#include <stddef.h>
#include <assert.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>

#include <libdaemon/dlog.h>

#include "modemman.h"
#include "modem.h"

#define MAX_CHANNELS 10
#define TTY_START 12

struct llist {
    struct modem *modem;
    struct llist *next;
};

static struct llist *llist = NULL;
static int n_llist = 0;

static void modem_try_open(const char *dev) {
    struct modem *m;
    
    if ((m = modem_open(dev))) {
        struct llist *l = malloc(sizeof(struct llist));
        assert(l);
        
        l->modem = m;
        l->next = llist;
        llist = l;
        n_llist++;
    }
}

int modem_manager_init(int channels) {
    int i;

    assert(channels <= MAX_CHANNELS && channels > 0); 
    assert(n_llist == 0);

    for (i = TTY_START; i < TTY_START+MAX_CHANNELS && n_llist < channels; i++) {
        char d[PATH_MAX];
        snprintf(d, sizeof(d), "/dev/ttyI%i", i);
        modem_try_open(d);
    }

    if (n_llist < channels) {
        daemon_log(LOG_ERR, "Failed to allocate the requested channels. Got %i of %i.", n_llist, channels);
        modem_manager_done();
        return -1;
    }

    return 0;
}

void modem_manager_done(void) {

    while (llist) {
        struct llist *l;

        modem_close(llist->modem);
        l = llist;
        llist = llist->next;
        free(l);
        n_llist--;
    }

    assert(!n_llist && !llist);
}