#include "sysvars.h"

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <time.h>

static const char *sysvar_nulltype_tostr(sysvar_t from, char *buf)
{
    (void)from;
    (void)buf;
    return NULL;
}

static bool sysvar_nulltype_fromstr(sysvar_t *to, const char *from)
{
    (void)to;
    (void)from;
    return false;
}

const struct sysvar_ops sysvar_nulltype_ops = {
    .tostr = sysvar_nulltype_tostr,
    .fromstr = sysvar_nulltype_fromstr
};

static const char *sysvar_bool_tostr(sysvar_t from, char *buf)
{
    buf[0] = '0' + from.v_bool;
    buf[1] = '\0';
    return buf;
}

static bool sysvar_bool_fromstr(sysvar_t *to, const char *from)
{
    char c = from[0] | 0x20;
    switch (c) {
    case '1':
    case 't':
    case 'y':
    case 'j':
    case 's':
	to->v_bool = true;
	return true;
    case '0':
    case 'f':
    case 'n':
	to->v_bool = false;
	return true;
    default:
	return false;
    }
}

const struct sysvar_ops sysvar_bool_ops = {
    .tostr = sysvar_bool_tostr,
    .fromstr = sysvar_bool_fromstr,
    .buflen = BOOL_BUFLEN
};

static const char *sysvar_int_tostr(sysvar_t from, char *buf)
{
    snprintf(buf, INT_BUFLEN, "%"PRId32, from.v_int);
    return buf;
}

static bool sysvar_int_fromstr(sysvar_t *to, const char *from)
{
    char *ep;
    long v = strtol(from, &ep, 0);
    if (ep == from || *ep)
	return false;
    to->v_int = v;
    return true;
}

const struct sysvar_ops sysvar_int_ops = {
    .tostr = sysvar_int_tostr,
    .fromstr = sysvar_int_fromstr,
    .buflen = INT_BUFLEN
};

static const char *sysvar_uint_tostr(sysvar_t from, char *buf)
{
    snprintf(buf, UINT_BUFLEN, "%"PRIu32, from.v_uint);
    return buf;
}

static bool sysvar_uint_fromstr(sysvar_t *to, const char *from)
{
    char *ep;
    unsigned long v = strtoul(from, &ep, 0);
    if (ep == from || *ep)
	return false;
    to->v_uint = v;
    return true;
}

const struct sysvar_ops sysvar_uint_ops = {
    .tostr = sysvar_uint_tostr,
    .fromstr = sysvar_uint_fromstr,
    .buflen = UINT_BUFLEN
};

static const char *sysvar_string_tostr(sysvar_t from, char *buf)
{
    (void)buf;
    return from.v_string;
}

static bool sysvar_string_fromstr(sysvar_t *to, const char *from)
{
    char *ns;

    if (!from) {
	ns = NULL;
    } else {
	ns = strdup(from);
	if (!ns)
	    return false;
    }
    to->v_string = ns;
    return true;
}

static bool sysvar_string_set(sysvar_t *to, sysvar_t from)
{
    return sysvar_string_fromstr(to, from.v_string);
}

const struct sysvar_ops sysvar_string_ops = {
    .set = sysvar_string_set,
    .tostr = sysvar_string_tostr,
    .fromstr = sysvar_string_fromstr,
    .is_ptr = true
};

static void sysvar_tz_update(sysvar_t val, bool isset)
{
    if (isset)
	setenv("TZ", val.v_tz, 1);
    else
	unsetenv("TZ");
    tzset();
}

const struct sysvar_ops sysvar_tz_ops = {
    .set = sysvar_string_set,
    .tostr = sysvar_string_tostr,
    .fromstr = sysvar_string_fromstr,
    .update = sysvar_tz_update,
    .is_ptr = true
};

static const char *sysvar_ip_tostr(sysvar_t from, char *buf)
{
    union ip_bytes {
	uint8_t b[4];
	uint32_t l;
    } ip;

    ip.l = from.v_ip;
    snprintf(buf, IP_BUFLEN, "%u.%u.%u.%u", ip.b[0], ip.b[1], ip.b[2], ip.b[3]);
    return buf;
}

static bool sysvar_ip_fromstr(sysvar_t *to, const char *str)
{
    union ip_bytes {
	uint8_t b[4];
	uint32_t l;
    } ip;

    ip.l = 0;
    for (int i = 0; i < 4; i++) {
	char *ep;
	unsigned long v = strtoul(str, &ep, 10);
	if (ep == str || *ep != (i == 3) ? '\0' : '.' || v > 255)
	    return false;
	str = ep + 1;
	ip.b[i] = v;
    }

    to->v_ip = ip.l;
    return true;
}

const struct sysvar_ops sysvar_ip_ops = {
    .tostr = sysvar_ip_tostr,
    .fromstr = sysvar_ip_fromstr,
    .buflen = IP_BUFLEN
};

static bool sysvar_mac_set(sysvar_t *to, sysvar_t from)
{
    uint8_t *buf;

    if (!from.v_mac) {
	buf = NULL;
    } else {
	buf = malloc(6);
	if (!buf)
	    return false;

	memcpy(buf, from.v_mac, 6);
    }
    to->v_mac = buf;
    return true;
}

static const char *sysvar_mac_tostr(sysvar_t from, char *buf)
{
    const uint8_t *m = from.v_mac;
    if (!m)
	return NULL;

    snprintf(buf, MAC_BUFLEN, "%x:%x:%x:%x:%x:%x",
	     m[0], m[1], m[2], m[3], m[4], m[5]);
    return buf;
}

static bool sysvar_mac_fromstr(sysvar_t *to, const char *str)
{
    sysvar_t from;
    uint8_t m[6];

    if (!str) {
	from.v_mac = NULL;
    } else {
	for (int i = 0; i < 6; i++) {
	    char *ep;
	    unsigned long v = strtoul(str, &ep, 16);
	    if (ep == str || *ep != (i == 5) ? '\0' : ':' || v > 255)
		return false;
	    str = ep + 1;
	    m[i] = v;
	}

	from.v_mac = m;
    }

    return sysvar_mac_set(to, from);
}

const struct sysvar_ops sysvar_mac_ops = {
    .set = sysvar_mac_set,
    .tostr = sysvar_mac_tostr,
    .fromstr = sysvar_mac_fromstr,
    .buflen = MAC_BUFLEN,
    .is_ptr = true
};

/* --- Generic getters/setters --- */

sysvar_t getvar(size_t var)
{
    if (var >= (size_t)sysvar_count)
	return sysvar_defval[sysvar_null];

    return sysvar_val[var];
}

static bool do_setvar(size_t var, sysvar_t val, bool is_set)
{
    const struct sysvar_ops *type = sysvar_type[var];
    sysvar_t *to = &sysvar_val[var];
    void *free_ptr = NULL;

    if (type->is_ptr)
	free_ptr = to->v_ptr;

    if (!type->set || (type->is_ptr && !val.v_ptr)) {
	sysvar_val[var] = val;
    } else {
	if (!type->set(to, val))
	    return false;
    }

    if (free_ptr)
	free(free_ptr);

    sysvar_isset[var] = is_set;
    if (type->update)
	type->update(*to, is_set);

    return true;
}

bool setvar(size_t var, sysvar_t val)
{
    if (var >= (size_t)sysvar_count)
	return false;

    return do_setvar(var, val, true);
}

bool unsetvar(size_t var)
{
    if (var >= (size_t)sysvar_count)
	return false;

    return do_setvar(var, sysvar_defval[var], false);
}

/* --- Getters/setters converting to/from strings --- */

const char *getvar_tostr(size_t var)
{
    static char buf[SYSVAR_BUFLEN];
    return getvar_tostr_r(var, buf);
}

const char *getvar_tostr_r(size_t var, char *buf)
{
    if (var >= (size_t)sysvar_count || !sysvar_isset[var])
	return NULL;

    const struct sysvar_ops *type = sysvar_type[var];

    /* A tostr method is required */
    return type->tostr(sysvar_val[var], buf);
}

bool setvar_fromstr(size_t var, const char *str)
{
    if (var >= (size_t)sysvar_count)
	return NULL;

    if (!str)
	return unsetvar(var);

    const struct sysvar_ops *type = sysvar_type[var];
    sysvar_t *to = &sysvar_val[var];
    void *free_ptr = NULL;

    if (type->is_ptr)
	free_ptr = to->v_ptr;

    /* A fromstr method is required */
    if (!type->fromstr(to, str))
	return false;

    if (free_ptr)
	free(free_ptr);

    sysvar_isset[var] = true;
    return true;
}

/* --- Initialization/reset to defaults --- */

void sysvar_reset(void)
{
    for (size_t i = sysvar_null; i < (size_t)sysvar_count; i++)
	unsetvar(i);
}