/*
 *   mootermpt-unix.c
 *
 *   Copyright (C) 2004-2007 by Yevgen Muntyan <muntyan@math.tamu.edu>
 *
 *   This library is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License version 2.1 as published by the Free Software Foundation.
 *
 *   See COPYING file that comes with this distribution.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#define MOOTERM_COMPILATION
#include "mooterm/mootermpt-private.h"
#include "mooterm/mooterm-private.h"
#include "mooterm/pty.h"
#include "mooutils/moomarshals.h"
#include "mooutils/mooutils-misc.h"
#include "mooutils/mooutils-debug.h"

#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <termios.h>

#ifdef HAVE_POLL_H
#  include <poll.h>
#elif HAVE_SYS_POLL_H
#  include <sys/poll.h>
#endif

#undef WATCH_CHILD
#if defined(MOO_OS_DARWIN)
#define WATCH_CHILD
#endif

#define TERM_EMULATION          "xterm"
#define WRITE_CHUNK_SIZE        4096
#define POLL_TIME               5
#define POLL_NUM                1


#define MOO_TERM_PT_UNIX(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), MOO_TYPE_TERM_PT_UNIX, MooTermPtUnix))
#define MOO_TERM_PT_UNIX_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass),  MOO_TYPE_TERM_PT_UNIX, MooTermPtUnixClass))
#define MOO_IS_TERM_PT_UNIX(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), MOO_TYPE_TERM_PT_UNIX))
#define MOO_IS_TERM_PT_UNIX_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass),  MOO_TYPE_TERM_PT_UNIX))
#define MOO_TERM_PT_UNIX_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj),  MOO_TYPE_TERM_PT_UNIX, MooTermPtUnixClass))

typedef struct _MooTermPtUnix           MooTermPtUnix;
typedef struct _MooTermPtUnixClass      MooTermPtUnixClass;


struct _MooTermPtUnix {
    MooTermPt   parent;

    GPid        child_pid;

    int         master;

    gboolean    non_block;
    GIOChannel *io;
    guint       io_watch_id;
#ifdef WATCH_CHILD
    guint       child_watch_id;
#endif
};

struct _MooTermPtUnixClass {
    MooTermPtClass  parent_class;
};


static void     moo_term_pt_unix_finalize       (GObject        *object);

static void     set_size            (MooTermPt      *pt,
                                     guint           width,
                                     guint           height);
static void     set_echo_input      (MooTermPt      *pt,
                                     gboolean        echo);
static gboolean fork_command        (MooTermPt      *pt,
                                     const MooTermCommand *cmd,
                                     GError        **error);
static gboolean fork_argv           (MooTermPt      *pt,
                                     char          **argv,
                                     const char     *working_dir,
                                     char          **envp,
                                     GError        **error);
static void     pt_write            (MooTermPt      *pt,
                                     const char     *string,
                                     gssize          len);
static void     kill_child          (MooTermPt      *pt);
static void     send_intr           (MooTermPt      *pt);
static char     get_erase_char      (MooTermPt      *pt);
static gboolean set_fd              (MooTermPt      *pt,
                                     int             master);

static gboolean read_child_out      (GIOChannel     *source,
                                     GIOCondition    condition,
                                     MooTermPtUnix  *pt);
static void     feed_buffer         (MooTermPtUnix  *pt,
                                     const char     *string,
                                     int             len);

static void     start_writer        (MooTermPt      *pt);
static void     stop_writer         (MooTermPt      *pt);


/* MOO_TYPE_TERM_PT_UNIX */
G_DEFINE_TYPE (MooTermPtUnix, _moo_term_pt_unix, MOO_TYPE_TERM_PT)


static void
_moo_term_pt_unix_class_init (MooTermPtUnixClass *klass)
{
    GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
    MooTermPtClass *pt_class = MOO_TERM_PT_CLASS (klass);

    gobject_class->finalize = moo_term_pt_unix_finalize;

    pt_class->set_size = set_size;
    pt_class->set_echo_input = set_echo_input;
    pt_class->fork_command = fork_command;
    pt_class->write = pt_write;
    pt_class->kill_child = kill_child;
    pt_class->get_erase_char = get_erase_char;
    pt_class->send_intr = send_intr;
    pt_class->set_fd = set_fd;
}


static void
_moo_term_pt_unix_init (MooTermPtUnix *pt)
{
    pt->child_pid = (GPid)-1;

    pt->master = -1;

    pt->non_block = FALSE;
    pt->io = NULL;
    pt->io_watch_id = 0;
#ifdef WATCH_CHILD
    pt->child_watch_id = 0;
#endif
}


static void
moo_term_pt_unix_finalize (GObject *object)
{
    MooTermPtUnix *pt = MOO_TERM_PT_UNIX (object);
    kill_child (MOO_TERM_PT (pt));
    G_OBJECT_CLASS (_moo_term_pt_unix_parent_class)->finalize (object);
}


static void
set_size (MooTermPt *pt,
          guint      width,
          guint      height)
{
    MooTermPtUnix *ptu;

    g_return_if_fail (MOO_IS_TERM_PT_UNIX (pt));

    ptu = MOO_TERM_PT_UNIX (pt);

    if (pt->alive)
        _vte_pty_set_size (ptu->master, width, height);

    pt->width = width;
    pt->height = height;
}

static void
set_echo_input (MooTermPt *pt,
                gboolean   echo)
{
    MooTermPtUnix *ptu;

    ptu = MOO_TERM_PT_UNIX (pt);

    if (pt->alive)
        _vte_pty_set_echo_input (ptu->master, echo);

    pt->echo = echo;
}


static gboolean
setup_master_fd (MooTermPtUnix *pt,
                 int            master)
{
    int flags;

    g_return_val_if_fail (master >= 0, FALSE);

#if 0
    _moo_message ("%s: attached to fd %d",
                  G_STRLOC, pt->master);
#endif

    pt->non_block = FALSE;
    if ((flags = fcntl (master, F_GETFL)) < 0)
        g_critical ("%s: F_GETFL on master", G_STRLOC);
    else if (-1 == fcntl (master, F_SETFL, O_NONBLOCK | flags))
        g_critical ("%s: F_SETFL on master", G_STRLOC);
    else
        pt->non_block = TRUE;

    pt->io =  g_io_channel_unix_new (master);
    g_return_val_if_fail (pt->io != NULL, FALSE);

    g_io_channel_set_encoding (pt->io, NULL, NULL);
    g_io_channel_set_buffered (pt->io, FALSE);

    pt->io_watch_id = _moo_io_add_watch_full (pt->io,
                                              MOO_TERM_PT(pt)->priority,
                                              G_IO_IN | G_IO_PRI | G_IO_HUP | G_IO_ERR,
                                              (GIOFunc) read_child_out,
                                              pt, NULL);

    pt->master = master;
    MOO_TERM_PT(pt)->alive = TRUE;

    _vte_pty_set_echo_input (pt->master, MOO_TERM_PT(pt)->echo);

    return TRUE;
}

#ifdef WATCH_CHILD
static void
child_died (GPid pid,
            G_GNUC_UNUSED int status,
            MooTermPtUnix *pt)
{
    g_return_if_fail (pid == pt->child_pid);
    _moo_message ("%s: child exited", G_STRLOC);
    gdk_threads_enter ();
    kill_child (MOO_TERM_PT (pt));
    gdk_threads_leave ();
}
#endif

static gboolean
fork_argv (MooTermPt      *pt_gen,
           char          **argv,
           const char     *working_dir,
           char          **envp,
           GError        **error)
{
    MooTermPtUnix *pt;
    int env_len = 0;
    char **new_env;
    int status, ret;
    int i;
    int master;

    g_return_val_if_fail (argv != NULL, FALSE);
    g_return_val_if_fail (MOO_IS_TERM_PT_UNIX (pt_gen), FALSE);

    if (!argv[0])
    {
        g_set_error (error, MOO_TERM_ERROR, MOO_TERM_ERROR_INVAL,
                     "empty arguments array");
        return FALSE;
    }

    pt = MOO_TERM_PT_UNIX (pt_gen);

    g_return_val_if_fail (!pt_gen->child_alive, FALSE);

    if (envp)
    {
        char **e;
        for (e = envp; *e != NULL; ++e)
            ++env_len;
    }

    new_env = g_new (char*, env_len + 2);

    for (i = 0; i < env_len; ++i)
        new_env[i] = g_strdup (envp[i]);

    new_env[env_len] = g_strdup ("TERM=" TERM_EMULATION);
    new_env[env_len + 1] = NULL;

    master = _vte_pty_open (&pt->child_pid, new_env,
                            argv[0],
                            argv,
                            working_dir,
                            pt_gen->width, pt_gen->height,
                            FALSE, FALSE, FALSE);
    g_strfreev (new_env);

    if (master == -1)
    {
        g_critical ("%s: could not fork child", G_STRLOC);

        if (errno)
            g_set_error (error, MOO_TERM_ERROR,
                         MOO_TERM_ERROR_FAILED,
                         "could not fork command: %s",
                         g_strerror (errno));
        else
            g_set_error (error, MOO_TERM_ERROR,
                         MOO_TERM_ERROR_FAILED,
                         "could not fork command");

        return FALSE;
    }

    ret = waitpid (pt->child_pid, &status, WNOHANG);

    if (ret == -1 || ret > 0)
    {
        if (ret < 0)
            g_critical ("%s: error in waitpid", G_STRLOC);
        else
            _moo_message ("%s: child died already", G_STRLOC);

        pt->child_pid = -1;
        kill_child (pt_gen);

        return FALSE;
    }

    if (0)
        _moo_message ("%s: forked child pid %d on fd %d",
                      G_STRLOC, pt->child_pid, master);

    pt_gen->child_alive = TRUE;
    pt_gen->alive = TRUE;

#ifdef WATCH_CHILD
    pt->child_watch_id = g_child_watch_add_full (pt_gen->priority,
                                                 pt->child_pid,
                                                 (GChildWatchFunc) child_died,
                                                 pt, NULL);
#endif

    setup_master_fd (pt, master);

    return TRUE;
}


static gboolean
set_fd (MooTermPt *pt_gen,
        int        master)
{
    kill_child (pt_gen);

    if (master >= 0)
        return setup_master_fd (MOO_TERM_PT_UNIX (pt_gen), master);
    else
        return TRUE;
}


static gboolean
fork_command (MooTermPt            *pt_gen,
              const MooTermCommand *cmd,
              GError              **error)
{
    g_return_val_if_fail (cmd != NULL, FALSE);
    g_return_val_if_fail (cmd->argv != NULL, FALSE);
    g_return_val_if_fail (MOO_IS_TERM_PT_UNIX (pt_gen), FALSE);

    return fork_argv (pt_gen, cmd->argv, cmd->working_dir, cmd->envp, error);
}


static void
kill_child (MooTermPt *pt_gen)
{
    MooTermPtUnix *pt = MOO_TERM_PT_UNIX (pt_gen);

#ifdef WATCH_CHILD
    if (pt->child_watch_id)
    {
        g_source_remove (pt->child_watch_id);
        pt->child_watch_id = 0;
    }
#endif

    if (pt->io_watch_id)
    {
        g_source_remove (pt->io_watch_id);
        pt->io_watch_id = 0;
    }

    if (pt->io)
    {
        g_io_channel_shutdown (pt->io, TRUE, NULL);
        g_io_channel_unref (pt->io);
        pt->io = NULL;
    }

    stop_writer (pt_gen);
    pt_discard_pending_write (pt_gen);

    if (pt->master != -1)
    {
        _vte_pty_close (pt->master);
        pt->master = -1;
    }

    pt->non_block = FALSE;

    pt->child_pid = (GPid)-1;
    pt_gen->alive = FALSE;

    if (pt_gen->child_alive)
    {
        pt_gen->child_alive = FALSE;
        g_signal_emit_by_name (pt, "child-died");
    }
}


static gboolean
read_child_out (G_GNUC_UNUSED GIOChannel     *source,
                GIOCondition    condition,
                MooTermPtUnix  *pt)
{
    gboolean error_occured = FALSE;
    int error_no = 0;

    char buf[INPUT_CHUNK_SIZE];
    guint again = POLL_NUM;
    gsize to_read;
    gsize current = 0;

    /* try to read leftover from the pipe */
    if (condition & G_IO_HUP)
    {
        int bytes;

        _moo_message ("%s: G_IO_HUP", G_STRLOC);

        bytes = read (pt->master, buf, sizeof (buf));

        if (bytes > 0)
            feed_buffer (pt, buf, bytes);

        goto error;
    }
    else if (condition & G_IO_ERR)
    {
        _moo_message ("%s: G_IO_ERR", G_STRLOC);
        error_no = errno;
        goto error;
    }

    g_assert (condition & (G_IO_IN | G_IO_PRI));

    to_read = _moo_term_pt_get_input_chunk_len (MOO_TERM_PT (pt), sizeof buf);

    if (!to_read)
    {
        if (0)
            _moo_message ("read_child_out: skipping\n");
        return TRUE;
    }

    if (pt->non_block)
    {
        int bytes;

        if (0)
            _moo_message ("reading %" G_GSIZE_FORMAT " bytes\n", to_read);

        errno = 0;
        bytes = read (pt->master, buf, to_read);

        switch (bytes)
        {
            case -1:
                if (errno != EAGAIN && errno != EINTR)
                {
                    error_occured = TRUE;
                    error_no = errno;
                    goto error;
                }
                break;

            case 0:
                break;

            default:
#if 0
            {
                char *s = _moo_term_nice_bytes (buf, r);
                g_print ("got '%s'\n", s);
                g_free (s);
            }
#endif
                feed_buffer (pt, buf, bytes);
                break;
        }

        return TRUE;
    }

    while (again && !error_occured && current < to_read)
    {
        int res;
        struct pollfd fd;

        fd.fd = pt->master;
        fd.events = POLLIN | POLLPRI;
        fd.revents = 0;
        res = poll (&fd, 1, POLL_TIME);

        switch (res)
        {
            case 0:
                --again;
                break;

            case 1:
                if (fd.revents & (POLLNVAL | POLLERR | POLLHUP))
                {
                    again = 0;
                    if (errno != EAGAIN && errno != EINTR)
                    {
                        error_occured = TRUE;
                        error_no = errno;
                    }
                }
                else if (fd.revents & (POLLIN | POLLPRI))
                {
                    int r = read (pt->master, buf + current, 1);

                    switch (r)
                    {
                        case -1:
                            error_occured = TRUE;
                            error_no = errno;
                            break;

                        case 0:
                            --again;
                            break;

                        case 1:
                            ++current;
                            break;

                        default:
                            g_assert_not_reached();
                    }
                }

                break;

            case -1:
                again = 0;

                if (errno != EAGAIN && errno != EINTR)
                {
                    error_occured = TRUE;
                    error_no = errno;
                }

                break;

            default:
                g_assert_not_reached();
        }
    }

    if (current > 0)
        feed_buffer (pt, buf, current);

    if (error_occured)
        goto error;

    return TRUE;

error:
    if (error_occured)
        _moo_message ("error in %s", G_STRLOC);

    if (error_no)
        _moo_message ("%s: %s", G_STRLOC, g_strerror (error_no));

    if (pt->io)
    {
        _vte_pty_close (pt->master);
        pt->master = -1;

        g_io_channel_shutdown (pt->io, TRUE, NULL);
        g_io_channel_unref (pt->io);
        pt->io = NULL;

        pt->io_watch_id = 0;
    }

    kill_child (MOO_TERM_PT (pt));

    return FALSE;
}


static void
feed_buffer (MooTermPtUnix  *pt,
             const char     *string,
             int             len)
{
    _moo_term_pt_process_data (MOO_TERM_PT (pt), string, len);
}


/* writes given data to file, returns TRUE on successful write,
   FALSE when could not write al teh data, puts start of leftover
   to string, length of it to len, and fills err in case of error */
static gboolean
do_write (MooTermPt      *pt_gen,
          const char    **string,
          guint          *plen,
          int            *err)
{
    int written;

    MooTermPtUnix *pt = MOO_TERM_PT_UNIX (pt_gen);

    g_return_val_if_fail (pt->io != NULL, FALSE);

    written = write (pt->master, *string,
                     *plen > WRITE_CHUNK_SIZE ? WRITE_CHUNK_SIZE : *plen);

    if (written == -1)
    {
        *err = errno;

        switch (errno)
        {
            case EAGAIN:
            case EINTR:
                g_warning ("%s", G_STRLOC);
                return TRUE;

            default:
                return FALSE;
        }
    }
    else
    {
        *string += written;
        *plen -= written;

        if (!*plen)
            *string = NULL;

        return TRUE;
    }
}


static void
append (MooTermPt      *pt,
        const char     *data,
        guint           len)
{
    GByteArray *ar = g_byte_array_sized_new (len);
    g_byte_array_append (ar, (const guint8*)data, len);
    g_queue_push_tail (pt->pending_write, ar);
}


static gboolean
write_cb (MooTermPt *pt)
{
    pt_write (pt, NULL, 0);
    return TRUE;
}

static void
start_writer (MooTermPt *pt)
{
    if (!pt->pending_write_id)
        pt->pending_write_id =
                _moo_idle_add_full (PT_WRITER_PRIORITY,
                                    (GSourceFunc) write_cb,
                                    pt, NULL);
}

static void
stop_writer (MooTermPt *pt)
{
    if (pt->pending_write_id)
    {
        g_source_remove (pt->pending_write_id);
        pt->pending_write_id = 0;
    }
}


static void
pt_write (MooTermPt      *pt,
          const char     *data,
          gssize          data_len)
{
    g_return_if_fail (data == NULL || data_len != 0);
    g_return_if_fail (pt->alive);

    while (data || !g_queue_is_empty (pt->pending_write))
    {
        int err = 0;
        const char *string;
        guint len;
        GByteArray *freeme = NULL;

        if (!g_queue_is_empty (pt->pending_write))
        {
            if (data)
            {
                append (pt, data, data_len > 0 ? (guint)data_len : strlen (data));
                data = NULL;
            }

            freeme = g_queue_peek_head (pt->pending_write);
            string = (const char *) freeme->data;
            len = freeme->len;
        }
        else
        {
            string = data;
            len = data_len > 0 ? (guint)data_len : strlen (data);
            data = NULL;
        }

        if (do_write (pt, &string, &len, &err))
        {
            if (len)
            {
                if (freeme)
                {
                    memmove (freeme->data, freeme->data + (freeme->len - len), len);
                    g_byte_array_set_size (freeme, len);
                }
                else
                {
                    append (pt, string, len);
                }

                break;
            }
            else if (freeme)
            {
                g_byte_array_free (freeme, TRUE);
                g_queue_pop_head (pt->pending_write);
            }
        }
        else
        {
            _moo_message ("%s: stopping writing to child", G_STRLOC);
            if (err)
                _moo_message ("%s: %s", G_STRLOC, g_strerror (err));
            kill_child (pt);
        }
    }

    if (!g_queue_is_empty (pt->pending_write))
        start_writer (pt);
    else
        stop_writer (pt);
}


static char
get_erase_char (MooTermPt *pt_gen)
{
    MooTermPtUnix *pt = MOO_TERM_PT_UNIX (pt_gen);
    struct termios tio;

    g_return_val_if_fail (pt->master != -1, 0);

    if (!tcgetattr (pt->master, &tio))
    {
        return tio.c_cc[VERASE];
    }
    else
    {
        g_warning ("%s: %s", G_STRLOC,
                   g_strerror (errno));
        return 127;
    }
}


static void
send_intr (MooTermPt *pt)
{
    g_return_if_fail (pt->alive);
    pt_discard_pending_write (pt);
    pt_write (pt, "\003", 1);
}


/* TODO: it should be in glib */
MooTermCommand *
_moo_term_get_default_shell (void)
{
    static char *argv[2] = {NULL, NULL};

    if (!argv[0])
    {
        argv[0] = g_strdup (g_getenv ("SHELL"));
        if (!argv[0]) argv[0] = g_strdup ("/bin/sh");
    }

    return moo_term_command_new_argv (argv, NULL, NULL);
}


/* it's a win32 function */
void
moo_term_set_helper_directory (G_GNUC_UNUSED const char *dir)
{
    g_return_if_reached ();
}


static char *argv_to_cmd_line (char **argv)
{
    GString *cmd = NULL;
    char **p;

    g_return_val_if_fail (argv && argv[0], NULL);

    for (p = argv; *p != NULL; ++p)
    {
        char *quoted = g_shell_quote (*p);
        /* TODO: may not happen? */
        g_return_val_if_fail (quoted != NULL,
                              g_string_free (cmd, FALSE));
        if (cmd)
            g_string_append_printf (cmd, " %s", quoted);
        else
            cmd = g_string_new (quoted);
        g_free (quoted);
    }

    return g_string_free (cmd, FALSE);
}


static char **cmd_line_to_argv (const char  *cmd_line,
                                GError     **error)
{
    int argc;
    char **argv;
    g_shell_parse_argv (cmd_line, &argc, &argv, error);
    return argv;
}


gboolean
_moo_term_check_cmd (MooTermCommand *cmd,
                     GError     **error)
{
    g_return_val_if_fail (cmd != NULL, FALSE);
    g_return_val_if_fail (cmd->cmd_line != NULL || cmd->argv != NULL, FALSE);

    if (cmd->argv)
    {
        if (!cmd->argv[0])
        {
            g_set_error (error, MOO_TERM_ERROR, MOO_TERM_ERROR_INVAL,
                         "empty arguments array");
            return FALSE;
        }

        g_free (cmd->cmd_line);
        cmd->cmd_line = argv_to_cmd_line (cmd->argv);

        g_return_val_if_fail (cmd->cmd_line != NULL, FALSE);

        return TRUE;
    }
    else
    {
        cmd->argv = cmd_line_to_argv (cmd->cmd_line, error);
        return cmd->argv != NULL;
    }
}