#include <gio/gio.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#ifdef G_OS_UNIX
#include <unistd.h>
#else
#include <io.h>
#endif

static GOptionEntry options[] = {
  G_OPTION_ENTRY_NULL
};

static void
write_all (int           fd,
	   const guint8* buf,
	   gsize         len)
{
  while (len > 0)
    {
      gssize bytes_written = write (fd, buf, len);
      int errsv = errno;
      if (bytes_written < 0)
	g_error ("Failed to write to fd %d: %s",
		 fd, g_strerror (errsv));
      buf += bytes_written;
      len -= bytes_written;
    }
}

static int
echo_mode (int argc,
	   char **argv)
{
  int i;

  for (i = 2; i < argc; i++)
    {
      write_all (1, (guint8*)argv[i], strlen (argv[i]));
      write_all (1, (guint8*)"\n", 1);
    }

  return 0;
}

static int
echo_stdout_and_stderr_mode (int argc,
			     char **argv)
{
  int i;

  for (i = 2; i < argc; i++)
    {
      write_all (1, (guint8*)argv[i], strlen (argv[i]));
      write_all (1, (guint8*)"\n", 1);
      write_all (2, (guint8*)argv[i], strlen (argv[i]));
      write_all (2, (guint8*)"\n", 1);
    }

  return 0;
}

static int
cat_mode (int argc,
	  char **argv)
{
  GIOChannel *chan_stdin;
  GIOChannel *chan_stdout;
  GIOStatus status;
  char buf[1024];
  gsize bytes_read, bytes_written;
  GError *local_error = NULL;
  GError **error = &local_error;

  chan_stdin = g_io_channel_unix_new (0);
  g_io_channel_set_encoding (chan_stdin, NULL, error);
  g_assert_no_error (local_error);
  chan_stdout = g_io_channel_unix_new (1);
  g_io_channel_set_encoding (chan_stdout, NULL, error);
  g_assert_no_error (local_error);

  while (TRUE)
    {
      do
	status = g_io_channel_read_chars (chan_stdin, buf, sizeof (buf),
					  &bytes_read, error);
      while (status == G_IO_STATUS_AGAIN);

      if (status == G_IO_STATUS_EOF || status == G_IO_STATUS_ERROR)
	break;

      do
	status = g_io_channel_write_chars (chan_stdout, buf, bytes_read,
					   &bytes_written, error);
      while (status == G_IO_STATUS_AGAIN);

      if (status == G_IO_STATUS_EOF || status == G_IO_STATUS_ERROR)
	break;
    }

  g_io_channel_unref (chan_stdin);
  g_io_channel_unref (chan_stdout);

  if (local_error)
    {
      g_printerr ("I/O error: %s\n", local_error->message);
      g_clear_error (&local_error);
      return 1;
    }
  return 0;
}

static gint
sleep_forever_mode (int argc,
		    char **argv)
{
  GMainLoop *loop;
  
  loop = g_main_loop_new (NULL, TRUE);
  g_main_loop_run (loop);

  return 0;
}

static int
write_to_fds (int argc, char **argv)
{
  int i;

  for (i = 2; i < argc; i++)
    {
      int fd = atoi (argv[i]);
      FILE *f = fdopen (fd, "w");
      const char buf[] = "hello world\n";
      size_t bytes_written;
      
      g_assert (f != NULL);
      
      bytes_written = fwrite (buf, 1, sizeof (buf), f);
      g_assert (bytes_written == sizeof (buf));
      
      if (fclose (f) == -1)
        g_assert_not_reached ();
    }

  return 0;
}

static int
read_from_fd (int argc, char **argv)
{
  int fd;
  const char expected_result[] = "Yay success!";
  guint8 buf[sizeof (expected_result) + 1];
  gsize bytes_read;
  FILE *f;

  if (argc != 3)
    {
      g_print ("Usage: %s read-from-fd FD\n", argv[0]);
      return 1;
    }

  fd = atoi (argv[2]);
  if (fd == 0)
    {
      g_warning ("Argument \"%s\" does not look like a valid nonzero file descriptor", argv[2]);
      return 1;
    }

  f = fdopen (fd, "r");
  if (f == NULL)
    {
      g_warning ("Failed to open fd %d: %s", fd, g_strerror (errno));
      return 1;
    }

  bytes_read = fread (buf, 1, sizeof (buf), f);
  if (bytes_read != sizeof (expected_result))
    {
      g_warning ("Read %zu bytes, but expected %zu", bytes_read, sizeof (expected_result));
      return 1;
    }

  if (memcmp (expected_result, buf, sizeof (expected_result)) != 0)
    {
      buf[sizeof (expected_result)] = '\0';
      g_warning ("Expected \"%s\" but read  \"%s\"", expected_result, (char *)buf);
      return 1;
    }

  if (fclose (f) == -1)
    g_assert_not_reached ();

  return 0;
}

static int
env_mode (int argc, char **argv)
{
  char **env;
  int i;

  env = g_get_environ ();

  for (i = 0; env[i]; i++)
    g_print ("%s\n", env[i]);

  g_strfreev (env);

  return 0;
}

static int
cwd_mode (int argc, char **argv)
{
  char *cwd;

  cwd = g_get_current_dir ();
  g_print ("%s\n", cwd);
  g_free (cwd);

  return 0;
}

static int
printenv_mode (int argc, char **argv)
{
  gint i;

  for (i = 2; i < argc; i++)
    {
      const gchar *value = g_getenv (argv[i]);

      if (value != NULL)
        g_print ("%s=%s\n", argv[i], value);
    }

  return 0;
}

int
main (int argc, char **argv)
{
  GOptionContext *context;
  GError *error = NULL;
  const char *mode;
  gboolean ret;

  context = g_option_context_new ("MODE - Test GSubprocess stuff");
  g_option_context_add_main_entries (context, options, NULL);
  ret = g_option_context_parse (context, &argc, &argv, &error);
  g_option_context_free (context);

  if (!ret)
    {
      g_printerr ("%s: %s\n", argv[0], error->message);
      g_error_free (error);
      return 1;
    }

  if (argc < 2)
    {
      g_printerr ("MODE argument required\n");
      return 1;
    }

  mode = argv[1];
  if (strcmp (mode, "noop") == 0)
    return 0;
  else if (strcmp (mode, "exit1") == 0)
    return 1;
  else if (strcmp (mode, "assert-argv0") == 0)
    {
      if (strcmp (argv[0], "moocow") == 0)
	return 0;
      g_printerr ("argv0=%s != moocow\n", argv[0]);
      return 1;
    }
  else if (strcmp (mode, "echo") == 0)
    return echo_mode (argc, argv);
  else if (strcmp (mode, "echo-stdout-and-stderr") == 0)
    return echo_stdout_and_stderr_mode (argc, argv);
  else if (strcmp (mode, "cat") == 0)
    return cat_mode (argc, argv);
  else if (strcmp (mode, "sleep-forever") == 0)
    return sleep_forever_mode (argc, argv);
  else if (strcmp (mode, "write-to-fds") == 0)
    return write_to_fds (argc, argv);
  else if (strcmp (mode, "read-from-fd") == 0)
    return read_from_fd (argc, argv);
  else if (strcmp (mode, "env") == 0)
    return env_mode (argc, argv);
  else if (strcmp (mode, "cwd") == 0)
    return cwd_mode (argc, argv);
  else if (strcmp (mode, "printenv") == 0)
    return printenv_mode (argc, argv);
  else
    {
      g_printerr ("Unknown MODE %s\n", argv[1]);
      return 1;
    }

  return TRUE;
}
