#ifndef SYSVAR_COMMON_H
#define SYSVAR_COMMON_H

#include <stddef.h>
#include <stdbool.h>
#include <inttypes.h>

#ifndef extern_c
# ifdef __cplusplus
#  define extern_c extern "C"
# else
#  define extern_c extern
# endif
#endif

typedef struct sysvar_namespace {
    const char *name;
    size_t first, count;
} sysvar_ns_t;

typedef union sysvar_value {
    bool v_bool;
    long int v_int;
    unsigned long int v_uint;
    const char *v_str;
    const char *v_tz;		/* Timezone */
    uint32_t v_ip;		/* IPv4 address */
    const uint8_t *v_mac;	/* MAC address */
    void *v_ptr;
} sysvar_t;

struct sysvar_ops {
    bool (*set)(sysvar_t *, sysvar_t);
    /* bool (*unset)(sysvar_t *); - not used */
    const char * (*tostr)(sysvar_t, char *);
    bool (*fromstr)(sysvar_t *, const char *);
    void (*update)(sysvar_t, bool); /* Called after set or fromstr; bool = isset */
    size_t buflen;		/* Minimal buffer size for string if needed */
    bool is_ptr;		/* Type is an allocated pointer */
};

typedef const struct sysvar_ops *sysvar_type_t;

#define SYSVAR_TYPE(x) (&sysvar_ ## x ## _ops)

/* Buffer size needed to represent some data types */
#define BOOL_BUFLEN 2
#define INT_BUFLEN  (3*sizeof(unsigned int)+2)
#define UINT_BUFLEN INT_BUFLEN
#define IP_BUFLEN   (4*4)
#define MAC_BUFLEN  (3*6)

#define SYSVAR_BUFLEN	32	/* Conservative minimum */

extern_c sysvar_t getvar(size_t var);
extern_c bool setvar(size_t var, sysvar_t val);
extern_c bool unsetvar(size_t var);
extern_c const char *getvar_tostr(size_t var);
extern_c const char *getvar_tostr_r(size_t var, char *buf);
extern_c bool setvar_fromstr(size_t var, const char *str);
extern_c void sysvar_reset(void);
extern_c size_t sysvar_find(size_t ns, const char *name);

extern_c const struct sysvar_ops sysvar_nulltype_ops;

/* Type-specific definitions/getters/setters */

#define SYSVAR_MKTYPE(t,c_type)					\
    static inline c_type getvar_ ## t (size_t var)		\
    {								\
	return getvar(var).v_ ## t ;				\
    }								\
    static inline bool setvar_ ## t (size_t var, c_type v)	\
    {								\
	sysvar_t vv;						\
	vv.v_ ## t = v;						\
	return setvar(var, vv);					\
    }								\
    extern_c const struct sysvar_ops sysvar_ ## t ## _ops

SYSVAR_MKTYPE(bool, bool);
SYSVAR_MKTYPE(int, long int);
SYSVAR_MKTYPE(uint, unsigned long int);
SYSVAR_MKTYPE(str, const char *);
SYSVAR_MKTYPE(tz, const char *);
SYSVAR_MKTYPE(ip, uint32_t);
SYSVAR_MKTYPE(mac, const uint8_t *);

#endif /* SYSVAR_COMMON_H */