/* This file is part of Ping903
   Copyright (C) 2020 Sergey Poznyakoff
  
   Ping903 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, or (at your option)
   any later version.
  
   Ping903 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 Ping903.  If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <pthread.h>
#include <stdarg.h>
#include <microhttpd.h>

void ping903(void);


/* Configuration file parser */

/* Callback mode */
enum {
	CF_PARSE,      /* parse input statement */
	CF_SERIALIZE   /* serialize configuration setting */
};

union cf_callback_arg {
	struct json_value *output;  /* Output value */
	struct cf_line {
		char const *val;    /* Statement value (after keyword) */
		char const *file;   /* Statement location: file name */
		unsigned line;      /*     ...  and input line number */
	} input;
};

enum {
	CF_RET_OK,
	CF_RET_FAIL,
	CF_RET_IGNORE
};

/* Configuration parser callback function */
typedef int (*CF_CALLBACK)(int mode, union cf_callback_arg *arg, void *data);

/* Built-in statement types */
enum {
	STMT_T_STRING,
	STMT_T_ULONG,
	STMT_T_BOOL,
	STMT_T_CALLBACK
};

int readconfig(char const *file);
int cf_trusted_ip(int mode, union cf_callback_arg *arg, void *data);
int cf_syslog_facility(int mode, union cf_callback_arg *arg, void *data);
int cf_auth(int mode, union cf_callback_arg *arg, void *data);

void pinger_setup(void);
int pinger_host_add(char const *name, struct sockaddr *addr, socklen_t addrlen);

/* Return codes for pinger update functions */
enum {
	UPD_OK,          /* Update successful. */
	UPD_NOMEM,       /* Not enough memory. */
	UPD_EXISTS,      /* When adding: such entry already exists. */
	                 /* When deleting: such entry does not exist. */
	UPD_NORESOLV     /* Host name does not resolve */
};

int pinger_host_delete_by_name(char const *name);
int pinger_host_add_name(char const *name);
int pinger_hostlist_set(struct json_value *obj, char const **err_text,
			int *err_pos);

char *get_remote_ip(struct MHD_Connection *conn);

enum {
	HOST_STAT_INIT,      /* Initial state: data are being collected */
	HOST_STAT_VALID,     /* The record is valid */
	HOST_STAT_PENDING,   /* The record is valid; new data are being
				collected */
	HOST_STAT_INVALID    /* The record is invalid (host unreachable) */
};

struct host_stat {
	int status;
	struct timeval start_tv;
	struct timeval stop_tv;
	unsigned long xmit_count;
	unsigned long recv_count;
	double tmin;             /* minimum round trip time */
	double tmax;             /* maximum round trip time */
	double avg;
	double stddev;
};

static inline int host_stat_is_valid(struct host_stat const *hs) {
	return hs->status == HOST_STAT_VALID || hs->status == HOST_STAT_PENDING;
}

typedef struct hostping {
	char *name;
	struct sockaddr *addr;
	socklen_t addrlen;

	pthread_mutex_t mutex;
	
	/* Current ping statistics */
	struct timeval start_tv;
	struct timeval xmit_tv;
	struct timeval recv_tv;
	unsigned long xmit_count;
	unsigned long recv_count;
	double tmin;             /* minimum round trip time */
	double tmax;             /* maximum round trip time */
	double tsum;             /* sum of all times, for doing average */
	double tsumsq;           /* sum of all times squared, for std. dev. */

	/* Last probe statistics */
	struct host_stat stat_last;

	struct hostping *prev, *next;
} HOSTPING;

extern int verbose;
extern int fatal_signals[];
extern char *httpd_addr;
extern int httpd_access_log;
extern int httpd_log_verbose;
extern char *pidfile;
extern unsigned long probe_interval;
extern unsigned long ping_interval;
extern unsigned long ping_count;
extern unsigned long ping_tolerance;
extern size_t data_length;
extern unsigned int httpd_backlog_size;

struct json_value *config_to_json(void);

/* Return codes for get_ function family. */
enum {
	GET_OK,     /* Success. */
	GET_NOMEM,  /* Not enough memory. */
	GET_NOENT   /* Requested entry not found. */
	            /* Obviously, this is never returned by get_all_*
		       functions. */
};
int get_hostname_stat(char const *name, struct json_value **retval);
int get_ipaddr_stat(struct sockaddr *sa, int salen, struct json_value **retval);
int get_all_hosts(struct json_value **);
int get_all_host_stat(struct json_value **);
struct addrinfo;
int get_host_matches(struct addrinfo **aip, struct json_value **retval);

int file_read_ip_list(FILE *fp, char const *fname);

void p903_init(void);
void *p903_sender(void *p);
void *p903_receiver(void *p);
void *p903_scheduler(void *p);
void *p903_saver(void *p);