/* ply-terminal.c - APIs for terminaling text
 *
 * Copyright (C) 2009 Red Hat, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 *
 * Written by: Ray Strode <rstrode@redhat.com>
 */
#include "ply-terminal.h"

#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/sysmacros.h>
#include <termios.h>
#include <unistd.h>
#include <wchar.h>

#include <linux/kd.h>
#include <linux/major.h>
#include <linux/vt.h>

#include "ply-buffer.h"
#include "ply-event-loop.h"
#include "ply-key-file.h"
#include "ply-list.h"
#include "ply-logger.h"
#include "ply-utils.h"

#ifndef TEXT_PALETTE_SIZE
#define TEXT_PALETTE_SIZE 48
#endif

#ifndef PLY_TERMINAL_REOPEN_TIMEOUT
#define PLY_TERMINAL_REOPEN_TIMEOUT 1.0
#endif

#ifndef PLY_TERMINAL_REOPEN_INTERVAL
#define PLY_TERMINAL_REOPEN_INTERVAL 0.05
#endif

typedef struct
{
        ply_terminal_input_handler_t handler;
        void                        *user_data;
} ply_terminal_input_closure_t;

typedef struct
{
        ply_terminal_active_vt_changed_handler_t handler;
        void                                    *user_data;
} ply_terminal_active_vt_changed_closure_t;

struct _ply_terminal
{
        ply_event_loop_t    *loop;

        struct termios       original_term_attributes;
        struct termios       original_locked_term_attributes;

        char                *name;
        const char          *keymap;
        int                  fd;
        int                  vt_number;
        int                  initial_vt_number;
        int                  number_of_reopen_tries;

        ply_list_t          *vt_change_closures;
        ply_list_t          *input_closures;
        ply_fd_watch_t      *fd_watch;
        ply_terminal_color_t foreground_color;
        ply_terminal_color_t background_color;

        uint8_t              original_color_palette[TEXT_PALETTE_SIZE];
        uint8_t              color_palette[TEXT_PALETTE_SIZE];

        int                  number_of_rows;
        int                  number_of_columns;

        uint32_t             original_term_attributes_saved : 1;
        uint32_t             original_locked_term_attributes_saved : 1;
        uint32_t             supports_text_color : 1;
        uint32_t             is_open : 1;
        uint32_t             is_active : 1;
        uint32_t             is_unbuffered : 1;
        uint32_t             is_watching_for_vt_changes : 1;
        uint32_t             should_ignore_mode_changes : 1;
};

typedef enum
{
        PLY_TERMINAL_OPEN_RESULT_INCOMPLETE,
        PLY_TERMINAL_OPEN_RESULT_FAILURE,
        PLY_TERMINAL_OPEN_RESULT_SUCCESS,
} ply_terminal_open_result_t;

static ply_terminal_open_result_t ply_terminal_open_device (ply_terminal_t *terminal);

ply_terminal_t *
ply_terminal_new (const char *device_name,
                  const char *keymap)
{
        ply_terminal_t *terminal;

        assert (device_name != NULL);

        terminal = calloc (1, sizeof(ply_terminal_t));

        terminal->loop = ply_event_loop_get_default ();
        terminal->vt_change_closures = ply_list_new ();
        terminal->input_closures = ply_list_new ();

        if (strncmp (device_name, "/dev/", strlen ("/dev/")) == 0)
                terminal->name = strdup (device_name);
        else
                asprintf (&terminal->name, "/dev/%s", device_name);

        terminal->fd = -1;
        terminal->vt_number = -1;
        terminal->initial_vt_number = -1;
        terminal->keymap = keymap;
        if (terminal->keymap)
                ply_trace ("terminal %s keymap: %s", terminal->name, terminal->keymap);

        return terminal;
}

static void
ply_terminal_look_up_color_palette (ply_terminal_t *terminal)
{
        if (ioctl (terminal->fd, GIO_CMAP, terminal->color_palette) < 0)
                terminal->supports_text_color = false;
        else
                terminal->supports_text_color = true;
}

static bool
ply_terminal_change_color_palette (ply_terminal_t *terminal)
{
        if (!terminal->supports_text_color)
                return true;

        if (ioctl (terminal->fd, PIO_CMAP, terminal->color_palette) < 0)
                return false;

        return true;
}

static void
ply_terminal_save_color_palette (ply_terminal_t *terminal)
{
        if (!terminal->supports_text_color)
                return;

        memcpy (terminal->original_color_palette, terminal->color_palette,
                TEXT_PALETTE_SIZE);
}

static void
ply_terminal_restore_color_palette (ply_terminal_t *terminal)
{
        if (!terminal->supports_text_color)
                return;

        memcpy (terminal->color_palette, terminal->original_color_palette,
                TEXT_PALETTE_SIZE);

        ply_terminal_change_color_palette (terminal);
}

void
ply_terminal_reset_colors (ply_terminal_t *terminal)
{
        assert (terminal != NULL);

        ply_terminal_restore_color_palette (terminal);
}

static void
ply_terminal_unlock (ply_terminal_t *terminal)
{
        struct termios locked_term_attributes;

        assert (terminal != NULL);

        if (terminal->original_locked_term_attributes_saved)
                locked_term_attributes = terminal->original_locked_term_attributes;
        else
                memset (&locked_term_attributes, 0x0, sizeof(locked_term_attributes));

        if (ioctl (terminal->fd, TIOCSLCKTRMIOS,
                   &locked_term_attributes) < 0)
                ply_trace ("couldn't unlock terminal settings: %m");

        terminal->original_locked_term_attributes_saved = false;
}

static void
ply_terminal_lock (ply_terminal_t *terminal)
{
        struct termios locked_term_attributes;

        assert (terminal != NULL);

        if (!terminal->original_locked_term_attributes_saved &&
            ioctl (terminal->fd, TIOCGLCKTRMIOS, &locked_term_attributes) == 0) {
                terminal->original_locked_term_attributes = locked_term_attributes;
                terminal->original_locked_term_attributes_saved = true;

                memset (&locked_term_attributes, 0xff, sizeof(locked_term_attributes));
                if (ioctl (terminal->fd, TIOCSLCKTRMIOS, &locked_term_attributes) < 0)
                        ply_trace ("couldn't lock terminal settings: %m");
        }
}

bool
ply_terminal_set_unbuffered_input (ply_terminal_t *terminal)
{
        struct termios term_attributes;

        ply_terminal_unlock (terminal);

        tcgetattr (terminal->fd, &term_attributes);

        if (!terminal->original_term_attributes_saved) {
                terminal->original_term_attributes = term_attributes;
                terminal->original_term_attributes_saved = true;
        }

        cfmakeraw (&term_attributes);

        /* Make return output new line like canonical mode */
        term_attributes.c_iflag |= ICRNL;

        /* Make \n return go to the beginning of the next line */
        term_attributes.c_oflag |= ONLCR | OPOST;

        if (tcsetattr (terminal->fd, TCSANOW, &term_attributes) != 0)
                return false;

        ply_terminal_lock (terminal);

        terminal->is_unbuffered = true;

        return true;
}

bool
ply_terminal_set_buffered_input (ply_terminal_t *terminal)
{
        struct termios term_attributes;

        if (!terminal->is_unbuffered)
                return true;

        ply_terminal_unlock (terminal);

        tcgetattr (terminal->fd, &term_attributes);

        /* If someone already messed with the terminal settings,
         * and they seem good enough, bail
         */
        if (term_attributes.c_lflag & ICANON) {
                terminal->is_unbuffered = false;

                return true;
        }

        /* If we don't know the original term attributes, or they were originally sucky,
         * then invent some that are probably good enough.
         */
        if (!terminal->original_term_attributes_saved || !(terminal->original_term_attributes.c_lflag & ICANON)) {
                term_attributes.c_iflag |= BRKINT | IGNPAR | ICRNL | IXON;
                term_attributes.c_oflag |= OPOST;
                term_attributes.c_lflag |= ECHO | ICANON | ISIG | IEXTEN;

                if (tcsetattr (terminal->fd, TCSANOW, &term_attributes) != 0)
                        return false;

                terminal->is_unbuffered = false;

                return true;
        }

        if (tcsetattr (terminal->fd, TCSANOW, &terminal->original_term_attributes) != 0)
                return false;

        terminal->is_unbuffered = false;

        return true;
}

void
ply_terminal_write (ply_terminal_t *terminal,
                    const char     *format,
                    ...)
{
        va_list args;
        char *string;
        int size;

        assert (terminal != NULL);
        assert (format != NULL);

        ply_terminal_set_mode (terminal, PLY_TERMINAL_MODE_TEXT);

        string = NULL;
        va_start (args, format);
        size = vasprintf (&string, format, args);
        va_end (args);

        write (terminal->fd, string, size);
        free (string);
}

static void
ply_terminal_reopen_device (ply_terminal_t *terminal)
{
        ply_terminal_open_result_t open_result;

        ply_trace ("trying to reopen terminal '%s' (attempt %d)",
                   terminal->name,
                   terminal->number_of_reopen_tries);

        terminal->number_of_reopen_tries++;

        open_result = ply_terminal_open_device (terminal);

        if (open_result == PLY_TERMINAL_OPEN_RESULT_INCOMPLETE) {
                int total_retries;

                total_retries = (int) (PLY_TERMINAL_REOPEN_TIMEOUT / PLY_TERMINAL_REOPEN_INTERVAL);

                if (terminal->number_of_reopen_tries < total_retries) {
                        ply_event_loop_watch_for_timeout (terminal->loop,
                                                          PLY_TERMINAL_REOPEN_INTERVAL,
                                                          (ply_event_loop_timeout_handler_t)
                                                          ply_terminal_reopen_device,
                                                          terminal);
                } else {
                        ply_trace ("couldn't reopen tty, giving up");
                        terminal->number_of_reopen_tries = 0;
                }
        }
}

static void
on_tty_input (ply_terminal_t *terminal)
{
        ply_list_node_t *node;

        node = ply_list_get_first_node (terminal->input_closures);
        while (node != NULL) {
                ply_terminal_input_closure_t *closure;
                ply_list_node_t *next_node;

                closure = ply_list_node_get_data (node);
                next_node = ply_list_get_next_node (terminal->input_closures, node);

                if (closure->handler != NULL)
                        closure->handler (closure->user_data, terminal);

                node = next_node;
        }
}

static void
on_tty_disconnected (ply_terminal_t *terminal)
{
        ply_trace ("tty disconnected (fd %d)", terminal->fd);
        terminal->fd_watch = NULL;
        terminal->fd = -1;
        terminal->number_of_reopen_tries = 0;

        ply_terminal_reopen_device (terminal);
}

bool
ply_terminal_refresh_geometry (ply_terminal_t *terminal)
{
        struct winsize terminal_size;

        ply_trace ("looking up terminal text geometry");

        if (ioctl (terminal->fd, TIOCGWINSZ, &terminal_size) < 0) {
                ply_trace ("could not read terminal text geometry: %m");
                terminal->number_of_columns = 80;
                terminal->number_of_rows = 24;
                return false;
        }

        terminal->number_of_rows = terminal_size.ws_row;
        terminal->number_of_columns = terminal_size.ws_col;

        ply_trace ("terminal is now %dx%d text cells",
                   terminal->number_of_columns,
                   terminal->number_of_rows);

        return true;
}

static void
ply_terminal_check_for_vt (ply_terminal_t *terminal)
{
        int major_number, minor_number;
        struct stat file_attributes;

        assert (terminal != NULL);
        assert (terminal->fd >= 0);

        if (fstat (terminal->fd, &file_attributes) != 0)
                return;

        major_number = major (file_attributes.st_rdev);
        minor_number = minor (file_attributes.st_rdev);

        if ((major_number == TTY_MAJOR) && (minor_number <= MAX_NR_CONSOLES))
                terminal->vt_number = minor_number;
        else
                terminal->vt_number = -1;
}

static int
get_active_vt (ply_terminal_t *terminal)
{
        struct vt_stat vt_state = { 0 };

        if (ioctl (terminal->fd, VT_GETSTATE, &vt_state) < 0)
                return -1;

        if (terminal->initial_vt_number < 0) {
                terminal->initial_vt_number = vt_state.v_active;
                ply_trace ("Remembering that initial vt is %d",
                           terminal->initial_vt_number);
        }

        return vt_state.v_active;
}

static void
do_active_vt_changed (ply_terminal_t *terminal)
{
        ply_list_node_t *node;

        node = ply_list_get_first_node (terminal->vt_change_closures);
        while (node != NULL) {
                ply_terminal_active_vt_changed_closure_t *closure;
                ply_list_node_t *next_node;

                closure = ply_list_node_get_data (node);
                next_node = ply_list_get_next_node (terminal->vt_change_closures, node);

                if (closure->handler != NULL)
                        closure->handler (closure->user_data, terminal);

                node = next_node;
        }
}

static void
on_leave_vt (ply_terminal_t *terminal)
{
        ioctl (terminal->fd, VT_RELDISP, 1);

        terminal->is_active = false;
        do_active_vt_changed (terminal);
}

static void
on_enter_vt (ply_terminal_t *terminal)
{
        ioctl (terminal->fd, VT_RELDISP, VT_ACKACQ);

        terminal->is_active = true;
        do_active_vt_changed (terminal);
}

void
ply_terminal_watch_for_vt_changes (ply_terminal_t *terminal)
{
        assert (terminal != NULL);

        struct vt_mode mode = { 0 };

        if (terminal->fd < 0)
                return;

        if (!ply_terminal_is_vt (terminal))
                return;

        if (terminal->is_watching_for_vt_changes)
                return;

        mode.mode = VT_PROCESS;
        mode.relsig = SIGUSR1;
        mode.acqsig = SIGUSR2;

        if (ioctl (terminal->fd, VT_SETMODE, &mode) < 0)
                return;

        ply_event_loop_watch_signal (terminal->loop,
                                     SIGUSR1,
                                     (ply_event_handler_t)
                                     on_leave_vt, terminal);

        ply_event_loop_watch_signal (terminal->loop,
                                     SIGUSR2,
                                     (ply_event_handler_t)
                                     on_enter_vt, terminal);

        terminal->is_watching_for_vt_changes = true;
}

void
ply_terminal_stop_watching_for_vt_changes (ply_terminal_t *terminal)
{
        struct vt_mode mode = { 0 };

        if (!ply_terminal_is_vt (terminal))
                return;

        if (!terminal->is_watching_for_vt_changes)
                return;

        terminal->is_watching_for_vt_changes = false;

        ply_event_loop_stop_watching_signal (terminal->loop, SIGUSR1);
        ply_event_loop_stop_watching_signal (terminal->loop, SIGUSR2);

        mode.mode = VT_AUTO;
        ioctl (terminal->fd, VT_SETMODE, &mode);
}

static ply_terminal_open_result_t
ply_terminal_open_device (ply_terminal_t *terminal)
{
        assert (terminal != NULL);
        assert (terminal->name != NULL);
        assert (terminal->fd < 0);
        assert (terminal->fd_watch == NULL);

        terminal->fd = open (terminal->name, O_RDWR | O_NOCTTY | O_NONBLOCK);

        if (terminal->fd < 0) {
                ply_trace ("Unable to open terminal device '%s': %m", terminal->name);

                /* The kernel will apparently return EIO spurriously when opening a tty that's
                 * in the process of closing down.  There's more information here:
                 *
                 * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
                 *
                 * Work around it here.
                 */
                if (errno == EIO)
                        return PLY_TERMINAL_OPEN_RESULT_INCOMPLETE;

                terminal->number_of_reopen_tries = 0;
                return PLY_TERMINAL_OPEN_RESULT_FAILURE;
        }

        ply_set_fd_as_blocking (terminal->fd);

        terminal->fd_watch = ply_event_loop_watch_fd (terminal->loop, terminal->fd,
                                                      PLY_EVENT_LOOP_FD_STATUS_HAS_DATA,
                                                      (ply_event_handler_t) on_tty_input,
                                                      (ply_event_handler_t) on_tty_disconnected,
                                                      terminal);

        ply_terminal_check_for_vt (terminal);

        if (!ply_terminal_set_unbuffered_input (terminal))
                ply_trace ("terminal '%s' will be line buffered", terminal->name);

        terminal->number_of_reopen_tries = 0;
        return PLY_TERMINAL_OPEN_RESULT_SUCCESS;
}

bool
ply_terminal_open (ply_terminal_t *terminal)
{
        ply_terminal_open_result_t open_result;

        assert (terminal != NULL);

        if (terminal->is_open) {
                ply_trace ("terminal %s is already open", terminal->name);
                return true;
        }

        ply_trace ("trying to open terminal '%s'", terminal->name);

        open_result = ply_terminal_open_device (terminal);
        if (open_result != PLY_TERMINAL_OPEN_RESULT_SUCCESS) {
                ply_trace ("could not open %s : %m", terminal->name);
                return false;
        }

        ply_terminal_refresh_geometry (terminal);

        ply_terminal_look_up_color_palette (terminal);
        ply_terminal_save_color_palette (terminal);

        ply_event_loop_watch_signal (terminal->loop,
                                     SIGWINCH,
                                     (ply_event_handler_t)
                                     ply_terminal_refresh_geometry,
                                     terminal);

        if (ply_terminal_is_vt (terminal)) {
                ply_terminal_watch_for_vt_changes (terminal);

                if (get_active_vt (terminal) == terminal->vt_number)
                        terminal->is_active = true;
                else
                        terminal->is_active = false;
        }

        terminal->is_open = true;

        return true;
}

int
ply_terminal_get_fd (ply_terminal_t *terminal)
{
        return terminal->fd;
}

bool
ply_terminal_is_vt (ply_terminal_t *terminal)
{
        return terminal->vt_number > 0;
}

bool
ply_terminal_is_open (ply_terminal_t *terminal)
{
        return terminal->is_open;
}

bool
ply_terminal_is_active (ply_terminal_t *terminal)
{
        return terminal->is_active;
}

void
ply_terminal_close (ply_terminal_t *terminal)
{
        if (!terminal->is_open) {
                ply_trace ("terminal %s is already closed", terminal->name);
                return;
        }

        terminal->is_open = false;

        ply_terminal_stop_watching_for_vt_changes (terminal);

        ply_trace ("restoring color palette");
        ply_terminal_restore_color_palette (terminal);

        if (terminal->fd_watch != NULL) {
                ply_trace ("stop watching tty fd");
                ply_event_loop_stop_watching_fd (terminal->loop, terminal->fd_watch);
                terminal->fd_watch = NULL;
        }

        if (terminal->loop != NULL) {
                ply_trace ("stop watching SIGWINCH signal");
                ply_event_loop_stop_watching_signal (terminal->loop, SIGWINCH);
        }

        ply_trace ("setting buffered input");
        ply_terminal_set_buffered_input (terminal);

        close (terminal->fd);
        terminal->fd = -1;
}

int
ply_terminal_get_number_of_columns (ply_terminal_t *terminal)
{
        return terminal->number_of_columns;
}

int
ply_terminal_get_number_of_rows (ply_terminal_t *terminal)
{
        return terminal->number_of_rows;
}

uint32_t
ply_terminal_get_color_hex_value (ply_terminal_t      *terminal,
                                  ply_terminal_color_t color)
{
        uint8_t red, green, blue;

        assert (terminal != NULL);
        assert (color <= PLY_TERMINAL_COLOR_WHITE);

        red = terminal->color_palette[3 * color];
        green = terminal->color_palette[3 * color + 1];
        blue = terminal->color_palette[3 * color + 2];

        return red << 16 | green << 8 | blue;
}

void
ply_terminal_set_color_hex_value (ply_terminal_t      *terminal,
                                  ply_terminal_color_t color,
                                  uint32_t             hex_value)
{
        assert (terminal != NULL);
        assert (color <= PLY_TERMINAL_COLOR_WHITE);

        terminal->color_palette[3 * color] = (hex_value >> 16) & 0xff;
        terminal->color_palette[3 * color + 1] = (hex_value >> 8) & 0xff;
        terminal->color_palette[3 * color + 2] = hex_value & 0xff;

        ply_terminal_change_color_palette (terminal);
}

bool
ply_terminal_supports_color (ply_terminal_t *terminal)
{
        return terminal->supports_text_color;
}

void
ply_terminal_set_mode (ply_terminal_t     *terminal,
                       ply_terminal_mode_t mode)
{
        assert (terminal != NULL);
        assert (mode == PLY_TERMINAL_MODE_TEXT || mode == PLY_TERMINAL_MODE_GRAPHICS);

        if (!ply_terminal_is_vt (terminal))
                return;

        if (terminal->should_ignore_mode_changes)
                return;

        switch (mode) {
        case PLY_TERMINAL_MODE_TEXT:
                if (ioctl (terminal->fd, KDSETMODE, KD_TEXT) < 0)
                        return;
                break;

        case PLY_TERMINAL_MODE_GRAPHICS:
                if (ioctl (terminal->fd, KDSETMODE, KD_GRAPHICS) < 0)
                        return;
                break;
        }
}

void
ply_terminal_ignore_mode_changes (ply_terminal_t *terminal,
                                  bool            should_ignore)
{
        if (!ply_terminal_is_vt (terminal))
                return;

        terminal->should_ignore_mode_changes = should_ignore;
}

static void
ply_terminal_detach_from_event_loop (ply_terminal_t *terminal)
{
        assert (terminal != NULL);
        terminal->loop = NULL;
        terminal->fd_watch = NULL;
}

static void
free_vt_change_closures (ply_terminal_t *terminal)
{
        ply_list_node_t *node;

        node = ply_list_get_first_node (terminal->vt_change_closures);
        while (node != NULL) {
                ply_terminal_active_vt_changed_closure_t *closure;
                ply_list_node_t *next_node;

                closure = ply_list_node_get_data (node);
                next_node = ply_list_get_next_node (terminal->vt_change_closures, node);

                free (closure);
                node = next_node;
        }
        ply_list_free (terminal->vt_change_closures);
}

static void
free_input_closures (ply_terminal_t *terminal)
{
        ply_list_node_t *node;

        node = ply_list_get_first_node (terminal->input_closures);
        while (node != NULL) {
                ply_terminal_input_closure_t *closure;
                ply_list_node_t *next_node;

                closure = ply_list_node_get_data (node);
                next_node = ply_list_get_next_node (terminal->input_closures, node);

                free (closure);
                node = next_node;
        }
        ply_list_free (terminal->input_closures);
}

void
ply_terminal_free (ply_terminal_t *terminal)
{
        if (terminal == NULL)
                return;

        if (terminal->loop != NULL) {
                ply_event_loop_stop_watching_for_exit (terminal->loop,
                                                       (ply_event_loop_exit_handler_t)
                                                       ply_terminal_detach_from_event_loop,
                                                       terminal);

                if (terminal->number_of_reopen_tries > 0) {
                        ply_event_loop_stop_watching_for_timeout (terminal->loop,
                                                                  (ply_event_loop_timeout_handler_t)
                                                                  ply_terminal_reopen_device, terminal);
                }
        }

        if (terminal->is_open)
                ply_terminal_close (terminal);

        free_vt_change_closures (terminal);
        free_input_closures (terminal);
        free (terminal->name);
        free (terminal);
}

const char *
ply_terminal_get_name (ply_terminal_t *terminal)
{
        return terminal->name;
}

const char *
ply_terminal_get_keymap (ply_terminal_t *terminal)
{
        return terminal->keymap;
}

bool
ply_terminal_get_capslock_state (ply_terminal_t *terminal)
{
        char state;

        if (ioctl (terminal->fd, KDGETLED, &state) < 0)
                return false;

        return state & LED_CAP;
}

int
ply_terminal_get_vt_number (ply_terminal_t *terminal)
{
        return terminal->vt_number;
}

static bool
set_active_vt (ply_terminal_t *terminal,
               int             vt_number)
{
        if (ioctl (terminal->fd, VT_ACTIVATE, vt_number) < 0)
                return false;

        return true;
}

static bool
wait_for_vt_to_become_active (ply_terminal_t *terminal,
                              int             vt_number)
{
        if (ioctl (terminal->fd, VT_WAITACTIVE, vt_number) < 0)
                return false;

        return true;
}

static bool
deallocate_vt (ply_terminal_t *terminal,
               int             vt_number)
{
        if (ioctl (terminal->fd, VT_DISALLOCATE, vt_number) < 0)
                return false;

        return true;
}

bool
ply_terminal_activate_vt (ply_terminal_t *terminal)
{
        assert (terminal != NULL);

        if (!ply_terminal_is_vt (terminal))
                return false;

        if (terminal->is_active)
                return true;

        if (!set_active_vt (terminal, terminal->vt_number)) {
                ply_trace ("unable to set active vt to %d: %m",
                           terminal->vt_number);
                return false;
        }

        return true;
}

bool
ply_terminal_deactivate_vt (ply_terminal_t *terminal)
{
        int old_vt_number;

        assert (terminal != NULL);

        if (!ply_terminal_is_vt (terminal)) {
                ply_trace ("terminal is not for a VT");
                return false;
        }

        if (terminal->initial_vt_number < 0) {
                ply_trace ("Don't know where to jump to");
                return false;
        }

        if (terminal->initial_vt_number == terminal->vt_number) {
                ply_trace ("can't deactivate initial VT");
                return false;
        }

        /* Otherwise we'd close and free the terminal before handling the
         * "leaving the VT" signal.
         */
        ply_terminal_stop_watching_for_vt_changes (terminal);

        old_vt_number = terminal->vt_number;

        if (ply_terminal_is_active (terminal)) {
                ply_trace ("Attempting to set active vt back to %d from %d",
                           terminal->initial_vt_number, old_vt_number);
                if (!set_active_vt (terminal, terminal->initial_vt_number)) {
                        ply_trace ("Couldn't move console to initial vt: %m");
                        return false;
                }

                if (!wait_for_vt_to_become_active (terminal, terminal->initial_vt_number)) {
                        ply_trace ("Error while waiting for vt %d to become active: %m",
                                   terminal->initial_vt_number);
                        return false;
                }
        } else {
                ply_trace ("terminal for vt %d is inactive", terminal->vt_number);
        }

        if (!deallocate_vt (terminal, old_vt_number)) {
                ply_trace ("couldn't deallocate vt %d: %m", old_vt_number);
                return false;
        }

        return true;
}

void
ply_terminal_watch_for_active_vt_change (ply_terminal_t                          *terminal,
                                         ply_terminal_active_vt_changed_handler_t active_vt_changed_handler,
                                         void                                    *user_data)
{
        ply_terminal_active_vt_changed_closure_t *closure;

        if (!ply_terminal_is_vt (terminal))
                return;

        closure = calloc (1, sizeof(*closure));
        closure->handler = active_vt_changed_handler;
        closure->user_data = user_data;

        ply_list_append_data (terminal->vt_change_closures, closure);
}

void
ply_terminal_stop_watching_for_active_vt_change (ply_terminal_t                          *terminal,
                                                 ply_terminal_active_vt_changed_handler_t active_vt_changed_handler,
                                                 void                                    *user_data)
{
        ply_list_node_t *node;

        if (!ply_terminal_is_vt (terminal))
                return;

        node = ply_list_get_first_node (terminal->vt_change_closures);
        while (node != NULL) {
                ply_terminal_active_vt_changed_closure_t *closure;
                ply_list_node_t *next_node;

                closure = ply_list_node_get_data (node);
                next_node = ply_list_get_next_node (terminal->vt_change_closures, node);

                if (closure->handler == active_vt_changed_handler &&
                    closure->user_data == user_data) {
                        free (closure);
                        ply_list_remove_node (terminal->vt_change_closures, node);
                }

                node = next_node;
        }
}

void
ply_terminal_watch_for_input (ply_terminal_t              *terminal,
                              ply_terminal_input_handler_t input_handler,
                              void                        *user_data)
{
        ply_terminal_input_closure_t *closure;

        closure = calloc (1, sizeof(*closure));
        closure->handler = input_handler;
        closure->user_data = user_data;

        ply_list_append_data (terminal->input_closures, closure);
}

void
ply_terminal_stop_watching_for_input (ply_terminal_t              *terminal,
                                      ply_terminal_input_handler_t input_handler,
                                      void                        *user_data)
{
        ply_list_node_t *node;

        node = ply_list_get_first_node (terminal->input_closures);
        while (node != NULL) {
                ply_terminal_input_closure_t *closure;
                ply_list_node_t *next_node;

                closure = ply_list_node_get_data (node);
                next_node = ply_list_get_next_node (terminal->input_closures, node);

                if (closure->handler == input_handler &&
                    closure->user_data == user_data) {
                        free (closure);
                        ply_list_remove_node (terminal->input_closures, node);
                }

                node = next_node;
        }
}

void
ply_terminal_flush_input (ply_terminal_t *terminal)
{
        if (!terminal->is_open)
                return;

        if (tcflush (terminal->fd, TCIFLUSH) < 0)
                ply_trace ("could not flush input buffer of terminal %s: %m", terminal->name);
}