/*
 * 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 <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "config.h"
#include "template.h"
#include "url.h"

/*
 * Reads the file denoted by path into a newly allocated output buffer. Returns
 * 0 for success, -1 for error. The size_t is the size of output buffer (only
 * to be used in case of success).
 */
static int
read_file(const char *path, char **output, size_t * read_size)
{
	long 	file_size;
	FILE   *fp;

	fp = fopen(path, "r");
	if (fp == NULL)
		return -1;

	/* get file size */
	if (fseek(fp, 0L, SEEK_END) != 0)
		return -1;

	file_size = ftell(fp);
	if (file_size < 0)
		return -1;

	/* rewind to file start */
	if (fseek(fp, 0L, SEEK_SET) != 0)
		return -1;

	/* create output buffer */
	*output = malloc(sizeof(char) * (file_size + 1));
	if (*output == NULL)
		return -1;

	/* read the file */
	*read_size = fread(*output, sizeof(char), file_size, fp);
	if (*read_size == 0 || ferror(fp) != 0) {
		free(*output);
		return -1;
	}
	/* enforce string termination */
	(*output)[*read_size] = '\0';

	return 0;
}

struct page_template *
page_template_new(const char *page)
{
	struct page_template *tmpl;
	char 	template_path[PATH_MAX];
	size_t 	path_size;
	size_t 	file_size;

	tmpl = (struct page_template *) calloc(1, sizeof(struct page_template));
	if (tmpl == NULL)
		return NULL;

	/* read global header */
	path_size = snprintf(template_path, sizeof(template_path), "%s/%s",
			     TEMPLATE_DIR, "head.html");
	if (path_size < 0 || path_size >= sizeof(template_path) ||
	    read_file(template_path, &tmpl->header, &file_size) < 0) {
		page_template_free(tmpl);
		return NULL;
	}
	/* read global footer */
	path_size = snprintf(template_path, sizeof(template_path), "%s/%s",
			     TEMPLATE_DIR, "foot.html");
	if (path_size < 0 || path_size >= sizeof(template_path) ||
	    read_file(template_path, &tmpl->footer, &file_size) < 0) {
		page_template_free(tmpl);
		return NULL;
	}
	/* read page header */
	path_size = snprintf(template_path, sizeof(template_path), "%s/%s_%s",
			     TEMPLATE_DIR, page, "head.html");
	if (path_size < 0 || path_size >= sizeof(template_path) ||
	    read_file(template_path, &tmpl->page_header, &file_size) < 0) {
		page_template_free(tmpl);
		return NULL;
	}
	/* read page footer (optional) */
	path_size = snprintf(template_path, sizeof(template_path), "%s/%s_%s",
			     TEMPLATE_DIR, page, "foot.html");
	if (path_size < 0 || path_size >= sizeof(template_path)) {
		page_template_free(tmpl);
		return NULL;
	}
	read_file(template_path, &tmpl->page_footer, &file_size);
	/* read page item (optional) */
	path_size = snprintf(template_path, sizeof(template_path), "%s/%s_%s",
			     TEMPLATE_DIR, page, "item.html");
	if (path_size < 0 || path_size >= sizeof(template_path)) {
		page_template_free(tmpl);
		return NULL;
	}
	read_file(template_path, &tmpl->page_item, &file_size);
	return tmpl;
}

void
page_template_free(struct page_template * tmpl)
{
	if (tmpl == NULL)
		return;

	if (tmpl->header != NULL)
		free(tmpl->header);
	if (tmpl->footer != NULL)
		free(tmpl->footer);
	if (tmpl->page_header != NULL)
		free(tmpl->page_header);
	if (tmpl->page_footer != NULL)
		free(tmpl->page_footer);
	if (tmpl->page_item != NULL)
		free(tmpl->page_item);

	free(tmpl);
}