/* B01902062 藍挺瑋 */
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include "common.h"

#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/select.h>

void* e_malloc (size_t size) {
	void* ptr;

	ptr = malloc (size);
	if (ptr == NULL)
		e_err_exit ("out of memory");

	return ptr;
}

char* e_strcat (const char* s1, const char* s2) {
	int s1len = strlen (s1);
	int s2len = strlen (s2);
	char* newstr = e_malloc (sizeof (char) * (s1len + s2len + 1));
	strcpy (newstr, s1);
	strcpy (newstr + s1len, s2);
	newstr[s1len + s2len] = '\0';
	return newstr;
}

void e_err_exit (const char* a) {
	perror (a);
	exit (1);
}

ftab* ftab_create (int maxfd) {
	ftab* ft = e_malloc (sizeof (ftab));
	ft->maxfd = maxfd;
	ft->flist = e_malloc (sizeof (fnode) * maxfd);
	memset (ft->flist, 0, sizeof (fnode) * maxfd);
	return ft;
}

fnode* ftab_insert (ftab* ft, dev_t fdev, ino_t fino, int fd) {
	fnode *search = ftab_search (ft, fdev, fino);
	if (search == NULL) {
		for (int i = 0; i < ft->maxfd; i++) {
			if (!(ft->flist[i].active)) {
				ft->flist[i].active = true;
				ft->flist[i].ref_count = 0;
				ft->flist[i].fdev = fdev;
				ft->flist[i].fino = fino;
				FD_ZERO (&(ft->flist[i].fset));
				fnode_ref (&(ft->flist[i]), fd);
				return &(ft->flist[i]);
			}
		}
		return NULL;
	} else {
		fnode_ref (search, fd);
		return search;
	}
}

fnode* ftab_search (ftab* ft, dev_t fdev, ino_t fino) {
	for (int i = 0; i < ft->maxfd; i++) {
		if (ft->flist[i].active &&
			ft->flist[i].fdev == fdev &&
			ft->flist[i].fino == fino)
		{
			return &(ft->flist[i]);
		}
	}
	return NULL;
}

void ftab_free (ftab* ft) {
	free (ft->flist);
	free (ft);
}

fnode* fnode_ref (fnode* fn, int fd) {
	if (fd >= 0 && !FD_ISSET (fd, &fn->fset)) {
		fn->ref_count++;
		FD_SET (fd, &fn->fset);
	}
	return fn;
}

void fnode_unref (fnode* fn, ftab* ft) {
	fn->ref_count--;
	if (fn->ref_count <= 0) {
		for (int i = 0; i < ft->maxfd; i++)
			if (FD_ISSET (i, &fn->fset))
				close (i);
		fn->active = false;
	}
}