/*
 * 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 <dirent.h>
#include <kcgi.h>
#include <kcgihtml.h>
#include <stdbool.h>
#include <string.h>

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

#define URL_LENGTH_MAX 8192

/*
 * Checks that the path can be safely processed. Namely, it should not contain "..", which denotes an attempt to get out of the DATA_DIR root folder.
 */
static 	bool
check_request_path(char *path)
{
	char   *p_found;

	p_found = strstr(path, "/..");
	if (p_found != NULL)
		return false;

	p_found = strstr(path, "../");
	return p_found == NULL;
}

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

	page_name = strlen(r->pagename) == 0 ? BROWSE_URL : r->pagename;
	return url_build(url, url_size, 4, r->pname, page_name, r->path, file);
}

int
browse(struct kreq * r)
{
	struct dirent *dir;
	DIR    *data_dir;
	char   *file_name;
	size_t 	url_size;
	char 	url[URL_LENGTH_MAX], current_dir[URL_LENGTH_MAX];
	struct khtmlreq html;

	/* check that the requested URL can be safely processed */
	if (strlen(r->path) >= URL_LENGTH_MAX) {
		http_open(r, KHTTP_414);
		return VAULT_URI_ERROR;
	}
	if (!check_request_path(r->path)) {
		http_open(r, KHTTP_400);
		return VAULT_URI_ERROR;
	}
	/* list requested directory content */
	url_size = url_build(current_dir, URL_LENGTH_MAX, 2, DATA_DIR, r->path);
	if (url_size == 0) {
		http_open(r, KHTTP_404);
		return VAULT_IO_ERROR;
	} else if (url_size >= URL_LENGTH_MAX) {
		http_open(r, KHTTP_414);
		return VAULT_URI_ERROR;
	}
	data_dir = opendir(current_dir);
	if (NULL == data_dir) {
		http_open(r, KHTTP_404);
		return VAULT_IO_ERROR;
	}
	http_open(r, KHTTP_200);

	if (KCGI_OK != khtml_open(&html, r, 0))
		return VAULT_CGI_ERROR;

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

	khtml_elem(&html, KELEM_UL);
	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_size = build_browse_url(r, url, URL_LENGTH_MAX, file_name);
		if (url_size == 0 || url_size >= URL_LENGTH_MAX)
			continue;
		khtml_elem(&html, KELEM_LI);
		khtml_attr(&html, KELEM_A, KATTR_HREF, url, KATTR__MAX);
		khtml_puts(&html, dir->d_name);
		khtml_closeelem(&html, 2);
	}
	khtml_close(&html);
	closedir(data_dir);

	return VAULT_SUCCESS;
}