -0.1;
	ymax = 0.1;

	// Specify initial tmin and tmax -- this determines length of window.
	// Also specify maximum jump in t
	// This can accomodate adaptive timesteps

	tmin  = 0.;
	tmax  = 10.;
	tjump = 0.3;        // percentage of plot to jump

	// Axes options same as plbox.
	// Only automatic tick generation and label placement allowed
	// Eventually I'll make this fancier

	colbox     = 1;
	collab     = 3;
	styline[0] = colline[0] = 2;        // pens color and line style
	styline[1] = colline[1] = 3;
	styline[2] = colline[2] = 4;
	styline[3] = colline[3] = 5;

	legline[0] = "in_accel_z_raw";                         // pens legend
	legline[1] = "not_used";
	legline[2] = "not_used";
	legline[3] = "not_used";

	xlab = 0.; ylab = 0.25;     // legend position

	autoy = 1;                  // autoscale y
	acc   = 1;                  // don't scrip, accumulate

	// Initialize plplot

	plinit();

	pladv( 0 );
	plvsta();

	// Register our error variables with PLplot
	// From here on, we're handling all errors here

	plsError( &pl_errcode, errmsg );

	plstripc( &id1, "bcnst", "bcnstv",
			tmin, tmax, tjump, ymin, ymax,
			xlab, ylab,
			autoy, acc,
			colbox, collab,
			colline, styline, legline,
			"t", "", "Strip chart demo" );

	if ( pl_errcode )
	{
		fprintf( stderr, "%s\n", errmsg );
		exit( 1 );
	}

	// Let plplot handle errors from here on

	plsError( NULL, NULL );

	autoy = 0;  // autoscale y
	acc   = 1;  // accumulate

	// This is to represent a loop over time
	// Let's try a random walk process

	for (t=0;;t++) {
		file = sftp_open(sftp, "/sys/bus/iio/devices/iio:device2/in_accel_z_raw",
				access_type, 0);
		if (file == NULL) {
			fprintf(stderr, "Can't open file for reading: %s\n",
					ssh_get_error(session));
			return SSH_ERROR;
		}

		for (;;) {
			nbytes = sftp_read(file, buffer, sizeof(buffer));
			if (nbytes == 0) {
				break; // EOF
			} else if (nbytes < 0) {
				fprintf(stderr, "Error while reading file: %s\n",
						ssh_get_error(session));
				sftp_close(file);
				return SSH_ERROR;
			}

			//printf("%s",buffer);
			//printf("%d\n",atoi(buffer));
			plstripa( id1, 0, t, atof(buffer));
		}
	}

	rc = sftp_close(file);
	if (rc != SSH_OK) {
		fprintf(stderr, "Can't close the read file: %s\n",
				ssh_get_error(session));
		return rc;
	}

	plstripd( id1 );
	plend();

	return SSH_OK;
}

// https://api.libssh.org/stable/libssh_tutor_guided_tour.html
int verify_knownhost(ssh_session session)
{
	enum ssh_known_hosts_e state;
	unsigned char *hash = NULL;
	ssh_key srv_pubkey = NULL;
	size_t hlen;
	char buf[10];
	char *hexa;
	char *p;
	int cmp;
	int rc;

	rc = ssh_get_server_publickey(session, &srv_pubkey);
	if (rc < 0) {
		return -1;
	}

	rc = ssh_get_publickey_hash(srv_pubkey,
			SSH_PUBLICKEY_HASH_SHA1,
			&hash,
			&hlen);
	ssh_key_free(srv_pubkey);
	if (rc < 0) {
		return -1;
	}

	state = ssh_session_is_known_server(session);
	switch (state) {
		case SSH_KNOWN_HOSTS_OK:
			/* OK */

			break;
		case SSH_KNOWN_HOSTS_CHANGED:
			fprintf(stderr, "Host key for server changed: it is now:\n");
			ssh_print_hexa("Public key hash", hash, hlen);
			fprintf(stderr, "For security reasons, connection will be stopped\n");
			ssh_clean_pubkey_hash(&hash);

			return -1;
		case SSH_KNOWN_HOSTS_OTHER:
			fprintf(stderr, "The host key for this server was not found but an other"
					"type of key exists.\n");
			fprintf(stderr, "An attacker might change the default server key to"
					"confuse your client into thinking the key does not exist\n");
			ssh_clean_pubkey_hash(&hash);

			return -1;
		case SSH_KNOWN_HOSTS_NOT_FOUND:
			fprintf(stderr, "Could not find known host file.\n");
			fprintf(stderr, "If you accept the host key here, the file will be"
					"automatically created.\n");

			/* FALL THROUGH to SSH_SERVER_NOT_KNOWN behavior */

		case SSH_KNOWN_HOSTS_UNKNOWN:
			hexa = ssh_get_hexa(hash, hlen);
			fprintf(stderr,"The server is unknown. Do you trust the host key?\n");
			fprintf(stderr, "Public key hash: %s\n", hexa);
			ssh_string_free_char(hexa);
			ssh_clean_pubkey_hash(&hash);
			p = fgets(buf, sizeof(buf), stdin);
			if (p == NULL) {
				return -1;
			}

			cmp = strncasecmp(buf, "yes", 3);
			if (cmp != 0) {
				return -1;
			}

			rc = ssh_session_update_known_hosts(session);
			if (rc < 0) {
				fprintf(stderr, "Error %s\n", strerror(errno));
				return -1;
			}

			break;
		case SSH_KNOWN_HOSTS_ERROR:
			fprintf(stderr, "Error %s", ssh_get_error(session));
			ssh_clean_pubkey_hash(&hash);
			return -1;
	}

	ssh_clean_pubkey_hash(&hash);
	return 0;
}

int main(void)
{
	ssh_session my_ssh_session;
	sftp_session sftp;
	int rc;

	// Open session and set options
	my_ssh_session = ssh_new();
	if (my_ssh_session == NULL)
		exit(-1);
	ssh_options_set(my_ssh_session, SSH_OPTIONS_HOST, "10.0.0.7");

	// Connect to server
	rc = ssh_connect(my_ssh_session);
	if (rc != SSH_OK)
	{
		fprintf(stderr, "Error connecting to 10.0.0.7: %s\n",
				ssh_get_error(my_ssh_session));
		ssh_free(my_ssh_session);
		exit(-1);
	}

	// Verify the server's identity
	// For the source code of verify_knownhost(), check previous example
	if (verify_knownhost(my_ssh_session) < 0)
	{
		ssh_disconnect(my_ssh_session);
		ssh_free(my_ssh_session);
		exit(-1);
	}

	// Authenticate ourselves
	// https://api.libssh.org/stable/libssh_tutor_authentication.html
	rc = ssh_userauth_publickey_auto(my_ssh_session, NULL, NULL);
	if (rc != SSH_AUTH_SUCCESS)
	{
		fprintf(stderr, "Error authenticating with key: %s\n",
				ssh_get_error(my_ssh_session));
		ssh_disconnect(my_ssh_session);
		ssh_free(my_ssh_session);
		exit(-1);
	}


	sftp = sftp_new(my_ssh_session);
	if (sftp == NULL)
	{
		fprintf(stderr, "Error allocating SFTP session: %s\n",
				ssh_get_error(my_ssh_session));
		return SSH_ERROR;
	}

	rc = sftp_init(sftp);
	if (rc != SSH_OK)
	{
		fprintf(stderr, "Error initializing SFTP session: code %d.\n",
				sftp_get_error(sftp));
		sftp_free(sftp);
		return rc;
	}

	sftp_read_sync(my_ssh_session,sftp);

	ssh_disconnect(my_ssh_session);
	ssh_free(my_ssh_session);
	// Segmentation fault (core dumped) error, why? maybe double free? so no free is ok?
	//sftp_free(sftp);

	return 0;
}