/* Copyright (C) 2017  June McEnroe <june@causal.agency>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <arpa/inet.h>
#include <err.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sysexits.h>
#include <unistd.h>

typedef unsigned char byte;

static void spawn(const char *cmd, const char *arg, int dest, int src) {
	pid_t pid = fork();
	if (pid < 0) err(EX_OSERR, "fork");

	if (pid) {
		int status;
		pid_t dead = waitpid(pid, &status, 0);
		if (dead < 0) err(EX_OSERR, "waitpid(%d)", pid);
		if (status) warnx("%s: status %d", cmd, status);

	} else {
		int fd = dup2(src, dest);
		if (fd < 0) err(EX_OSERR, "dup2");

		execlp(cmd, cmd, arg, NULL);
		err(EX_UNAVAILABLE, "%s", cmd);
	}
}

static int pbd(void) {
	int error;

	int server = socket(PF_INET, SOCK_STREAM, 0);
	if (server < 0) err(EX_OSERR, "socket");

	error = fcntl(server, F_SETFD, FD_CLOEXEC);
	if (error) err(EX_IOERR, "fcntl");

	struct sockaddr_in addr = {
		.sin_family = AF_INET,
		.sin_port = htons(7062),
		.sin_addr = { .s_addr = htonl(0x7F000001) },
	};
	error = bind(server, (struct sockaddr *)&addr, sizeof(addr));
	if (error) err(EX_UNAVAILABLE, "bind");

	error = listen(server, 0);
	if (error) err(EX_UNAVAILABLE, "listen");

	for (;;) {
		int client = accept(server, NULL, NULL);
		if (client < 0) err(EX_IOERR, "accept");

		error = fcntl(client, F_SETFD, FD_CLOEXEC);
		if (error) err(EX_IOERR, "fcntl");

		char c = 0;
		ssize_t size = read(client, &c, 1);
		if (size < 0) warn("read");

		switch (c) {
			break; case 'p': spawn("pbpaste", NULL, STDOUT_FILENO, client);
			break; case 'c': spawn("pbcopy", NULL, STDIN_FILENO, client);
			break; case 'o': spawn("xargs", "open", STDIN_FILENO, client);
		}

		close(client);
	}
}

static int pbdClient(char c) {
	int client = socket(PF_INET, SOCK_STREAM, 0);
	if (client < 0) err(EX_OSERR, "socket");

	struct sockaddr_in addr = {
		.sin_family = AF_INET,
		.sin_port = htons(7062),
		.sin_addr = { .s_addr = htonl(0x7F000001) },
	};
	int error = connect(client, (struct sockaddr *)&addr, sizeof(addr));
	if (error) err(EX_UNAVAILABLE, "connect");

	ssize_t size = write(client, &c, 1);
	if (size < 0) err(EX_IOERR, "write");

	return client;
}

static void copy(int out, int in) {
	byte buf[4096];
	ssize_t readSize;
	while (0 < (readSize = read(in, buf, sizeof(buf)))) {
		ssize_t writeSize = write(out, buf, readSize);
		if (writeSize < 0) err(EX_IOERR, "write(%d)", out);
	}
	if (readSize < 0) err(EX_IOERR, "read(%d)", in);
}

static int pbcopy(void) {
	int client = pbdClient('c');
	copy(client, STDIN_FILENO);
	return EX_OK;
}

static int pbpaste(void) {
	int client = pbdClient('p');
	copy(STDOUT_FILENO, client);
	return EX_OK;
}

static int open1(const char *url) {
	if (!url) return EX_USAGE;
	int client = pbdClient('o');
	ssize_t size = write(client, url, strlen(url));
	if (size < 0) err(EX_IOERR, "write");
	return EX_OK;
}

int main(int argc, char *argv[]) {
	for (int opt; 0 < (opt = getopt(argc, argv, "co:ps"));) {
		switch (opt) {
			case 'c': return pbcopy();
			case 'o': return open1(optarg);
			case 'p': return pbpaste();
			case 's': return pbd();
			default:  return EX_USAGE;
		}
	}
	return pbd();
}