#include <stddef.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <fnmatch.h>
#include <stdio.h>
#include <unistd.h>

#include <libdaemon/dlog.h>

#include "msntab.h"

#define MAX_ENTRIES 100
#define MAX_INCLUDES 10

static struct tabentry *first = NULL;
static struct tabentry *last = NULL;
static int n_entries = 0;

static int n_includes = 0;

struct tabentry* msntab_check_call(const char *callee, const char *caller) {
    struct tabentry *l = first;
    
    while (l) {
        assert(l->local && l->remote);
        
        if (!fnmatch(l->local, callee, 0) &&  !fnmatch(l->remote, caller, 0)) {
            daemon_log(LOG_INFO, "MSN table entry from '%s:%u' matched.", l->filename, l->line);
            return msntab_ref(l);
        }
        
        l = l->next;
    }

    return NULL;
}


struct tabentry* msntab_ref(struct tabentry *t) {
    assert(t && t->ref_counter >= 1);
    t->ref_counter++;
    return t;
}

void msntab_unref(struct tabentry *t) {
    assert(t && t->ref_counter >= 1);
    t->ref_counter--;

    if (t->ref_counter == 0) {
        
        if (t->args) {
            char **a = t->args;
            while (*a) {
                free(*a);
                a++;
            }
            free(t->args);
        }

        free(t->local);
        free(t->remote);
        free(t->filename);
        
        free(t);
    }
}

void msntab_flush(void) {
    while (first) {
        struct tabentry *l = first;
        first = first->next;

        if (first)
            first->prev = NULL;

        if (last == l)
            last = NULL;
        
        msntab_unref(l);
    }

    n_entries = 0;
    n_includes++;
}

#define MAX_ARGS 16

static char** parse_args(const char *s) {
    char *o, **a;
    char *c = (char*) s;
    int i = 0;

    a = malloc(sizeof(char *)*MAX_ARGS);
    memset(a, 0, sizeof(char *)*MAX_ARGS);

    while ((o = strsep(&c, " \t"))) {
        a[i++] = strdup(o);

        if (i >= MAX_ARGS-1)
            break;
    }

    return a;
}


static int parse_options(const char *s, struct tabentry *t) {
    char *o;
    char *c = (char*) s;

    assert(s && t);
    
    while ((o = strsep(&c, ","))) {

        if (!strcmp(o, "defaults"))
            continue;
        else if (!strcmp(o, "shbuf")) {
            t->shbuf = 1;
            continue;
        } else if (!strncmp(o, "rings=", 6)) {
            t->rings = atoi(o+6);
            continue;
        }

        daemon_log(LOG_INFO, "Unknown option '%s'", o);
        return -1;
    }

    return 0;
}

int msntab_load(const char *fn) {
    int n;
    struct tabentry *t = NULL;
    FILE *f = NULL;

    daemon_log(LOG_INFO, "Loading MSN table '%s'.", fn);
    
    if (!(f = fopen(fn, "r"))) {
        daemon_log(LOG_ERR, "Failed to open MSN table '%s'.", fn);
        goto fail;
    }

    n = 0;
    while (!feof(f)) {
        char l[256], *c, *e, *local, *remote, *options, *action;

        n++;

        if (!fgets(l, sizeof(l), f))
            break;

        c = l+strspn(l, " \t");
        if ((e = strchr(c, '\r')))
            *e = 0;
        if ((e = strchr(c, '\n')))
            *e = 0;
        e = strchr(c, 0);

        if (*c == '#' || *c == 0)
            continue;

        if (!(local = strsep(&c, " \t"))) {
            daemon_log(LOG_ERR, "Parse failure on local MSN field in '%s:%i'.", fn, n);
            goto fail;
        }

        if (c)
            c+=strspn(c, " \t");

        if (!strcmp(local, "@include")) {
            char *include;
            
            if (n_includes ++ >= MAX_INCLUDES) {
                daemon_log(LOG_ERR, "Recursive include directive detected.");
                goto fail;
            }            

            if (!(include = strsep(&c, ""))) {
                daemon_log(LOG_ERR, "Parse failure on include field in '%s:%i'.", fn, n);
                goto fail;
            }

            if (msntab_load(include) < 0)
                goto fail;
            
            continue;
        }
        
        if (!(remote = strsep(&c, " \t"))) {
            daemon_log(LOG_ERR, "Parse failure on remote MSN field in '%s:%i'.", fn, n);
            goto fail;
        }

        if (c)
            c+=strspn(c, " \t");

        if (!(options = strsep(&c, " \t"))) {
            daemon_log(LOG_ERR, "Parse failure on options field in '%s:%i'.", fn, n);
            goto fail;
        }

        if (c)
            c+=strspn(c, " \t");

        if (!(action = strsep(&c, ""))) {
            daemon_log(LOG_ERR, "Parse failure on action field in '%s:%i'.", fn, n);
            goto fail;
        }

        t = malloc(sizeof(struct tabentry));
        assert(t);
        memset(t, 0, sizeof(struct tabentry));

        t->line = n;
        t->filename = strdup(fn);
        
        t->ref_counter = 1;
        
        t->local = strdup(local);
        assert(t->local);

        t->remote = strdup(remote);
        assert(t->remote);

        if (action[0] == '@') {
            if (!strcmp(action, "@hangup"))
                t->action = CALL_ACTION_HANGUP;
            else if (!strcmp(action, "@ignore"))
                t->action = CALL_ACTION_IGNORE;
            else {
                daemon_log(LOG_ERR, "Unknown action command '%s' in '%s:%i'.", action, fn, n);
                goto fail;
            }
        } else {
            t->action = CALL_ACTION_ACCEPT;
            t->args = parse_args(action);
        }

        if (parse_options(options, t) < 0) {
            daemon_log(LOG_ERR, "Parse failure on options field in '%s:%i'.", fn, n);
            goto fail;
        }

        if (last) {
            t->prev = last;
            last->next = t;
            last = t;
        } else
            last = first = t;

        n_entries ++;

        t = NULL;

        if (n_entries > MAX_ENTRIES) {
            daemon_log(LOG_INFO, "Too many MSN table entries");
            goto fail;
        }
    }

    fclose(f);
    daemon_log(LOG_INFO, "MSN table '%s' successfully read.", fn);
    
    return 0;
    
fail:

    if (t)
        msntab_unref(t);
    
    if (f)
        fclose(f);
    
    return -1;
}


static void dump_entry(struct tabentry *t) {
    char s[256];
    assert(t);

    s[0] = 0;
    
    if (t->args) {
        char **a = t->args;
        
        while (*a) {
            char *p = strchr(s, 0);
            snprintf(p, sizeof(s)-(p-s), a == t->args ? "%s" : " %s", *a);
            a++;
        }
    } else
        strncpy(s, "NOARGS", sizeof(s));
    
    daemon_log(LOG_INFO, "[%s:%02u] %-12s -> %-12s; shbuf=%-3s; rings=%u; action=%s; args=<%s>",
               t->filename,
               t->line,
               t->local,
               t->remote,
               t->shbuf ? "yes" : "no",
               t->rings,
               t->action == CALL_ACTION_ACCEPT ? "ACCEPT" : (t->action == CALL_ACTION_HANGUP ? "HANGUP" : "IGNORE"),
               s);
}

void msntab_dump(void) {
    struct tabentry *l;

    daemon_log(LOG_INFO, "=== Dumping MSN table ===");

    l = first;
    while (l) {
        dump_entry(l);
        l = l->next;
    }

    daemon_log(LOG_INFO, "=== MSN table dump complete ===");
}