#ifndef _BSD_SOURCE
#define _BSD_SOURCE
#endif

#include <pty.h>

#include <utmp.h>
#include <errno.h>
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <termios.h>

#ifdef READLINE_HACK
#include <readline/readline.h>
#endif

#include <Python.h>


static int terminal_fd = -1;
static FILE *terminal  = NULL;
static struct termios terminal_settings, default_settings;


#ifdef READLINE_HACK

static void set_files0(void)
{
	//(note that python will replace these with stdin and stdout, respectively, every iteration, so they have to be reset
	rl_instream  = terminal;
	rl_outstream = terminal;
	//(python will configure the stdin terminal, not the one passed to it)
	tcsetattr(STDIN_FILENO, TCSAFLUSH, &default_settings);
	tcsetattr(terminal_fd, TCSAFLUSH, &terminal_settings);
}

//called by 'readline' when preparing to read a line of input
static void set_files1(int flag)
{
	set_files0();
	rl_prep_terminal(flag);
}

#endif


int main(int argc, char *argv[])
{
	if (argc < 2)
	{
	fprintf(stderr, "%s [terminal command...]\n", argv[0]);
	return 1;
	}


	int master = -1, slave = -1, outcome = 0;

	openpty(&master, &slave, NULL, NULL, NULL);
	pid_t process = fork();


	if (process < 0)
	{
	fprintf(stderr, "error allocating ptty: %s\n", strerror(errno));
	return 1;
	}


	else if (process != 0)
	{
	close(master);
	terminal = fdopen((terminal_fd = slave), "a+");

	//prepare the settings for the "real" terminal
	tcgetattr(slave, &terminal_settings);
	terminal_settings.c_lflag &= ~ISIG;
	terminal_settings.c_lflag &= ~ICANON;
	terminal_settings.c_lflag &= ~ECHO;

#ifdef READLINE_HACK
	//save the stdin terminal settings to restore after python messes them up
	tcgetattr(STDIN_FILENO, &default_settings);
#else
	tcsetattr(terminal_fd, TCSAFLUSH, &terminal_settings);
#endif

	//set up the interpreter and I/O redirection

	Py_InitializeEx(0);

	PyRun_SimpleString("import sys, os");

	char redirect[128];

	snprintf(redirect, sizeof redirect, "sys.stdin = os.fdopen(%i, \"r\")", (int) slave);
	PyRun_SimpleString(redirect);
	snprintf(redirect, sizeof redirect, "sys.stdout = os.fdopen(%i, \"w\")", (int) slave);
	PyRun_SimpleString(redirect);
	snprintf(redirect, sizeof redirect, "sys.stderr = os.fdopen(%i, \"w\")", (int) slave);
	PyRun_SimpleString(redirect);

#ifdef READLINE_HACK
	rl_prep_term_function = &set_files1;
	PyRun_SimpleString("import readline");

	int dump = 1;

	//read and discard the first line, which is the X window ID that xterm prints
	while (dump > 0)
	 {
	if (!readline(NULL)) break;
	--dump;
	 }
#endif

	fprintf(terminal, "***** Interactive Python Terminal (%i on %s) *****\n", getpid(), ttyname(slave));
	//THE LINE BELOW IS THE MOST IMPORTANT!!!
	outcome = PyRun_InteractiveLoop(terminal /*<-- this is the pty!*/, ttyname(slave));

	fclose(terminal);

	PyRun_SimpleString("sys.stdin  = sys.__stdin__");
	PyRun_SimpleString("sys.stdout = sys.__stdout__");
	PyRun_SimpleString("sys.stderr = sys.__stderr__");

	Py_Finalize();
	}


	else
	{
	//run xterm

	close(slave);
	login_tty(master);
	execvp(argv[1], argv + 1);
	fprintf(stderr, "execvp error: %s\n", strerror(errno));
	_exit(0);
	}


	return 0;
}