/*
 * 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 <stdlib.h>
#include <kcgi.h>
#include <kcgihtml.h>
#include <limits.h>
#include <string.h>

#include "browse.h"
#include "cgi.h"
#include "http.h"
#include "template.h"
#include "upload.h"
#include "url.h"

/*
 * upload url = r->pname / UPLOAD_URL / file->path
 */
size_t
build_upload_url(const struct kreq * r, struct file * file)
{
	char 	action_url[PATH_MAX];
	size_t 	action_url_len;

	if (!file->is_dir)
		return 0;

	action_url_len = url_build(action_url, PATH_MAX, r->pname, UPLOAD_URL,
				   file->path, NULL);
	if (action_url_len == 0 || action_url_len >= PATH_MAX) {
		kutil_warn(r, NULL,
			   "upload: action URL overflow: %s", action_url);
		return 0;
	}
	file->action_url = strndup(action_url, action_url_len);
	if (file->action_url == NULL) {
		kutil_warn(r, NULL,
			   "upload: unable to allocate file url buffer: %s",
			   action_url);
		return 0;
	}
	return action_url_len;
}

/*
 * data required in the template functions
 */
struct template_data {
	struct kreq *r;
	struct khtmlreq *html;
	struct file *f;
};

static const char *const header_template_keys[] = {"path", "submit_url"};

static int
header_template_callback(size_t index, void *arg)
{
	struct kreq *r;
	struct khtmlreq *html;
	struct template_data *data;

	if (arg == NULL) {
		kutil_warn(NULL, NULL,
			   "Invalid data for upload header template");
		return 0;
	}
	data = arg;
	r = data->r;
	html = data->html;

	switch (index) {
	case 0:
		/* path */
		K_OK(khtml_puts(html, data->f->path), r);
		break;
	case 1:
		/* submit_url */
		K_OK(khtml_puts(html, data->f->action_url), r);
		break;
	default:
		kutil_warnx(r, NULL,
			 "Invalid key index for upload header template: %zd",
			    index);
		return 0;
	}

	return 1;
}

/*
 * GET request, we print upload form
 */
void
upload_get(struct kreq * r, struct http_ret * ret, struct file * file)
{
	struct khtmlreq html;
	struct ktemplate template;
	struct page_template *tmpl;
	struct template_data data;

	tmpl = NULL;

	/* action url is form submit url */
	if (build_upload_url(r, file) == 0) {
		*ret = (struct http_ret) {
			KHTTP_500,
			    "upload: Can't build upload url"
		};
		goto end;
	}
	/* read template */
	tmpl = page_template_new(UPLOAD_URL);
	if (tmpl == NULL) {
		*ret = (struct http_ret) {
			KHTTP_500,
			    "upload: Unable to read template"
		};
		goto end;
	}
	/* print upload form */
	http_open(r, KHTTP_200, r->mime);

	K_OK(khttp_puts(r, tmpl->header), r);
	K_OK(khtml_open(&html, r, 0), r);

	template.key = header_template_keys;
	template.keysz = 2;
	template.cb = header_template_callback;
	template.arg = &data;
	data.r = r;
	data.html = &html;
	data.f = file;
	K_OK(khttp_template_buf(r, &template, tmpl->page_header,
				strlen(tmpl->page_header)), r);

	K_OK(khttp_puts(r, tmpl->page_footer), r);
	K_OK(khttp_puts(r, tmpl->footer), r);

	K_OK(khtml_close(&html), r);

end:
	page_template_free(tmpl);
}

/*
 * POST request, we handle upload form
 */
void
upload_post(struct kreq * r, struct http_ret * ret, struct file * f)
{
	char 	path[PATH_MAX];
	FILE   *to_write;
	size_t 	path_len, i;

	/* prepare action url for return redirection in case of success */
	if (build_browse_url(r, f) == 0) {
		*ret = (struct http_ret) {
			KHTTP_500,
			"upload: can't build return url"
		};
		return;
	}

	/*
	 * data should have been validated prior to handling the request, so
	 * here we should have an array of fields named "file", each field
	 * corresponding to one uploaded file
	 */
	for (i = 0; i < r->fieldsz; i++) {
		struct kpair *upl = &(r->fields[i]);
		path_len = file_get_data_path(f, path, PATH_MAX, upl->file);
		if (path_len == 0 || path_len >= PATH_MAX) {
			*ret = (struct http_ret) {
				KHTTP_500,
				"upload: can't build file path"
			};
			return;
		}
		to_write = fopen(path, "wb");
		if (to_write == NULL) {
			*ret = (struct http_ret) {
				KHTTP_500,
				"upload: can't open file for writing"
			};
			return;
		}
		if (fwrite(upl->val, sizeof(char), upl->valsz, to_write)
		    != upl->valsz) {
			*ret = (struct http_ret) {
				KHTTP_500,
				"upload: error while writing file"
			};
			return;
		}
		if (fclose(to_write) != 0) {
			*ret = (struct http_ret) {
				KHTTP_500,
				"upload: error while closing file"
			};
			return;
		}
	}

	/* on success, redirect to the directory where new files were created */
	khttp_head(r, kresps[KRESP_LOCATION], "%s", f->action_url);
	http_open(r, KHTTP_303, r->mime);

	*ret = (struct http_ret) {
		KHTTP_303,
	        ""
	};
}


struct http_ret
upload(struct kreq * r)
{
	struct file *file;
	struct http_ret ret;

	file = NULL;
	ret = (struct http_ret) {
		KHTTP_200, ""
	};

	/* build file corresponding to request (ie. upload) path */
	file = file_new(r->path);
	if (file == NULL) {
		ret = (struct http_ret) {
			KHTTP_404,
			"upload: Unable to build data file"
		};
		goto end;
	}
	/* print form or handle submission according to HTTP method */
	if (r->method == KMETHOD_POST)
		upload_post(r, &ret, file);
	else
		upload_get(r, &ret, file);

end:
	file_free(file);
	return ret;
}