/*
 * Influx C (ic) client for data capture
 * Developer: Nigel Griffiths.
 * (C) Copyright 2021 Nigel Griffiths

    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/>.

    Compile: cc ic.c -g -O3 -o ic
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <ctype.h>
#include <math.h>
#include <string.h>
#include <sys/errno.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>

#define DEBUG   if(debug)
#define MEGABYTE ( 1024 * 1024 ) /* USed as the default buffer sizes */

int debug = 0; /* 0=off, 1=on basic, 2=trace like output */

char influx_hostname[1024 + 1] = { 0 };/* details of the influxdb server or telegraf */
char influx_ip[16 + 1] = { 0 };
long influx_port = 0;

char influx_database[256+1];		/* the influxdb database  */
char influx_username[64+1];		/* optional for influxdb access */
char influx_password[64+1];		/* optional for influxdb access */

char *output; /* all the stats must fit in this buffer */
long output_size = 0;
long output_char = 0;

char *influx_tags; /* saved tags for every influxdb line protocol mesurement */

int subended = 0;		/* stop ic_subend and ic_measureend both enig the measure */
int first_sub = 0;		/* need to remove the ic_measure measure before adding ic_sub measure */
char saved_section[64];
char saved_sub[64];

int sockfd;			/* file desciptor for socket connection */

void error(char *buf)
{
    fprintf(stderr, "error: \"%s\" errno=%d meaning=\"%s\"\n", buf, errno, strerror(errno));
    close(sockfd);
    sleep(2);			/* this can help the socket close cleanly at the remote end */
    exit(1);
}

void ic_debug(int level)
{
	debug = level;
}

/* ic_tags() argument is the measurement tags for influddb */
/* example: "host=vm1234"   note:the comma & hostname of the virtual machine sending the data */
/* complex: "host=lpar42,serialnum=987654,arch=power9" note:the comma separated list */
void ic_tags(char *t)	
{
    DEBUG fprintf(stderr,"ic_tags(%s)\n",t);
    if( influx_tags == (char *) 0) {
        if( (influx_tags = (char *)malloc(MEGABYTE)) == (char *)-1)
           error("failed to malloc() tags buffer");
    }

    strncpy(influx_tags,t,256);
}

void ic_influx_database(char *host, long port, char *db) /* note: converts influxdb hostname to ip address */
{
	struct hostent *he;
	char errorbuf[1024 +1 ];

	influx_port = port;
	strncpy(influx_database,db,256);

	if(host[0] <= '0' && host[0] <='9') { 
		DEBUG fprintf(stderr,"ic_influx(ipaddr=%s,port=%ld,database=%s))\n",host,port,db);
		strncpy(influx_ip,host,16);
	} else {
		DEBUG fprintf(stderr,"ic_influx_by_hostname(host=%s,port=%ld,database=%s))\n",host,port,db);
		strncpy(influx_hostname,host,1024);
		if (isalpha(host[0])) {

		    he = gethostbyname(host);
		    if (he == NULL) {
			sprintf(errorbuf, "influx host=%s to ip address convertion failed gethostbyname(), bailing out\n", host);
			error(errorbuf);
		    }
		    /* this could return multiple ip addresses but we assume its the first one */
		    if (he->h_addr_list[0] != NULL) {
			strcpy(influx_ip, inet_ntoa(*(struct in_addr *) (he->h_addr_list[0])));
			DEBUG fprintf(stderr,"ic_influx_by_hostname hostname=%s converted to ip address %s))\n",host,influx_ip);
		    } else {
			sprintf(errorbuf, "influx host=%s to ip address convertion failed (empty list), bailing out\n", host);
			error(errorbuf);
		    }
		} else {
		    strcpy( influx_ip, host); /* perhaps the hostname is actually an ip address */
		}
        }
}

void ic_influx_userpw(char *user, char *pw)
{
	DEBUG fprintf(stderr,"ic_influx_userpw(username=%s,pssword=%s))\n",user,pw);
	strncpy(influx_username,user,64);
	strncpy(influx_password,pw,64);
}

int create_socket() 		/* returns 1 for error and 0 for ok */
{
    int i;
    static char buffer[4096];
    static struct sockaddr_in serv_addr;

    if(debug) DEBUG fprintf(stderr, "socket: trying to connect to \"%s\":%ld\n", influx_ip, influx_port);
    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
	error("socket() call failed");
	return 0;
    }

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = inet_addr(influx_ip);
    serv_addr.sin_port = htons(influx_port);

    /* connect tot he socket offered by the web server */
    if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) {
	DEBUG fprintf(stderr, " connect() call failed errno=%d", errno);
	return 0;
    }
    return 1;
}

void ic_check(long adding) /* Check the buffer space */
{
    if(output == (char *)0) {			/* First time create the buffer *
	if( (output = (char *)malloc(MEGABYTE)) == (char *)-1)
	    error("failed to malloc() output buffer");
    }
    if(output_char + (2*adding) > output_size) /* When near the end of the output buffer, extend it*/
	if( (output = (char *)realloc(output, output_size + MEGABYTE)) == (char *)-1)
	    error("failed to realloc() output buffer");
    }
}

void remove_ending_comma_if_any()
{
    if (output[output_char - 1] == ',') {
	output[output_char - 1] = 0;	/* remove the char */
	output_char--;
    }
}

void ic_measure(char *section)
{
    ic_check( strlen(section) + strlen(influx_tags) + 3);

    output_char += sprintf(&output[output_char], "%s,%s ", section, influx_tags);
    strcpy(saved_section, section);
    first_sub = 1;
    subended = 0;
    DEBUG fprintf(stderr, "ic_measure(\"%s\") count=%ld\n", section, output_char);
}

void ic_measureend()
{
    ic_check( 4 );
    remove_ending_comma_if_any();
    if (!subended) {
         output_char += sprintf(&output[output_char], "   \n");
    }
    subended = 0;
    DEBUG fprintf(stderr, "ic_measureend()\n");
}

/* Note this added a further tag to the measurement of the "resource_name" */
/* measurement might be "disks" */
/* sub might be "sda1", "sdb1", etc */
void ic_sub(char *resource)
{
    int i;

    ic_check( strlen(saved_section) + strlen(influx_tags) +strlen(saved_sub) + strlen(resource) + 9);

    /* remove previously added section */
    if (first_sub) {
	for (i = output_char - 1; i > 0; i--) {
	    if (output[i] == '\n') {
		output[i + 1] = 0;
		output_char = i + 1;
		break;
	    }
	}
    }
    first_sub = 0;

    /* remove the trailing s */
    strcpy(saved_sub, saved_section);
    if (saved_sub[strlen(saved_sub) - 1] == 's') {
	saved_sub[strlen(saved_sub) - 1] = 0;
    }
    output_char += sprintf(&output[output_char], "%s,%s,%s_name=%s ", saved_section, influx_tags, saved_sub, resource);
    subended = 0;
    DEBUG fprintf(stderr, "ic_sub(\"%s\") count=%ld\n", resource, output_char);
}

void ic_subend()
{
    ic_check( 4 );
    remove_ending_comma_if_any();
    output_char += sprintf(&output[output_char], "   \n");
    subended = 1;
    DEBUG fprintf(stderr, "ic_subend()\n");
}

void ic_long(char *name, long long value)
{
    ic_check( strlen(name) + 16 + 4 );
    output_char += sprintf(&output[output_char], "%s=%lldi,", name, value);
    DEBUG fprintf(stderr, "ic_long(\"%s\",%lld) count=%ld\n", name, value, output_char);
}

void ic_double(char *name, double value)
{
    ic_check( strlen(name) + 16 + 4 );
    if (isnan(value) || isinf(value)) { /* not-a-number or infinity */
	DEBUG fprintf(stderr, "ic_double(%s,%.1f) - nan error\n", name, value);
    } else {
	output_char += sprintf(&output[output_char], "%s=%.3f,", name, value);
	DEBUG fprintf(stderr, "ic_double(\"%s\",%.1f) count=%ld\n", name, value, output_char);
    }
}

void ic_string(char *name, char *value)
{
    int i;
    int len;

    ic_check( strlen(name) + strlen(value) + 4 );
    len = strlen(value);
    for (i = 0; i < len; i++) 	/* replace problem characters and with a space */
	if (value[i] == '\n' || iscntrl(value[i]))
	    value[i] = ' ';
    output_char += sprintf(&output[output_char], "%s=\"%s\",", name, value);
    DEBUG fprintf(stderr, "ic_string(\"%s\",\"%s\") count=%ld\n", name, value, output_char);
}

void ic_push()
{
    char header[1024];
    char result[1024];
    char buffer[1024 * 8];
    int ret;
    int i;
    int total;
    int sent;
    int code;

    if (output_char == 0)	/* nothing to send so skip this operation */
	return;
    if (influx_port) {
	DEBUG fprintf(stderr, "ic_push() size=%ld\n", output_char);
	if (create_socket() == 1) {

	    sprintf(buffer, "POST /write?db=%s&u=%s&p=%s HTTP/1.1\r\nHost: %s:%ld\r\nContent-Length: %ld\r\n\r\n",
		    influx_database, influx_username, influx_password, influx_hostname, influx_port, output_char);
	    DEBUG fprintf(stderr, "buffer size=%ld\nbuffer=<%s>\n", strlen(buffer), buffer);
	    if ((ret = write(sockfd, buffer, strlen(buffer))) != strlen(buffer)) {
			fprintf(stderr, "warning: \"write post to sockfd failed.\" errno=%d\n", errno);
	    }
	    total = output_char;
	    sent = 0;
	    if (debug == 2)
		fprintf(stderr, "output size=%d output=\n<%s>\n", total, output);
	    while (sent < total) {
		ret = write(sockfd, &output[sent], total - sent);
		DEBUG fprintf(stderr, "written=%d bytes sent=%d total=%d\n", ret, sent, total);
		if (ret < 0) {
		    fprintf(stderr, "warning: \"write body to sockfd failed.\" errno=%d\n", errno);
		    break;
		}
		sent = sent + ret;
	    }
	    for (i = 0; i < 1024; i++) /* empty the buffer */
		result[i] = 0;
	    if ((ret = read(sockfd, result, sizeof(result))) > 0) {
		result[ret] = 0;
		DEBUG fprintf(stderr, "received bytes=%d data=<%s>\n", ret, result);
		sscanf(result, "HTTP/1.1 %d", &code);
		for (i = 13; i < 1024; i++)
		    if (result[i] == '\r')
			result[i] = 0;
		if (debug == 2)
		    fprintf(stderr, "http-code=%d text=%s [204=Success]\n", code, &result[13]);
		if (code != 204)
		    fprintf(stderr, "code %d -->%s<--\n", code, result);
	    }
	    close(sockfd);
	    sockfd = 0;
	    DEBUG fprintf(stderr, "ic_push complete\n");
	} else {
	    DEBUG fprintf(stderr, "socket create failed\n");
	}
    } else error("influx port is not set, bailing out");

    output[0] = 0;
    output_char = 0;
}
