/*
 * Copyright 2023, Vincent Douillet <vincent@vdouillet.fr>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors
 * may be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/queue.h>

#include <dirent.h>
#include <kcgi.h>
#include <kcgihtml.h>
#include <limits.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>

#include "browse.h"
#include "cgi.h"
#include "config.h"
#include "http.h"
#include "url.h"

/*
 * list of files for current directory
 */
SLIST_HEAD(, file) list;
struct file {
	char   *name;
	char   *url;
	SLIST_ENTRY(file) files;
};

/*
 * should be able to free incomplete files as per file_new usage
 */
static void
file_free(struct file * file)
{
	if (file == NULL)
		return;

	if (file->name != NULL) {
		free(file->name);
		file->name = NULL;
	}
	if (file->url != NULL) {
		free(file->url);
		file->url = NULL;
	}
	free(file);
}

static struct file *
file_new(char *name, size_t name_len, char *url, size_t url_len)
{
	struct file *file;

	file = calloc(1, sizeof(struct file));
	if (file == NULL)
		return NULL;
	file->name = malloc(sizeof(char) * (name_len + 1));
	if (strlcpy(file->name, name, name_len + 1) >= name_len + 1) {
		free(file);
		return NULL;
	}
	file->url = malloc(sizeof(char) * (url_len + 1));
	if (strlcpy(file->url, url, url_len + 1) >= url_len + 1) {
		free(file);
		return NULL;
	}
	return file;
}

/*
 * file url = r->pname / r->pagename / r->path / file_name
 */
static 	size_t
build_browse_url(struct kreq * r, char *url, size_t url_len, const char *file)
{
	char   *page_name;

	page_name = strlen(r->pagename) == 0 ? BROWSE_URL : r->pagename;
	return url_build(url, url_len, r->pname, page_name, r->path, file,
			 NULL);
}

static int
build_file_list(struct kreq * r, char *request_dir)
{
	char   *file_name;
	char 	url[PATH_MAX];
	DIR    *data_dir;
	size_t 	url_len;
	struct dirent *dir;
	struct file *file;
	struct file *last_file;

	data_dir = opendir(request_dir);
	if (NULL == data_dir)
		return -1;

	SLIST_INIT(&list);
	last_file = NULL;
	while ((dir = readdir(data_dir)) != NULL) {
		/* ignore special . and .. folders */
		file_name = dir->d_name;
		if (strcmp(".", file_name) == 0 || strcmp("..", file_name) == 0)
			continue;
		url_len = build_browse_url(r, url, PATH_MAX, file_name);
		if (url_len == 0 || url_len >= PATH_MAX) {
			kutil_warn(r, NULL, "browse: Detected URL overflow: %s", url);
			continue;
		}
		/* build file and add to list */
		file = file_new(dir->d_name, dir->d_namlen, url, url_len);
		if (file == NULL) {
			kutil_warn(r, NULL, "browse: unable to build file info");
			continue;
		}
		if (last_file == NULL)
			SLIST_INSERT_HEAD(&list, file, files);
		else
			SLIST_INSERT_AFTER(last_file, file, files);

		last_file = file;
	}

	closedir(data_dir);
	return 0;
}

void
browse(struct kreq * r)
{
	size_t 	url_len;
	char 	current_dir[PATH_MAX];
	struct file *file;
	struct khtmlreq html;

	/* check that the requested URL can be safely processed */
	if (!check_request_path(r->path))
		http_exit(r, KHTTP_400, "browse: Invalid request path");

	/* list requested directory content */
	url_len = url_build(current_dir, PATH_MAX, DATA_DIR, r->path,
			    NULL);
	if (url_len == 0)
		http_exit(r, KHTTP_404, "browse: Unable to build data path");
	if (url_len >= PATH_MAX)
		http_exit(r, KHTTP_414, NULL);
	if (build_file_list(r, current_dir) < 0)
		http_exit(r, KHTTP_500, "browse: Unable to build file list");

	/* we have all the data we need, we can start to write output page */
	http_open(r, KHTTP_200, r->mime);

	K_OK(khtml_open(&html, r, 0), r);

	K_OK(khtml_elem(&html, KELEM_DOCTYPE), r);
	K_OK(khtml_elem(&html, KELEM_HEAD), r);
	K_OK(khtml_attr(&html, KELEM_META, KATTR_CHARSET, "utf-8", KATTR__MAX),
	     r);
	K_OK(khtml_elem(&html, KELEM_HTML), r);
	K_OK(khtml_elem(&html, KELEM_BODY), r);
	K_OK(khtml_elem(&html, KELEM_P), r);
	K_OK(khtml_puts(&html, "/"), r);
	K_OK(khtml_closeelem(&html, 1), r);

	K_OK(khtml_elem(&html, KELEM_UL), r);
	SLIST_FOREACH(file, &list, files) {
		K_OK(khtml_elem(&html, KELEM_LI), r);
		K_OK(khtml_attr(&html, KELEM_A, KATTR_HREF, file->url, KATTR__MAX),
		     r);
		K_OK(khtml_puts(&html, file->name), r);
		K_OK(khtml_closeelem(&html, 2), r);
	}
	K_OK(khtml_close(&html), r);

	/* free list */
	file = NULL;
	while (!SLIST_EMPTY(&list)) {
		file = SLIST_FIRST(&list);
		SLIST_REMOVE_HEAD(&list, files);
		file_free(file);
		file = NULL;
	}
}