/* -*- c-basic-offset:2; tab-width:2; indent-tabs-mode:nil -*- */

#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h> /* getenv */
#include <unistd.h>
#include <fcntl.h>      /* open */
#include <sys/select.h> /* select */
#include <errno.h>
#include <string.h> /* memcpy */
#include <signal.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netdb.h>
#include <netinet/in.h>
#include <termios.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/wait.h>

#if defined(__CYGWIN__) || defined(__MSYS__)
#ifndef BINDIR
#define BINDIR "/bin"
#endif
#define MLLIBEXECDIR BINDIR
#else
#ifndef LIBEXECDIR
#define LIBEXECDIR "/usr/local/libexec"
#endif
#define MLLIBEXECDIR LIBEXECDIR "/mlterm"
#endif

/* --- static variables --- */

static int connect_fd = -1;
static int pty_fd = -1;
static struct termios std_tio;

/* --- static functions --- */

static void exit_cb(void) {
  tcsetattr(pty_fd, TCSANOW, &std_tio);
}

static void sig_child(int sig) { waitpid(-1, NULL, WNOHANG); }

static void help(void) { printf("Usage: mlclient-con [options]\n"); }

static char *get_path(char *file) {
  char *home;
  char *path;
  char *p;

  if (!(home = getenv("HOME")) || !(path = malloc(strlen(home) + 16 + strlen(file) + 1))) {
    return NULL;
  }

  sprintf(path, "%s/.config/mlterm/%s", home, file);
  p = strrchr(path, '/');
  if (p > path + strlen(home) + 15) {
    struct stat st;

    *p = '\0';
    if (stat(path, &st) == 0) {
      *p = '/';

      return path;
    }
  }

  sprintf(path, "%s/.mlterm/%s", home, file);

  return path;
}

static void debug_printf(const char *format, ...) {
  va_list arg_list;
  static char *path;
  FILE* fp;

  va_start(arg_list, format);

  if (!path && !(path = get_path("msg.log"))) {
    return;
  }

  if ((fp = fopen(path, "a"))) {
    vfprintf(fp, format, arg_list);
    fclose(fp);
  }
}

static void sig_winch(int sig) {
  struct winsize ws;

  if (ioctl(pty_fd, TIOCGWINSZ, &ws) == 0) {
    char msg[10 + 11 * 4 + 1];

    sprintf(msg, "\x1b[8;%d;%d;4;%d;%dt", ws.ws_row, ws.ws_col, ws.ws_ypixel, ws.ws_xpixel);
    write(connect_fd, msg, strlen(msg));
  }

  signal(SIGWINCH, sig_winch);
}

static int set_cloexec(int fd) {
  int old_flags;

  if ((old_flags = fcntl(fd, F_GETFD)) == -1) {
    return 0;
  }

  if (!(old_flags & FD_CLOEXEC) && fcntl(fd, F_SETFD, old_flags | FD_CLOEXEC) == -1) {
    return 0;
  }

  return 1;
}

static int connect_to_server(int argc, char **argv) {
  char *path;
  struct sockaddr_un servaddr;
  int count;
  struct termios tio;

  if (!(path = get_path("socket-con"))) {
    return 0;
  }

  if ((connect_fd = socket(AF_LOCAL, SOCK_STREAM, 0)) == -1) {
    free(path);

    return 0;
  }

  set_cloexec(connect_fd);

  memset(&servaddr, 0, sizeof(servaddr));
  servaddr.sun_family = AF_LOCAL;
  strcpy(servaddr.sun_path, path);
  free(path);
  path = servaddr.sun_path;

  fcntl(connect_fd, F_SETFL, fcntl(connect_fd, F_GETFL, 0) & ~O_NONBLOCK);

  if (connect(connect_fd, (struct sockaddr*)&servaddr, sizeof(servaddr)) == -1) {
    pid_t pid;

    unlink(path);

    signal(SIGCHLD, sig_child);

    if ((pid = fork()) == 0) {
      char **new_argv;

      if (!(new_argv = alloca((argc + 2 + 1) * sizeof(char*)))) {
        exit(1);
      }

      /* Remove command path */
      argv++;
      argc--;

      count = 0;
      new_argv[count++] = "mlterm-con-server";
      new_argv[count++] = "-j";
      new_argv[count++] = "genuine";
      for (; count < argc + 3; count++) {
        new_argv[count] = argv[count - 3];
      }
      new_argv[count] = NULL;

      execv(MLLIBEXECDIR "/mlterm-con-server", new_argv);
      exit(-1);
    }

    if (pid < 0) {
      close(connect_fd);

      return 0;
    }

    for (count = 0; count < 100; count++) {
      struct stat st;

      usleep(10000); /* waiting for mlterm-con-server to call bind(). */
      if (stat(path, &st) == 0) {
        /* XXX Following processing is for Oracle Solaris 11. */
        usleep(50000); /* waiting for mlterm-con-server to become a daemon and to call listen(). */
        if (connect(connect_fd, (struct sockaddr*)&servaddr, sizeof(servaddr)) == 0) {
          goto connected;
        }
        break;
      }
    }

    close(connect_fd);

    return 0;
  }

connected:
  if ((pty_fd = open(ttyname(STDIN_FILENO), O_RDWR)) == -1) {
    close(connect_fd);

    return 0;
  }

  set_cloexec(pty_fd);

  close(STDIN_FILENO);
  close(STDOUT_FILENO);
  close(STDERR_FILENO);

  tio = std_tio;
#ifdef IMAXBEL
  tio.c_iflag &= ~(IXON | IXOFF | ICRNL | INLCR | IGNCR | IMAXBEL | ISTRIP);
#else
  /* IMAXBEL is not defined on HaikuOS */
  tio.c_iflag &= ~(IXON | IXOFF | ICRNL | INLCR | IGNCR | ISTRIP);
#endif
  tio.c_iflag |= IGNBRK;
  tio.c_oflag &= ~(OPOST | ONLCR | OCRNL | ONLRET);
#ifdef ECHOPRT
  tio.c_lflag &=
      ~(IEXTEN | ICANON | ECHO | ECHOE | ECHONL | ECHOCTL | ECHOPRT | ECHOKE | ECHOCTL | ISIG);
#else
  /* ECHOPRT is not defined on cygwin. */
  tio.c_lflag &= ~(IEXTEN | ICANON | ECHO | ECHOE | ECHONL | ECHOCTL | ECHOKE | ECHOCTL | ISIG);
#endif
  tio.c_cc[VMIN] = 1;
  tio.c_cc[VTIME] = 0;

  tcsetattr(pty_fd, TCSANOW, &tio);

  atexit(exit_cb);

  write(connect_fd, argv[0], strlen(argv[0]));
  for (count = 1; count < argc; count++) {
    write(connect_fd, " \"", 2);
    write(connect_fd, argv[count], strlen(argv[count]));
    write(connect_fd, "\"", 1);
  }
  write(connect_fd, "\n", 1);

  sig_winch(SIGWINCH);

  return 1;
}

/* --- global functions --- */

int main(int argc, char **argv) {
  fd_set fds;
  int maxfd;

  if (argc == 2 && strcmp(argv[1], "-h") == 0) {
    help();

    return 0;
  }

  tcgetattr(STDIN_FILENO, &std_tio);

  if (!connect_to_server(argc, argv)) {
    debug_printf("Failed to connect to mlterm-con-server.\n");
    return -1;
  }

  while (1) {
    char buf[1024];
    ssize_t len;

    FD_ZERO(&fds);

    FD_SET(pty_fd, &fds);
    FD_SET(connect_fd, &fds);

    if (pty_fd > connect_fd) {
      maxfd = pty_fd;
    } else {
      maxfd = connect_fd;
    }

    if (select(maxfd + 1, &fds, NULL, NULL, NULL) < 0) {
      /* received signal */
      continue;
    }

    if (FD_ISSET(pty_fd, &fds)) {
      fcntl(pty_fd, F_SETFL, fcntl(pty_fd, F_GETFL, 0) | O_NONBLOCK);

      while ((len = read(pty_fd, buf, sizeof(buf))) > 0) {
        /* XXX */
        if (buf[0] == 0x7f && std_tio.c_cc[VERASE] == 0x7f) {
          /* Convert to BackSpace */
          buf[0] = 0x08;
        }

        write(connect_fd, buf, len);
      }

#if 0
      if (len == -1 && errno != EAGAIN) {
        break;
      }
#endif

      fcntl(pty_fd, F_SETFL, fcntl(pty_fd, F_GETFL, 0) & ~O_NONBLOCK);
    }

    if (FD_ISSET(connect_fd, &fds)) {
      fcntl(connect_fd, F_SETFL, fcntl(connect_fd, F_GETFL, 0) | O_NONBLOCK);

      while ((len = read(connect_fd, buf, sizeof(buf))) > 0) {
        write(pty_fd, buf, len);
      }

      /*
       * XXX
       * Even if read() has no problem, len is -1 and errno is ECONNRESET on fedora 24,
       * mlterm-con exits by SIGPIPE.
       */
#if 0
      if (len == -1 && errno != EAGAIN) {
        break;
      }
#endif

      fcntl(connect_fd, F_SETFL, fcntl(connect_fd, F_GETFL, 0) & ~O_NONBLOCK);
    }
  }

  tcsetattr(pty_fd, TCSANOW, &std_tio);

  return 0;
}