#include <sys/types.h>
#include <sys/stat.h>
#include <linux/limits.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <libgen.h>
#include "io.h"

int stream_open(struct stream *in)
{
	struct stat st;
	mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP;
	char *dname = NULL;
	int ret = 0;

	if (!in || in->fd > 0 || !in->name) {
		ret = EINVAL;
		goto err;
	}

	if (in->out) {
		char *tmp[2];

		tmp[0] = strdup(in->name);
		tmp[1] = dirname(tmp[0]);
		dname = strdup(tmp[1]);
		free(tmp[0]);

		if (stat(dname, &st)) {
			ret = errno;
			/* TODO: error message */
			goto err;
		}

		if(!(st.st_mode & S_IFDIR)) {
			ret = EINVAL;
			/* TODO: error message */
			goto err;
		}

		if (!stat(in->name, &st)) {
			if (!(st.st_mode & S_IFREG)) {
				ret = EINVAL;
				/* TODO: error message */
				goto err;
			}
			mode = st.st_mode;
		}
	} else if (stat(in->name, &st)) {
		ret = errno;
		/* TODO: error message */
		goto err;
	} else if (!(st.st_mode & S_IFREG) || !st.st_size || (st.st_size % in->stride)) {
		ret = EINVAL;
		/* TODO: error message */
		goto err;
	} else {
		in->n = st.st_size / in->stride;
	}

	if (in->out) {
		in->fd = open(dname, O_TMPFILE | O_WRONLY, mode);
		if (in->fd < 0) {
			ret = errno;
			/* TODO: error message */
			goto err;
		}

		if (ftruncate(in->fd, in->stride * in->n)) {
			ret = errno;
			/* TODO: error message */
			goto err;
		}
	} else {
		in->fd = open(in->name, O_RDONLY | O_NOATIME);
		if (in->fd < 0) {
			ret = errno;
			/* TODO: error message */
			goto err;
		}
	}

err:
	free(dname);
	return ret;
}

int stream_close(struct stream *in)
{
	char path[PATH_MAX];
	int ret = 0;

	if (!in || in->fd < 0) {
		ret = EINVAL;
		goto early_err;
	}

	if (in->out && in->name) {
		snprintf(path, PATH_MAX, "/proc/self/fd/%i", in->fd);
		if (linkat(AT_FDCWD, path, AT_FDCWD, in->name, AT_SYMLINK_FOLLOW)) {
			ret = errno;
			/* TODO: error message */
			goto err;
		}
	} else {
		ret = EINVAL;
		goto err;
	}

err:
	close(in->fd);
	in->fd = -1;
early_err:
	return ret;
}