/*
 * Copyright (C) 2026  Verdant <im@verdant.ee>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <asm-generic/socket.h>
#include <stdbool.h>
#include <errno.h>
#include <netdb.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/sendfile.h>
#include <unistd.h>

#define PROGRAM_NAME "shsd"
#define VERSION "0.0.1"
#define COPYRIGHT_YEAR "2026"
#define AUTHOR "Verdant <im@verdant.ee>"

typedef enum { GET = 0, POST = 1, UNKNOWN = -1 } HTTP_METHODS;

static void usage(const char *progname)
{
	fprintf(stderr, "Usage: %s <port>\n", progname);
	exit(EXIT_FAILURE);
}

static void version()
{
	printf("%s %s\n", PROGRAM_NAME, VERSION);
	printf("Copyright (C) %s %s\n", COPYRIGHT_YEAR, AUTHOR);
	printf("License GPLv3+: GNU GPL version 3 or later <https://www.gnu.org/licenses/gpl-3.0.html>.\n");
	printf("This is free software: you are free to change and redistribute it.\n");
	printf("There is NO WARRANTY, to the extent permitted by law.\n");
}

static int shsd_sendfile(int in_fd, FILE *ou_fd)
{
	struct stat s;
	int stat_result = fstat(fileno(ou_fd), &s);
	if (stat_result != 0) {
		perror("fstat");
		return -1;
	}
	sendfile(in_fd, fileno(ou_fd), NULL, s.st_size);

	return 0;
}

static HTTP_METHODS get_require_method(char *method)
{
	HTTP_METHODS m;
	if (strcmp(method, "GET") == 0) {
		return m = GET;
	}

	if (strcmp(method, "POST") == 0) {
		return m = POST;
	}

	else {
		return m = UNKNOWN;
	}
}

static bool sdhd_isdir(const char *path, int fd)
{
	struct stat st;
	stat(path, &st);
	if (S_ISDIR(st.st_mode)) {
		return true;
	}

	return false;
}

static int handle_client(int client_fd, char *buf)
{
	char method[16], path[256];
	if (sscanf(buf, "%15s %255s", method, path) < 2) {
		close(client_fd);
		return -1;
	}

	if (strcmp(path, "/") == 0) {
		strcpy(path, "/index.html");
	}

	char local_path[1024];
	snprintf(local_path, sizeof(local_path), "./www%s", path);
	printf("Path = %s\n", local_path);

	if (sdhd_isdir(local_path, client_fd)) {
		strcat(local_path, "/index.html");
	}

	printf("Path = %s\n", local_path);

	FILE *fp = fopen(local_path, "r");
	if (!fp) {
		perror("fopen");
		fp = fopen("./www/404.html", "r");
		shsd_sendfile(client_fd, fp);
		return -1;
	}

	shsd_sendfile(client_fd, fp);

	return 0;
}

int main(int argc, char **argv)
{
	if (argc < 2) {
		usage(argv[0]);
		exit(1);
	} else if (strcmp(argv[1], "-v") == 0 ||
		   strcmp(argv[1], "--version") == 0) {
		version();
		exit(0);
	}

	struct addrinfo hints, *res;
	struct sockaddr_storage their_addr;
	socklen_t addr_size;
	int sockfd, new_fd;
	int yes = 1;

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = AF_INET; // use IPv4 or IPv6, whichever
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_flags = AI_PASSIVE; // fill in my IP for me
	getaddrinfo(NULL, argv[1], &hints, &res);

	sockfd = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
	if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) ==
	    -1) {
		perror("setsockopt");
		exit(1);
	}

	if (bind(sockfd, res->ai_addr, res->ai_addrlen) == -1) {
		perror("bind");
		close(sockfd);
		exit(1);
	}

	if (listen(sockfd, 10) == -1) {
		perror("listen");
		close(sockfd);
		exit(1);
	}

	addr_size = sizeof(their_addr);

	char buf[1024];
	memset(buf, 0, 1024);
	int recv_result;

	while (1) {
		new_fd = accept(sockfd, (struct sockaddr *)&their_addr,
				&addr_size);
		recv_result = recv(new_fd, (void *)buf, 1024, 0);
		if (recv_result == -1) {
			perror("recv");
			return -1;
		}
		for (int i = 0; i < sizeof(buf); i++) {
			printf("%c", buf[i]);
		}

		if (strncmp(buf, "GET", 3) == 0) {
			char *http_status = "HTTP/1.1 200 OK\r\n";
			char *http_content_type = "text/html\r\n\r\n";

			printf("Received GET request.\n");
			send(new_fd, http_status, strlen(http_status), 0);

			send(new_fd, http_content_type,
			     strlen(http_content_type), 0);
			handle_client(new_fd, buf);
		}

		memset(buf, 0, 1024);
		close(new_fd);
	}

	close(sockfd);
	close(new_fd);

	return 0;
}